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Journal of Clinical EEG & Neuroscience, July, 2009AbstractsAbstracts of peer-reviewed presentations at the ASP2008 18th Annual Conference of the Australasian Society for Psychophysiology, November 27-29, 2008, University of Tasmania, Hobart, Australia.Abstracts of these presentations are listed in alphabetical order of the first authors surname. The Effects of Glucose on Attention in a Driving Based TaskAndrea R. Adam, Emma M. Rainbird and Frances H. Martin The aim of this study was to examine the effects of glucose on attention in a driving-based task. Interpretation of previous research into the effects of glucose on cognitive processing has been complicated by fasting, limited control of caffeine use, and the lack of blood glucose level measurements. Based on recent research (Mertens, 2006) it was hypothesised that increased consumption of glucose would be associated with a decrement in attentional processing and performance. Sixteen female participants consumed 32g or 50g of glucose, on separate occasions, and engaged in a dual task involving the simultaneous presentation of visual and auditory stimuli. Task performance (reaction time and accuracy) for both tasks, and P300 amplitude in response to the visual stimuli, were analysed as measures of allocation of attentional resources. The hypothesis was partially supported; glucose resulted in lengthened reaction time in the visual task, and decreased attentional resource allocation in the most difficult task condition after consumption of 50g of glucose. Importantly, the results of the current study suggested that hyperglycaemia was not the reason for the reduction in performance and processing. This research suggests that non-diabetics’ driving abilities can be negatively affected by normal blood glucose fluctuations. Email: Attentional Startle Modulation: Effects of Trial Structure and Cue-Target IntervalSakinah S. J. Alhadad and Ottmar V. Lipp Previous research has yielded evidence for modality specificity of attentional startle modulation (ASM) in continuous performance tasks (CPT), and for modality non-specificity in trial-structured tasks. Modality specific ASM was also found in a modified CPT, in which a trial structure had been imposed. The current study assessed whether the stimulus onset asynchrony (SOA) between cue and target affects the nature of ASM. Participants were to respond by pressing a button whenever the digit 7 appeared. The digit 3 always preceded the 7. In one task block, the SOA was 5,050 ms, with startles elicited at 3,500 or 4,500 ms, to resemble a differential reaction time paradigm. In the second, the SOA was 1,700 ms, with startles elicited at 120 or 1,200 ms, to resemble a CPT. Modality non-specific ASM seen previously in the differential RT paradigm was replicated. However, there was no evidence for modality specific ASM with a 1,700 ms SOA. The second study explicitly informed the participants of the predictive relationship among the digits. This manipulation resulted in modality non-specific ASM at 1,200 ms and 3,500 ms. Thus, the cue-target SOA does not seem to be critical for determining the modality specificity of ASM seen in the CPT. Email: EEG Determinants of the ERP: Explorations in an Auditory Go/NoGo ParadigmRobert J. Barry, Frances De Blasio and Lisa Woods This study explored the “phase reset” and “evoked activity” models of ERP genesis in an auditory Go/NoGo task. Pre- and post-stimulus EEGs in traditional EEG bands, and the averaged ERPs, were examined. EEG amplitudes were derived from each trial using FFTs on 0.5 s epochs pre-and post-stimulus onset, and averaged to obtain estimates of total activity before and after stimulus onset, each of which includes both ongoing activity unrelated to the stimulus, and stimulus-related activity. Averaged stimulus-related EEG activity pre- and post-stimulus was similarly derived from the ERP. Topographies of the major ERP peaks (N1, P2, N2, and P3) were related to the topographies of the post-stimulus EEG data by step-wise multiple regression, seeking the EEG determinants of each ERP component. Time-frequency analysis of single trial data was also used to help integrate the findings. Results indicate that both evoked activity and phase locking of ongoing EEG activity contribute substantially to the different Go and NoGo ERP components. Phase locking contributes strongly to the early exogenous ERP components, with evoked brain activity related to cognitive processing contributing strongly to the endogenous ERP components. Evidence also suggests that extensive phase realignments may generate the power increases associated with early exogenous components. Email: Psychophysiological Changes Associated With Gambling Behaviour on Electronic Gaming Machines: the Effects of Gambling Outcome, Betting Stakes and PersonalityKathryn Baudinette and Craig Gonsalvez It has been argued that electronic gaming machines (EGM) are extremely addictive, often described as the “crack cocaine of gambling”. Little research has been conducted on the psychophysiology of gambling behaviours. This study used state-of-the-art technology to investigate the effect of gambling outcome (wins and losses) and betting stake (high and low) on physiological responding. HR and SCL were recorded on a second-by-second basis to win and loss events in high and low stake conditions while healthy controls (N=43) gambled on an EGM. The relationship between personality (impulsivity and reward/punishment sensitivity) and physiological responding to wins and losses were also investigated. Results indicated that psychophysiological measures were sufficiently sensitive to detect subtle changes in physiological responding. Wins resulting in SCL and HR increases, this pattern was amplified during the higher betting stake condition, for SCL only. Personality traits failed to demonstrate a relationship with physiological responding. The current study demonstrates that physiological changes associated with gambling on an EGM can be measured reliably, and are sensitive to gambling outcome and stake manipulations. The present study is an essential first step in determining whether problem gamblers can be identified by a physiologically distinctive pattern of responding to