Contralateral connections of the dog's frontal association cortex

We studied the topography of contralateral connections of both prefrontal and premotor regions of the dog's frontal association cortex (FAC) by charting distributions of retrogradely labeled cells following unilateral HRP injections to various areas of this cortex. Generally, in the contralateral hemisphere the labeled cells were most numerous in the FAC areas localized homotopically to the injection sites, less numerous in FAC areas heterotopic to injections, and the least numerous in cortical areas situated outside the frontal lobe. The nonfrontal areas which project to the dorsal and ventral FAC differ from one another. Dorso-caudal parts of the cingular and insular areas, as well as the auditory, somatosensory and visual association cortices project to the dorsal FAC, while the ventro-rostral parts of the cingular and insular areas, together with the prepiriform and periamygdaloid areas of the olfactory cortex as well as the subcallosal area send their axons to the ventral FAC. Thus, the dorsal and ventral FAC areas are supplied by contralateral afferents originating from different cortical areas. Similar organization of ipsilateral FAC connections was described previously.