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At least 19 recordsLinked to original sources

Learning: rapid aversive conditioning in the gastropod mollusk Pleurobranchaea.

Untrained Pleurobranchaea feed voraciously when presented food and withdraw from electrical shocks. We trained experimental animals in ten trials spaced 1 hour apart to withdraw from food alone by electrically shocking them if they fed or were indifferent to food. The greatest increase in the number of learned withdrawal responses occurred within 12 hours after conditioning, and was accompanied by long-lasting increased in the threshold and latency of feeding responses. Control animals, which received food and shock alternately (unpaired) every half hour, showed considerably weaker changes than experimentals. These control responses quickly returned to initial levels after conditioning.

Animals

A neural network model rapidly learning gains and gating of reflexes necessary to adapt to an arm's dynamics.

Effects of dynamic coupling, gravity, inertia and the mechanical impedances of the segments of a multi-jointed arm are shown to be neutralizable through a reflex-like operating three layer static feedforward network. The network requires the proprioceptively mediated actual state variables (here angular velocity and position) of each arm segment. Added neural integrators (and/or differentiators) can make the network exhibit dynamic properties. Then, actual feedback is not necessary and the network can operate in a pure feedforward fashion. Feedforward of an additional load can easily be implemented into the network using "descendent gating", and a negative feedback control loop added to the feedforward control reduces errors due to external noise. A training, which combines a least squared error based simultaneous learning rule (LSQ-rule) with a "self-imitation algorithm" based on direct inverse modeling, enables the network to acquire the whole inverse dynamics, limb parameters included, during one short training movement. The considerations presented also hold for multi-jointed manipulators.

Animals

Learning neural dynamics through instructive signals.

Rapid learning is essential for flexible behavior, but its basis in the brain remains unknown. Here we introduce the PRISM plasticity rule, a unifying mechanistic model of three well-established, fast-acting synaptic plasticity rules-in hippocampus, cerebellum and mushroom body-which relies exclusively on pre-synaptic activity and an "instructive signal" from another brain area. Using a multi-region network model we show that guiding PRISM plasticity with instructive signals enables the network to quickly learn extremely flexible nonlinear dynamics underlying behaviorally relevant computations, as well as to emulate unknown external system dynamics from real-time error signals, which we demonstrate with comprehensive simulations supported by exact mathematical theory. Thus, PRISM plasticity guided by instructive signals is well-suited to rapidly learn general-purpose neural computations-in contrast to canonical Hebbian rules. Finally, we show how including this plasticity rule in artificial learning algorithms can solve long-range temporal credit assignment, a long-standing challenge in machine learning.

cerebellum

GABAergic modulation of memory with regard to passive avoidance and conditioned suppression task in mice.

The role of GABAergic neuronal system in learning and memory was investigated using the step-down typed passive avoidance and rapidly learned conditioned suppression tasks in mice. GABA antagonists, picrotoxin and bicuculline, or a GABA synthesis inhibitor, 3-mercaptopropionic acid (3-MP), were administered just after the training test. All of these drugs caused amnesia: they shortened the step-down latency (SDL) and attenuated the conditioned suppression of motility in the retention test conducted 24 h after the administration. Furthermore, we investigated the effect of GABA receptor agonists, muscimol and baclofen, or a GABA transaminase inhibitor, aminooxyacetic acid (AOAA), on these amnesia models. GABA agonists showed an antiamnesic action as follows: in the passive avoidance task, 1) picrotoxin-induced amnesia was antagonized by muscimol, baclofen and AOAA. 2) Bicuculline-induced amnesia was antagonized by muscimol and AOAA but not by baclofen. 3) 3-MP-induced amnesia was antagonized only by muscimol. 4) In the rapidly learned conditioned suppression task, picrotoxin-, bicuculline- and 3-MP-induced amnesia were antagonized by muscimol, baclofen and AOAA. These results suggest that the GABAergic neuronal system plays an important role in the memory retention of passive avoidance and rapidly learned conditioned suppression tasks.

4-Aminobutyrate Transaminase

[Analysis of hippocampal RNA in rats with genetically determined differences in their ability to learn].

