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At least 199 records · Page 11Linked to original sources
PubMed1989

Hyperthermia impairs retrieval of an overtrained spatial task in the Morris water maze.

Fifteen rats were trained to learn the location of a spatially fixed platform hidden in a Morris water maze (40 +/- 2 degrees C). Then retention of the spatial task was assessed immediately after raising core body temperature (Tc) to 42 or 40 degrees C or stabilizing at 37 degrees C (the normothermic control). The hyperthermic treatment order was counterbalanced according to a Latin-square design. Hyperthermia at 42 degrees C Tc significantly impaired spatial performance. Hyperthermic animals were cooled to normothermia (Tc = 37 degrees C) and spatial performance was tested again approximately 30 min later. Cooling resulted in a complete recovery of spatial performance. These results demonstrate that hyperthermia-induced amnesia can be obtained on an overtrained spatial-mapping strategy and cooling to normothermia initiates recovery of spatial performance.

Animals↗
PubMed1989

Vestibular stimulation disrupts acquisition of place navigation in the Morris water tank task.

The significance of vestibular input for place navigation in the Morris water maze was examined in 11 hooded rats. A 5-min rotation (2 Hz) immediately preceding retrieval of an overtrained place navigation task prolonged escape latencies by about 10 s corresponding to circular swimming induced by postrotatory aftereffects, but did not otherwise interfere with target location. A 1-min rotation immediately following the acquisition trial in the working memory version of the water maze task did not deteriorate performance in the retrieval trial performed 5 min later. Two components of the acquisition trial, i.e., active search of the hidden target (up to 1 min) and latent learning during the 30-s stay on the platform, contribute almost equally to the formation of the working memory trace. A 1-min rotation immediately preceding the isolated platform learning component impaired subsequent retrieval but was ineffective when applied 3 min earlier. Latent learning was completely disrupted when the platform with the animal was rotated during the entire 30-s stay on the target platform or when the 30-s stay on the stationary platform was followed 0 or 3 min later by a 30-s rotation on the platform. The interfering effect of the latter procedure was suppressed by covering the platform with the animal by an opaque cylinder. It is concluded that vestibular cues are particularly important for the orientation of the animal in the gravitation field and for the estimation of the angles between vectors plotted from the animal toward external landmarks. Agreement between vestibular and visual signals is a prerequisite of efficient navigation.

Animals↗
PubMed1998

Timed active avoidance learning in lurcher mutant mice.

Lurcher mutant mice (+/Lc) which exhibit a massive loss of neurons in the cerebellar cortex and in the inferior olivary nuclei were subjected to an active avoidance learning task; the animals' avoidance response must occur within a small time window after a short or a long delay. The control mice needed a mean of 8.3 sessions of 10 trials (short delay group) and of 11.8 sessions (long delay group) and showed good retention after a 24 h interval. When subjected to the same number of sessions, the +/Lc mice were unable to learn the timing task. However, a subgroup of lurcher mutants was able to learn after a high number of sessions (25.4 sessions as a mean). There was no intergroup difference in the standard version of one-way active avoidance. These results indicate that the cerebellar cortex is involved in time processing during active avoidance. The cerebellum may be part of a loop including the cerebral cortex known to be involved in time perception. An alternative explanation is that the cerebellar mutant animals had persevering tendencies acquired during performance of the one-way avoidance task.

Animals↗
PubMed1997

The nomadic engram: overtraining eliminates the impairment of discriminative avoidance behavior produced by limbic thalamic lesions.

Combined lesions of the medial dorsal and anterior thalamic nuclei severely impair the acquisition of discriminative avoidance behavior, wherein rabbits learn to prevent foot-shock by stepping after a tone conditional stimulus (CS+), and they learn to ignore a different tone (CS-) that does not signal foot-shock. Neurons in these thalamic nuclei exhibit training-induced firing pattern changes during behavioral acquisition to asymptotic performance levels. However, the changes decline in magnitude during the course of post-asymptotic training (overtraining), suggesting a declining participation of the thalamic neurons in task mediation. In order to test this hypothesis, electrolytic or sham limbic thalamic lesions were induced either immediately after asymptotic performance was reached, or after the administration of training to asymptote and ten additional overtraining sessions. Retention after the lesions was assessed using an extinction procedure (CS presentation without foot-shock) followed by re-acquisition. Rabbits given lesions after criterion attainment exhibited a significant retention deficit during both the extinction and re-acquisition tests. However, no significant retention deficit was found in rabbits given 10 days of overtraining prior to the lesions. These results support the prediction derived from the neuronal data, of a time-limited involvement of limbic thalamic neurons in mediation of discriminative avoidance behavior.

Animals↗
PubMed1998

Effects of MK-801 on vicarious trial-and-error and reversal of olfactory discrimination learning in weanling rats.

