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At least 523 records · Page 29Linked to original sources
PubMed1998

Learning reaching strategies through reinforcement for a sensor-based manipulator.

This paper presents a neural controller that learns goal-oriented obstacle-avoiding reaction strategies for a multilink robot arm. It acquires these strategies on-line from local sensory data. The controller consists of two neural modules: an actor-critic module and a module for differential inverse kinematics (DIV). The input codification for the controller exploits the inherent symmetry of the robot arm kinematics. The actor-critic module generates actions with regard to the Shortest Path Vector (SPV) to the closest goal in the configuration space. However, the computation of the SPV is cumbersome for manipulators with more than two links. The DIV module aims to overcome the SPV calculation. This module provides a goal vector by means of the inversion of a neural network that has been trained previously to approximate the manipulator forward kinematics. Results for a two-link robot arm show that the combination of both modules speeds up the learning process.

Journal Article↗
PubMed2006

Extinction learning, reconsolidation and the internal reinforcement hypothesis.

Retrieving a consolidated memory--by exposing an animal to the learned stimulus but not to the associated reinforcement--leads to two opposing processes: one that weakens the old memory as a result of extinction learning, and another that strengthens the old, already-consolidated memory as a result of some less well-understood form of learning. This latter process of memory strengthening is often referred to as "reconsolidation", since protein synthesis can inhibit this form of memory formation. Although the behavioral phenomena of the two antagonizing forms of learning are well documented, the mechanisms behind the corresponding processes of memory formation are still quite controversial. Referring to results of extinction/reconsolidation experiments in honeybees, we argue that two opposing learning processes--with their respective consolidation phases and memories--are initiated by retrieval trials: extinction learning and reminder learning, the latter leading to the phenomenon of spontaneous recovery from extinction, a process that can be blocked with protein synthesis inhibition.

Animals↗
PubMed1963

Operant control of vocal behavior in the cat.

EVIDENCE OF OPERANT CONTROL OF VOCAL BEHAVIOR IN THE CAT IS PRESENTED: (1) On mult FR 12 S(Delta) schedule, cats miaowed rapidly during periods of S(D) and much less or not at all during S(Delta). (2) This control was re-established following reversal of stimuli. (3) The frequency distribution of response durations was shifted to both shorter and longer values by the differential reinforcement of shorter or longer response durations respectively. Since both the frequency and duration of vocal responses were shown to be under the control of the schedule of reinforcement, it is concluded that at least some of the vocal behavior of the cat is susceptible to operant control.

Conditioning, Classical↗
PubMed1999

Ontogenetic adaptation and learning: a developmental constraint in learning for a thermal reinforcer.

Hoffman, Flory, and Alberts (1999) demonstrated that 1-, 5-, and 11-day-old rats in a cool environment (25 degrees C) acquired an operant head-turning response when rewarded with a 20-s warming of the platform on which they lay. In the current experiment 5- and 11-day-old rats in a hot environment (40 degrees C) acquired the head-turning response when rewarded with a 20-s cooling of the platform on which they lay, but 1-day-olds did not. The concept of ontogenetic adaptation helps us interpret these results: Neonatal thermotaxis constrains the 1-day-olds from learning a novel operant response for a cool reinforcer in a hot environment. Because the thermotaxis wanes from birth, it is not as strong in 5- and 11-day-old pups that are thus able to learn the operant for a cool reinforcer.

Adaptation, Physiological↗