Selection for twelve generations, by the speed of elaboration of a food-procuring motor conditioned reflex, produced an increased intensity of the synthesis of n and c fractions of the hippocampal RNA in rapidly learning animals as compared with those slowly learning. Electrophoretic analysis of the two fractions revealed similar series of RNA classes in the initial and the learning animals' groups. With high molecular RNA classes, insertion of the radioactive precursor was higher in the rapidly learning animals than in the slow learning ones. The learning process was attended with an increased insertion of the radioactive precursor in the area of high molecular n-RNA classes and in the area of 18S-4S RNA c-RNA. The percentage of radioactivity inserted in the poly-A RNA, as well as a change due to learning were significantly higher in the rapidly learning animals.

Animals

Taste avoidance, but not aversion, learning in rats lacking gustatory cortex.

Control rats rapidly learned to avoid drinking either a sucrose solution (Experiment 1) or a NaCl solution (Experiment 2) when the taste was paired with illness. These rats also produced aversive reactivity to each of these solutions in a taste reactivity test. Rats that lacked gustatory cortex (GC) learned to avoid drinking sucrose and NaCl, albeit at a slower rate than control rats. GC rats failed to display aversive reactivity to these tastes. The GC rats did show normal aversive reactivity to a strong quinine HCl solution during additional tests. It is suggested that the avoidance developed by GC rats did not entail a palatability shift of the conditional stimulus as it did in control rats. This altered learning strategy may account for the consistent learning deficits found in GC rats trained to avoid tastes.

Animals

Operant performance patterns of normal and nervous water-deprived dogs.

Previous studies have shown that most food-deprived genetically nervous pointer dogs fail to learn a bar-pressing response for food reward and those which do learn are erratic in bar-pressing compared to genetically normal pointer dogs which usually learn rapidly and perform well. Benzodiazepine drugs facilitate learning and performance of the responses in nervous dogs. The present study aimed at finding whether a stronger drive producing state, such as water deprivation, would facilitate learning and performance in even severely nervous dogs. Eight normal line and 7 nervous line dogs successfully learned to perform well a paddle-pressing response which activates a valve releasing water into a drinking pan. One disturbing dog of each line did not learn successfully. Behavior shaping was about as easy and as rapid in nervous line dogs as in normals. Nervous line dogs tended to be as consistent in responding. However, response rates of nervous line dogs averaged about two-thirds those of normal line dogs, the slowed rate of responses being taken up mostly in excessive, rather stereotyped, licking of the water pan. Response rates correlated well with degree of nervousness as measured on independent well standardized behavior tests. This behavior seems to add another dimension to the characterization of the nervousness of these "spooky" pointer dogs.

Animals

Learning and using specific instances.

A biologically plausible method for rapidly learning specific instances is described. It is contrasted with a formal model of classical conditioning (Rescorla-Wagner learning/perception training), which is shown to be relatively good for learning generalizations, but correspondingly poor for learning specific instances. A number of behaviorally relevant applications of specific instance learning are considered. For category learning, various combinations of specific instance learning and generalization are described and analyzed. Two general approaches are considered: the simple inclusion of Specific Instance Detectors (SIDs) as additional features during perception training, and specialized treatment in which SID-based categorization takes precedence over generalization-based categorization. Using the first approach, analysis and empirical results demonstrate a potential problem in representing feature presence and absence in a symmetric fashion when the frequencies of feature presence and absence are very different. However, it is shown that by using the proper representation, the addition of SIDs can only improve the convergence rate of perceptron training, the greatest improvement being achieved when SIDs are preferentially allocated for peripheral positive and negative instances. Some further improvement is possible if SIDs are treated in a specialized manner.

Animals

Learned suppression of ingestion: role of discriminative stimuli, ingestive responses, and aversive tastes.

Three experiments were designed to demonstrate that animals learn to suppress contact with aversive-tasting foods and fluids, and to investigate the behavioral mechanisms of this learning. In Experiment 1, domestic chicks (Gallus gallus) rapidly learned to suppress drinking during a visual stimulus (SQ) that signaled ingestion of a quinine solution but drank normally during a second visual stimulus (SW) that signaled water access. In Experiment 2, chicks in Group Con received oral infusions of quinine contingent upon drinking during SQ. Group Non received oral quinine infusions during SQ yoked to those of Group Con and noncontingent upon drinking. Only Group Con suppressed drinking during SQ. The third experiment investigated the contribution of the aversive taste and the postingestive effects into either the beak or the crop following drinking during SQ. Only the orally infused subjects suppressed drinking during SQ. These studies suggest that the relation between the drinking response and the aversive taste of quinine during SQ is crucial to the learned suppression of ingestion produced by the present procedures. The implications of these results for theories of food selection and Batesian mimicry are discussed.

