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B Poucet

Publications and source records attributed to B Poucet.

46 records · Page 3Linked to original sources
PubMed1990

A further characterization of the spatial problem-solving deficit induced by lesions of the medial frontal cortex in the rat.

Two experiments were conducted to investigate the basis of the spatial impairment displayed by rats with lesions to the medial frontal cortex, using a three-table Y-shaped apparatus. In both experiments, animals were first given an exploratory experience of the maze, followed by a short feeding experience on one of the tables, and were then required to return to the location where they had just been fed. In Expt. 1, a spatial working memory procedure was used in which the location of the goal table was varied from day to day. When compared to normal animals frontal rats showed a marked impairment, despite the addition of (a) distinctive visual cues on the tables and their associated runways, or (b) a conspicuous visual pattern placed directly above the goal. Expt. 2 used a spatial learning procedure, in which the spatial location of the goal table remained constant over days. However, the whole apparatus was daily rotated so that animals could not learn to associate the goal table with specific cues located behind it. This procedure did not prevent frontal animals from learning the consistent location of the food by using the spatial relationships of the environment. These results, together with previous ones, suggest that frontal animals suffer from a specific (though not restricted to the domain of spatial information) working memory deficit, and their spatial reference memory is not impaired.

Animals↗
PubMed1990

Septum and medial frontal cortex contribution to spatial problem-solving.

An attempt was made to contrast the effects of lesions to the medial frontal cortex and septum in two spatial tasks. In the fixed-goal (FG) task, the food was located on the same table throughout testing, and the start table was randomly varied from day to day. In the variable-goal (VG) task, the start table remained constant but the food was randomly distributed on one or the other of the two remaining tables. In both tasks, normal animals performed better than frontal and septal rats whose performance, however, improved over days in the FG, but not in the VG, task. In both tasks, significant improvement within days was found in medial frontal animals, but not in septal animals. Additional analyses revealed that septal animals had a general pattern of disrupted exploration and a tendency to use a response strategy (i.e. to repeat the same response both within and between days) which decreased over days in the FG task. In contrast, medial frontal animals did not demonstrate disrupted exploration nor any response tendency. It is concluded that both septal and medial frontal cortical damage produce a common spatial working memory impairment. However, there is some evidence to suggest that this common memory impairment could result from disruption of distinct mechanisms in septal and frontal animals. It is proposed that medial frontal lesions could affect some specific mechanism related either to attentional processes or to the ability to anticipate future events, whereas septal damage would interfere with the building of comprehensive and flexible spatial memories.

Animals↗
PubMed1990

Spatial behaviour of normal and septal rats on alternate route maze problems.

The behaviour of normal rats and rats with lesions of the septum was compared on a variety of alternate route variations of the three-table problems. In all variations of the task, septal rats were impaired on test trial performance when they displayed stereotypic body turn responses and demonstrated a strong preference for the most direct route between tables both during exploration and testing in all conditions. Normal rats displayed a similar route choice tendency in the simplest situations but shifted route choice behaviour in the most complex configuration, when they chose the inner, but longer, path. The use of the inner path may have allowed delayed-choice, single-point reference orientation, or reduction in the number of available alternatives. It is concluded that normal rats form a cognitive representation that allows them to identify environmental factors likely to facilitate solution, whereas septal rats rely on "taxon"-type strategies that can combine guidances and orientational responses.

Animals↗
PubMed1989

Scopolamine impairs response-to-change based on distal cues in the rat.

The effect of a scopolamine injection (1 mg/kg, IP) on response-to-change behavior was investigated in two experiments. After exploration of a T-maze with one arm black and the other white (Trial 1), rats were tested with both arms either black or white (Trial 2). Experiment 1 revealed that the opportunity to make body turns into the arms did not help scopolamine-injected rats to locate the changed arm after visual exploration of the arms during Trial 1. Saline-injected animals chose the changed arm. In Experiment 2, rats were allowed to move freely into the arms during Trial 1. During Trial 2, they were tested either from the same start as that used during Trial 1 or from a different start 180 degrees from the original start. While scopolamine-injected animals reacted appropriately to the change when tested from the same start, they were impaired when tested from the opposite start. In both conditions, saline-injected animals chose the changed arm. These results, together with others, support the notion that the cholinergic system plays a crucial role in the processing of distal information.

Animals↗
PubMed1989

Object exploration, habituation, and response to a spatial change in rats following septal or medial frontal cortical damage.

Normal rats and rats sustaining septal or medial frontal cortex lesions were compared in experiments dealing with object exploration, habituation, and reaction to novelty (measured by renewed exploration following a spatial change). Normal rats exhibited high levels of initial exploratory activity which decreased over time. Following a spatial change, they reinvestigated both the displaced object and the nondisplaced ones. Frontal animals were similar to normal subjects with respect to their initial exploratory level and habituation pattern. However, frontal rats reexplored only the displaced object and completely neglected the nondisplaced ones. In contrast, the behavioral pattern displayed by septal rats was markedly different from that of normal and frontal animals. Septal rats had lower levels of initial exploratory activity, did not habituate over time, and failed to react to either displaced or nondisplaced objects. These results show that although the septo-hippocampal complex and the medial frontal cortex may share some common function in spatially organized behaviors, both structures have unique roles. Some hypotheses about the possible basic processes subtended by the septal area or the medial frontal cortex are briefly mentioned and discussed.

Animals↗
PubMed1985

Spatial problem solving in a dual runway task by normal and septal rats.

The addition of a dual runway configuration did not disrupt the successful performance of normal animals, nor did it improve the deficit of septal rats on the Maier three-table spatial integration task. Both groups of animals displayed a preference for the outside runway configuration during exploration. During testing, however, septal animals retained this preference, whereas normal subjects attempted solution by using the inside runway configuration. This fact, in addition to the apparent lack of a habituation pattern during exploration, suggests that septal animals do not acquire a spatial representation of the test situation. It is suggested that the inability of septal rats in spatial situations is due to an inability to form rather than an inability to use spatial maps.

Animals↗
PubMed1984

Evaluation of connectedness by cats in path-selection problems.

4 cats were given path-selection problems, with reference to the property of the correct path to lead to a visible goal. Choices were related first to the direction of the goal, then to the connectedness properties of the path if direction of the goal could not be used as a pertinent cue.

Animals↗
PubMedDate not supplied

The associative parietal cortex and spatial processing in rodents.

It is widely acknowledged that the hippocampal formation has a central function in rodents' spatial memory and navigation. However, recent work has shown that other structures participate in specific spatial processing. That is so for the associative parietal cortex (APC). Although this neocortical region is far less developed in rodents than in humans and non-human primates, APC damage in rodents induces deficits which affect both egocentrically and allocentrically organized spatial behaviours. On the basis of behavioural (following parietal lesions) and neuroanatomical data, we propose that the APC could be at the interface between the level of perception of the physical world (egocentrically organized) and that of representations or maps (allocentrically organized) of this world. Reciprocally, the APC could also be involved in the transformation, in the opposite direction, of computations made on the basis of representations into motor actions necessary for the efficient execution of oriented behaviours within the physical world.

Animals↗