events on an EGM. Email: Effects of Resistance and Flexibility Exercise Interventions on Balance and Related Measure in Older AdultsMarie-Louise Bird, Keith Hill, Madeleine Ball and Andrew Williams Healthy aging is associated with changes in balance. This research explored the balance benefits to untrained older adults of participating in community based exercise training. In a randomised cross-over trial, 32 older adults [mean=66.9 years] participated in resistance exercise (RT) training and flexibility exercise (FLX) training for 16 weeks each. Sway velocity was recorded using a force platform. Lower limb strength and functional balance were measured. Significant improvements in both intervention groups were seen in the parameters of sway velocity with eyes open (RT 14%, p=0.02; FLX 20%, p<0.001) and closed, (RT 16%, p=0.05; FLX 14%, p<0.001) but not while performing a mental dual task activity. Similar improvements were seen with Timed up and Go, (RT 14%, p=0.006; FLX 12.4%, p<0.001), Ten times sit-to-stand (RT 24.7%, p<0.001; FLX 20.5%, p<0.001) and Step test (RT 34.4%, p<0.001; FLX 30.1%, p<0.001); with no significant differences between the two groups. Significant increases in strength were observed following resistance training (11.9 %, p<0.001) but not flexibility training. Both resistance training and standing flexibility training programs lead to significant improvements in balance performance in healthy untrained older adults, however further investigation is required to determine the mechanisms responsible. Email: Effects of Arousal State on Readiness PotentialMarta Bortoletto, Marianna Lemonis and Ross Cunnington Voluntary movements are preceded by pre-movement cortical activity associated with the planning and readiness for action. Previous studies have suggested that movement-related brain activity is affected by higher cognitive functions such as attention and motivation. In this study, we investigated the effect of arousal on pre-movement activity by examining the Readiness Potential (RP) under conditions of relatively high and low physiological arousal. Eighteen participants performed a Readiness Potential paradigm in which they executed self-paced voluntary movements approximately every 4-5 s. The arousal state was manipulated by the experimenter through interaction with participants during rest breaks. 64 channels EEG, skin conductance level and heart rate were recorded. Skin Conductance level was significantly different between high and low arousal conditions, showing that the experimental manipulation effectively altered arousal state. The RP amplitude was significantly higher under conditions of low arousal compared with high arousal, with no change in the RP scalp topography. However, this effect was restricted to the late component of the RP immediately preceding the movement. Results suggest that Readiness Potential and arousal are not linearly related. Therefore neural mechanisms associated with increasing arousal are unlikely to directly influence the premotor pathways important for the preparation and readiness for action. Email: Cognitive Coherence in LearningPeter G. Burton Disciplines of the brain as an organ fail currently to connect with the models of cognitive sciences, and these both remain disconnected from meta-cognitive concerns of the mind. The circle of interlinked disciplinary explanation has three prominent gaps: i. (between the brain and the experience of consciousness) how to naturalise consciousness in the brain; ii. (between neuro- and cognitive-psychology) how to understand the brain as a coherent processor of learning; and iii. (between logic and the mind) how to explain the acquisition and “inhabiting” of an objective self-model from within subjective experience. All three puzzles must be jointly addressed for a coherent and competent theory of human higher brain function. Cognitive System Theory (CST) by the author (http://homepage.mac.com/blinkcentral) takes a complex dynamic system approach to resolving the complexity of brain operations, rather than the “process” model common in psychology. Five distinct axiomatic analyses resolve content to demonstrate logical coherence, expose dynamic interdependencies (such as that between cognition and consciousness) and to assure ecological validity for a new integrative theory of Mind, Brain and Knowledge. CST elucidates all three of the “explanatory gaps” identified above, and provides a grounded scientific resolution of mind-brain “duality”. CST embodies punctuated coherence as its operating modality; process punctuation shows up as structured eye blinking. Email: The Quantification of Ne: a Comparison of MethodsAndrea R. Carr, Frances H. Martin and Andrea R. Adam The quantification of event-related potentials (ERP) has taken many forms and the advantages and disadvantages of standard methods, such as peak detection and mean amplitude measures are well documented. Yet there are few direct comparisons of methods in the literature. This investigation examined a number of approaches to ERP quantification frequently used in research on error-negativity (Ne). These included peak amplitude and latency, mean amplitude and 50% area latency. Additionally these measures of amplitude and latency were calculated from two derivations of difference waveforms; averaged errors minus averaged correct trials (equal and unequal trial numbers), were also considered. Data were collected from 38 right-handed female participants during an experiment investigating the effect of task salience, personality type and decoding ability in a language-based task on Ne. There was a marked divergence in significant outcomes between the analyses of mean amplitude and 50% area latency of difference waveforms derived from equal and unequal trial numbers. It was concluded that, for any use of a particular method of ERP quantification, an a priori justification for the use of that method be clearly delineated. Email: Childhood EEG as a Predictor of Adult Attention-Deficit/Hyperactivity DisorderAdam R. Clarke,1 Robert J. Barry,1 Franca E. Dupuy,1 Rory McCarthy,2 Mark Selikowitz2 and Patrick Heaven1 AD/HD is a common psychiatric disorder of childhood that often continues into adulthood. The aim of this study was to determine whether EEG differences exist between children with AD/HD who later outgrow the disorder and those who continue to be symptomatic as adults. 