CNS Function in Cocaine Babies

Chelonis, John

Abstract

The research described in this proposal is designed to determine whether chronic exposure to cocaine in utero results in long-term or residual functional consequences in rhesus monkey offspring as adults. It was determined previously that the ability of cocaine-exposed offspring to learn to perform several complex behavioral tasks at a young age was no different from that of control subjects. A variety of tasks were utilized, including those thought to model aspects of learning, short-term memory, color and position discrimination and motivation. Likewise, data to date suggest that these offspring are not different from controls in their behavioral responses to pharmacological challenges with a variety of centrally acting compounds chosen to interact with specific neurotransmitter systems. These data, thus, suggest that the neural circuitry subserving performance of these complex behaviors survives intact and that important neurochemical systems appear to be functioning normally in these animals. Preliminary data recently obtained from the oldest offspring in this group are now suggesting that animals exposed to cocaine in utero are, as adults, showing severe problems in adjusting to important changes in their environment: the rules of reinforcement associated with the performance of a task with which they have had extensive history. Such behavioral challenges, or reversals, may prove to be useful tools for unmasking abnormalities in CNS function in subjects that otherwise appear to be normal. The purpose of the current proposal is to obtain additional data from other animals exposed to cocaine in utero so that we can further support or refute the findings from our preliminary reversal data. In the color and position discrimination task, subjects are presented with a red, yellow, blue or green stimulus that determines the correctness of subsequent position choices: left for red or yellow; right for blue or green. In the present study, the rules will be changed such that the correct position choices are reversed (left for green or blue, right for red or yellow). The number of sessions required by subjects to master the new rules of reinforcement will provide data concerning the ability of these animals to cope with important changes in their environment and demonstrate how developmental cocaine exposure can affect those processes.