Neural dynamics of error processing in medial frontal cortex.

Contains fulltext : 56338.pdf (publisher's version ) (Closed access)Adaptive behavior requires an organism to evaluate the outcome of its actions, such that future behavior can be adjusted accordingly and the appropriate response selected. During associative learning, the time at which such evaluative information is available changes as learning progresses, from the delivery of performance feedback early in learning to the execution of the response itself during learned performance. Here, we report a learning-dependent shift in the timing of activation in the rostral cingulate zone of the anterior cingulate cortex from external error feedback to internal error detection. This pattern of activity is seen only in the anterior cingulate, not in the presupplementary motor area. The dynamics of these reciprocal changes are consistent with the claim that the rostral cingulate zone is involved in response selection on the basis of the expected outcome of an action. Specifically, these data illustrate how the anterior cingulate receives evaluative information, indicating that an action has not produced the desired result

Dynamics of visual recognition revealed by fMRI

In our daily lives, recognizing a familiar object is an effortless and seemingly instantaneous process. Our knowledge of how the brain accomplished this formidable task, however, is quite limited. The present study takes a holistic approach to examining the neural processes that underlie recognition memory. A unique paradigm, in which visual information about the identity of a person or word is slowly titrated to human observers during a functional imaging session, is employed to uncover the dynamics of the visual recognition in the brain. The results of study reveal multiple unique stages in visual recognition that can be dissociated from one another based on temporal asynchronies and hemodynamic response characteristics.14 page(s

Practice effects in the brain: changes in cerebral activation after working memory practice depend on task demands

Several studies have examined the neural effects of working memory practice, but due to different task demands, diverse patterns of neural changes have been reported. In the present study, we examined neural effects of practice using a task with different working memory demands within a single practice paradigm. Fifteen adults practiced during 6 weeks with a task that required maintenance and manipulation of information under low and high working memory loads. Functional magnetic resonance imaging (FMRI) data were acquired in the first week and last week of the practice period. Results were compared with results of a control group who did not practice the task. We demonstrated that practice was beneficial for both working memory maintenance and manipulation processes but that these processes were supported by different neural changes. While maintenance trials showed increased activation (i.e., less deactivation) in default-mode regions after practice, manipulation trials experienced increased activation in the striatum. Changes were also observed in left ventrolateral prefrontal cortex (VLPFC), bilateral dorsolateral prefrontal cortex (DLPFC) and left superior parietal cortex (SPC). However, for bilateral DLPFC and left SPC, these changes were not specific to the practice group. These findings illustrate the importance of controlling for test-retest effects in training or intervention studies. Behavioral follow-up tests demonstrated that practice effects lasted over a 6-month period, but the absence of transfer effects indicated that the acquired skills were specific for the practiced working memory task

Spatial representation of overlearned arbitrary visuomotor associations

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