38 boys with AD/HD as children, were assessed 11 years later to determine who met criteria for adult AD/HD. At the childhood assessment, an EEG was recorded from the AD/HD group and a control group, during an eyes-closed resting condition. This was analysed for absolute and relative power in the traditional bands, and the theta/beta ratio. At the childhood assessment, the AD/HD group had increased absolute and relative theta, reduced relative alpha, and increased theta/beta ratio. EEG differences were found between those who later outgrew the disorder and those who continued to have AD/HD as adults. The adult AD/HD group had greater relative beta across the entire scalp than those that outgrew the disorder. Frontal lobes differences were found between the two groups for absolute beta, relative theta, the theta/beta ratio, and relative beta. These results suggest the existence of specific CNS differences in childhood which may be used to predict the developmental course of the disorder. Email: Effect of Neurofeedback Training of Mu and Beta Rhythms on Behavioural Measures Using Brain Computer Interface Technology (BCI2000)Emily C. Connors The current study explores the effects on cognitive functioning of training healthy individuals to control the mu and beta rhythms with neurofeedback (NF), using a Brain-computer interface program (BCI2000). Previous research has identified beneficial effects of NF training in enhancing cognition and behaviour using therapeutic NF training. A pre/post design was used to examine changes in scores for behavioural measures of attention (Trail Making Tests and Conner’s CPT-II) and working memory/imitation (WMS Spatial Span subtest) following NF training. The behavioural data from an experimental group (n=10) who took part in eight BCI2000 NF sessions was compared with a control group who received no NF (n=10). While a number of significant changes occurred in behavioural measure scores between pre/post administrations, no significant interactions occurred for pre/post behavioural scores between the groups. Linear regression on the experimental group data showed no relationship between BCI2000 NF accuracy and scores on behavioural tasks. Further analysis of the BCI NF data indicated that accuracy on the NF task was most likely achieved through EMG artefact. This and the inability to set consistent feedback variables are a major impediment to drawing straightforward conclusions regarding behavioural results. The implications of these findings and future directions are discussed. Email: Repetition Effects in the Auditory ERP: Evidence for Two Generators of Repetition Positivity That are Differentially Affected by AgeRowena Cooper, Juanita Todd, Rosemary Clark, Rebekkah Atkinson and Pat Michie RP is an ERP waveform that is thought to reflect the establishment of auditory sensory memory traces. We explored factors contributing to RP elicitation (study 1) and examined the effect of age on RP (studies 2 and 3). Across studies, we used a roving standard oddball design and manipulated the number of consecutive repetitions of a tone. For study 1, we added a constant standard oddball condition. Young adults (<35 years) participated in studies 1, 2, and 3 (n = 24 - 25). Older participants (>50 years) took part in studies 2 and 3 (n= 24 - 25). We measured N1 and P2 amplitude (covering the latency range of RP) in the standard ERP in different repetition conditions. We found an effect of repetition in the standard ERP at frontal and mastoid sites in the roving standard condition and also at mastoid sites in the constant standard condition. An age-related change in RP was observed only at frontal, not mastoid sites. Study 1 results imply that there are at least two generators of RP encoding local and global aspects of stimulus history. Study 2 and 3 show that age affects the encoding of contextual information related to global stimulus history. Separate Form and Surface Cortical Colour Systems – Evidence From Chromatic VEPDavid P. Crewther1 and Sheila G. Crewther2 Recent primate optical imaging experiments have demonstrated several specialized systems for processing colour, including the blobs of V1 and the thin stripes of V2. Electrophysiological evidence indicates that the chromatic surface (diffuse) VEP contains separable luminance and colour components (Klistorner et al, 1998). This study extends the investigation into the processing of blue colour and compares surface and patterned colour responses from six participants with normal colour vision. The VERIS mfVEP system was used, with alternation between colour and background grey either at the same luminance (36 cd/m2) or with a constant luminance contrast of 30%. Patterned coloured were presented in appearance-disappearance mode. A blue saturation-dependent potential separable from achromatic contrast was found with most power in the second order Wiener kernel response. Patterned stimulation at constant luminance contrast was much less dependent on the level of saturation. Spectral dependence of the isoluminant surface chromatic (colour/grey) VEP showed a null point at yellow (570 nm), while the pattern spectral response showed no such null. Given that the vast majority of neuroscientific experimentation on colour uses gratings as stimuli, there may be a need to revise the interpretation of the contributions from form and colour respectively. Email: Mobile Phone-Related Human Sleep EEG Changes are Replicable in the Same IndividualsRodney J. Croft,1 Sarah P. Loughran,1 Melinda L. Jackson,1 Peter Rochford2 and Mark E. Howard This research re-tests participants from a previous mobile phone/sleep EEG study (Loughran et al, Neuroreport 2005:1973-6), to determine whether their neural changes during sleep, in response to a mobile phone exposure prior to sleep, are reproducable. Twenty participants (13 females; mean age = 27.9 years, SD = 6.8 slept three consecutive nights in a sleep laboratory. The first was an adaptation night, and the second and third were experimental nights. On the experimental nights a GSM mobile phone (MP), either transmitting (ACTIVE) or turned off (SHAM), was mounted on the right side of the head