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Schedule-controlled learning and memory in a regulatory context
Citation:
Bushnell, P. Schedule-controlled learning and memory in a regulatory context. Presented at Neurobehavioral Toxicology Society Meeting, Tucson, AZ, June 26, 2013.
Impact/Purpose:
This abstract will be presented at the Neurobehavioral Toxicology Society Meeting in Tucson, AZ., June 26, 2013
Description:
Control of behavior by the manipulation of contingencies provides powerful techniques for assessing the hazard of chemical toxicants on the nervous system. When applied to evaluate the consequences of developmental exposure, these techniques are well suited for characterizing persistent effects on cognitive functions including learning, memory and attention, due to their ability to specify effects on cognitive processes in relation to sensorimotor dysfunction or altered motivation. However, the extensive training required for their implementation renders most of these methods unsuitable for screening-level tests, so they are often excluded from routine toxicity assessments. This exclusion is based on a lack of evidence that cognitive deficits were present at doses of selected toxicants lower than those that altered screening-level behavioral tests after exposures during adulthood. However, the same case is difficult to make for developmental exposure: for example, it is unlikely that the persistent cognitive consequences of exposure to lead or PCBs during development could be predicted by a screening battery applied during adulthood. In addition, in recent work at the EPA, an operant reaction-time method has revealed evidence for impulsivity in the offspring of rats exposed to vapors of ethanol or gasoline in utero, in the absence of systematic effects on other neurobehavioral or neurophysiological outcome measures. Thus tests of cognitive function may continue to be useful for developmental neurotoxicity testing. In addition, these tests can provide evidence to characterize effects, dose-response, and potential health impacts in support of regulatory decisions based on effects observed in humans or obtained from screening tests. This abstract does not represent or reflect EPA policy.