The effects of dizocilpine maleate (MK-801) on vicarious trial-and-error (VTE), and on simultaneous olfactory discrimination learning and its reversal, were observed in weanling rats. The term VTE was used by Tolman (The determiners of behavior at a choice point. Psychol. Rev. 1938;46:318-336), who described it as conflict-like behavior at a choice-point in simultaneous discrimination learning. It takes the form of head movements from one stimulus to the other, and has recently been proposed by Amsel (Hippocampal function in the rat: cognitive mapping or vicarious trial-and-error? Hippocampus, 1993;3:251-256) as related to hippocampal, nonspatial function during this learning. Weanling male rats received systemic MK-801 either 30 min before the onset of olfactory discrimination training and its reversal, or only before its reversal. The MK-801-treated animals needed significantly more sessions to acquire the discrimination and showed significantly fewer VTEs in the acquisition phase of learning. Impaired reversal learning was shown only when MK-801 was administered during the reversal-learning phase, itself, and not when it was administered throughout both phases.

Animals↗
PubMed1984

Behavioral monitoring of pharmacological interventions for self-injury.

Pharmacological interventions are often the treatment of choice for controlling the maladaptive behavior of institutionalized mentally retarded children. However, the efficacy of various psychotropic drugs for controlling the behavior of given individuals has not been well established. Further, it is not always clear that decisions to alter a drug regimen are based on actual changes in the behavior of interest. The present study illustrates the use of behavioral observation to assess the effects of various drugs prescribed for the self-injurious behavior of a profoundly mentally retarded 15 year old male. The clinical effectiveness of various dosages of carbamazepine (Tegretol), thioridazine (Melleril), and chlorpromazine (Largactil) was assessed. Except for Melleril 100 mg, tid, when a marked downward trend in the daily rate was observed, no significant reduction in self-injury occurred. Subsequently overcorrection (forced arm exercise) made contingent on each response reduced self-injury to near zero, but only when the last prescribed drug, Tegretol 200 mg, tid, had been withdrawn for several days.

Adolescent↗
PubMed1986

Principles of learning.

This article discusses some general principles of learning as well as possible constraints and how such principles can apply to horses. A brief review is presented of experiments that were designed to assess learning in horses. The use of behavior modification techniques to treat behavior problems in horses is discussed and several examples of the use of these techniques are provided.

Animals↗
PubMed1990

Conditioned taste aversion is disrupted by prolonged retrograde effects of intracerebral injection of tetrodotoxin in rats.

Acquisition of conditioned taste aversion (CTA) is disrupted when 10 ng tetrodotoxin (TTX) is injected into both parabrachial nuclei of rats immediately after saccharin drinking and before LiCl poisoning (Ivanova & Bures, in press). Further analysis of this finding showed that parabrachial TTX injection (a) elicited retrograde amnesia also when applied 1, 2, or 4 days but not 8 days after CTA acquisition; (b) did not abolish CTA produced by 2 or 3 saccharin-LiCl pairings; (c) did not cause persistent increase of quinine threshold; and (d) elicited anterograde CTA amnesia when applied 1 but not 2, 4, or 8 days before CTA acquisition. TTX-induced amnesia is not due to persistent gustatory agnosia but rather to disruption of the protracted consolidation of the permanent CTA engram by prolonged cessation of impulse activity in the information storing network.

Animals↗
PubMed1985

Serial ablations of the telencephalon and avoidance learning by goldfish (Carassius auratus).

Simultaneous bilateral ablation of the teleost telencephalon was confirmed to dramatically impair the retention, extinction, and "reversal learning" of a preoperatively learned instrumental avoidance response in a shuttle box. The focus of the experiment was on whether two-stage serial unilateral ablations of the teleost telencephalon would ameliorate the effects seen following one-stage bilateral ablation and whether such amelioration would be a function of the fish's experiences between the staged ablations. The degree of retention, relearning, and extinction of the avoidance response was not modulated by the serial ablation procedure whether or not there was interoperation retraining experience. However, reversal learning, in which the previous warning signal became the safety signal and the previous safety signal became the new warning signal, was less impaired following serial ablations than following single-stage bilateral ablation. These results are contrasted with those from experiments with mammalian subjects.

Animals↗
PubMed1991

Age, activity, and physical performance: an evaluation of performance models.

Two performance models relating age, physical activity, and physical performance were evaluated on 5 age cohorts involving more than 6,000 persons ranging in age from 20 to 69 years. Significant age and activity main effects, without 1 Age X Activity interaction, were obtained on 5 fitness measures and 2 activity indexes. These results are inconsistent with predictions from the moderation model, but they fit predictions from a recently formulated tonic and overpractice model of physical performance.

Activities of Daily Living↗