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Results for “Reversal Learning”

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At least 955 records · Page 53Linked to original sources
PubMed1982

Negative transfer abolished by REM sleep deprivation in rats.

Brief deprivation of REM sleep (REMD) immediately following inhibitory avoidance training abolished negative transfer in an active avoidance situation without impairing retention of the inhibitory avoidance response. REMD beginning 3 hr after inhibitory training had no effect. A reminder treatment (brief placement in the apparatus) between 30 min and 24 hr before active avoidance training counteracted the REMD impairment of negative transfer. The reminder treatment was not impaired by subsequent REMD.

Animals↗
PubMed1986

Memory formation in birds: 1. Avoidance conditioning of the budgerigar (Melopsittacus undulatus) to sound stimuli.

A system is described for avoidance conditioning of the budgerigar (Melopsittacus undulatus), for sound patterns consisting of one or two sequential subunits and to discriminate between two closely resembling sounds. Electric shock was used as the unconditioned stimulus. Simple conditioning was accomplished in about 300-400 trials. After a given sound pattern was firmly fixed by conditioning, discrimination between this and a new sound pattern was established relatively rapidly by using several consecutive sessions in which the two patterns were mixed. Discrimination was reinforced by associating the two signals by opposing electric shocks. An overnight rest period after the first few sessions improved the rate of conditioning during the following experimental period. A temporary, partial or complete extinction of conditioning was produced by longer rest intervals, but the original conditioning was reestablished by subjecting the animal to a few trials of reconditioning. Short intercalations of a new conditioned stimulus had no effect on the retention of the original conditioning whereas a random mixing of the first conditioned stimulus with a second produced a temporary decay in the original conditioning. The experimental system described here is useful for studying physiological and biochemical changes accompanying a memory process based on a linear sequence of sound patterns.

Animals↗
PubMed2006

Use of salient and non-salient visuospatial cues by rats in the Morris Water Maze.

In the Morris Water Maze (MWM), an animal learns the location of a hidden platform relative to distal visual cues in a process known as spatial learning. The visual cues used in MWM experiments are invariably salient in nature, and non-salient cues, such as subtle environmental variations, have not traditionally been considered to play a significant role. However, the role of non-salient cues in spatial navigation has not been adequately investigated experimentally. The objective of this experiment was therefore to determine the relative contribution of salient and non-salient visual cues to spatial navigation in the MWM. Animals were presented with an environment containing both types of visual cues, and were tested in three successive phases of water maze testing, each with a new platform location. Probe tests were used to assess spatial accuracy, and several cue variation trials were run in which both salient and non-salient visual cues were manipulated. It was observed that removal of the salient visual cues did not cause a significant deterioration in performance unless accompanied by disruption of the non-salient visual cues, and that spatial navigation was unimpaired when only the salient visual cues were removed from view. This suggests that during place learning in Long-Evans rats, non-salient visual cues may play a dominant role, at least when salient cue presentation is limited to four cues.

Analysis of Variance↗
PubMed1986

Brain stem reticular formation neuronal correlates of stimulus significance and behavior during discriminative avoidance conditioning in rabbits.

Multiple-unit activity in the reticular formation of the midbrain and pons was recorded in rabbits during discriminative conditioning of locomotor (wheel-running) avoidance behavior. The conditional stimuli (CS+ and CS-) were pure tones of different auditory frequency, and the unconditional stimulus (US) was a constant-current footshock (1.5-2.5 mA) delivered through the grid floor of the wheel. The pontine, but not the midbrain, sites manifested development during behavioral acquisition, of brief-latency (10-40-ms) discriminative neuronal discharges (i.e., greater discharges to the CS+ than to the CS-). The greatest magnitude of the discriminative discharges in the rostral pontine loci occurred in the first conditioning session. The discriminative response in the caudal loci developed more slowly, and it persisted to the criterial stage of training. Both rostral and caudal pontine loci, during the interval from CS onset to US onset, manifested a progressive build-up of neuronal firing in anticipation of the behavioral response. The occurrence in the rostral and caudal pontine areas, respectively, of early- and late-developing discriminative discharges is analogous to effects observed in past studies in the limbic mesocortical and thalamic systems. These findings provide a basis for establishing the possible functional relatedness or independence of these analogous effects.

