Three types of experiments will be conducted. One type will use reversible cooling techniques to inactivate temporarily various discrete OT and OP regions, and to assess the effects of cooling on a range of behavioral functions. These functions include orienting, detection of movement, segregation of static from moving features, and pattern and object discrimination. It is hypothesized that cooling OP will selectively disrupt orienting, and spatial and motion processing, whereas cooling OT will have principal effects on the perception of static patterns and objects. The extent of cooling-produced neuronal inactivation will be verified electrophysiologically. The second and third types of experiments will trace the afferent and efferent connections to OP and OT regions. Red and green fluorescing microspheres will be injected into OP and OT cortices, and the distribution of labelled afferents in thalamic, neocortical and limbic areas will be determined. It is predicted that the OP and OT regions will receive inputs from similar nuclei but in varying proportion. Efferent connections will be identified by injecting an anterograde tracer into OT and OP regions and counting the number of labelled boutons in limbic and neocortical destinations.It is predicted that OT cortex targets parahippocampal and rhinal cortices, whereas the output from OP cortex reaches cingulate and retrosplenial cortices.
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