Discrete-trial alternation in the rat

Reinforcement schedules: the role of responses preceding the one that produces the reinforcer

In a two-key pigeon chamber, variable-interval reinforcement was scheduled for a specified number of pecks, emitted either on a single key or in a particular sequence on the two keys. Although the distribution of pecks between the two keys was affected by whether pecks were required on one or on both keys, the total pecks emitted was not; the change from a one-key to a two-key requirement simply moved some pecks from one key to the other. Thus, each peck preceding the one that produced the reinforcer contributed independently to the subsequent rate of responding; the contribution of a particular peck in the sequence was determined by the time between its emission and the delivery of the reinforcer (delay of reinforcement), and was identified by the proportion of pecks moved from one key to the other when the response requirement at that point in the sequence was moved from one key to the other.

Effects of pesticides and drugs on working memory in rats: continuous delayed response

Effects of four pesticides (carbaryl, propoxur, chlordimeform, and deltamethrin) and four reference drugs (physostigmine, scopolamine, methscopolamine, and chlordiazepoxide) were measured in two delayed response, working memory procedures: go-no go alternation in which rats initiated their own trials, and spatial reversals. Four of these compounds (carbaryl, propoxur, physostigmine, and scopolamine) were also tested in a go-no go alternation procedure in which animals did not initiate their trials. The pesticides and physostigmine did not selectively affect working memory in any of the procedures: low doses only moderately decreased response accuracy, whereas higher doses suppressed responding indiscriminately. The pesticides and physostigmine had similar effects on go-no go alternation (i.e., working memory) and analogous go-no go discrimination performance. Effects on go-no go alternation performance did not depend on whether the animals initiated their own trials. Scopolamine, in contrast, appeared to disrupt working memory. It profoundly disrupted accuracy at doses that only moderately decreased over-all responding and impaired go-no go alternation accuracy much more than discrimination accuracy.