Cortico-Cortical Projection to the Inferior Prefrontal Cortex Via the Uncinate Fascicle in the Rhesus Monkey
Pelak, Victoria S.
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The cortico-cortical projection from the anterior portion of the temporal lobe to the inferior prefrontal cortex by way of the uncinate fascicle in the rhesus monkey (Macaca mulatta) was investigated. In order to trace the pathway of the uncinate fascicle, one monkey was injected with tritiated amino acids, which are retrogradely transported, in the anterior inferior temporal cortex. Another monkey received bilateral injections of the inferior prefrontal cortex with two fluorescent dyes, which are anterogradely transported, in order to determine all the regions projecting to this cortex. In two other monkeys, unilateral lesions of the uncinate fascicle were made, and a fluorescent dye was injected in the inferior prefrontal cortex of the same hemisphere, in order to determine the precise areas that send projections through this fiber bundle. The uncinate fascicle was observed to project anteriorly from the inferior temporal cortex, and then to course dorsally toward the inferior prefrontal cortex, where it terminates in the inferior limb of the arcuate sulcus and on the inferior prefrontal convexity ventral to the principal sulcus. Regions in the temporal cortex that were found to project to the prefrontal cortex via the uncinate fascicle include the rostral portion of areas TA and TE, area TG, and possibly anterior portions of area STP. The premotor cortex and areas PF and PG were also found to project to prefrontal cortex, but these regions do not project via the uncinate fascicle.