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PubMed1991

Effects of tianeptine on spontaneous alternation, simple and concurrent spatial discrimination learning and on alcohol-induced alternation deficits in mice.

The effects of systemic administration of tianeptine, a new psychotropic agent with antidepressant properties, were investigated on spontaneous alternation behavior, and on simple and concurrent spatial discrimination, in normal mice of the BALB/c strain. Tianeptine increased rates of spontaneous T-maze alternation, facilitated retention of a T-maze left-right discrimination, and speeded up acquisition of concurrent discrimination in a radial maze. These effects were consistent across successive experiments with a dose of 10mg/kg; lower doses (2.5 and 5.0mg/kg) had less or no effect depending on the task. These results, together with theoretical considerations, led us to investigate the effect of tianeptine on the sequential-specific alternation deficit induced by long-term ethanol administration in the same strain of mice. Results showed that, at the dose of 10mg/kg, the drug completely alleviated the alcohol-induced deficit. Unlike tianeptine, fluoxetine impaired discrimination performance in the radial maze. These data are discussed in light of the effects of tianeptine on serotonergic transmission and of the role of serotonin and acetylcholine in learning and memory processes.

Journal Article↗
PubMed1992

Changes in PKC gamma immunoreactivity in mouse hippocampus induced by spatial discrimination learning.

In the present study, we examined changes in immunoreactivity (ir) for the gamma-isoform of protein kinase C (PKC gamma) in mouse hippocampus in relation to spatial memory processes employing the monoclonal antibody 36G9 raised against purified PKC gamma. Learning and memory were assessed by performance in a free-choice spatial pattern paradigm in a hole board in which the animals learned the pattern of 4 baited holes out of 16 holes. Adult male house mice were used, divided in four groups. Three control groups were formed: group N, naive (blank controls); group H, habituated (animals were for 5 consecutive days introduced to the hole board with all holes baited); and group PT, pseudotrained (animals were for 13 consecutive days introduced to the hole board with all holes baited). The T (trained) group was for 5 consecutive days introduced to the hole board with all holes baited (similar to the H and PT groups) followed by 8 successive days with only four holes baited in a fixed pattern. Behaviorally, following the first 5 d, the PT group crossed the hole board randomly, whereas the T group gradually learned to orientate in the hole board. The mice were killed 24 hr after the last performance. A shift in 36G9-ir appeared from the cell somata to the dendrites of hippocampal principal neurons when comparing the H and PT group, respectively. In contrast, the T group showed strong PKC gamma-ir in both cell somata and dendrites, which clearly exceeded that of the H and PT mice. In this way, 36G9-ir reveals the physiologically activated neurons involved in hole board learning.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Sex differences in shock motivated behaviors, activity, and discrimination learning of northern grasshopper mice (Onychomys leucogaster).

Sex differences in the behavior of the highly predatory northern grasshopper mouse (Onychomys leucogaster) were investigated in a series of eight experiments. Female mice acquired two-way avoidance behavior more slowly, but passive avoidance more rapidly, than males. Females also buried a shock probe more completely than males and showed more escape behavior during open field testing. There were no sex differences in flinch-jump thresholds or escape from electric shock, general activity levels, or acquisition and reversal of a position discrimination. It is suggested that the sex differences in aversively motivated behavior result from an increased tendency of females to respond defensively to focal sources of aversive stimuli. The enhanced defensiveness of females may be an adaptation to higher levels of pup predation resulting from the large territories required by their predatory specialization and their association with other, more abundant, rodent species.

Animals↗
PubMed2001

Olfactory-based discrimination learning in the moth, Manduca sexta.

Moths possess highly tuned olfactory capabilities, which can detect very low concentrations of pheromonal odorants. Much is known about the structure and function of the moth olfactory system with respect to detection of pheromones. However, we lack an understanding of the broader olfactory system, in particular, to what degree are moths capable of detecting and discriminating odorants that are not components of pheromone blends. Here we describe a methodology used to investigate the discriminability of nonpheromonal odors in moths. In a series of experiments we show that the moth Manduca sexta can (1) discriminate a number of different odors but (2) that methyl jasmonate, neither readily conditions to a food reward nor is it readily discriminated from another odor. The lack of a response to methyl jasmonate may be related to its role in host plant defense. This work provides a basis for future mapping of physiological and pharmacological studies of nonpheromonal coding in insects onto learned behavioral responses to those odorants.

Journal Article↗
PubMed1975

Stimulus-specific contrast effects during operant discrimination learning.