in a position that simulated normal use for a period of 30 minutes prior to sleep. EEG data from the first NREM period were analysed (FFT, mean of C3/C4). For statistical purposes, participants were divided into two groups based on whether their 11.5-12.25 Hz alpha power increased (Increasers) or decreased (Decreasers) in Loughran et al. The twenty participants as a group exhibited more 11.5-12.25 Hz power in the ACTIVE condition than SHAM (t[19]=1.78; p=0.045). Further, the ACTIVE condition resulted in more of an increase in the Increasers than Decreasers (t[18]=1.95; p=0.03). This suggests that the Loughran et al results are real and not statistical anomalies. Attention and the Readiness for Voluntary ActionRoss Cunnington, Julie Keegel, Ottmar Lipp and Marta Bortoletto The Bereitschaftspotential, or readiness potential, is a slowly increasing negative potential arising from activity of premotor and supplementary motor areas preceding voluntary action. Brain imaging studies have suggested that attention directed towards the intention to initiate action selectively increases activity of the supplementary motor area. In this study, we examined the effect of attention on the readiness potential within a paradigm that focused participants’ attention on their intentional decision to initiate action. We manipulated the degree to which participants could allocate attention to the voluntary movement task by giving a secondary working memory n-back task at high and low levels of attentional load. 64-channel EEG was recorded from 16 participants as they performed voluntary finger movements and judged their times of intentions within a standard Libet paradigm. The readiness potential amplitude was significantly reduced under conditions of high attentional load, when attentional resources available for the voluntary movement task were limited. This effect was evident even in the earliest component of premovement activity, up to 1000 ms prior to movement. Results suggest that neural activity contributing to the early readiness potential represents cognitive processes that are dependent on attention, possibly including the intentional decision of the time to initiate action. Email: Deception Detection With ERPs Using Pictures of Crime ObjectsTim Cutmore, Tatjana Djakovic, Tahlee Marian, Mark Kebbell and David Shum Two experiments used a mock crime followed by an oddball methodology to uncover hidden memories. In Experiment 1 a wallet was the crime (“stolen”) object. Different memory cue types (Words, Pictures of Objects and Faces) were created to investigate their relative efficacy in identifying guilt. A peak-to peak (p-p) P300 response was computed for a rare known non-guilty item (target), a rare guilty knowledge item (probe) and frequently presented unknown items (irrelevant). The object-picture cue was found to be the most effective, particularly at the parietal site and a bootstrap procedure showed the object cue to provide the best individual detection rate. Furthermore, using all three of the cue types together provided high detection accuracy (94%). It was concluded that direct cueing with a picture of the crime object may be more effective than using a word (consistent with the “picture superiority effect”). To extend the generalizability of the object cuing paradigm, in Experiment 2 a variety of different objects (randomized over participants) were used as the “stolen item” and innocent and guilty groups were compared. A sensitivity of 80% was found with a specificity of 100%. Results are discussed with respect to appropriate methodology, practical application and future directions. Email: Auditory Event-Related Potential Changes in Chronic Low-Level Exposure to Organophosphate PesticidesTharaka Dassanayake,1,2 Indika Gawarammana,1 Vajira Weerasinghe,1 Prasanna Dissanayake,1 Background: Cognitive effects of long-term exposure to organophosphate compounds have been investigated over a few decades but the clinical evidence is inconclusive. Objective of this study was to determine whether chronic occupational exposure to organophosphate pesticides leads to cognitive impairment using event-related potentials (ERPs). Methods: ERPs of 38 vegetable farmers applying organophosphate pesticides and 38 matched controls were recorded using auditory oddball paradigm. The P300 ERP component, the ERP components related to early processing (N100, P200, N200) and the number of counting errors were compared between the groups. Conclusions: Chronic occupational exposure to organophosphate pesticides may lead to a delay in ERP components related to later stages of information processing, particularly P300. This suggests that organophosphate compounds adversely affect neurophysiological processes underlying updating of working memory and stimulus classification. Email: The Viability of a Non-Deceptive Variant of the Object Cue P300-Guilty Knowledge Test (P300-GKT)Rachel A. Dati, Tim H.R. Cutmore and David H.K. Shum The current study examined the viability of a non-deceptive and non-discriminative variant of the object cue P300-Guilty Knowledge Test (GKT). The study’s 24 participants enacted a mock crime, wherein a pre-designated object was stolen (probe). Participants were randomly assigned to either a Deceptive or Non-Deceptive P300-GKT. The Deceptive paradigm required immediate Yes/No key-press responses of object recognition (the probe stimulus requiring a deceptive “No” response). A “Yes” response was required for known non-crime-related targets. The Non-Deceptive paradigm required a delayed object naming response (beyond 1600ms), ensuring stimulus attendance. Both tests were able to detect the presence of crime-relevant information via statistically distinguishable probe-irrelevant peak-to-peak P300s over electrode sites Fz, Cz, and Pz. For the Deceptive task larger probe-irrelevant differences were observed at Fz, possibly as a result of its unique engagement of the frontal lobes to manage the deceptive and discriminatory responses. Individual detection sensitivity was significantly better in the Deceptive (78%), then the Non-Deceptive task (28%). These results indicate that deceptive responding is not required to produce differential brain responses in group average data; however the practical utility for individual