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Journal of Clinical EEG & Neuroscience, April, 2010Abstracts of peer-reviewed presentations at the ASP2009 19th Annual Conference of the Australasian Society for Psychophysiology, November 28-30, 2009, University of Newcastle, Newcastle, Australia.Abstracts of these presentations are listed in alphabetical order of the first author's surname. Impairment of Duration Mismatch Negativity in the Schizophrenia Prodrome R. Atkinson,1,2 U. Schall,1,2,3 W. Stojanov,1 R. Inkpen,1 S. Hunt,1 K. Helmbold,1 S. Halpin,1,3 V. Carr,1,2,3 J. Todd1,2 and P. Michie1,2 Mismatch negativity (MMN) to tone duration deviants has consistently been shown to be reduced in schizophrenia and has been linked to neurochemical and neuroanatomical abnormalities implicated in the disorder. Here we report on an ongoing study investigating MMN as a possible risk factor for the later development of psychosis. MMN data has been obtained from 20 healthy controls and 72 individuals indentified as being at ultra-high risk (UHR) of developing psychosis on referral to a specialized service. MMN was derived as subtraction waveforms of event related potentials (ERPs) to frequent short (50 ms) or long-duration (100ms) standard tones minus ERPs to infrequent long or short-duration deviant tones, respectively. The largest MMN amplitudes were recorded in controls compared with MMN from 13 referrals meeting criteria for first-episode psychosis (FEP) and 25 UHR referrals. The UHR group showed a reduction of the MMN amplitude that was intermediate between the healthy controls and FEP groups. A reduced, though non-significant reduction of MMN was recorded in 7 UHR individuals making a confirmed transition to schizophrenia one year after UHR identification compared to 19 UHR individuals who did not make such a transition. Our preliminary findings suggest reduced MMN may be associated with prodromal schizophrenia. The Effect of Cognitive Load on Pre-Movement Activity During the Readiness for Action Katharine Baker and Ross Cunnington Brain activity associated with the planning of voluntary actions manifests as the readiness potential (RP), a slowly increasing negativity seen in motor areas of the brain up to 2 seconds prior to movement initiation. Little is understood about the attentional or cognitive resources involved in the early stage of this pre-movement planning. In the current study, this was investigated by manipulating cognitive resources available for preparation for action in a dual-task paradigm. Participants performed voluntary finger movements approximately every 4 to 5 s while concurrently performing an n-back working memory task in both high load and low load conditions. EEG was recorded from 21 participants and RPs prior to movement initiation were averaged. Results showed that over central electrode sites, where RP amplitudes are maximal, early RP amplitude was reduced under conditions of high cognitive load, when cognitive resources available for preparation for the action were limited. This shows that the neural processes involved in early pre-movement planning, reflected in the early readiness potential, draw upon the same cognitive resources as the n-back working memory task. We suggest that this early pre-movement activity represents cognitive-level processes associated with anticipation and timing of the initiation of the forthcoming movement. Preferred brain states in the auditory Go/NoGo task as a function of EEG frequency Robert J. Barry and Frances De Blasio Our previous work has demonstrated the preferential occurrence of different EEG phases at stimulus onset in an auditory oddball task. This study examined relationships between the phase of narrow-band EEG activity at stimulus onset and the resultant ERPs in an equiprobable auditory Go/NoGo task. Prestimulus narrow-band EEG activity (in 1 Hz bands from 1 to 13 Hz) at Cz was assessed for each trial using FFT decomposition of the EEG data. ERP responses to each stimulus type were analysed. For each frequency, the cycle at stimulus onset was used to sort trials into four phases, for which ERPs were derived from the raw EEG activity at 9 central sites. The occurrence of preferred phase-defined brain states was confirmed at a number of frequencies, crossing the traditional frequency bands. As expected, these did not differ between Go and NoGo stimuli. These preferred states were associated with differences in latency and/or amplitude of the N1 and P3 ERP components. The present results, although derived in a different paradigm by EEG decomposition methods different from those used previously, confirm the existence of preferred brain states and their impact on the brain dynamics involved in perceptual and cognitive processing. Chronic Cannabis Use Alters Neurophysiological Functioning During the Stroop Color-Naming Task Robert A. Battisti,1,2,3 Steven Roodenrys,2 Stuart Johnstone,2 Nicole Pesa,2 Daniel Hermens,1 and Nadia Solowij,2,4 Chronic cannabis use has been related to deficits in cognition as well as changes in the normal functioning of structures within the brain that are sensitive to exogenous cannabinoids (i.e. cannabis). While impairments in memory-related processes have been well documented, there is increasing evidence that inhibitory control processes may also be affected. This study sought to examine the ability to inhibit an automatic reading response in order to activate a more difficult naming response in a variant of the discrete trial Stroop colour-naming task in a group of chronic cannabis users. Event-related brain potentials (ERPs) were compared between 24 cannabis users (mean 17 years of near daily use) in the unintoxicated state and 23 non-using controls. Cannabis users showed increased errors on colour-incongruent trials (e.g., “RED” printed in blue ink) but no differences on colour congruent (e.g., “RED” printed in red ink) or neutral trials (e.g., “*****” printed in green ink). Users also showed longer and shorter latency for the P2 and P3 ERP components, respectively, and differing activation for congruent and neutral relative to incongruent trials on a late sustained potential. These findings indicate that chronic cannabis use alters the functioning of inhibitory control and conflict resolution processes. Varying Task Difficulty in the Go/Nogo Task: A Preliminary Analysis Nicholas Benikos, Stuart J. Johnstone and Steven Roodenrys This study aimed to investigate the effect of varying task difficulty, via manipulation of reaction time deadline (RTD), on response inhibition using behavioural and ERP indices. Forty-five adults completed a Go/Nogo task (70% Go) after being randomly assigned to one of three conditions: high (H), moderate (M) and low (L) time pressure, with RTDs of 300 ms, 500 ms and 1000 ms respectively. Task performance results indicated that reductions in RTD can be an effective method for increasing response activation and inhibition difficulty in the Go/Nogo task, with a significant reduction in Go RT and increased Go and Nogo errors for the H group. Several ERP effect were found, with the Nogo N2 being largest in the H condition and displaying incremental amplitude increases with each RTD reduction (H > M >L). Similarly, the anterior shift of the Nogo P3 also appeared to be linked to task difficulty and was largest in the H group. The implications of these results are discussed in terms of designing individually adaptive response inhibition training paradigms. Natural Control Architecture of the Human Cognitive System Peter G. Burton It is argued that the evolved complexity of the natural control structure exhibited in the system of human cognition and consciousness bears little resemblance to the simplified computational models adopted by cognitive science over the last half-century. Cognitive System Theory (CST; see website repository http://homepage.mac.com/blinkcentral) of human higher brain function developed by the author provides instead an exadaptively instantiable model of consciousness as the means of cognitive control in human cognition. In CSTs favour, it provides de-mystifying explanations of fundamental brain phenomena, from describing the nature of consciousness operating in the brain, through exposing the true scientific nature of the mind-brain “interaction,” to explaining how it is in fact logically possible for an objective self-model to be acquired from within purely subjective experience. The clarifications of CST derive from a dimensionally adequate conceptualisation of human cognition and consciousness, one capable of encompassing from first principles its fundamental system characteristics of autonomy, directedness and animation. Is Error Negativity Task Specific? Andrea Carr, Frances Martin and Andrea Adam Error negativity (ERN/Ne) and correct response negativity (CRN) are generated as negative response-locked event-related potentials that occur approximately 50-100 milliseconds following a response. Explanations for these components are derived from theories of response monitoring where it is argued that amplitudes reflect a mismatch between actual and intended responses. Amplitudes of the ERN/Ne are consistently reported as being significantly greater than those associated with the CRN. Two choice reaction time tasks provided conflicting evidence in terms of this amplitude difference. In Experiment 1 a standard arrowhead flanker task was completed by participants (N = 16), while Experiment 2 required participants (N = 37) to complete a phonological decision task. Experiment 1 provided results consistent with past research, in that the Ne/ERN displayed significantly greater negativity than the CRN. However, analysis of mean amplitude for correct and error responses for the language-based task showed no significant differences. Results suggest explanations of the Ne/ERN and CRN may involve a task specific factor. Anxiety and the Attentional Blink: A Paradox for Older Adults Iris Carter and Kristen Pammer Older adults are often reported as being