TRANSIENT MOLECULAR VISUALIZATION OF OCULAR DOMINANCE COLUMNS (ODCS) IN NORMAL ADULT MARMOSETS DESPITE THE DESEGREGATED TERMINATION OF THE RETINO-GENICULO-CORTICAL PATHWAYS

The activity-dependent immediate early gene protein Krox-24, expressed in the neocortex at high basal levels, decreases rapidly upon neurona l deactivation (Chaudhuri et al. [1995] Vis. Neurosci. 12:35-50). In i nfant marmosets, as in most primates, the geniculo-cortical terminatio ns segregate into eye-specific anatomical ocular dominance columns (OD Cs), which disappear, however, during adolescence (Spatz [1989] Brain Res. 488:376-380), resulting in balanced inputs from the two eyes (Sen gpiel et al. [1996] Vis. Neurosci. 13:145-160). Nevertheless, we found , in adult marmosets, 24 hours after monocular retinal activity blocka de by tetrodotoxin, distinct alternating compartments of potentiated a nd depressed Krox-24-like immunoreactivity (Krox-IR) in layer IV of ar ea 17. This pattern of Krox-IR disappeared at 10 days of retinal silen cing, but was still present at this survival time in stains for cytoch rome oxidase or NADPH-diaphorase. After 20 days of retinal silencing, the pattern was not demonstrable with any of the three stains. We term these compartments physiological ODCs, in contrast to the anatomical ODCs of most primates. If the anatomical ODCs of infant marmosets disa ppear by collateral sprouting into the inappropriate ODCs, then the co llateral geniculo-cortical synapses might differ slightly in their pro perties from the original ones. We silenced the sets of original and c ollateral synapses of the one ocularity. This apparently transiently i nitiated, at the synapses driven by the intact eye, two different comp lex processes leading to molecular potentiation at the original synaps es and to molecular depression at the collateral synapses. J. Comp. Ne urol. 393:118-134, 1998. (C) 1998 Wiley-Liss, Inc.