classification is, at present, limited. Increased stimulus salience and task relevance should be examined in future studies. Relationship Between Pre-Stimulus Alpha and P3 Amplitude in the Context of ArousalFrances De Blasio and Robert J. Barry The direct relationship documented between pre-stimulus EEG alpha activity and resulting P3 amplitude contradicts recent arousal/activation literature which predicts an inverse relationship. Twenty participants completed an auditory Go/NoGo paradigm with 50% target probability. EEGLAB was utilised to precisely quantify and order successful experimental trials according to pre-stimulus RMS alpha activity at Cz. Analysis was extended to include both Target and Non-Target responses, with the pre-stimulus RMS alpha P3 amplitude relationship assessed at the within-, and across-participants levels, across several electrode sites, and for two, and then ten, Alpha level groupings. In accordance with the differential arousal/activation model, mean Target reaction-time was found to show no systematic relationship to pre-stimulus RMS alpha. Overall, a direct relationship was confirmed between pre-stimulus RMS alpha and P3 amplitude across the various levels of analysis at the nine main electrode sites. Furthermore, Target responses exhibited a greater enhancement frontally, and Non-Target responses parietally, revealing this relationship as a localised effect. The topographic analysis was exploratory in nature, however, the strength of the effect suggests future research directions. Although these findings were consistent with the pre-stimulus alpha P3 amplitude liiterature, this relationship remains in contradiction to the arousal literature and warrants further investigation. Email: Physiological Responses to Persistent Images Presented Outside of AwarenessStephanie C. Goodhew, Ottmar V. Lipp and Derek H. Arnold There is an enduring debate about the extent to which the brain can process visual stimuli in the absence of conscious awareness. Existing methods for suppressing stimuli (e.g. backward masking) require very brief stimulus durations, which limits the measures that can be used to probe the sprocessing of suppressed stimuli. We adopted a new method for suppression that overcomes such limitations: binocular switch suppression (BSS). In BSS, a pixelated visual noise mask that is higher in visual stimulus strength than the to-be-suppressed target image is presented to one eye and the target image to the other eye, and the images are switched between eyes at a frequency of 1 Hz. On an unsuppressed trial, the target image is presented alternatively to either eye and switched at the same frequency. Coloured images from the IAPS database were presented for six seconds at a time, suppressed or unsuppressed . Skin conductance responses were larger to unsuppressed pleasant and unpleasant pictures than to neutral ones and decreased across trials. Responses to suppressed pictures seemed to show a similar pattern, but only for the final blocks of pictures. Replication and further work is required. Email: Vulnerability to Developing Anxiety and Depression in 10-12 Year Olds and its Relationship to Autonomic Cardiac ControlYvonne Groot, Julian Simmons, Nina Cook, Laurie O’Brien-Simpson, Kylie Altson, Michelle Byrne and Nick Allen Adolescence is a developmentally vulnerable period as many cortical and subcortical changes take place affecting autonomic regulation. This study examines whether negative affect is associated with decreased parasympathetic and increased sympathetic cardiac autonomic control in 10-12 year olds. A group of 2453 secondary school students from the Melbourne metropolitan area completed the Early Adolescent Temperament Questionnaire (EATQ), from which 109 students were selected. Included were participants considered temperamentally extreme, as well as a random selection of those with intermediate scores. Within the selected sample, the Vrije Universiteit Ambulatory Monitoring System was used to measure autonomic cardiac control based on the electrocardiogram (ECG) and the impedance cardiogram (ICG). Measures of resting Respiratory Sinus Arrhythmia, indicating parasympathetic cardiac innervation, Heart Rate and Pre-ejection Period, indicating sympathetic cardiac innervation were established. Preliminary results have shown that children with a negative affective style as measured by the EATQ had a small but significant increase in sympathetic cardiac activation, and a reduction in parasympathetic cardiac activation compared to children with low negative affect. This suggests that autonomic regulation and negative affect, indicating vulnerability for the development of affective disorders, are related. Therefore, assessing autonomic functioning could play a significant role in illness prevention and progression. Email: How Do Fixational Eye Movements Contribute to the Effects of Stimulus Motion on Binocular Rivalry Between Simple and Complex Images?Laila Hugrass and David Crewther Stimulus movement increases the perceptual stability of binocular rivalry between simple (pattern) stimuli, yet destabilises rivalry between complex (face/house) stimuli. This interaction may be attributed to the effects of movement on local vs. global adaptation, or to its effects on fixational saccade rate. We compared the relationship between fixational saccades and binocular rivalry for stationary vs. orbiting, checkerboard and face/house stimulus pairs. Eye movements were recorded from five participants, who reported their perceptual state while fixating centrally on the rival stimuli. On average, saccade rate was higher in the orbiting condition for both simple and complex stimuli. The modulation of saccade rate around perceptual alternations was greater for the stationary than moving checkerboards, yet virtually equal for the stationary and moving face/house pair. Our results suggest that the interaction between stimulus movement and complexity on rivalry cannot be explained in terms of saccade frequency alone. For the orbiting checkerboards, the reduction in local neural adaptation may have offset the destabilising influence of saccades. Yet, orbit does not prevent global adaptation, so increasing the saccade frequency lowered perceptual stability of face/house rivalry. We