slower, less accurate and more easily distracted in cognitive tasks than younger adults. These differences are mostly attributed to slowing processing speed, impaired working memory and/or an impairment in the ability to ignore distractions. An example is performance in an attentional blink (AB) task where a participant is report two targets from a stream of distractors. Three existing studies of an older population all found older adults demonstrated a deeper, longer blink than a younger sample. However, older adults’ performance may have been influenced by situational state anxiety, which in turn may have created performance vigilance and self-checking leading to interference with the primary task. The current study investigated this possibility by measuring heart rate activity as well as performance during the task. Over time, as heart rate decreased performance in the AB task significantly improved, to the extent that it was comparable to that of a younger group. This finding suggests that cognitive test anxiety may be a contributor to poorer performance in tests of this nature in this population. This also raises questions about other cognitive test results in this population, which may be confounded by cognitive test anxiety. Age-Related Change in the Response to Auditory Repetition: Evidence of Compensatory Activity? Rowena Cooper, Juanita Todd and Pat Michie The relationship between age-related change in auditory sensory memory and auditory verbal memory was investigated. In two studies we delivered 11 different sounds to a group of young and older adults. The number of times an identical sound occurred consecutively was manipulated. We recorded the response to auditory stimulus repetition in the event-related potential (ERP) which is thought to indicate memory trace formation. Scores on the Rey Auditory Verbal Memory (RAVLT) test were also collected and were correlated with ERP data (rate of change in the ERP with increasing repetition). In both studies we observed a significant interaction between age group and repetition such that the ERP of older adults did not show differentiation between repetition conditions to the same extent as young adults. The correlations between the ERP data and memory performance were positive for young adults but negative for older adults. For young adults, the greater the rate of change in the ERP with increasing repetition, the better the performance on the RAVLT. The lack of differentiation between repetition conditions in the ERP of older adults might relate to better memory performance if older adults compensate for explicit memory deficits by valuing content-related information over contextual information. If Electrophysiology Plus Psychophysics Predict Autistic Class Membership What Are the Implications for the Development of Core Signs? David P. Crewther and Alexandra Sutherland Autism is characterized by a triad of signs: impairment in social interaction; impairment in communication; and repetitive behaviours with restricted interests. Autistic tendency is also present in the general population in varying degrees, measurable on scales such as the Autism Quotient. Here we demonstrate that nonlinear visual evoked potential (VEP) components reflecting visual Magnocellular (M) pathway activity, show a delay for high AQ compared to low AQ groups (14 and 15 respectively recruited from a total population of 129) when the Parvocellular (P) pathway is active. Such individuals also demonstrate difficulty in identifying the global components of locally salient Navon figures. Discriminant analysis correctly classified all high and low AQ individuals using a mix of physiologically and psychophysically derived parameters. It is remarkable that a mixture of psychophysical and physiological parameters can predict group membership of a scale based purely on social and behavioural tendencies. We propose that delay in cortical V1/V2 processing of M input, negates the advantage of its early arrival to V1, and is associated with impaired global visual perception. This lack of global perception and the consequent domination of early cortical processing could be the basis for inappropriate perception and hence response in social situations. The Acute Effects of Caffeinated Coffee on the Mismatch Negativity in a Healthy Older Population Vanessa Cropley,1 Rodney Croft,2 Beata Silber,3 Con Stough,1 Andrew Scholey,1 and Jeroen Schmitt,3 Previous research has indicated that caffeine exerts positive effects on various cognitive and behavioural processes, particularly reaction time, vigilance and arousal, and especially in sub-optimal conditions when arousal is low. However, it remains uncertain whether caffeine exerts any discreet effects on early cognitive processes, rather than a general effect on arousal and attention. The present study examined whether acute administration of caffeine modulates automatic auditory stimulus discrimination as measured by the mismatch negativity (MMN) event-related potential (ERP). As the MMN is attention-independent, modulation of the MMN by caffeine can be distinguished from a change in attention and arousal. ERP responses to tone duration deviants were recorded at baseline and following a cup of coffee with caffeine (200 mg) or decaffeinated coffee in a crossover study of 39 healthy older participants. No effect of Treatment was observed on the mean MMN amplitude at frontal electrodes, suggesting that caffeine has no effect on the brain’s automatic, preconscious auditory change detection system. Physiological and Self-Reported Responses to Dynamic Emotional Change in Actual Computer Game Avatars James J. Cummings,1,2 and Robert F. Potter,1,3 Massively-multiplayer online games (MMOGs) are an increasingly widespread entertainment phenomenon where players create their own representative characters known as avatars. Communication between players, by way of their avatars, has traditionally been text-based (through chat windows or command lines) and more recently verbal by way of headset microphones. However, increases in graphics technology are leading to more examples of “face-to-face” communication between avatars, including non-verbal communication of facial emotion. This experiment extends current work in the literature by selecting stimuli from actual avatar types found in genuine MMOG environments. In a 2 (avatar character disposition) x 2 (human likeness) x 2 (dynamic valence expression) x 3 (repetition) within-subjects factorial experiment, seventy participants saw a series of 24 game avatars which dynamically changed from a neutral expression to either a positive or negative expression over a 12s epoch. Skin conductance and facial EMG (corrugator and zygomatic) activity were collected at 20 Hz, time locked to the media stimuli. Results show greater response in high human likeness compared to low in corrugator and zygomatic muscle groups during dynamic negative and positive avatar changes respectively. Genetic Modulation of Behavioural and Neural Measures of Response Inhibition Tarrant D. R. Cummins,1 Julia Hocking,1 Sanjay Nandam,1 Pradeep J. Nathan,3
Ajay Panwar,1 Joseph Wagner,1 Jason B. Mattingley,1,2 and Mark A. Bellgrove,1,2 The ability to inhibit behaviour is a key aspect of executive function that allows humans to behave flexibly. Twin studies have shown that behavioural measures of inhibitory control, such as stop-signal reaction time (SSRT), are highly heritable, and inhibitory dysfunction has been touted as a candidate endophenotype for ADHD and OCD. The neurochemical substrates of inhibitory control in the human brain remain unresolved with evidence supporting modulation by dopamine, noradrenaline and serotonin. We surveyed the association between a theoretically motivated set of catecholamine genes (including DAT1, DRD4, DBH, COMT, DRD2 and NET) and SSRT in a sample of 308 non-clinical adults. Markers on DRD2, DRD4 and NET accounted for significant variance in SSRT, after controlling for age and gender. The influence of these genetic markers was further investigated in a targeted fMRI study of inhibitory control in a subset of the larger cohort (n=50). Our genetic and brain imaging data suggest a prominent role for catecholamine, particularly dopamine modulation of inhibitory control but little evidence for modulation by serotonin. Motor Plans Influence the Perceptual Processing of Observed Actions Ross Cunnington, Marta Bortoletto and Jason B. Mattingley The perception and execution of action are suggested to be closely linked. While previous studies have shown that the perception of others’ actions directly influences the motor system, it has also been suggested that action preparation and execution may modulate the perception of others’ actions. Here we tested whether planned actions influence the visual processing of observed actions. We examined visual evoked potentials (VEPs) to images of hand gestures presented while participants planned either a matching (congruent) or non-matching (incongruent) gesture. Neural activity associated with the visual processing of the hand gestures (N170 and Vertex Positive Potential) was significantly enhanced when those gestures were incongruent with the participant’s concurrently planned action. In a second experiment, we showed that this effect was specific to the congruency of motor plans rather than more general anticipation or semantic representations of action. These results show that motor plans or representations of intended actions in the motor system can influence the visual processing of observed actions. An Evaluation of P50 Suppression Methodologies Anna Dalecki, Rodney J. Croft and Stuart J. Johnstone “P50 suppression,” an index of sensory gating, has demonstrated utility in schizophrenia research. It is widely reported that P50 suppression is deficient in schizophrenia patients and an endophenotypic marker for the disorder. However, unresolved methodological issues including the unestablished reliability of the measure, unknown effects of time-on-task and long protocol