Distribution of α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionate‐type glutamate receptor subunits (GluR2/3) along the ventral visual pathway in the monkey

By using immunohistochemical methods, we examined the distribution of cells expressing subunits of α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionate (AMPA)‐selective glutamate receptors (GluR2/3) in the cortical areas of the occipitotemporal pathway in monkeys. GluR2/3‐immunoreactive (‐ir) cells were primarily pyramidal cells; this category, however, also included large stellate cells in layer IVB of the striate cortex (V1) and fusiform cells in layer VI of all the areas examined. GluR2/3 immunoreactivity differed among the areas in laminar distribution and intensity. In V1, GluR2/3‐ir cells were identified mainly in layers II, III, IVB, and VI. The prestriate areas V2 and V4 and the inferior temporal areas TEO and TE contained GluR2/3‐ir cells in layers II, III, and VI. In the TE, GluR2/3‐ir cells were also abundant in layer V. In area 36 of the perirhinal cortex, neurons in layers II, III, V, and VI were labeled in a similar manner to the TE labeling, but with greater staining intensity and numbers, especially in layer V. Thus, GluR2/3 immunoreactivity increased rostrally along the pathway. Within V1 and V2, cells strongly stained for GluR2/3 formed clusters that colocalized with cytochrome oxidase (CO)‐rich regions. These distinct laminar and regional distribution patterns of GluR2/3 expression may contribute to the specific physiological properties of neurons within various visual areas and compartments. J. Comp. Neurol. 456:396–407, 2003. © 2003 Wiley‐Liss, Inc.