Cerebral cortex
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The brain determines positions and movements of body parts from inputs arising at least from vision and proprioception. Using the brain event-related potential called the lateralized readiness potential, which reflects motor cortical activity during motor programming, we showed in a motor task that viewing one hand in a sagittal mirror-giving the impression to see the opposite hand-generated activity in the motor cortex of the seen hand (i.e., of the nonmoving hand hidden behind the mirror). ⋯ This dominance vision over proprioception was greatly reduced when the task was executed in the dark with hand position represented by small lights fixed on the moving hand, with no motor activity being recorded in the cortical area of the inactive hand. These results give new insights into how the brain weights and integrates visual and proprioceptive information in motor control.
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The oligodendrocyte myelin glycoprotein is a glycosylphosphatidylinositol-anchored protein expressed by neurons and oligodendrocytes in the central nervous system. Attempts have been made to identify the functions of the myelin-associated inhibitory proteins (MAIPs) after axonal lesion or in neurodegeneration. However, the developmental roles of some of these proteins and their receptors remain elusive. ⋯ At the cellular level, we located OMgp neuronal membranes in dendrites and axons as well as in brain synaptosome fractions and axon varicosities. Lastly, the analysis of the barrel field in OMgp-deficient mice revealed that although thalamo-cortical connections were formed, their targeting in layer IV was altered, and numerous axons ectopically invaded layers II-III. Our data support the idea that early expressed MAIPs play an active role during development and point to OMgp participating in thalamo-cortical connections.
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Damage to various regions of the prefrontal cortex (PFC) impairs decision making involving evaluations about risks and rewards. However, the specific contributions that different PFC subregions make to risk-based decision making are unclear. We investigated the effects of reversible inactivation of 4 subregions of the rat PFC (prelimbic medial PFC, orbitofrontal cortex [OFC], anterior cingulate, and insular cortex) on probabilistic (or risk) discounting. ⋯ Anterior cingulate or insular inactivations were without effect. The effects of prelimbic inactivations were not attributable to disruptions in response flexibility or judgments about the relative value of probabilistic rewards. Thus, the prelimbic, but not other PFC regions, plays a critical role in risk discounting, integrating information about changing reward probabilities to update value representations that facilitate efficient decision making.