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Results for “Reversal Learning”

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At least 775 records · Page 43Linked to original sources
PubMed2005

Rapid associative encoding in basolateral amygdala depends on connections with orbitofrontal cortex.

Certain goal-directed behaviors depend upon interactions between basolateral amygdala (ABL) and orbitofrontal cortex (OFC). Here we describe neurophysiological evidence of this cooperative function. We recorded from ABL in intact and OFC-lesioned rats during learning of odor discrimination problems and reversals. During learning, rats with ipsilateral OFC lesions exhibited a marked decline in the proportion of ABL neurons that fired differentially during cue sampling both before and after reversal and in the proportion of neurons that reversed odor preference when the odor-outcome associations were reversed. This decline appeared to reflect a loss of rapid flexibility in cue selectivity that characterized activity in intact rats. In addition, lesioned rats had fewer neurons that fired in anticipation of the predicted outcome during a delay period after responding but before outcome delivery. These findings support a role for OFC in facilitating the encoding of information about expected outcomes in ABL.

Amygdala↗
PubMed2005

Contextual modulation of spatial discrimination reversal in developing rats.

Reversal of discrimination learning is influenced by manipulation of the training context. In adult and developing rats, contextual changes made between acquisition and reversal aid the learning of the new discrimination, possibly by serving to release proactive interference from the originally acquired discrimination (M. E. Bouton & D. C. Brooks, 1993; N. Spear, G. Smith, R. Bryan, & W. Gordon, 1980). The present study sought to examine this effect in an appetitive T-maze task, as a function of different contextual manipulations. Rats of three ages, Postnatal Day (PND) 19, PND23, and PND30, were tested for their ability to acquire and reverse a position habit in a T-maze. Contextual changes were made between acquisition and reversal sessions and consisted of one of three manipulations: (a) texture; the texture of the maze floor was changed via the addition or subtraction of wire mesh; (b) maze; subjects were reversed in a different maze that was identical in construction to the training maze, but differed in spatial location; (c) texture and maze; subjects were shifted to the new maze, the floor of which differed in texture from the training maze but was otherwise identical in construction. Results showed that the texture-maze combination was an effective aid to reversal learning at all ages tested. The texture alone, however, was not effective at any age. The maze alone also was an effective cue for reversal, but proved to have the greatest effect for PND30 subjects. During ontogeny, the contextual modulation of reversal learning is importantly influenced by the nature and the salience of the contextual cue.

Age Factors↗
PubMed2005

Deficits on a probabilistic response-reversal task in patients with pediatric bipolar disorder.

OBJECTIVE: Patients with bipolar disorder become hyperhedonic when manic and anhedonic when depressed; therefore, it is important to test whether patients with bipolar disorder show deficits on behavioral paradigms exploring reward/punishment mechanisms. METHOD: A probabilistic response-reversal task was administered to 24 bipolar children and 25 comparison subjects. RESULTS: Patients made more errors during probabilistic reversal, took longer to learn the new reward object, and were less likely to meet the learning criterion. CONCLUSIONS: Children with bipolar disorder may have a reversal learning deficit.

Adolescent↗
PubMed1987

Effects of selective lesions of fimbria-fornix on learning set in the rat.

The effects of selective partial lesions of the Fimbria-Fornix (FiFx) on reversal and place learning sets were investigated in rats by using a T-maze and a semi-circular multiple discrimination apparatus. Lesions restricted to the Fimbria (Fi) produced a significant deficit in reversal and place learning set, whereas lesions to the Fornix (Fx) only disturbed the learning set based on a reversal procedure. Combined Fi + Fx lesions resulted in impairment in the retention of spatial discrimination tested in the two mazes. Ventral Hippocampal Commissure (vhc) had no significant effect on reversal learning set. These results confirm previous data that the hippocampal formation is involved in learning transfer, and suggest that the Fi and the Fx may play a role in learning set. Our data also confirm previous demonstrations of the ability of rats to rapidly acquire place learning set.

Animals↗
PubMed1996

Kindling of hippocampal field CA1 impairs spatial learning and retention in the Morris water maze.

We used two procedures to assess the spatial learning and memory of rats in the Morris water maze task subsequent to kindling of hippocampal field CA1: (1) seizures were kindled with stimulation of CA1 prior to training in the water maze (acquisition); and (2) maze training was imposed until performance stabilized, seizures were kindled with stimulation of CA1, and then performance in the maze was reassessed (retention). In both conditions, behavioral testing occurred 24 h after the last kindled seizure. When the effects of CA1 kindling on acquisition were tested, we found that kindling of generalized seizures with stimulation of field CA1 (kindling), but not kindling of non-convulsive or partial seizures (partial kindling), produced deficits in the water maze. When the effects of CA1 kindling on retention were tested, however, we found that kindling of either partial or generalized seizures produced deficits in the water maze. The results suggest that the processing of spatial information is vulnerable to the long-lasting changes in neural excitability associated with kindling.

Animals↗
PubMed1993

Context specificity of operant discriminative performance in pigeons: II. Necessary and sufficient conditions.

Six experiments were performed to explore the necessary and sufficient conditions for producing context specificity of discriminative operant performance in pigeons. In Experiment 1, pigeons learned a successive discrimination (red S+/blue S-) in two chambers that had a particular odor present and between which they were frequently switched. The birds subsequently learned the reversal (blue S+/ red S-) in one of these chambers with a different odor present. When switched to the alternative chamber, although the odor and the reinforcement contingency were still appropriate to the reversal, performance appropriate to the original discrimination recurred in subjects for which the houselights were on during training and testing but not for those for which the houselights were off. This indicated the importance of visual contextual cues in producing context specificity. Experiment 2 showed that the frequent switching between boxes in initial training was of no consequence, presumably because the apparatus cues were highly salient to the subjects. Experiment 3 showed significantly less context specificity when odor cues were omitted. Experiment 4 showed that simply using a different reinforced stimulus in each phase of training was ineffective in producing context specificity. Experiment 5 showed that the generalization test procedure used in Experiment 4 was sensitive to context specificity when discrimination-reversal training was used with different odors in the two training phases. Experiment 6 replicated the results of Experiment 4, but then showed that when different odors accompanied the two training phases, context specificity was obtained with the single-stimulus paradigm. Thus in both single-stimulus and discrimination-reversal paradigms, redundant odor cues potentiated learning about apparatus cues.

Journal Article↗