Matthew Hughes

The spatial and temporal dynamics of anticipatory preparation and response inhibition in task-switching

We investigated ERP and fMRI correlates of anticipatory preparation and response inhibition in a cued task-switching paradigm with informatively cued, non-informatively cued and no-go trials. Cue-locked ERPs showed evidence for a multicomponent preparation process. An early cue-locked differential positivity was larger for informative vs. non-informative cues and its amplitude correlated with differential activity for informatively vs. non-informatively cued trials in the dorsolateral prefrontal cortex (DLPFC), consistent with a goal activation process. A later differential positivity was larger for informatively cued switch vs. repeat trials and its amplitude correlated with informatively cued switch vs. repeat activity in the posterior parietal cortex (PPC), compatible with a category-response (C-R) rule activation process. No-go trials elicited a frontal P3, whose amplitude was negatively correlated with activity in the ventrolateral prefrontal cortex (VLPFC) and basal ganglia motor network, suggesting that a network responsible for response execution was inhibited in the course of a no-go trial. These findings indicate that anticipatory preparation in task-switching is comprised of at least two processes: goal activation and C-R rule activation. They also support a functional dissociation between DLPFC and VLPFC, with the former involved in top-down biasing and the latter involved in response inhibition.

The Potential for New Understandings of Normal and Abnormal Cognition by Integration of Neuroimaging and Behavioral Data: Not an Exercise in Carrying Coals to Newcastle

Discovering the means to prevent and cure schizophrenia is a vision that motivates many scientists. But in order to achieve this goal, we need to understand its neurobiological basis. The emergent metadiscipline of cognitive neuroscience fields an impressive array of tools that can be marshaled towards achieving this goal, including powerful new methods of imaging the brain (both structural and functional) as well as assessments of perceptual and cognitive capacities based on psychophysical procedures, experimental tasks and models developed by cognitive science. We believe that the integration of data from this array of tools offers the greatest possibilities and potential for advancing understanding of the neural basis of not only normal cognition but also the cognitive impairments that are fundamental to schizophrenia. Since sufficient expertise in the application of these tools and methods rarely reside in a single individual, or even a single laboratory, collaboration is a key element in this endeavor. Here, we review some of the products of our integrative efforts in collaboration with our colleagues on the East Coast of Australia and Pacific Rim. This research focuses on the neural basis of executive function deficits and impairments in early auditory processing in patients using various combinations of performance indices (from perceptual and cognitive paradigms), ERPs, fMRI and sMRI. In each case, integration of two or more sources of information provides more information than any one source alone by revealing new insights into structure-function relationships. Furthermore, the addition of other imaging methodologies (such as DTI) and approaches (such as computational models of cognition) offers new horizons in human brain imaging research and in understanding human behavior.

Static and dynamic face emotion processing in adults along the autism spectrum: an fMRI study

The N400 is a human neuroelectric response to semantic incongruity in on-line sentence processing, and implausibility in context has been identified as one of the factors that influence the size of the N400. In this paper we investigate whether predictors derived from Latent Semantic Analysis, language models, and Roark’s parser are significant in modeling of the N400m (the neuromagnetic version of the N400). We also investigate significance of a novel pairwise-priming language model based on the IBM Model 1 translation model. Our experiments show that all the predictors are significant. Moreover, we show that predictors based on the 4-gram language model and the pairwise-priming language model are highly correlated with the manual annotation of contextual plausibility, suggesting that these predictors are capable of playing the same role as the manual annotations in prediction of the N400m response. We also show that the proposed predictors can be grouped into two clusters of significant predictors, suggesting that each cluster is capturing a different characteristic of the N400m response.s From Peer-Reviewed Presentations at the Australasian Cognitive Neurosciences Conference (21st meeting of the Australasian Society for Psychophysiology), December 9-12, 2012, Macquarie University, Sydney, Australia Keynote Presentations The Prospective Brain: Using the Past to Imagine the Future Donna Rose Addis Department of Psychology, The University of Auckland Recently, traditional theories of episodic memory have been extended to consider the role of memory in future thinking. In particular, patient and neuroimaging research suggests that episodic memory and associated neural structures such as the hippocampus may play a critical role in future simulation. I will describe a number of studies that examine how flexible and constructive memory processes, supported by the hippocampus and associated networks, allow us to construct detailed simulations that serve to guide and enhance our future behaviours. Limits of Subliminal Processing and Signatures of Conscious Access Stanislas Dehaene INSERM-CEA Cognitive Neuroimaging Unit, Collège de France The nature of conscious processing can be investigated by presenting subjects with stimuli below, at, or above the threshold for conscious reportability, and evaluating how their cognitive and cerebral processing differs. I will present new experiments that, on the one hand, extend the known limits of subliminal processing and, on the other hand, reveal specific processes that can only be deployed consciously. The results suggest that, non-consciously, evidence can be accrued in parallel and from multiple target stimuli, thus biasing even complex cognitive processes (e.g. addition or averaging). However, conscious processing is characterised by the flexible deployment of strategic top-down processes. Neural signatures of conscious processing are characterised by long-lasting and long-distance interactions in the beta and alpha frequency bands, compatible with the theory of a global neuronal workspace for conscious processing. Temporal Processing in Neurodevelopmental Disorders Revisited Joel B. Talcott School of Life and Health Sciences, Aston University Many neurodevelopmental disorders are characterised by a constellation of symptoms that extend well beyond the core cognitive deficit and which overlap highly with diagnostic features associated with presumed independent disorder phenotypes. One such instance of symptom overlap is a deficit in the perception and processing of those temporal dimensions of stimuli that occur on a timescale of milliseconds. Deficits of this kind are frequently reported in neurodevelopmental disorders. However, the effect-size correlations between measures of this construct and the core cognitive and behavioural symptoms of the disorder are rarely as large as those demonstrated in comparisons between deficit and non-deficit groups. This suggests that stimulus timing, a generic functional property of the nervous system, may help to explain the high diagnostic comorbidity of some of these neurodevelopmental disorders, though perhaps less so their unique symptom sets. Using developmental dyslexia and co-morbid disorders as a model, this presentation will evaluate some of central methodological and theoretical issues for current research and for future investigations of temporal processing deficits as candidate endophenotypes of developmental disorder. Neural Oscillations in Schizophrenia and during Brain Development: Perspectives From Magnetoencephalography Peter J. Uhlhaas Department of Neurophysiology, Max-Planck Institute for Brain

Functional brain imaging of auditory prepulse inhibition.

280 this study was to use functional magnetic resonance imaging (fMRI) to identify the neural circuits underlying disturbances processing oddball stimuli in fi rstepisode schizophrenia (FES). Method: fMRI data were collected from 24 people with FES (within 3 months of service contact) and 24 matched healthy controls while performing an auditory oddball task comprising 15% target (high) tones and 85% standard (low) tones. Data were analyzed in SPM2, with event-related analysis of the supramarginal gyrus, thalamus, and limbic and prefrontal cortical areas. Results: The FES group showed signifi cantly reduced activity in the thalamus, hippocampus, dorsal lateral prefrontal cortex and supramarginal gyrus, but a pattern of enhancement as well as reduction in medial prefrontal/anterior cingulate activity, compared with controls. Conclusions: These fi ndings suggest that schizophrenia is associated with impairments in networks for processing salience as well as context from the fi rst episode of this illness. Dysregulation of medial prefrontal areas may refl ect an attempt to compensate for a fundamental breakdown in the coordination of these processes.