undermine its usefulness. In order to address these methodological issues, twenty healthy participants’ P50 suppression was measured in a long P50 paradigm. This enabled the measurement of within-session reliability, temporal course of P50 suppression, and effects of the inter-pair interval parameter. Results indicated good within-session reliability for P50 suppression (ICC = .668); changes in P50 suppression across the session (a 31% increase over the 78 minute recording); and comparable P50 suppression at long (9 s) and short (3 s) inter-pair intervals. It is concluded that given appropriate conditions, P50 suppression can be measured reliably within-session. Further, time-on-task effects need to be taken into account when measuring P50 suppression in a long paradigm or calculating reliability. Lastly, the inter-pair interval can be substantially shortened in studies with healthy participants allowing for an appreciable reduction in P50 suppression recording time. Neural Processing of Human Faces: Insights From Fixation-Related Potentials Peter de Lissa,1 Romina Palermo,2 Genevieve McArthur,1 Stefan Hawelka,3 Yatin Mahajan,1 and Florian Hutzler,3 When measuring event-related potentials (ERPs), we often need to focus a subject’s attention onto a particular stimulus. This can result in presentations of unrealistic stimuli, such as a pair of eyes cut out of a face. It is possible to present more realistic stimuli by integrating electroencephalography (EEG) and eye-tracking technology to generate fixation-related potentials (FRPs). In this study, we did two FRP experiments to determine if different facial features (eyes and mouths) elicit different neural activity when presented within a whole face. In the first experiment, we directed eye fixations to a cross, which induced stimulus presentation. In the second experiment, we used eye fixations on specific facial features as time-locked events from which evoked potentials were formed. The results of these two experiments will be discussed in terms of understanding face processing, as well as the benefits using of the different FRP approaches. Emotions in Voice and Music: Overlapping Neural Correlates? Nicolas Escoffier, Jidan Zhong, Anqi Qiu and Annett Schirmer Philosophers have long debated whether music and voice conveys emotions by the same means. The contributions of recent behavioral research have suggested many similarities. Using functional magnetic resonance imaging, we explored whether those similarities imply overlapping neural correlates for emotion evaluation of music and voice. Participants judged changes in either emotion or pitch in voice and music excerpts expressing happy, neutral or sad emotions. Comparing emotion and pitch judgments revealed three activated areas in the medial prefrontal lobe supporting emotion evaluation of both materials. These were previously implicated in emotion evaluation from social stimuli and inferences about other’s mental state. One of these regions showed a sensitivity to emotional content in both materials with enhanced responses to happy as compared to neutral stimuli. Whole brain analysis also revealed an effect of emotional content in a range of regions, varying with the emotion, the material and the task. Overall these results indicate that the evaluation of emotions from music and voice is supported by overlapping brain regions, suggesting similar mechanism for both materials. The resulting emotional representations however differ in localization for both material and task, possibly because of variable relevance to different contexts and goals. An Examination of fMRI and EEG Methodologies Ross Fulham Functional Magnetic Resonance Imaging (fMRI) is one of many neuroimaging techniques that are being used in conjunction with EEG studies to provide convergent lines of evidence in research. fMRI measures a time-series of localised changes in blood oxygenation levels triggered by cognitive processes. In contrast, EEG measures a time-series of the far-field electric potentials produced by post-synaptic membrane potentials in response to cognitive activity. Fundamentally, interpretation of both fMRI and EEG involves the time-series analysis of multivariate spatial data. However, the traditional approaches to the analysis of fMRI and EEG data are radically different (i.e. Modelling of the haemodynamic response vs. averaged event-related responses). This presentation will examine why the two research methodologies apply different analysis strategies; look at some of the benefits and pitfalls of both; and speculate about what EEG researchers can learn about data analysis from the fMRI field and similarly for fMRI researchers from EEG. Intergroup Bias Influences the Perception of Action Veronika Halasz,1,2 Pascal Molenberghs,2 Jason B Mattingley,1,2 Eric Vanman,1 and Ross Cunnington,1,2 People tend to evaluate the actions of their own group or team members more positively than those of out-group members – an effect known as intergroup bias. We tested whether intergroup bias truly influences perceptual processing of others’ actions by examining behavioural and brain correlates of perceptual judgements made on in-group and out-group members’ actions. In Experiment 1 participants were randomly assigned to red and blue teams and were asked to judge the speed of in-group and out-group members’ hand movements. Participants tended to judge the relative speed of actions performed by in-group members as occurring more quickly than those performed by out-group members, even though the actions were in fact performed equally quickly. In Experiment 2, we used fMRI to examine brain activity associated the perception of observed actions of in-group and out-group members. We found significantly greater activation within the action-perception network, in the left inferior parietal lobule when participants watched their own team members’ actions compared with the other team members’ actions. These results suggest that, in addition to the known effect of group membership on social cognition, belonging to a group can directly influence the neural mechanisms that underlie perceptual processing of others’ actions. Driven to Distraction! The Influence of Central Attentional Load on Steady-State Evoked Potentials to Irrelevant Visual Stimuli Sarah E. Hall and Jason B. Mattingley The perceptual-load model of selective attention proposes that effective exclusion of irrelevant distractors occurs when limited-capacity resources are exhausted by a central task. We investigated whether perceptual load effects are comparable for target and distractor stimuli presented within versus between sensory modalities. We used steady-state evoked potentials (SSEPs) and frequency-tagged stimuli to examine whether neural activity evoked by an irrelevant, peripheral visual stimulus was modulated by the attentional load of a central visual or auditory task. In separate experiments, participants monitored a task-relevant central stream of coloured crosses or spoken phonemes presented at 4 Hz, while ignoring a 10 Hz contrast-modulated checkerboard in the periphery. The difficulty of the central task was manipulated to create low- and high-load conditions. Fast Fourier transforms on SSEP amplitude revealed that neural activity evoked by the distractor stimulus was attenuated as task load increased for the central visual stimulus. By contrast, neural activity associated with the same peripheral stimulus was enhanced with increases in task load for the central auditory task. These results imply that central and peripheral visual stimuli compete strongly for limited attentional resources, whereas central auditory stimuli potentiate neural representations of ignored visual distractors. Stop-Signal ERPs Matthew E. Hughes,1 Patricia T. Michie,2 Ross Fulham,2 Janette L. Smith,2 and Patrick Johnston,1 Response inhibition refers to the capacity to inhibit planned or on-going behaviour, and is often studied using the stop-signal paradigm (Logan and Cowan, 1984). This paradigm is increasingly being used for research largely due to the indices of control stop-signal procedures afford, notably the speed of stopping, in addition to its capacity to detect impaired stopping in psychiatric groups (e.g., schizophrenia patients). Various authors of ERP studies have emphasized N2 and/or P3 ERPs in stopping (Boxtel et al., 2001; De Jong et al., 1990), however a recent study that used ADJAR correction procedures (Woldorff, 1993) to remove distorting Go ERPs from stops-signal waveforms reported larger N1 and P3 amplitudes during Stops compared to Stop Failures (Bekker et al., 2005). Here are reported two stop-signal ERP investigations employing ADJAR correction procedures; one in healthy participants and another comparing schizophrenia patients to matched controls. In healthy participants, N1 and P3 amplitudes were larger for Stops compared to Stop Failures, and Stop-P3s peaked earlier than Stop Failure-P3s. Interestingly, N2 was evident only in Stop Failures. Patients with schizophrenia revealed no modulation of N1 amplitude or P3 latency, but patient stop-signal waveforms exhibited consistent N2s for Stops and Stop Failures. The Development of Multisensory Integration as Indexed by an Auditory-Visual Illusion Hamish Innes-Brown,1,2 Ayla Barutchu,2 David Crewther,1 Mohit Shivdasani,2 and Antonio Paolini,3 When two brief beeps are paired with a single flash, observers often report seeing two flashes (fission illusion). Similarly, when two flashes are paired with a single beep, some studies have reported that a single flash is observed (fusion illusion). This study aimed to investigate the neural correlates of these illusions, in both adults (N=22) and children (N=27). Children showed increased susceptibility to fission, but not fusion illusions compared to adults, but only on fission-illusion trials. Adults were faster than children for all stimulus types, except when illusion stimuli were responded to incorrectly (ie the illusion occurred). Due to the small number