Abstract

BUENO, José Lino Oliveira  and  BUENO JUNIOR, Lézio Soares. Temporal estimation of rats with hippocampal lesion in operant conditional discrimination. Interam. j. psychol. [online]. 2007, vol.41, n.3, pp. 329-340. ISSN 0034-9690.

The performance of rats with hippocampus´ dentate gyrus lesion was evaluated during an operant conditional discrimination task with manipulation of the duration of the feature-stimulus. Sixteen rats under water deprivation were used: eight lesioned in the dentate gyrus by colchicine microinjections and eight sham-operated. The rats were submitted to a conditional discrimination training with feature-positive practices (L15T5+ and T5-) and feature-negative practices (L5R15- and R15+), where L is feature-stimulus white light, T (pure tone) and R (white noise) are target-stimuli, 5 and 15 are durations in seconds, arrow () is a 5 s empty interval and + and - are presence and absence of reinforcement, respectively. In the test, practices in extinction were used, with L durations of 15, 13, 11, 9, 7 and 5 s. The data indicated acquisition of positive and negative conditional discrimination, without differences between the experimental group and the control group. Different durations of a stimulus can acquire conditional properties. However, the feature-stimulus duration processing apparently do not depends on the hippocampus´ dentate gyrus alone.

Keywords : Temporal estimation; Conditional discrimination; Hippocampus; Lesion; Rats.

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