conclude that adaptation affects rivalry at not one, but multiple neural levels. Email: Are Response Inhibition and Interference Control Affected in Children With AD/HD?Stuart J. Johnstone,1 Robert J. Barry,1 Valentina Markovska,1 Aneta Dimoska2 and Adam R. Clarke1 One prominent model proposes that behavioural disinhibition is at the core of Attention-deficit Hyperactivity Disorder (AD/HD), including deficits in withholding responses and interference control. Investigations of both of these domains in the same groups of children are scarce, especially with ERP measures, but are a necessary requirement for testing the model. Twenty children with AD/HD and 20 matched controls aged between 8 and 14 years performed visual Go/NoGo (30% NoGo) and Flanker tasks while EEG was recorded. Results indicated that children with AD/HD traded off speed for accuracy in the Go/NoGo task, resulting in similar levels of response inhibition accuracy to controls. In the Flanker task, response speed and errors were at control levels, while misses were increased and showed an enhanced interference effect. Go/NoGo task ERPs showed a reduced central N2 Nogo>Go effect and more anterior Go/NoGo P3, for the AD/HD compared to controls, while for the Flanker task, the AD/HD group showed delayed N1 and P2, dramatically reduced N2 to Incongruent stimuli, enhanced N2 to Neutral stimuli, as well as increased P3 to Incongruent stimuli. These results indicate that Go/NoGo response inhibition and Flanker interference control were not equally impaired in children with AD/HD, challenging Barkley’s (1997) model. Email: Electrophysiological Indices of Recognition Memory Related Change Following Mild Head Injury Using Event Related PotentialsJason S. Little and Frances H. Martin In an ongoing study with the Tasmanian Neurotrauma Register, two groups of mild head injured (MHI) males were tested at either one month (n=18) or at 24 months post-injury (n=18) using the remember/know recognition memory paradigm. Previous research consistently shows that in comparison to ERPs to unstudied words, ERPs to studied words recognised with a familiarity judgment display an early frontal positive-going modulation (FN old/new effect, 300-500ms), and ERPs to studied words identified with a remember judgment display a late parietal positive-going modulation (late parietal old/new effect, 400-800ms). Control group results are largely consistent with previous research however MHI groups differed from the control group in a number of ways. While late parietal old/new effects were comparable to the control group parietally, at frontal sites both MHI groups displayed this effect at more positive amplitude. Furthermore a reduced sample analysis (n=12) showed that when words were shallowly encoded the control group displayed FN effects for both familiarity and remember responses as expected however no FN effects were found for either MHI group for either response type. This indicates psychophysiological change in familiarity based memory processes following MHI. Email: The Effect of Music Tempo and Intensity on Visual Selective AttentionIsobel C. Ludford and Frances H. Martin This investigation examined the independent and combined effects of music tempo and intensity on visual attention to a driving based task. The presence of an auditory distracter is thought to increase the mental workload and reduce the amount of attentional resources available for a given task. Using a repeated measures design, 18 female non-musicians completed a driving based oddball task in five auditory conditions (fast tempo high intensity, fast temp low intensity, slow tempo high intensity, slow tempo low intensity, and music absent control), and reaction time and accuracy to the targets were recorded. Amplitude and latency of ERP components, N2 and P3b, were also recorded and analysed as measures of evaluation and resource allocation. Fast tempo music decreased the amplitude of the visual P3b with a trend towards significance for larger P3b amplitude in the presence of low intensity music found. However, contrary to the hypothesised effect of intensity on N2 amplitude, the component increased with intensity. Significant latency differences were not observed for either component. The results suggest that the impact of distracting music on cognitive processes varies according to the tempo and intensity of the music; fewer resources are available in the presence of loud, fast music. Email: Race and Fear-Relevance: Resistance to Extinction of Fear-Learning With Other Race Faces is not an Incident of Prepared LearningKimberley Mallan, James Sax and Ottmar Lipp The current study aimed to replicate and extend the observation that fear conditioning with racial out-group faces as CSs shows resistance to extinction (Olsson et al. 2005). In Experiment 1, the impact of verbal instruction on extinction of fear learning with evolutionarily prepared fear relevant (FR; spiders) and non-fear relevant (NFR; birds) stimuli was examined. An unpleasant shock US was paired in a differential fear conditioning paradigm with one CS (CS+) during acquisition whereas a second CS (CS-) was presented alone and no US was presented during extinction. Acquisition of differential fear conditioning, as indexed by larger electrodermal responses and fear-potentiated startle during CS+, was observed in all groups. Resistance to extinction of fear conditioning was present in both FR groups and was not affected by verbal instructions. In Experiment 2, pictures of Caucasian and Chinese faces replaced birds and spiders in a conditioning procedure identical to that used in Experiment 1. Acquisition of differential fear conditioning was observed in all groups. However, resistance to extinction was observed only in uninstructed participants conditioned with out-group (Chinese) faces. This susceptibility to verbal instruction suggests that fear-conditioning with other race faces, though resistant to extinction, is not an incident of prepared learning. Email: Searching for a Trait-Marker of Gray’s BIS: MPQ Harm Avoidance/Control and the Novelty P300Meredith McHugh, Adrian Diery, Penelope Davis and David Shum In 2000, Gray revised his Behavioural Inhibition System (BIS) to account for an observed behavioural, pharmacological and neurological