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Results for “Discrimination Learning”

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At least 1,117 records · Page 62Linked to original sources
PubMed1966

Serial discrimination-reversal learning with and without errors by the California sea lion.

A sea lion under water performed virtually without errors on a series of three form-discrimination reversals. Significant training requirements were the combining of a previously well-established size cue preference with the nonpreferred form cue, followed by the gradual reduction of the size cue until it was completely eliminated. Orienting responses reached a peak and then decreased during progressive-dimensional-change training, suggesting critical stages in the transition of attention from the size dimension to the form dimension. Further experimentation revealed that intensive training during these critical stages obviated the need to reduce very gradually the size cue. Without special training sea lions make perseverative errors on a series of form-discrimination reversals. "Emotional" or nontest-oriented behavior was associated only with the occurrence of successive errors.

Animals↗
PubMed2001

Mice can learn roughness discrimination with vibrissae in a jump stand apparatus.

An adaptation of roughness discrimination task successfully used on rats was performed on mice. It was found that mice can master discrimination of rough surfaces using only mystacial vibrissae. This task can be used for studying sensory abilities of genetically modified mice as well as dynamics and pharmacology of complex sensory learning.

Animals↗
PubMed1995

Magnetic field effects on spatial discrimination and melatonin levels in mice.

Previous research has demonstrated a decrement in spatial discrimination learning following exposure to a .30 Tesla magnetic field. It had been suggested that those findings might be the result of an interaction between the magnetic field and physiological ferromagnetic material (magnetite). In the present study, mice were exposed for 100 min to a 2.0 Tesla field and both their left-right discrimination learning ability and serum melatonin levels were compared with a control group. Results indicated a significant interference with spatial discrimination learning following exposure, but no significant differences in serum melatonin levels. These findings appeared to rule out magnetically induced melatonin fatigue as an explanation of the decrement in spatial learning, as opposed to other possibilities such as magnetic effects on brain magnetite. However, additional controls are suggested for future research.

Animals↗
PubMed2001

Visual agnosia and Klüver-Bucy syndrome in marmosets (Callithrix jacchus) following ablation of inferotemporal cortex, with additional mnemonic effects of immunotoxic lesions of cholinergic projections to medial temporal areas.

Inferotemporal ablations in the New World monkey, the common marmoset (Callithrix jacchus), produced a persistent impairment on visual discrimination learning and a florid, but transient, Klüver-Bucy syndrome. Monkeys with these ablations were impaired on acquisition of object discriminations to a high criterion and on concurrent discrimination learning, to a single high criterion across all trials. Neither the control monkeys nor the monkeys with inferotemporal ablations found acquisition more difficult when the component discriminations of a set were presented concurrently compared to consecutively, although the monkeys with inferotemporal ablations found acquisition under both these conditions somewhat more difficult than did control monkeys. This suggests that the severe impairment caused by inferotemporal ablations on concurrent learning measured across all trials is due to the need for sustained performance across a concurrent set rather than to the extra mnemonic demands of concurrent presentation. When immunotoxic lesions of the cholinergic projection to the hippocampal formation were added to the inferotemporal ablations, a further impairment on retention, and a differential impairment on concurrent, compared to consecutive, learning was observed. Previous studies have shown that lesions of the cholinergic projection to the hippocampus alone, or excitotoxic hippocampal lesions, do not affect simple visual discrimination learning. It is suggested that large inferotemporal ablations in monkeys produce a visual agnosia which causes severe 'psychic blindness' in the first instance, and a persistent impairment on visual discrimination learning. The hippocampus makes a contribution, which may be mnemonic, to discrimination performance after inferotemporal ablations.

Acetylcholinesterase↗
PubMed2005

Learning and discrimination of individual cuticular hydrocarbons by honeybees (Apis mellifera).

In social insect colonies, recognition of nestmates, kinship, caste and reproductive status is crucial both for individuals and for the colony. The recognition cues used are thought to be chemical, with the hydrocarbons found on the cuticle of insects often cited as being particularly important. However, in honeybees (Apis mellifera) the role of cuticular hydrocarbons in nestmate recognition is controversial. Here we use the proboscis extension response (PER) conditioning paradigm to determine how well honeybees learn long-chain linear alkanes and (Z)-alkenes present on the cuticle of worker bees, and also how well they can discriminate between them. We found large differences both in learning and discrimination abilities with the different cuticular hydrocarbons. Thus, the tested hydrocarbons could be classified into those which the bees learnt and discriminated well (mostly alkenes) and those which they did not (alkanes and some alkenes). These well-learnt alkenes may constitute important compounds used as cues in the social recognition processes.

Alkanes↗
PubMed1998

Hippocampal modulation of cingulo-thalamic neuronal activity and discriminative avoidance learning in rabbits.

Two experiments assessed the effects of 1) combined subicular complex and posterior cingulate cortical lesions on training-induced neuronal activity (TIA) in the anterior ventral (AV) and medial dorsal (MD) thalamic nuclei; 2) hippocampal (Ammon's horn and dentate gyrus) lesions on TIA in cingulate cortex and in the AV and MD thalamic nuclei. The rabbits acquired a conditioned avoidance response (CR), stepping in an activity wheel upon hearing a 0.5-s tone (CS+), in order to prevent a foot-shock scheduled 5 s after tone onset. No response was required after a different, safety-predictive tone (CS-). In experiment 1 the combined subicular and cingulate cortical lesions enhanced thalamic TIA during acquisition and increased CR incidence in the first session of acquisition. These results confirmed the hypothesis that subicular and cingulate cortical efferents are not essential for thalamic TIA or for avoidance learning. Hippocampal lesions (experiment 2) also enhanced thalamic TIA. However, unlike subicular lesions, hippocampal lesions enhanced posterior cingulate cortical TIA as well, especially during extinction training. Hippocampal lesions did not affect CR performance. The results suggested that subicular excitatory efferents are responsible for incrementing cingulate cortical TIA, which is viewed as subserving associative attention. Activity from hippocampus downregulates the cue-elicited neuronal activity of the cingulo-thalamic circuits by suppressing the excitatory influence of the subiculum. The hippocampal influence reduces cingulo-thalamic cue-elicited activation in particular circumstances, such as the onset of CR extinction, when an expected reinforcer is omitted.

Animals↗
PubMed1986

Drug discrimination procedures: differential characteristics of the drug A vs drug B and the drug A vs drug B vs no drug cases.

Two groups of pigeons with a history of two choice operant drug discrimination tasks (3.0 mg/kg morphine versus 5.6 mg/kg cocaine, and 3.0 mg/kg morphine versus 3.0 mg/kg cocaine, respectively; Swedberg and Järbe 1985) were subjected to three choice tasks in which responses on a third manipulandum were reinforced in the no drug condition. Training drugs generalization gradients in both groups were similar to those normally obtained in two choice drug versus no drug tasks. The salience differences between the training stimuli within the groups observed in the previous two choice task did not differentially affect the three choice discrimination gradients. Tests with novel drugs after the introduction of the no drug condition yielded increased responding to the no drug condition with the exception of the dopamine agonist apomorphine. Results are discussed in terms of a discrimination learning model specifying principles of relative discriminative stimulus control in various discrimination cases.

Animals↗