Biomedical subjects

N Fresquet

Publications and source records attributed to N Fresquet.

4 recordsLinked to original sources

PubMed1999

Effects of aging on the acquisition and extinction of excitatory conditioning in Drosophila melanogaster.

Young (7-day-old), middle-aged (28-day-old), and old (49-day-old) Drosophila melanogaster were compared for acquisition, then extinction, of excitatory conditioning of the Proboscis Extension Response. The contribution of nonassociative processes (sucrose-induced Central Excitatory State, Pseudoconditioning) in the elicitation of conditioned responses was simultaneously assessed. Old flies displayed a faster and stronger acquisition than middle-aged ones, whereas no significant acquisition was stated in young flies. The influence of nonassociative processes on the acquisition was of minor importance, even though Central Excitatory State increased with age. Old flies proved also to be the slowest to extinguish. Because nonassociative contamination was not involved during extinction, one may wonder whether extinction was delayed in old flies mainly due to a higher level of acquisition or to a behavioral rigidity.

Aging↗

PubMed1998

A new attempt to assess the effect of learning processes on the cholinergic system: studies on fruitflies and honeybees.

The effect of training on the functioning of the cholinergic system was investigated in fruitflies and in honeybees. Drosophila were submitted to a passive avoidance conditioning of the proboscis extension response (PER). Flies had to learn to suppress the sugar-induced PER to avoid an aversive quinine reinforcement. In a yoked control group, the punishment was administered with no relation to the response displayed. Honeybees underwent a five-trial olfactory conditioning of the PER elicited by an antennal gustatory stimulation. In the control group, olfactory and gustatory stimulations were unpaired to prevent a learning process from developing. Immediately at the end of the learning session, acetylcholinesterase (AChE) activity was individually measured on the whole animal for Drosophila and on the head for the honeybee in experimental and in control groups. In fruitflies and honeybees, the AChE rate did not differ between the experimental group and its respective control group. Moreover, no significant correlation could be found individually between the learning performance and the AChE rate in either Drosophila or in honeybees. This experiment did not reveal any modulatory effect of the learning acquisition level on the AChE activity in insects as was previously reported in honeybees.

Acetylcholinesterase↗

PubMed1993

Hypergravity, aging and longevity in Drosophila melanogaster.

1. Drosophila melanogaster flies have been used in studies of the effect of hypergravity (HG) on aging and longevity. 2. There is no clear longevity decrease with the gravity level up to 4 g and, even at 7 g, flies still live for roughly 40 days. 3. The HG-related changes in fecundity suggest that flies counteract an increased metabolic demand. 4. Viability is barely affected in HG. 5. These results show that flies remain able to lay viable eggs and to live for a fairly long life, even at high HG levels. 6. The study of three behavioral traits affected by aging (climbing activity, pattern of movement, spontaneous locomotor activity) suggests that flies age faster in HG, while no HG effect is clearly detected at young age. 7. These results are observed at HG levels where longevity is not yet affected. 8. Results are discussed in relation with Pearl's rate of living theory (1928).

Aging↗

PubMed1993

Effects of ageing on visual discrimination learning in Drosophila melanogaster.

Two experiments examined conditioned suppression of the Proboscis Extension Response (PER), unconditionally released by sucrose stimulation of gustatory tarsal receptors, in young (7-day-old), middle-aged (30-day-old) and old (50-day-old) Drosophila melanogaster males, reared at 25 degrees C. Individual flies were trained in a differential conditioning procedure in which a white stimulus signalled a quinine reinforcer, whereas a black stimulus was non-reinforced. When trained from the outset with the discriminative procedure, flies of all ages acquired the discrimination, although the acquisition of PER suppression to the white stimulus was retarded in middle-aged and old flies. The retardation of the acquisition of PER suppression in middle-aged and old flies was replicated in a second study in which the files received simple conditioning to the white stimulus prior to discrimination training.

Age Factors↗