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 6weeks with a task that required maintenance and manipulation of information under low and high working memory loads.

Spatial representation of overlearned arbitrary visuomotor associations.

Our movements can be guided directly by spatial information, but also more flexibly through arbitrary rules. We have recently shown that as arbitrary visuomotor mappings became overlearned, they come to rely not only on fronto-striatal circuits, but also on the posterior parietal cortex (PPC). Since this region supports multiple reference frames for hand movements, the question arose whether overlearned visuomotor associations could come to rely on a spatial framework, similar to spatially guided movements.

Perceptuo-motor interactions during prehension movements.

Adaptive behavior relies on the integration of perceptual and motor processes. In this study, we aimed at characterizing the cerebral processes underlying perceptuo-motor interactions evoked during prehension movements in healthy humans, as measured by means of functional magnetic resonance imaging. We manipulated the viewing conditions (binocular or monocular) during planning of a prehension movement, while parametrically varying the slant of the grasped object.

Parieto-frontal connectivity during visually guided grasping.

Grasping an object requires processing visuospatial information about the extrinsic features (spatial location) and intrinsic features (size, shape, orientation) of the object. Accordingly, manual prehension has been subdivided into a reach component, guiding the hand toward the object on the basis of its extrinsic features, and a grasp component, preshaping the fingers around the center of mass of the object on the basis of its intrinsic features. In neural terms, this distinction has been linked to a dedicated dorsomedial "reaching" circuit and a dorsolateral "grasping" circuit that process extrinsic and intrinsic features, linking occipital areas via parietal regions with the dorsal and ventral premotor cortex, respectively.

The role of immediate and final goals in action planning: an fMRI study.

To interact effectively with our environment, we need to specify the intended outcomes (goals) of our actions. In this process, immediate goals and final goals can be regarded as different levels within a hierarchically organized system for action planning: immediate goals and movement details are selected to accomplish more remote goals. Behavioral studies support this notion of different levels of action planning, but the neurophysiological basis remains unclear.

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.

Cerebral changes during performance of overlearned arbitrary visuomotor associations.

The posterior parietal cortex (PPC) is known to be involved in the control of automatic movements that are spatially guided, such as grasping an apple. We considered whether the PPC might also contribute to the performance of visuomotor associations in which stimuli and responses are linked arbitrarily, such as producing a certain sound for a typographical character when reading aloud or pressing pedals according to the color of a traffic light when driving a motor vehicle. The PPC does not appear to be necessary for learning new arbitrary visuomotor associations, but with extensive training, the PPC can encode nonspatial sensory features of task-relevant cues.

Neural dynamics of error processing in medial frontal cortex.

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.