of non-fission trials for children, a direct comparison of fission vs non-fission ERPs could not be made. In adults, differences in fission vs non-fission responses were seen at ~300 ms. For fusion trials, adults showed early (~100 ms) and mid-latency (~170 ms) differences, whereas children showed no differences. Increased susceptibility to fusion illusions in children is accompanied by faster motor responses, and a lack of modulation of the ERP to illusion-capable stimuli when the illusion was reported vs not reported. These results support an “early integration” model, and suggest that development of this ability is relatively slow. Visual Cues Can Improve Musical Stream Segregation for Cochlear Implant Users Hamish Innes-Brown,1 Jeremy Marozeau,2 David B. Grayden,1,2 Anthony N. Burkitt,1,2 and Peter Blamey,1 Enjoyment of music is an important part of life that may be degraded for people with hearing impairments, especially those using cochlear implants or hearing aids. Hearing impairment often leads to reduced auditory stream segregation, and hence reduced appreciation of music. Recent work in cognitive neuroscience has suggested that the integration of auditory and visual information in the brain occurs extensively, at earlier processing stages than once thought, and that sensory ambiguities can be resolved through this process. The aim of this study was to assess whether a visual cue could improve the segregation of a simple melody from a background of distracter notes. To assess the effect of training on the utility of the visual cue, trained musicians were also tested. The distracter notes varied in pitch throughout the experiment providing a range of difficulty. The results showed that for normal-hearing listeners, the visual cue reduced the difficulty of extracting the melody across a wide difficulty range, but only for non-musicians. Listeners with cochlear implants improved dramatically when using the visual cue, performing similarly to normal-hearing listeners. These results suggest that it may be possible to use a visual display to improve music appreciation for people with impaired hearing. Task-Switching Performance in Schizophrenia Sharna Jamadar, Pat Michie and Frini Karayanidis Previous studies have reported intact task-switching ability in schizophrenia. The current study used ERP and fMRI measures of task-switching in order to understand this effect. Individuals with schizophrenia (n=12) and controls (n=12) switched randomly between letter and digit tasks using informative and non-informative cues. Consistent with previous findings, patient RT switch cost and its reduction with time for preparation did not differ from that of controls. The amplitude of the cue-locked switch-positivity was also intact in patients, however, the amplitude of the stimulus-locked switch-negativity and pre-response negative component were significantly reduced in patients relative to controls. fMRI showed that showed increased activity in the DLPFC and PPC in switch trials relative to controls. ERP results suggest that while patients could effectively prepare for the task, they had difficulty in implementing the task. DLPFC hypofunction in schizophrenia only occurs when other areas of the frontoparietal network (i.e., PPC) are able to support task-specific processing. However when the PPC is unable to support this processing, this results in hyperactivity of the PFC and PPC, as observed here. These results suggest that patients adopted compensatory mechanisms in order to overcome difficulties in task implementation and achieve the same behavioural outcome as controls. Magnetoencephalography Blake Johnson This talk will review the basic principles behind the measurement of neuromagnetic signals with MEG. It will explain the technology of MEG measurements, the neural origins of MEG signals, and provide an overview of the main approaches to MEG analysis and source localization. I will also examine the types of neuronal signals that can and those that cannot be measured by this technique, the similarities and differences between EEG and MEG signals, and contrast the relative advantages and disadvantages of EEG and MEG in cognitive neuroscience. Principles of MEG data acquisition and analysis will be illustrated with work being carried out at the KIT-Macquarie Brain Research Laboratory. I will describe capabilities for combining standard psychophysiological measurements, including EEG, EMG and SCR, with MEG recordings. Finally, I will describe our new work on cognitive brain development being carried out in our laboratory with a novel, whole-head MEG system custom sized for work with pre-school aged children. If the Only Tool You Have is a Hammer…. An Exploration of the Value of a Multi-Method Approach Using Facial Affect Processing as an Example Patrick Johnston A set of interconnected neural structures collectively referred to as the mirror neuron (MNS) system have been hypothesised to play an important role in aspects of social cognition through supporting an embodied simulation of observed actions. It has been suggested that the MNS may play a role in the processing of facial displays of emotion, and data from a number of behavioural, psychophysical and neuroimaging studies offer tentative evidence to support this. Over the past couple of years my lab has been conducting research relating to the putative involvement of the MNS in the processing of facial affect using a variety of techniques including EEG, fMRI, MEG and TMS. This talk will look at what we have learned through the process of applying (hopefully) complementary modalities about the involvement of the MNS in face processing, and potentially different routes for the processing of static and dynamic depictions of facial affect. The talk will also focus upon how adopting particular methods might constrain the way we tend to think about particular problems in terms of the behavioural paradigms that we apply, and conversely how broadening the scope of the methods we use encourages us to think about things in new ways. Preliminary Validation of Portable Single-Channel EEG Recording Device Stuart Johnstone While a laboratory and research-grade EEG equipment allow control of variables and high quality multiple-channel EEG recording, there are situations and populations for which this is not suitable. The present study examined the convergent validity of a single-channel EEG measurement device that is portable, comfortable and uses dry sensor technology. For study 1, EEG was recorded simultaneously from the portable device (PD) and a research-grade EEG system while the adult male participant sat quietly with eyes open and eyes closed. For study 2, 23 healthy children had EEG recorded from the PD during eyes open and closed resting conditions, and eyes open relaxation, attention and cognitive load conditions. For study 1, EEG recorded simultaneously from the PD and research-grade system and analysed using the same procedures in Scan were highly correlated (r = .91) as was PD EEG processed in Scan and on-board the PD (r = .93) and research-grade EEG processed in Scan and PD EEG processed on-board (r = .94). For study 2, among other changes, compared to the eyes open resting baseline relative theta was decreased and alpha increased in the eyes-closed resting condition. These results suggest good convergent validity for EEG data recorded using the PD. Identification of ERP Components Underlying Task-Switching Performance Using Variation Across the RT Distribution Frini Karayanidis, Alexander L. Provost, Sharna Jamadar, Scott Brown, Bryan Paton and Andrew Heathcote In cued-trials paradigms, switch trials produce a larger cue-locked centroparietal positivity than repeat trials which has been variably associated with a switch-specific or general preparation process. A stimulus-locked broad negativity for switch as compared to repeat trials has been interpreted as representing either larger P300 for repeat trials or a superimposed negativity for switch trials. We examined variation in these cue-locked and stimulus-locked ERP effects as a function of variation across the RT distribution using a revised orthogonal polynomial trend analysis procedure. We extracted ERP waveforms corresponding to semi-deciles of each participant’s RT distribution (i.e., fastest to slowest 5% of trials) for switch and repeat trials. In cue-locked waveforms, the amplitude of the cue-locked positivity was varied as a function of RT and RT switch cost for switch but not repeat trials consistent with a switch-specific preparation process, whereas the later pre-target negativity was negatively correlated with RT for both switch and repeat trials, consistent with a general anticipatory preparation processes. Target-locked waveforms showed evidence for variation in both N2 and P3 as a function of RT for both switch and repeat trials. Implications for models of task-switching and other applications of the OPTA procedure will be discussed. The Psychophysiology of Decision Making: Attempting to Identify Impairments in Social Functioning Using a Novel Task Michelle A Kelly,1 Skye McDonald,1 Jacqueline Rushby,1 and David Kellett,2 Decision making forms an important part of our everyday lives and is commonly impaired after a severe traumatic brain injury (TBI). This study aimed to develop and pilot a social decision making task, and examine the electrodermal and heart rate activity associated with good and bad social choices. Participants play a game of “catch and throw” with four pseudo players over the internet. Two pseudo players are regarded “good choices” as they return the ball at a probability of 60% or 30%; the other two players are “bad choices,” returning the ball at a probability of 10% or 0%. Behavioural data are presented for 13 adults with severe TBI, and 11 control participants. A significant interaction between group and choice type was observed with control participants making more good choices and less bad choices than the TBI group (F=8.61, p=.009). Psychophysiological