Neurochemical gradient along the monkey occipito-temporal cortical pathway.

We have examined the neuronal distribution of two calcium-binding proteins, calbindin (CB) and parvalbumin (PV), along the occipito-temporal cortical pathway, which sequentially connects visual areas V1, V2, V4, TEO, and TE, and then areas TG and 36 in monkeys. Immunohistochemical staining showed that CB-containing pyramidal cells, which were mostly limited to layers 2 and 3, gradually increased in population from the posterior to the anterior areas. PV-containing non-pyramidal cells were sparser in areas TG and 36 than in the other areas. The posterior and anterior areas of the occipito-temporal cortical pathway are different in the chemical characteristics of their neurones.