Cocaine affects cerebral neocortical cytoarchitecture in primates only if administered during neocortical neuronogenesis

Previously, we demonstrated that chronic exposure of fetal monkeys to cocai ne could result in development of the neocortex with significant cytoarchit ectonic abnormalities [Synapse, 21 (1995) 435-444]. In the present study, w e examined the developmental time-frame within which neocortical cytoarchit ecture is susceptible to modifications by prenatal cocaine exposure. For th is purpose, we assessed the integrity of cortical lamination and the positi on, density, and total number of occipital cortical neurons in 2-month-old monkeys which were prenatally exposed to chronic cocaine treatment either p rior to the period of neocortical neuronogenesis, during the period of neoc ortical neuronogenesis, or after the period of neocortical neuronogenesis. We found that cocaine can interfere with the neocortical laminar organizati on and induce a reduction in the density and number of neocortical neurons only if it is administered at the time of neocortical neuronogenesis. Durin g this window of vulnerability, an abnormal neocortex is generated as long as cocaine exposure is maintained, with corticogenesis becoming normal as s oon as the administration of this drug is discontinued. (C) 2001 Elsevier S cience BN. All rights reserved.