data was collected for 11 control participants. Preliminary results indicate that heart rate is highest and skin conductance lowest prior to making a good choice. This novel task may help elucidate the nature of poor social decision-making in TBI patients. A Role for V5 in Word Identification? Robin Laycock,1 David Crewther,2 Paul Fitzgerald,3 and Sheila Crewther,1 Although word recognition is a skill commonly expected to rely more on ventral rather than dorsal stream processing, there is some evidence for a magnocellular/dorsal impairment in dyslexia. The early rapid feedforward/feedback loop through the dorsal stream seen in primate has been suggested to allow both early activation of transient attention, and an initial global analysis facilitating more local level detailed ventral stream processing in humans. To test this model in humans, we used transcranial magnetic stimulation (TMS) to probe the role of early visual cortex (V1/V2) and V5/MT+ in single word identification. TMS over V1/V2, 4-36 ms post word onset disrupted accurate word discrimination, with disruption also evident at approximately 99 ms. TMS over V5/MT+ also disrupted accuracy following stimulation at 4 ms and again at 130 ms post word onset. Thus, a role for V5/MT+ in accurate single word identification is apparent suggesting rapid attentional activation may be required prior to processing in primary and temporal cortical regions. Effects of 2G and 3G Mobile Phones on Performance and Neurophysiology in Adolescents, Young Adults and Older Adults Sumie Leung,1 Rodney Croft,2 Ray McKenzie,1 Steve Iskra,1 Nicholas Cooper,3 and Denise Hamblin,1 Objective: This study was conducted to examine sensory and cognitive processing in adolescents, young adults and older adults, when exposed to 2nd (2G) and 3rd (3G) generation mobile phone signals. Methods: Tests employed were the auditory oddball and the N-back. Forty-one 13-15 year olds, forty-two 19-40 year olds and twenty 55-70 year olds were tested using a double-blind cross-over design, where each participant received Sham, 2G and 3G exposures, separated by at least 4 days. Results: Accuracy was not affected by exposure overall, but an augmented N1 was found in the 2G condition (independent of age group). The combined groups performed less accurately on the N-back during the 3G exposure (compared to Sham), with post-hoc tests finding this effect in the adolescents only. No 2G exposure effect on N-back was found either overall or in any group separately, and no 2G or 3G exposure effect was found on reaction time. Neurophysiological underpinnings (event-related alpha; ERA) of the 3G behavioural effects were also affected, with more early ERA and slower late ERA in the 3G (compared to Sham). Conclusion: Employing tasks tailored to each individual’s ability level, this study provides support for an acute 3G exposure effect on human cognitive function. Heart-Rate and Electrodermal Changes to Win and Loss Events During a Computer-Simulated Gambling Task Lisa Lole,1 Craig Gonsalvez,1 Alex Blaszczynski,2 Adam Clarke,1 and Renata Hadzic,1 Gambling on electronic gaming machines (EGM) is the most common and most addictive type of gambling within Australia, but there is limited psychophysiological research on the topic. Preliminary research has shown that heart rate (HR) and skin conductance level (SCL) differ for win and loss events while healthy participants gamble on EGMs. However, it remains unclear whether these results are a consequence of the elaborate visual or auditory cues normally associated with these events. We designed a computer task that simulated the EGM experience, and simultaneously recorded HR and SCL while participants “gambled.” Different types of win and loss events were tagged by electronic markers, and the differences between these events examined. The results showed a significant difference between wins and losses on SCL, but not HR. No differences were found between high and low bet options. These events were also compared to pre-play tonic HR and SCL. The results suggest that psychophysiological measures are sufficiently sensitive to reliably differentiate between winning and losing in the absence of elaborate auditory or visual cues, and even when participants do not bet with their own money. Future investigation into how problem gamblers respond when they play is warranted and is underway. Computerised Inhibition and Working Memory Training for Children With and Without Attention-Deficit/Hyperactivity Disorder: An Active-Task EEG Analysis Kylie Loveday, Stuart J. Johnstone and Steven Roodenrys Extending upon previous research evaluating the utility of cognitive training, this study examined behavioural and electrophysiological effects of computer-based inhibition and working memory training for children with and without Attention-Deficit/Hyperactivity Disorder (AD/HD). The study employed a 2 (software/waitlist) ? 2 (AD/HD/non-AD/HD) experimental design. In order to assess training efficacy, 50 participants completed a 5 week at-home cognitive training program as well as pre- and post-training sessions which included assessment of overt behaviour and EEG. EEG was recorded at one frontal site (Fp1) during one baseline and three active conditions using dry-sensor technology. Results indicated that children with AD/HD who completed training showed reduced frequency of specific inattentive, hyperactive, impulsive and oppositional symptoms, and overall AD/HD behaviours. Children without AD/HD also demonstrated improved behaviour. For children with and without AD/HD there were also changes in active EEG post-training (reduced frontal relative delta; increased frontal relative beta; increased frontal relative theta). Despite limitations, this study demonstrates the potential for combined working memory and inhibition training to be used as an alternative or complimentary treatment for AD/HD, and that an initial deficit was not necessary for training benefits to occur. The Independent and Combined Effects of Taurine and Alcohol on Attentional Processes Bethany Lusk and Frances Martin This study investigated the independent and combined effects of synthetic taurine and alcohol on attentional processing. Accuracy, reaction time and ERP measures were recorded from 20 female participants during a dual-task which involved the manipulation of attention priority. Four separate substance conditions were administered to the participants: 1000mg of taurine, .82ml/kg of alcohol, 1000mg of taurine and .82ml/kg of alcohol combined, and placebo. The results demonstrated that taurine’s proposed ability to antagonise alcohol-induced performance decrements was dependent on the explicit nature of the cognitive processes involved. That is, taurine was shown to have stimulatory properties during early and mid processing but depressive properties during late attentional processing when processing demand was high. The results of this study provided support for Wicken’s (2002) multiple resource theory of divided attention as performance was impaired during the dual-component conditions due to shared demand for the same central-perceptual processing stage and manual response format. Overall, results provided mixed support for the hypotheses ultimately providing insight into the complex interplay between two psychoactive substances on attentional processes. It was concluded that the effect of taurine and of alcohol alone and in combination differed according to the attentional processing stage and degree of attentional demand. Working Memory in Women at Risk of Cognitive Decline and Dementia Helen Macpherson, Andrew Pipingas and Kathryn Ellis Across the lifespan, the ageing process is associated with ongoing alterations to the brain and nervous system. The consequences of these neurophysiological changes are apparent during old age, when deleterious cognitive changes occur across a range of functions, particularly those which rely on working memory. This study aimed to investigate the steady state visually evoked potential (SSVEP) associated with performance of a spatial working memory task in 53 community dwelling women, aged 64-82 years, who reported subjective memory complaints. Specifically, it was hypothesised that risk factors for cognitive decline such as advancing age, ApoE status and overall memory performance would exert effects on the neural correlates of working memory. The results of this study provided support for this prediction and will be discussed within a compensatory framework of ageing. Investigating Top-Down Control in Task-Switching: ERP Evidence From a Voluntary Task-Switching Paradigm Elise Mansfield,1 and Frini Karayanidis,1,2,3 Cognitive control processes orchestrate our intentions and actions, and allow us to anticipate and efficiently prepare for impending changes in our environment. Behavioural, electrophysiological and neuroimaging evidence suggests that switching between tasks requires an active control process, part of which can be completed in anticipation of an upcoming task. Traditionally, the cued-trials task-switching paradigm (Meiran, 1996) has been used to examine these endogenous control processes. However, some researchers have argued that the relevant task-set may be automatically retrieved when the associated cue is presented. If this is the case, the cued-trials paradigm would have little requirement for top-down control. In this study, we designed a voluntary task switching paradigm in which we compare cued-trials task-switching against a condition in which participants select the task to complete on a trial by trial basis. By allowing participants to voluntarily choose which task to perform next, the demand for internally-generated plans for action is increased, thus allowing us to more directly target the active control processes required to switch between tasks. Further, comparing ERP waveform morphology for the externally-cued vs. internally-generated conditions will allow us to determine the degree to which externally-cued paradigms are