distinction between anxiety (attributed to the BIS) and fear (attributed to the Fight, Flight, Freeze system, FFFS). The revised BIS functions to detect and resolve goal-conflict and inhibit ongoing behaviour. Gray identifies a hippocampal-prefrontal network and associated theta (4-8Hz) activity as the core neurological/neurophysiological basis for the BIS. The novelty P300 has also been linked to hippocampal-prefrontal regions, has a frontal theta component, and is reduced in disorders associated with poor behavioural inhibition (e.g., substance dependence, ADHD). In the current study it was expected that novelty P300 and theta would be positively associated with proposed measures of the new BIS construct (MPQ Harm Avoidance and Control) but unrelated to measures of the former BIS construct (Sensitivity to Punishment, SPSRQ; STAI-T; CW-BIS). Self-report measures were administered to 95 females who completed a visual-oddball task whilst electroencephalography was recorded. Control and Harm Avoidance predicted enhanced novelty P300, but unexpectedly, reduced theta amplitude. SP, STAI-T and CW-BIS were not related to either P300 or theta to novel stimuli. Findings support the construct validity of MPQ Harm Avoidance and Control as measures of Gray’s revised BIS. Email: The Impact of Arousal on Stages of Information ProcessingAmy Peacock and Frances H. Martin This study investigated whether arousal mediates the input stage of information processing, as in Sander’s cognitive-energetic model (1983), or extends to the central and output stages, as shown in previous empirical research. Data from 19 female participants were collected during a stimulus degradation task (intact, low, high) within four separate arousal conditions. Arousal was manipulated through: 80mg of caffeine, 1000mg of taurine, 80mg caffeine and 1000mg taurine combined, and placebo, via double-blind capsule administration. Behavioural measures revealed faster reaction time for caffeine only than placebo, and for intact stimuli compared to high degraded stimuli. The mean amplitude of event-related potentials revealed differential effects of caffeine and taurine across processing stages. The presence of caffeine, either independently or combined with taurine, improved information processing across all stages. The independent administration of taurine was only facilitative at the output stage of processing. Whereas caffeine and taurine combined facilitated performance at the input stage, there was no significant effect at the central stage, and the presence of taurine negated the effect of caffeine at the output stage. The results of this study did not support Sander’s cognitive-energetic model of information processing, suggesting that all processing stages are impacted by modulations in arousal. Email: Cortical Contributions to Probabilistic Category Learning in Healthy AdultsJacqueline A. Rushby,1,2,3 Colleen Loo,1,4 Cynthia S. Weickert1,2,3 and Thomas W. Weickert1,2,3 Functional neuroimaging studies routinely display prefrontal and parietal cortex activation during probabilistic category learning (PCL); however the relative contributions of the prefrontal and parietal cortices to PCL are unknown. Based on previous results suggesting a role for the parietal cortex, the hypothesis for the present study posits that disruption of inferior parietal cortex (iPAR) function will impair PCL whereas disruption of dorsolateral prefrontal cortex (DLPFC) function will not impair PCL. Using a single-blind, cross-over, counter-balanced, within-subject design, low frequency (1 Hz) repetitive transcranial magnetic stimulation (rTMS) was utilised to alternately and transiently disrupt left DLPFC and iPAR function in 23 healthy volunteers during the â??weather predictionâ?? PCL test. Each individual participated in five separate sessions: an initial baseline session without stimulation, followed by randomized administration of active and sham rTMS to the left DLPFC and iPAR. A dissociation in regional engagement of the iPAR relative to the DLPFC was obtained, as reflected in greater acquisition rate impairment only during active iPAR stimulation, suggesting a functional role for the iPAR and not the DLPFC during PCL acquisition. Email: Sequence Effects in the Go/NoGo Task Suggest Conflict Interpretations of N2 and P3Elizabeth A. Smith, Janette L. Smith and Andrew Heathcote In two-choice tasks the preceding sequence of stimuli robustly influences both the P3 ERP component and reaction time (RT) to the current stimulus. We examined sequence effects in both two-choice and Go/NoGo tasks to distinguish between inhibition and conflict accounts of the N2 and P3 components. RT results suggested similar subjective expectancies were generated in the Go/NoGo and two-choice task. N2 was increased for all unexpected stimuli, even when no response inhibition was required, consistent with a conflict interpretation. The Go/NoGo P3 results also suggested a conflict explanation, yet the N2 and P3 were affected in distinctive ways by different stimulus sequences. These results suggest a reconsideration of the roles of N2 and P3 in all inhibition and conflict tasks, and the Go/NoGo task in particular. Email: Homocysteine Compromises Brain Functional Connectivity Modulation in a Recognition Memory TaskRichard B. Silberstein,1,4 Andrew Pipingas,1 Avni Sali2 and Luis Vitetta3 Elevated plasma concentration of homocysteine (HC) is a recognized risk factor for Alzheimer’s dementia. In this study, we investigate the relationship between blood HC concentration and brain functional connectivity changes during a recognition memory task. Thirty eight (38) normal male subjects with a mean age of 58.2 (SD = 4.1) performed a delayed recognition memory task where they had to indicate whether an image had been presented some 30 minutes earlier, and subsequently to identify in which of 4 screen locations it had been presented. While performing the task, the steady state visually evoked potential (SSVEP) was elicited by a spatially uniform 13Hz visual flicker superimposed over the visual field and SSVEP. Event-related partial coherence, an index of brain functional connectivity was calculated during the recognition memory task for all 2016 unique electrode pairs. On calculating the correlation