Regulation of Calcium-Binding Protein Immunoreactivity in GABA Neurons of Macaque Primary Visual Cortex

Monocular deprivation produces an imbalance in visual drivefrom the two eyes, which in adult macaque V1 leads to markedchanges in the neurochemistry of GABA interneurons. Such changeswere further examined by studying immunoreactivity for calbindin,calretinin, and parvalbumin, three calcium-binding proteinsthat mark distinct subpopulations of GABA neurons, in macaquesthat had been monocularly deprived by intravitreal injectionof tetrodotoxin. Deprivation for 5 d or longer produced a reversalin the normal pattern of calbindin immunostaining in layer III,from one in which intense neuronal immunostaining surroundedthe cytochrome oxidase-rich puffs to one in which it occupiedthe puffs. Over the same period, calbindin immunostaining inother layers was reduced across the entire width of deprived-eyecolumns or extended into flanking regions of normal-eye columns.In contrast, reduction in parvalbumin immunostaining occurredonly in deprived-eye columns and included only terminals withshort periods of deprivation (up to 17 d) but both terminalsand somata with longer periods. No change in calretinin immunoreactivitywas observed. These findings demonstrate that GABA neurons ofmacaque V1 vary in their response to monocular deprivation accordingto their neurochemistry and position, suggesting that the weightof inputs from the two eyes and the intrinsic characteristicsof each GABA population determine how a neuron responds to achange in visual input.