In two experiments, pigeons' responding was equally reinforced in the presence of four line-orientation stimuli. Responding was then reinforced when only two of the four orientation stimuli were present; the remaining two orientations appeared during extinction. Response rates were often highest in the stimulus adjacent to the orientations presented during extinction and often lowest in that orientation adjacent to the orientations presented with reinforcement. These effects were stronger and more persistent when the stimuli were separated by a smaller angle, rendering the discrimination more difficult. These and other data suggest that discrimination training may not be accurately explained in terms of the simple effects of reinforcement and nonreinforcement associated with isolated stimuli, nor by accounts that depend upon stimulus generalization. Recent accounts of contrast that depend upon "emotionality" produced by nonreinforced responding or upon reinforcement-elicited responses are also difficult to apply to these data.

Journal Article↗
PubMed2006

Skills training to learn discrimination of ABCDE criteria by those at risk of developing melanoma.

OBJECTIVE: To develop skin self-examination skills by improving the use of the ABCDE criteria by those at risk of developing melanoma. DESIGN: Ten single-sex groups of 10 unrelated adults received a knowledge-based intervention followed by skills training. SETTING: Classroom in the ambulatory care area of a hospital. Patients One hundred unrelated adults with either a personal or family history of melanoma and no previous skin self-examination counseling. Interventions A dermatologist presented information, and each subject read a brochure and reviewed a bookmark. The facilitator led the group discussions about scoring each feature and the decision to seek medical care. Measurement of moles with a ruler and a pencil eraser and the use of an illuminated magnifying lens were demonstrated. Preintervention and postintervention assessments were performed for each intervention. MAIN OUTCOME MEASURE: Recognition of A, B, C, D, and E traits. RESULTS: The subjects preferred the bookmark (87% of subjects), opaque ruler (94% of subjects), and lighted magnifying lens (81% of subjects) to reading the brochure, which was felt to take too long. Recognition of border irregularity, color variation, and diameter improved significantly after the intervention. Women recognized color variation more often than men (94% vs 62%; odds ratio [OR], 23.7; 95% confidence interval [CI], 16.1-50.5). Men identified irregular borders more often than women (91% vs 75%; OR, 16.8; 95% CI, 4.5-22.6). Women appropriately decided to see a physician more often than men (81% vs 57%; OR, 13.5; 95% CI, 7.1-28.4). CONCLUSIONS: Determining the presence of the A, B, C, and E criteria is challenging for the novice. Skills training aided performance of skin self-examination. Differences in proclivities according to sex suggest that if men and women form partnerships for skin checks, they may learn from each other, and their combined strengths will promote detection of early melanomas.

Adult↗
PubMed1977

Behaviors observed during S- in a simple discrimination learning task.

Key pecking of pigeons was reinforced with food in the presence of a horizontal line and never reinforced in the presence of a vertical line. Highly stereotyped behaviors, as well as key pecking, were observed and recorded in the presence of both stimuli. Results showed that a high proportion of time spent in the presence of the horizontal line was occupied by key pecking, a high proportion of time in the presence of the vertical line was occupied by stereotyped nonkey-pecking behaviors, and intermediate proportions of time spent in the presence of intermediate stimuli were occupied by each class of behavior during generalization tests. Similar running rates (number of key pecks divided by observed key-pecking time) were obtained in the presence of all stimuli, indicating that changes in time rather than tempo accounted for the changes in overall rates of key pecking. An exception occurred in responding to the horizontal line as differential performance was developing. In addition to an increase in time spent key pecking, increased running rates occurred in seven of eight birds, suggesting that both time allocation and tempo play a role in behavioral contrast of overall rates of key pecking.

Journal Article↗
PubMedDate not supplied

Dorsal hippocampus function in learning and expressing a spatial discrimination.

Learning to discriminate between spatial locations defined by two adjacent arms of a radial maze in the conditioned cue preference paradigm requires two kinds of information: latent spatial learning when the rats explore the maze with no food available, and learning about food availability in two spatial locations when the rats are then confined in one arm with food and the other with no food. Previous research showed that a functional dorsal hippocampus is not required for latent learning. The present experiments show that it is required for learning about food availability, and during retrieval of both types of information.

Analysis of Variance↗
PubMed1991

Perceptual learning in maze discriminations.

In Experiment 1, rats were trained on a discrimination between rubber- and sandpaper-covered arms of a maze after one group had been pre-exposed to these intra-maze cues. Pre-exposure facilitated subsequent discrimination learning, unless the discrimination was made easier by adding further discriminative stimuli, when it now significantly retarded learning. In Experiment 2, rats were trained on an extra-maze spatial discrimination, again after one group, but not another, had been pre-exposed to the extra-maze landmarks. Here too, pre-exposure facilitated subsequent discrimination learning, unless the discrimination was made substantially easier by arranging that the two arms between which rats had to choose were always separated by 135 degrees. The results of both experiments can be explained by supposing that perceptual learning depends on the presence of features common to S+ and S-.

Animals↗