Geometry learning while navigating: The importance of task difficulty and sex differences.

Cheng (1986) trained male rats to search for food in a rectangular arena that also contained distinctive visual patterns. He found that the rats used mainly the geometric framework of the box itself to find the food and claimed that geometrical information is processed in a specialized module, which is independent of feature information. The aim of the present set of experiments was to check if the previous results with male rats and an appetitive task could be extended to an aversive task while using both male and female rats and three-dimensional landmarks.

Generalisation decrement and not overshadowing by associative competition among pairs of landmarks in a navigation task with humans.

In three experiments, a virtual preparation for humans of the Morris water task (VMWT) was used. Experiment 1 established that four landmarks were of similar salience. Then, in Experiments 2 and 3, participants were trained to locate a hidden platform in the presence or either two or four of the previous landmarks.

Anti-oxidative effects produced by environmental enrichment in the hippocampus and cerebral cortex of male and female rats.

Both physical and intellectual activity may reduce the incidence of neurodegenerative disorders. There is evidence that environmental enrichment (EE) can induce profound behavioral, neurochemical and neuroanatomical changes, thus producing lasting improvements in memory and learning tasks. In this study we evaluated the anti-oxidative effects produced by EE in the hippocampus and the cerebral cortex of male and female rats.

Navigation with two landmarks in rats (Rattus norvegicus): the role of landmark salience.

In two experiments, male and female rats were trained in a Morris pool in the presence of 1 (Experiment 1) or 2 (Experiment 2) landmarks, which were placed relatively close in relation to a hidden platform. Experiment 1 established the relative salience of 3 landmarks. Two of them revealed a similar salience, and smaller than a third one, the most salient landmark, both in training and on a test trial without the platform.

Generalization decrement and not overshadowing by associative competition among pairs of landmarks in a navigation task.

When they are trained in a Morris water maze to find a hidden platform, whose location is defined by a number of equally spaced visual landmarks round the circumference of the pool, rats are equally able to find the platform when tested with any two of the landmarks (Prados, & Trobalon, 1998; Rodrigo, Chamizo, McLaren, & Mackintosh, 1997). This suggests that none of the landmarks was completely overshadowed by any of the others. In Experiment 1 one pair of groups was trained with four equally salient visual landmarks spaced at equal intervals around the edge of the pool, while a second pair was trained with two landmarks only, either relatively close to or far from the hidden platform.

Order effects after blocked preexposure to two compound flavors.

In the first three experiments two groups of rats received prolonged blocked preexposure to AX-BX or to BX-AX. Experiment 1 showed that conditioning of AX after preexposure resulted in less generalization to BX in the AX-BX group than in the BX-AX group. Experiments 2 and 3 constituted, respectively, retardation and summation tests of the inhibitory properties acquired by B after preexposure and conditioning of A.

The conditioned stimulus elicits taste aversion but not sickness behavior in conditioned mice.

Objectives: This article extends previous reports on (i) elicitation of taste aversion after pairing a flavored beverage (saccharin solution) with a disease-provoking microbial product (lipopolysaccharide, LPS, or polyinosinic:polycytidylic acid, poly I:C); (ii) elicitation of sickness behavior (assessed as diminished ingestion of water and food) by the conditioned stimulus, and (iii) development of tolerance to those microbial products.

Methods: Mice of the CD1 strain were conditioned by pairing ingestion of 0.15% saccharin solution with injection of LPS (100 mug/mouse) or poly I:C (6 mg/kg).

Taste-aversion conditioning, but not immunosuppression conditioning, occurs under partial water deprivation.

The authors investigated whether conditioned taste aversion and immunosuppression took place when water was available during conditioning and test protocols. The authors elicited taste-aversion conditioning and immunosuppression in outbred CD1-strain mice by pairing a conditioned stimulus (sucrose or saccharin solution) with an unconditioned stimulus (cyclophosphamide) that causes gastrointestinal upset and is immunosuppressive. The authors introduced a new conditioning protocol: 5 pairings of a saccharin solution with a low-dose injection of cyclophosphamide.