Subcortical connections of the prefrontal cortex in dogs: afferents to the orbital gyrus.

Afferent subcortical connections to the lateral prefrontal cortex (orbital gyrus) in the dog brain were investigated using the horseradish peroxidase retrograde transport method. It was shown that: (i) the main projection to this area derives from the ventral and intermediate regions of the mediodorsal nucleus of the thalamus, (ii) fairly rich projection arises from the midline, intralaminar as well as from ventromedial and lateroposterior thalamic nuclei, (iii) scanty extrathalamic projection to the lateral prefrontal area originates from several other structures like claustrum, hypothalamus, amygdala, ventral tegmental area, raphe nuclei and locus coeruleus. Distribution of labeled cells after particular injections showed that in the orbital gyrus two subdivisions may be distinguished: dorsal and ventral. It is suggested that the dorsal orbital subdivision in dog corresponds to the lateral prefrontal cortex in monkey.