able to target active control processes. Applications of Transcranial Magnetic Stimulation in Cognitive Neuroscience Jason B. Mattingley Transcranial magnetic stimulation (TMS) is being used increasingly in cognitive neuroscience as a tool for investigating the causal role of discrete cortical subregions in perception, cognition and motor behaviour. In this talk I will provide an overview of the various approaches to the use of TMS, and highlight its relative strengths and weaknesses relative to other techniques in cognitive neuroscience. I will then describe some recent applications of TMS in studies of brain-behaviour relationships, focusing in particular on the combined use of TMS with eye-tracking, electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). Atypical Brain Responses to Sounds in Children With Specific Language and Reading Impairments Genevieve McArthur, Carmen Atkinson and Danielle Ellis This study tested if children with specific language impairment (SLI) or children with specific reading disability (SRD) had abnormal brain responses to sounds. We tested 6- to 12-year-old children with SLI (N = 19), children with SRD (N = 55), and age matched controls (N = 36) for their passive auditory event-related potentials (ERPs) to tones, rapid tones, vowels, and consonant-vowels. Thirty-eight percent of the children with SLI or SRD had less typical passive auditory ERPs in the N1-P2 window to sounds in general, rather than to tones, rapid tones, vowels, or consonant-vowels specifically. The ERPs of these children were significantly “flatter” in the N1-P2 region than normal. All the children with flatter ERPs in the N1-P2 region had poor nonword reading. A subgroup of these poor nonword readers also had poor nonword repetition. These findings support the hypothesis that impaired auditory processing is a causal risk factor for both SLI and SRD. Effects of Attention on the N1 Reactivity Profile David N. McKenzie and Robert J. Barry Onset of a pure tone produces at ~100 ms a negative, vertex-maximal, electrical wave called the N1. Following the first tone with another of slightly different frequency produces a diminished N1 response. This second N1’s amplitude increases with increasing frequency difference between the tones (N1 reactivity profile). Previous results suggest a narrower profile for rapidly presented sounds. We investigated whether attention alters this reactivity profile. Seventeen participants were each presented two sets of tones (either 800 or 2000 Hz, all 60 ms and 85 dB SPL), one set to each ear. Participants attended the tones in one ear. Mixed within both sets of tones were occasional (1 in 4) probe tones that differed in frequency (± 2.5, 5, 10, 20 or 40%) from the regular tone. Temporal PCA was used to retrieve the N1 from overlapping activity and derive the amplitudes of the probe tone responses. Behavioral results indicated that participants attended to the designated tones. A strong quadratic trend was found in the N1 amplitudes as a function of frequency. This trend interacted with attention, but with too small an effect size to explain the previous results. We suggest that our greater sound intensities invoked an attention switch. Facial EMG Can Predict Ethnic Discrimination in an Australian Sample Sashenka I. Milston and Eric J. Vanman This study examined the roles of prejudice and social identity complexity (SIC) in predicting racial discrimination. Prejudice was measured by recording facial electromyography (EMG) while White Australian participants viewed photos of White and Chinese faces. Participants also completed a computerised measure of SIC as well as a behavioural measure of discrimination, in which they chose and rank ordered Chinese and White applicants for a teaching position. Analyses revealed that both EMG bias and SIC were valid predictors of discrimination. Additionally, although EMG bias was not related to SIC, a moderation effect was found. Those individuals who exhibited more implicit negative affect for the outgroup were more likely to choose a White candidate for the teaching position, and this relationship was stronger in those individuals with low SIC. Mismatch Negativity and Other Auditory Evoked Potentials in a Rodent Model of Schizophrenia Tamo Nakamura,1,2 Patricia T. Michie,1,2 W. Ross Fulham,1,2 Mick Hunter,1 T. W. Budd,1,2
Ulli Schall,1,2 Anthony J. Kemp,1 Gavin Cooper,1,2 Juanita Todd,1,2 and Deborah M. Hodgson,1,2 Reduced mismatch negativity (MMN) is a robust finding in schizophrenia. It is correlated with other cognitive impairments in patients and with grey matter loss in frontotemporal regions. The goal of the present project is to establish a rodent model based on the “two-hit” hypothesis of schizophrenia and assess the success of the model by the extent to which it produces a reduction in MMN. However, the first step is to assess whether MMN-like activity in the rat meets criteria for identification as MMN, namely, sensitivity to probability effects. Event related potentials to 3 kHz tones were measured over auditory cortex in a freely moving animal. The stimulus paradigms allow (1) control for stimulus attributes and extraction of long (100 ms) and short (50 ms) duration MMN, (2) the effects of deviant probability on long duration MMN and (3) investigation of other auditory evoked potentials (AEPs). Preliminary data indicate a negativity around 50 ms after the offset of the longer duration deviant. In addition, we observed four AEPs in non-deviant ERPs. While the preliminary data are encouraging, data need to be collected from more animals. EEG Spectral Modulations Associated With Self-Induced Emotional Imagery Julie Onton This study attempted to discover the brain correlates of emotion imagination using a guided imagery method. Subjects seated comfortably with eyes closed were asked, via voice recordings, to recall and/or imagine a series of scenarios in which they had felt or would feel each suggested emotion. They were asked to attempt to experience each emotion as vividly as possible, with particular focus on their somatic experience. After recording 256 channels of EEG data and using independent component analysis (ICA) to separate it into maximally independent processes, we applied a novel approach to identify characteristic modes of power spectral modulation occurring during emotion imagination. This analysis separated independent modulator processes acting on the theta (4-8 Hz), alpha (8-12 Hz plus harmonics), and beta (15-30 Hz) bands, respectively, plus broadband spectral modulations (from 10 Hz to 200 Hz or above), that were distinct from scalp muscle (EMG) activity, and differentially associated with the various emotions. Though these associations differed considerably across subjects, global associations between spectral modulation and emotional valence were identified. The results imply that emotional experience affects EEG source spectral power profiles, suggesting possible applications to mood/emotion monitoring and/or biofeedback therapy. Predicting Visual Consciousness Electrophysiologically Robert P. O’Shea,1,2 Jürgen Kornmeier,3,4 and Urte Roeber,2 When each eye views different images, visual consciousness alternates irregularly between them: binocular rivalry. Interrupting rival stimuli by a short gap can prompt alternations. We showed rival gratings for 1000 ms, then a 200-ms gap, then the same stimuli for another 1000 ms; this yielded about 50% alternations and about 50% of no alternations. We compared event-related potentials from these two outcomes, the event being onset of the first set of rival stimuli. At about 1000 ms before onset of the second set of rival stimuli, we could predict from occipital electrodes which trials would yield an alternation. The first negative deflection (N1, 180 ms) was larger when there was a later alternation than when not. We propose that this enhanced response to rival stimuli yields greater adaptation, making it more likely that some perturbation, such as a gap, will lead to an alternation. The Posterior Parietal Cortex in an RSVP Reading Task Kristen Pammer,1 and Ian Holliday,2 How the “dorsal stream” of visually responsive cortical regions emanating from the primary visual cortex, and in particular the posterior parietal cortex (PPc), may be involved in reading has sparked considerable debate. One possibility is that the PPc is involved in the attentional allocation required for binding of local elements of letters and words such that edges, lines, dots and letters arrive at the correct locations within words. Another possibility is that regions within the dorsal stream in and around the PPC act as a “spatial navigation” mechanism guiding saccades along a sequence of words. Moreover, it is entirely possible that the dorsal stream is involved in both processes. In this study, subjects read simple 9-word coherent sentences, presented in a Rapid Serial Visual Presentation (RSVP) format. The RSVP format is important because the sentences are read in the absence of eye movements, therefore in the absence of any “spatial navigation.” Brain signals were recorded using Magnetoencepholography (MEG), and analysed using Synthetic Aperture Magnetometry (SAM). Our analysis demonstrated localised activity in the PPc in both the alpha and beta frequency bands. The results suggest that the dorsal stream is likely to have a role in local element binding when reading. The Rubber Hand Illusion and Its Relation to Perceptual Inference and Psychological Cooling Bryan Paton,1,2 and Jakob Hohwy,1 Rubber hand and outer body illusions occur when touch sensations are projected onto non-body parts and objects. These kinds of illusions and the more general motoric-perception literature, have given insight into the relationship between general body schemas or representations and the veridical appearance and location of a person’s actual body. The subsequent perceptual and cognitive consequences of these processes have not been fully explored which is surprising given the ease with