Animals↗
PubMed1970

S100 brain protein: correlation with behavior.

The brain-specific acidic protein, S100, in the pyramidal nerve cells of the hippocampus was investigated as a possible correlate to learning during transfer of handedness in rats. The amount of S100 increased during training. Intraventricular injection of antiserum against the S100 protein during the course of training prevented the rats from further increases in learned behavior but did not affect motor function in the animals. Antibodies against the S100 protein could be localized after injection by immunofluorescence, in hippocampal structures, penetrating presumably through slight ependymal lesions caused by the injection. By contrast, control animals subjected to the same training and injected with S100 antiserum that had been absorbed with S100 protein or with other antisera against gamma-globulins showed no decrease in their ability to learn. The conclusion is that the brain-specific protein, S100, is linked to the learning process, at least within the training used.

Animals↗
PubMed2005

Human neural learning depends on reward prediction errors in the blocking paradigm.

Learning occurs when an outcome deviates from expectation (prediction error). According to formal learning theory, the defining paradigm demonstrating the role of prediction errors in learning is the blocking test. Here, a novel stimulus is blocked from learning when it is associated with a fully predicted outcome, presumably because the occurrence of the outcome fails to produce a prediction error. We investigated the role of prediction errors in human reward-directed learning using a blocking paradigm and measured brain activation with functional magnetic resonance imaging. Participants showed blocking of behavioral learning with juice rewards as predicted by learning theory. The medial orbitofrontal cortex and the ventral putamen showed significantly lower responses to blocked, compared with nonblocked, reward-predicting stimuli. In reward-predicting control situations, deactivation in orbitofrontal cortex and ventral putamen occurred at the time of unpredicted reward omissions. Responses in discrete parts of orbitofrontal cortex correlated with the degree of behavioral learning during, and after, the learning phase. These data suggest that learning in primary reward structures in the human brain correlates with prediction errors in a manner that complies with principles of formal learning theory.

Adult↗
PubMed1999

5-HT1A receptors modulate the consolidation of learning in normal and cognitively impaired rats.

Attempts were made to further analyze the role of 5-HT1A receptors in consolidation of learning by evaluating the role of these receptors in cognitively normal and impaired animals. The effects of post-training administration of 8-OH-DPAT and 5-HT1A receptor antagonists, WAY 100135, WAY 100635, and S-UH-301, plus the cholinergic and glutamatergic antagonists, scopolamine and dizolcipine, respectively, were determined using an autoshaping learning task. The results showed that 8-OH-DPAT increased the number of conditioned responses, whereas WAY100135, WAY100635, and S-UH-301, and the 5-HT depleter, p-chloroamphetamine (PCA), had no effect. PCA did not change the silent properties of the 5-HT1A receptor antagonists. PCA, WAY100635, and S-UH-301, but not GR127935 (a 5-HT1B/1D-receptor antagonist) or MDL100907 (a 5-HT2A receptor antagonist), reversed the effect to 8-OH-DPAT. Ketanserin (a 5-HT2A/2C receptor antagonist) and ondansetron (a 5-HT3 receptor antagonist), at a dose that increased the conditioned responses by itself, reversed the effect of 8-OH-DPAT. Moreover, 8-OH-DPAT or S-UH-301 reversed the learning deficit induced by scopolamine and dizocilpine whereas WAY100635 reversed the effect of scopolamine only. These data confirm a role for presynaptic 5-HT1A receptors during the consolidation of learning and support the hypothesis that serotonergic, cholinergic, and glutamatergic systems interact in cognitively impaired animals.

8-Hydroxy-2-(di-n-propylamino)tetralin↗