between HC concentration and functional connectivity we found that higher HC levels were associated with increased left-frontal to right occipital functional connectivity, especially at the time subjects were prompted to identify the original object location. This suggests that HC interferes with the capacity to transiently modulate brain functional connectivity. Email: Evidence for the Absence of a Magnocellular Advantage in High Autism Quotient (AQ) ScorersAlexandra Sutherland and David P. Crewther While the behavioural effects of autism spectrum disorder (ASD) can be devastating, many individuals in normal life exhibit certain characteristics of ASD. We were interested in whether differences in early visual processing shown by autistic children would be demonstrated by adult individuals (of normal intelligence) with high versus low autism quotient scores (AQ; Baron-Cohen, 2001). Fifteen low AQ (AQ< 11) and 14 high AQ (AQ > 20) individuals were selected for further testing from a sample of 129 individuals who completed the AQ online. Participants completed a salience-based Navon figures task in which they were asked to identify the global or local form of locally or globally salient (and congruent or incongruent) figures. Non-linear VEPs were measured using the VERIS multifocal system for achromatic stimuli of high (94%) or low (24%) contrast. A nonlinear VEP component reflecting magnocellular pathway activity demonstrated a delay for high AQ compared to low AQ groups at high contrast, such individuals also demonstrating difficulty in identifying the global components of the locally salient Navon figures. Physiological evidence for a delayed magnocellular VEP at high contrast for the high AQ group may help explain locally dominated visual processing in ASD. Email: Facilitation and Inhibition in the Go/NoGo TaskSusan J. Thomas, Craig J. Gonsalvez and Stuart J. Johnstone Facilitation and inhibition are asymmetric aspects of attention that differentially affect response times (RTs), accuracy and neuroelectric activity in many experimental tasks. Both vary as a function of sequences of immediately preceding stimuli, with stimulus repetitions, for example, often resulting in facilitation in terms of speed, accuracy or reduced neural activity. Although inhibition has been extensively studied in the Go/NoGo task, facilitation has been overlooked. Twenty healthy adults performed an adapted Go/NoGo task which manipulated levels of facilitation and inhibition. Event-related potential (ERP) and behavioural measures were averaged according to immediately preceding stimulus sequences in trains. Established Go/Nogo effects for N2 and P3 components were replicated. The preceding context of stimuli systematically affected behavioural and ERP measures for both Go and NoGo stimuli. Go stimulus repetition was associated with marginal reductions in P1 latency, and topographic effects in P1 and N2. As the number of Go stimuli immediately preceding NoGo stimuli increased, N1, P2 and N2 latencies increased. The results suggest that both facilitatory and inhibitory processes underlie performance in the Go/NoGo task. As Go stimuli are typically more frequently presented than NoGo stimuli, facilitatory mechanisms may be confounded with inhibitory processes when sequence effects are not considered. Email: Ad Skipping: Novelty Seeking or Avoidance?Shiree Treleaven-Hassard, Steven Bellman, Peter Drummond, Dee Marevic and Duane Varan. Digital video recorders have made it easier for television viewers to avoid ads by fast forwarding and ad skipping. If viewers skip to avoid ads, they would not be interested in the next ad they skip to. Alternatively, if viewers skip because the current ad is uninteresting, they may still be receptive to the next ad, provided it was interesting for them. Data from 52 students was used to measure skin conductance (SCL) before and after skipping and to investigate whether ad skipping was followed by heart rate deceleration. Data from 5 seconds before and after viewer-controlled ad skips were compared to the same time period before and after the change from one commercial to another. SCL began increasing three seconds prior to ad skipping and continued to increase until three seconds after the ad skip, whereas there was a downward trend across natural commercial changes, so that average SCL was higher in response to skipped ads. These results indicate the decision to skip is associated with increased physiological arousal, consistent with mobilizing physical resources to press the skip button. Males appear to skip to avoid, whereas female skippers are potentially still receptive to the next ad, following a skip. Email: The Influence of Stimulus Degradation on Interference Control in Children With Attention Deficit Hyperactivity Disorder: An ERP InvestigationAnnelie J. Watt and Stuart J. Johnstone Ongoing debate concerns the role of dysfunctional inhibition and interference control (a sub-domain of inhibition) in AD/HD. Whereas Barkley (1997) implicates inhibition as the core deficit, the cognitive-energetic model of AD/HD (Sergeant et al., 1999) considers it secondary to dysfunctional regulation of the energetic pools: effort, activation and arousal. Twenty children with AD/HD and 23 controls aged 7-14 years performed an Eriksen Flanker task whilst EEG and SCL were recorded. Effort was manipulated using three levels of target stimulus degradation. Compared to non-degraded trials, overall task performance improved with moderate target stimulus degradation, but worsened with high degradation. Groups did not differ in SCL or error rate; however, the AD/HD group showed greater reaction time variability, and tended to respond more slowly. Children with AD/HD showed no deficits in response interference at the behavioural level. Two functionally distinct N2 components were apparent, one of which, along with the P3, was larger to incongruent stimuli, thus linking this component to inhibitory processing. Children with AD/HD showed atypical activation and timing of these components, which was not specific to inhibitory processing. Taken together, these findings support the role of other factors such as dysfunctional energetic regulation in AD/HD. Email: |
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