which these illusions can be induced. We present a new variation of the method for obtaining such illusions, which was found to generate a strong illusion of touch on a foreign limb. After initial illusion onset, further, incongruent visuotactile stimulation tended to generate unusual experiences. In particular, participants reported a very strong causal illusion of a supernatural or magical touch without physical contact. The presence of the illusion was ascertained with participant ratings and psychologically induced cooling of the real arm. These and subsequent results are discussed, with an emphasis on the cooling of the real arm, in the broader context of perceptual inference. Illuminating Brain Function With Optical Imaging Trevor Penney Optical imaging can be used to detect changes in the concentration of oxygenated and deoxygenated blood in the brain (functional near-infrared spectroscopy – fNIRS), as well as membrane-potential related changes in the light scattering properties of neurons (Event Related Optical Signal – EROS). fNIRS offers relatively good spatial resolution, and EROS combines good temporal and spatial resolution. Hence, these techniques provide a window on the brain basis of cognition in humans that nicely complements other brain measurement modalities such as fMRI and EEG/ERP. In my talk, I will provide an overview of the application of optical imaging to the study of human cognitive function, outline the strengths and weaknesses of the approach, and explain steps that can be taken to improve the robustness of the data. The focus will be on the EROS technique, which I will illustrate using data from a series of passive deviance detection experiments conducted in my lab. Specifically, I will describe what optical imaging tells us about the role of the STC and the IFC in passive change detection. Neural Processing of Phrase Boundaries in Speech and Music Varghese Peter,1 Genevieve McArthur,1 Bill Thompson,2 and Stephen Crain,1 In speech, phrase boundaries divide the continuous acoustic signal into smaller chunks of meaningful information. In music, phrase boundaries divide a melody into structural subunits. An important cue for phrase boundaries in both speech and music is an increase in sound duration. In this study, we used the closure positive shirt (CPS) event-related potential (ERP) to investigate adults’ processing of phrase boundaries in speech and music that are defined by an increase in sound duration. The results revealed a similar CPS response with both types of stimuli, suggesting similar neural processing of phrase boundaries in speech and music. An Investigation of the Inhibition and Conflict Accounts of N2 and P3 in the Go/NoGo and Two-Choice Tasks Using Sequence Effects Eve Pregal, Janette L. Smith and Andrew Heathcote In the two-choice task, effects of trial sequence differ based on inter-stimulus interval (ISI), with expectancy dominating long ISI results, and facilitation with short ISI. Sequence effects in the Go/NoGo task with a long ISI have determined that increases in the N2 and P3 ERP components reflect response conflict. The current study examined how cognitive expectancy and/or facilitation affect the components when participants execute and withhold responses within a short time frame. We predicted that Go and NoGo trials would be similarly affected by trial sequence, thus supporting the response conflict theory. Participants (N=24) completed the Go/NoGo task and a speeded two-choice task with a mean stimulus onset asynchrony of 600 ms. Results showed that reaction time (RT), errors and P3 for two-choice and NoGo trials, and RT for Go trials, were affected by expectancy. Errors and P3 for Go trials, and N2 for Go and two-choice trials, were insensitive to expectancy and facilitation. Only the NoGo N2 was affected by facilitation. Given that overall Go trials were not influenced by expectancy or facilitation and NoGo trials were influenced mainly by expectancy, results suggest that inhibition rather than conflict was occurring. Reasons why expectancy effects were obtained will be discussed. Brain Activity Associated With Extensive Practice in a Mental Rotation Task Alexander Provost,1 Blake Johnson,2 Scott Brown,1 and Andrew Heathcote,1 The ability to imagine the rotation of an object, referred to as mental rotation, is fundamental to many aspects of cognitive functioning. Theories from both cognitive science and brain sciences propose that when participants repeatedly practice with the same stimuli, improvements in mental rotation occur not by developing this specific spatial ability but result from a shift in strategy to categorisation (automaticity). We examined the effects of practice on the development of automaticity by collecting reaction time (RT) and event-related brain responses during performance of a Shepard-Metzler mental rotation task. Concurrent electroencephalography (EEG) and Magnetoencephalography (MEG) was recorded from 11 participants before and after extensive practice. Pre-practice RT showed a monotonic increase as a function of angular mismatch. Participant’s mean RT and variability decreased with practice while performance became insensitive to rotation angle. Brain responses prior to training showed an orientation-sensitive component over the parietal cortex, approx 300-500 ms post stimulus. Post-practice brain responses lacked this component and had an enhanced and earlier latency P300 component compared to pre-practice responses. These results show practice-related changes in measures of cognitive brain activity associated with a change in cognitive strategy. Executing, Inhibiting and Changing Planned and Unplanned Responses in the Go/NoGo Task: Examination of the Conflict and Inhibition Accounts of N2 and P3 William M. Randall and Janette L. Smith Current debate centres on the inhibitory and conflict interpretations of the N2 and P3 in the Go/NoGo task. We examined behavioural responses and ERPs in a cued-Go/NoGo task, especially when participants were required to inhibit a planned response (NoGo target after Go cue), change a planned response to a different one (Invalid cueing), and activate an unexpected response (Go target after NoGo cue). Responses were slower to both unexpected Go and Invalidly-cued than Validly-cued targets. N2 was increased when participants had to execute an unplanned motor response, but not when inhibiting a planned response, suggesting a response selection/activation interpretation of N2. P3 was increased when participants had to change or inhibit a planned response, but not when executing a response where none was planned, suggesting that P3 reflects cancellation of a planned motor response. Response Inhibition in an Implicitly Cued Go/NoGo Task William M. Randall and Janette L. Smith The implicitly cued Go/NoGo task models realistic scenarios in which events requiring response inhibition are preceded by implicit cues. This study aimed to determine the benefits of explicit prior knowledge of cue-NoGo relationships in such a task, and whether these relationships can be learned. Thirty adult participants were randomly allocated into two groups; Aware or Unaware of cue-NoGo relationships. Both groups completed a Go/NoGo task, in which certain Go stimuli were likely, or unlikely, to be followed by a NoGo stimulus (Cued vs. Non-cued NoGo, respectively). Error rates, response time, and the ERP components N2, P3 and late CNV were recorded over four experimental blocks. Results failed to support the hypotheses, with no group or block main effects, or group by block interactions, evident for any variable. However, a main effect of stimulus type (cued/ non-cued) was consistently observed. These findings suggest that prior knowledge of cue-NoGo relationships produces no benefit to inhibition, and that these relationships are not learned over time. This implies that the most important factor in improving inhibition is the strength of the link between cue and NoGo, rather than the knowledge of this link. Changes in Autonomic Responses to Facial Expressions Following Severe Traumatic Brain Injury Rushby J.A.,1 McDonald S.,1 Li S.,1 DeSousa A.,1 Dimoska A.,1 and Tate R.,2 It is well established that many people with traumatic brain injury (TBI) have poor recognition of emotional expression in others, with negative emotions more frequently impaired. Previous research has found that people with TBI display abnormal affective responses when passively viewing emotionally charged material, however, the neuropsychological mechanisms underpinning such deficits are as yet unclear. This study examined whether emotion perception deficits can be improved by focusing attention. Eighteen adults with moderate-to-severe TBI and 18 control participants viewed facial expressions from the Ekman and Friesen series while their autonomic responses (skin conductance and heart rate) were monitored. Each individual was presented with two blocks of faces (8 angry and 8 happy per block). Participants passively viewed the faces for block one, and were instructed to identify the emotional expression for block two. For the passive task the control group showed an increase in SCR and HR acceleration when viewing angry compared with happy faces, but no differences were shown for the TBI group. For the attend task a significant increase in HR deceleration was found for angry compared with happy facial expression for both groups. The results support the view that increasing attention facilitates emotion recognition in people with TBI. When Sexual Arousal Leads to Sexual Aggression: Does Working Memory Capacity Play an Inhibitory Role? Tara Spokes,1 Don Hine,2 Graham Jamieson,2 and Tony Marks,2 Research into sexually aggressive behaviour has provided evidence of a range of physiological, cognitive, affective and developmental risk factors. In particular, there is a strong positive association between arousal to deviant sexual stimuli and sexually aggressive behaviour that has been demonstrated both in criminal and community populations. The “inhibition model of sexual aggression,” posits that general sexual cues incite sexual responding, which is then suppressed in the presence of additional cues of violence, such as force, pain or fear. It is when the additional violence cues fail to suppress the initial sexual responding that sexual aggression is more likely to occur. This study investigated individual differences in sexually aggressive behaviour and the moderating role of working memory capacity (WMC). Congruent with previous findings, male participants (N = 59) with greater arousal (SCR) to violent images reported greater sexually aggressive behaviour (p < .01), however, this relationship was moderated by WMC and only held for participants with low or medium WMC (p < .05), but not for participants with high WMC. These findings suggest that it is reasonable to consider sexual aggression also as a provisional behaviour which depends on transient factors that may impact on WMC. Is it About the Mirror Neuron System or Top-Down Selective Attention Mechanisms? An fMRI Study of Self-Name Recognition P. Tacikowski,1 A. Brechmann,2 A. Marchewka,1 K. Jednorog,1 M. Dobrowolny,2 and A. Nowicka,1 In everyday life our own name is one of the most socially self-relevant stimuli. Different neuroimaging studies on self-name recognition report different structures as involved in this process. This inconsistency in results might be due to: (1) not exclusively self-specific stimuli (many people share the same first name); (2) “distant” control conditions (unfamiliar or familiar names apart from “me vs. not-me” distinction differ in terms of emotional content and frequency of occurrence in everyday life). In this fMRI study the compound of subject’s first and last name was presented. As one of the control conditions we used first and last name of the most important person in our subjects’ lives i.e. significant other. This central to our study contrast revealed activations specifically in the right inferior frontal gyrus (IFG). Further analyses showed that this structure was involved also in the processing of significant other’s name, however, no such effects were found for famous or unfamiliar names. Apparently, the activation of right IFG is determined more by the “significance to the subject” feature than the “self-representational” one. We suggest that the self-preference in social information processing might result from more general mechanisms i.e. selective attention rather than exclusively self-specific ones. Neuroelectric Evidence of Early Attentional Bias Towards Threat in Obsessive-Compulsive Disorder Susan J. Thomas,1,2 Craig J. Gonzalvez,1 and Stuart J. Johnstone,1 The clinical presentation of obsessive-compulsive disorder (OCD) includes preoccupation with, and hypervigilance towards, threatening stimuli, however the presence of attentional biases in OCD has not been reliably established in laboratory reaction time (RT) tasks. We used event-related potentials (ERPs) as a measure of attention to threat while participants with OCD, panic disorder (PD) and healthy controls (HCs; 20 per group) performed an emotional Stroop task. Consistent with previous studies, only the PD group showed delayed RT to colour-name threatening words. OCD participants, however, showed ERP indications of enhanced attention to threat words including higher P1 amplitude and longer N1 latency to threat versus neutral words, relative to the other groups. The PD group additionally showed patterns of shorter P1, N2 and P3 latencies to threat than neutral words. It is concluded that both OCD and PD are characterised by early attentional biases towards threat. The finding of augmented early attention to threat words in both anxiety disorders might indicate that attentional bias is a core component of anxiety disorders, although the nature of the attentional mechanism (earlier capture in PD versus slower and enhanced processing in OCD) may differ between disorders. Temporal Processing Ability Linked to Ear-Asymmetry in Mismatch Negativity to Between-Channel Gap Sounds Juanita Todd,1 Brayden Finch,1 Ulrich Schall,2 and T. W. Budd,1 A temporal processing advantage is thought to explain the left-hemisphere-dominance of language processing. This temporal processing advantage produces a right-ear-advantage on certain auditory tasks. We report on two studies demonstrating an ability-related right-ear-advantage in mismatch negativity (MMN) to between-channel gap-deviant sounds. In both studies, the right-ear-advantage is present only in “good discriminators”- those with low gap-detection thresholds in behavioural ability measures. In study1, gap-detection threshold was positively correlated with MMN measures of gap-detection in forty-seven adults (18-73 years), where larger right-ear-advantage in MMN correlated with better temporal discrimination ability (rs= .51, p<.005). In Study 2, MMN sequences were presented to 19 adults in silence and against a background of broadband noise. The right-ear-advantage for MMN in silence exhibited by good discriminators was reversed to a left-ear-advantage for MMN in noise. Poor discriminators showed no ear-advantage or differential sensitivity of the ears to noise. We conclude that in good temporal discriminators, the MMN to between-channel gap sounds behaves like that to speech sounds by exhibiting a right-ear/left-hemisphere dominance in silence which is altered by the presence of noise. These asymmetries are likely to emerge as a result of both structural hemispheric differences and top-down modulation of information flow to the cortices. Multiple Aspects of Self Awareness Peter Walla The effect of possessive pronouns on the encoding of pronoun-noun associations (e.g., my garden) was investigated using electroencephalography (EEG) and magnetoencephalography (MEG). EEG data showed that between 250ms and 400ms after stimulus onset “my” and “his” conditions elicit similar brain activity over occipital electrodes. On the other hand, at left temporal sites “my” conditions elicit more negative going potentials than both other conditions. In the MEG experiment, two chronological processing stages appeared to be significant, one between 200ms and 400ms after stimulus onset and the other between 500ms and 800ms. The earlier stage was found over occipito-parietal sensors and was different between personal engagement (my and his) and no personal engagement (a) whereas the later stage occurred over left frontal sensors and differentiated between self and non-self. Both experiments seem to highlight two important areas which are sensitive to the concept of a person. One area is located in the occipital region and distinguishes between personal engagement and no personal engagement and the other area is located in the temporal region and can distinguish between oneself and somebody else. These findings led to the so called “multiple aspects”-hypothesis related to research on self awareness and the awareness of others. Strategy Development in Aging: Behavioural and ERP Evidence for Practice Improvements in Task-Switching Lisa R. Whitson, Frini Karayanidis and Patricia T. Michie Task-switching has been used to examine age-related decline in cognitive control. Participants alternate between single and mixed task blocks. Mixing cost [(repeats in switch blocks)–(single task trials)] reflects working memory load, and switch cost [(switch–repeat trials)] reflects task-set reconfiguration processes. Behavioural and ERPs were recorded from well-practiced participants (18-80 years). Mixing cost was larger for the Older group, but reduced for all groups across practice days and with increased preparation time. Middle and Older adults took longer to develop a strategy for reducing switch costs than younger adults. While mixing costs continued to be larger for Older adults, switch cost differences were eliminated by the final test. Mixing and switch positivities in cue-locked waveforms were prolonged and broadly distributed for Older adults. This pattern for mixing positivities emerged at 30 years, despite no behavioural evidence for increased mixing cost. Behavioural results suggest Older adults have difficulty with working memory, however, have intact reconfiguration abilities. ERPs suggest strategic differences emerging early in adulthood. These include less efficient preparation and greater activation of post-stimulus processing resources to handle the task at a similar level to that of younger adults. Findings are discussed in the context of cognitive ageing theories. Neural Correlates of Prospective Memory: Validating and Improving an Experimental Paradigm Jennifer Wilson,1 Tim Cutmore,1 Raymond C. K. Chan,2 and David Shum,1 Prospective memory (PM) shares important features with aspects of vigilance and working memory. Experiment 1 compared the neural correlates of 18 undergraduates (12 males) performing a PM and vigilance task. The same stimuli were used for both tasks. An oddball paradigm was used for the vigilance task, and semantic category judgment task for the ongoing condition of the PM task. Experiment 2 involved 33 undergraduates (11 males) and evaluated the effects of cue frequency (10%, 30%) and cue repetition (high, low) on ERPs associated with PM. PM cues in both experiments elicited the prospective positivity and frontal positivity, while vigilance targets in Experiment 1 elicited a P300 and a frontal positivity over the left hemisphere. No N300 was observed in the PM task, perhaps due to use of a semantic cue. Waveforms reflected the shared and distinct neural processes underlying PM and vigilance. Experiment 2 revealed an interesting but unexpected interaction between PM cue frequency and cue repetition at frontal and parietal regions, highlighting the importance of accounting for both factors in future study design. The findings support a multiprocess theory of PM (McDaniel and Einstein, 2007), suggesting different neural processes may be recruited depending on task demands. |
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