Prearcuate cortex in the cebus monkey has cortical and subcortical connections like the macaque frontal eye field and projects to fastigial-recipient oculomotor-related brainstem nuclei

Abstract

The cortical and subcortical connections of the prearcuate cortex were studied in capuchin monkeys ( Cebus apella, albifrons) using the anterograde and retrograde transport capabilities of the horseradish peroxidase technique. The findings demonstrate remarkable similarities to those of the macaque frontal eye field and strongly support their homology. The report then focuses on specific prearcuate projections to oculomotor-related brainstem nuclei that were shown in a companion experiment to entertain connections with the caudal oculomotor portion of the cerebellar fastigial nucleus. The principal corticorticol connections of the cebus prearcuate cortex were with dorsomedial prefrontal cortex, lateral intraparietal sulcal cortex, posterior medial parietal cortex, and superior temporal sulcal cortex, which were for the most part reciprocal and columnar in organization. The connections of the dorsal prearcuate region were heavier to the dorsomedial prefrontal and posterior medial parietal cortices, and those of the ventral region were heavier to the superior temporal sulcal cortex. The prearcuate cortex projects to several brainstem areas which also receive projections from the caudal fastigial nucleus, including the supraoculomotor periaqueductal gray matter, superior colliculus, medial nucleus reticularis tegmenti pontis, dorsomedial basilar pontine nucleus, dorsolateral basilar pontine nucleus, nucleus reticularis pontis caudalis, pontine raphe, and nucleus prepositus hypoglossi. The findings define a neuroanatomical framework within which convergence of prearcuate (putative frontal eye field) and caudal fastigial nucleus connections might occur, facilitating their potential interaction in saccadic and smooth pursuit eye movement.