[The role of quinine chlorhydrate in the conditioned inhibition of the tarsal reflex in Drosophila melanogaster]. / Le rôle du chlorhydrate de quinine dans l'inhibition conditionnée du réflexe tarsal chez Drosophila melanogaster.

The proboscis extension reflex (PER) can be elicited by applying a sucrose stimulation to the tarsus of a walking fly. This reflex decreases in frequency with repetition, presumably habituation, a nonassociative learning. If each sucrose stimulation is followed by a bitter stimulation, quinine chloride, the PER declines more rapidly, probably the result of conditioning, an associative learning. The present work shows that quinine chloride does not always inhibit PER suppressions but depends on the moment of delivery, being most effective when presented immediately after a sucrose stimulation. A bitter stimulus presented before, or simultaneously with a sucrose stimulation is less effective than habituation to sucrose alone. This experiment provides evidence for an interpretation in terms of cognitive association. The model of learning is not a Pavlovian conditioning as advanced by Medioni and Vaysse (1975), but corresponds to the punishment paradigm of Dyal and Corning (1973).

Topographic analysis of the rat's bar behaviour in the Skinner box.

We analysed precisely, with video tapes, the behaviour of 38 Wistar rats submitted to a continuous reinforcement in a Skinner box. Animals displayed 14 different behavioural patterns close to the bar. We found that the increasing frequency of the bar press, generally considered as a unitary response was, in fact, due to summation of the development of several different behaviour frequencies. A CAH analysis led to the distinction of 5 behavioural categories. The frequency of each category of behavioural patterns varied throughout learning in respect with the number of sessions before criterion. So, learning in the Skinner box would result from an association of the reinforcers with the successive units of behaviour exhibited by animals at the bar whose sequential organization and nature change according to acquisition rapidity.

L'apprentissage spatial du rat en situation de conditionnement operant.

Rats which have been conditioned up to 50 or 600 reinforcements with CRF. procedure are submitted to a modification of the position of the lever or the food hopper. We show the existence of a spatial orientation learning, starting with a direction learning given by the "objects" (lever, food hopper) of the set-up and followed by a definite location learning.