http://nova.newcastle.edu.au/vital/access/services/Feed ${session.getAttribute("locale")} 5 http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:9437 Individuals with schizophrenia tend to perform poorly on many measures of cognitive control. However, recent task-switching studies suggest that they show intact task-switching performance, despite the fact that the regions involved in task-switching are known to be structurally and functionally impaired in the disorder. Behavioral, event-related potential (ERP) and functional magnetic resonance imaging (fMRI) measures were used to compare the temporal and spatial dynamics of task-switching performance in individuals with schizophrenia and controls. Consistent with previous studies, reaction time (RT) switch cost and its reduction with anticipatory preparation did not differ between groups. There were also no group differences on cue-locked ERP components associated with anticipatory preparation processes. However, both stimulus- and response-locked ERPs were significantly disrupted in schizophrenia, suggesting difficulty with task-set implementation. fMRI analyses indicated that individuals with schizophrenia showed hyperactivity in the dorsolateral prefrontal cortex and posterior parietal cortex. RT-fMRI and ERP-fMRI associations suggested that individuals with schizophrenia employ compensatory mechanisms to overcome difficulties in task-set implementation and thereby achieve the same behavioral outcomes as controls. 2012-01-30T05:14:15.102Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:9438 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. 2012-01-30T05:14:12.567Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:5479 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. 2011-10-25T23:40:03.824Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:1284 Objective: The present study used behavioral and event-related potential (ERP) indices of task-switching to examine whether schizophrenia patients have a specific deficit in anticipatory task-set reconfiguration. Methods: Participants switched between univalent tasks in an alternating runs paradigms with blocked response-stimulus interval (RSI) manipulation (150, 300, 600, and 1200 ms). Nineteen high functioning people with schizophrenia were compared to controls that were matched for age, gender, education and premorbid IQ estimate. Results: Schizophrenia patients had overall increased RT, but no increase in corrected RT switch cost. In the schizophrenia group, ERPs showed reduced activation of the differential positivity in anticipation of switch trial at the optimal 600 ms RSI and reduced activation of the frontal post-stimulus switch negativity at both 600 and 1200 ms RSI compared to the control group. Conclusions:Despite no behavioral differences in task switching performance, anticipatory and stimulus-triggered ERP indices of task-switching suggest group differences in processing of switch and repeat trials, especially at longer RSI conditions that for control participants provide opportunity for anticipatory activation of task-set reconfiguration processes. Significance: These results are compatible with impaired implementation of endogenously driven processes in schizophrenia and greater reliance on external task cues, especially at long preparation intervals. 2010-04-27T06:55:01.518Z ]]>