Animals

Learning child psychiatry skills on the adult inpatient service.

Integration of child psychiatry training into general psychiatric residency programs is often unsuccessful. The authors describe an innovative model of training in child psychiatry that involves the children of adult inpatients. This model offers several advantages: splitting of child-adult psychiatric training is avoided, child diagnostic and evaluative skills tend to be learned rapidly, preventive orientations develop, and family process is both learned and used. Preliminary experience with this model on two inpatient services suggests that it is both didactically effective and economical in child psychiatry staff hours.

Adolescent

The effect of delta 9-tetrahydrocannabinol and LSD on the acquisition of an active avoidance response in the rat.

The course of active avoidance learning of rats in a symmetrical Y-maze under the influence of 1, 3, and 9 mg/kg of delta 9-THC i.p., and 5, 20, and mug/kg of LSD was investigated. Delta-THC in a dosage of 1 mg/kg had no effect on avoidance learning. Three to a lesser extent 9 mg/kg produced more rapid learning with a significantly better performance. Learning under delta 9-THC proved to be state-dependent. The withdrawal of delta 9-THC caused a decrease in the avoidance rate, which was dependent on the dosage. Upon renewal of the THC doses, the animals reattained their earlier preformance. In the course of the experiment there was rapid tolerance development, especially of the sedative properties of THC. LSD retarded the rate of acquisition of the active avoidance response. Whereas the control animals displayed over 80% successful active avoidance from the 14th session onwards, this was achieved by the LSD groups only after the 20th session. However, in contrast to the control group the LSD animals were able to increase their avoidance rate to over 90%, and this was maintained to the end of the experiment (a total of 24 sessions with LSD). The sudden withdrawal of LSD produced a fall in avoidance rate, which was dependent on the pervious training dosage; as with delta 9-THC state-dependent learning can also be assumed for LSD.

Animals

Voice, speech, and language habilitation in young children without laryngeal function.

We discuss aphonia in children, secondary to laryngeal obstruction, with regard to the development of a voice, speech, and language system that can be an effective and efficient means of communication while obstruction persists and a precursor to good voice and speech habits if and when the laryngeal function is reestablished. Several methods were considered. A technique of esophageal voice training for children was developed and implemented, which combined the aspects of normal language learning with the mechanical aspects of esophageal voice production. Results showed rapid learning in a 2 1/2-year-old child with severe juvenile laryngeal papillomatosis and normal speech and language at the age of 4 years when laryngeal function returned. A second technique, a communication board, was used with a 4-year-old child with total subglottic stenosis and brain damage.

Aphonia

Practice effect of volunteers in repeated psychometric testing. How to handle this intervening variable in clinical pharmacology studies?

Performance in psychometric tests may show a practice effect with repeated testing. Ideally, a plateau of efficiency should be reached prior to first drug intake. In order to assess the period of familiarization in a multiple choice reaction task (MCRT) 17 healthy subjects practiced the test up to 36 times in the drug free run-in period of 2 trials. A tentative "inclusion criterion" was used in 7 subjects to decide whether their learning phase could be regarded as being finished. Seven to 20 training sessions were required for a first rapid learning phase. There were remarkable differences in the absolute performance of the subjects and in the time course of their practice effect. However, the time course of the learning phase was not dependent on the absolute performance level. By means of the tentative "inclusion criterion" it was possible to reject a subject with a low but highly variable performance. However, it was not stringent enough to indicate the final plateau of efficiency. More "drug free" data concerning the practice effect should be published to enable the users of psychometric tests to make a reasonable selection according to their needs and to help them design their trials properly.

Adult

Reversal and nonreversal shifts under amphetamine.

Rats were trained in a Y maze on a two-choice simultaneous brightness discrimination with light as S+ and dark as S- (position irrelevant). Half of the animals were then switched to reversal, where the reinforcement contingencies of the original training were reversed, and the other half were switched to nonreversal, in which they learned a simultaneous right-left discrimination. Nonreversal was acquired faster than reversal in saline injected animals. The administration of 1 mg/kg d-amphetamine did not affect the acquisition of the initial brightness discrimination and of nonreversal. In contrast, the drug facilitated dramatically reversal learning. The results indicate that amphetamine enhances the attention to, or the associability of, the discriminative stimuli, leading to rapid learning to these stimuli under changed contingencies of reinforcement.

Animals