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PubMedDate not supplied

The inability of CCK to block (or CCK antagonists to substitute for) the stimulus effects of chlordiazepoxide.

To further examine the relationship between cholecystokinin (CCK) and GABA, the present study assessed the ability of the CCK-A antagonist devazepide and the CCK-B antagonist L-365,260 to substitute for the stimulus effects of chlordiazepoxide (CDP), as well as the ability of CCK-8s to block these effects, in female Long-Evans rats within the conditioned taste aversion baseline of drug discrimination learning. Both devazepide and L-365,260 failed to substitute for the discriminative stimulus properties of CDP, and CCK-8s failed to block its stimulus effects. The benzodiazepine diazepam did substitute for, and the benzodiazepine antagonist flumazenil did block, the stimulus effects of CDP. This suggests that the lack of substitution for, or antagonism of, CDP by the CCK antagonists and CCK-8s, respectively, was not due to the inability of the present design to assess such effects. Possible bases for the current findings, e.g., necessity of an anxiogenic baseline, drug and receptor specificity, as well as the dose-response nature of the interaction, were discussed. Given that a relationship between CCK and GABA has been reported in other designs, the present results suggest that such a relationship may be preparation specific.

Animals↗
PubMed2003

Successive two-item same-different discrimination and concept learning by pigeons.

Four pigeons were trained in a successive same/different procedure involving the alternation of two stimuli per trial. Using a go/no-go procedure, two different or two identical color photographs were alternated, with a brief, dark, inter-stimulus interval, on a computer screen for 20s. Pigeons learned to discriminate between same (S+) and different (D-) sequences with moderate to large contrasts between successive pictures. Analyses of pecking behavior within single trials revealed this discrimination emerged at the earliest possible point in the sequence (i.e. by the presentation of the second item). Pigeons transferred to novel color and gray-scale pictures, and showed savings in tests with novel video stimuli. These results suggest that same/different discrimination and concept formation can be acquired with successively presented pairs of stimuli by pigeons. When combined with results using simultaneous same/different presentations, these findings further support a qualitative similarity among birds and primates in their capacity to judge certain types of stimulus relations.

Journal Article↗
PubMed1985

Perceptual learning in frequency discrimination.

This study was concerned with the effects of training on the frequency discrimination ability of human listeners. Frequency discrimination at 200 Hz was tested before and after training. Four groups of listeners received training in four different frequency regions, 200, 360, 2500, and 6000 Hz. It was found that training at 200, 360, and 2500 Hz all provided comparable improvement in discrimination performance at 200 Hz whereas training at 6000 Hz provided less improvement. This result is consistent with the idea that frequency discrimination and pitch perception are mediated by different processes at high (greater than 5000 Hz) and low (less than 5000 Hz) frequencies.

Adult↗
PubMed1986

Retention interval and intertrial interval in a serial learning or delayed discrimination task.

In each of four experiments, rats were provided with the same three-event decreasing series (18-1-0) of 0.045-g food pellets in a runway. Tracking, running fast to 18 pellets and running slow to 1 and 0 pellets, was investigated as a function of the temporal interval elapsing between the events of the series (the retention interval), shifts in retention interval, and number of trials each day (or the intertrial interval), a trial being defined as presentation of each of the three events of the series. Neither retention interval, which varied from 15 s to 30 min in various investigations, nor shifts in retention interval affected tracking when only one trial was given each day. But when more than one daily trial was given, tracking was acquired more slowly and was disrupted by a shift in retention interval from 15 s to 5 min. Tracking was also disrupted by a shift from one to two trials each day. These results indicate that when given one 18-1-0 trial each day, the rat partitions events on a first-event/subsequent-event basis; that little forgetting occurs even at long retention intervals; that somewhat different memories signal events when one or more than one 18-1-0 trial occurs each day; and that retention interval deficits can arise owing to the same or similar memories' signaling different events. The results described limit the generality of three hypotheses suggested in two recent investigations: that as retention interval increases, rats find it increasingly difficult to remember and utilize serial position cues; that tracking in serial tasks is not influenced by number of trials each day; and that there are specific stimuli associated with each retention interval which, when changed, necessarily disrupt performance.

Animals↗
PubMed1980

Rapid assessment of stereopsis in pre-verbal children using operant techniques: a preliminary study.

A new operant conditioning program, based upon principles of errorless discrimination learning, was used to assess stereopsis in 24-35 months old children. Results indicated that this program was more successful in generating responding to stereograms than standard contour or random dot tests of stereopsis. It was concluded that the most effective procedure for evaluating subjective visual findings in pre-verbal patients is one that recognizes the importance of programmed discrimination learning and operant motivational techniques.

Age Factors↗
PubMed1987

Sex differences and reversal of brain asymmetry by testosterone in chickens.

The study examined the effect of testosterone on the asymmetry of visual discrimination performance of young chicks. Two-week-old chicks were tested on the pebble floor visual discrimination task. Male chicks were found to have brain asymmetry for visual discrimination learning, since chicks tested binocularly, or tested monocularly using their right eye system, have superior learning performance compared to chicks tested monocularly using their left eye system. Control female chicks were not found to have brain asymmetry. Testosterone treatment (12.5 mg of testosterone oenanthate on day 2 posthatch) reversed the pattern of brain asymmetry observed in control males but not females. In addition, asymmetry of visual discrimination learning is demonstrated in both male and female chicks after unilateral intracranial treatment with monosodium glutamate.

Animals↗
PubMed2003

[Neuroprotective effects of Astragulus membranaceus on hypoxia-ischemia brain damage in neonatal rat hippocampus].

OBJECTIVE: To study neuroprotective effects of astragulus membraneaceus on a neonatal rat hippocampus of hypoxia-ischemia brain damage (HIBD). METHOD: The neonatal hypoxia-ischemia model was established with 7-day-old rat pups. Brain injury was examined by neuron death rate in the hippocampal CA1 area. Caspase-3 (cysteinyl aspartate-specific proteinase) mRNA expression in ipsilateral hippocampal was measured by half-quantitative reverse transcription and polymerization chain reaction (RT-PCR). 90-day-old rats were used in tri-equal-arm maze to observe discrimination learning ability. Sham, model and astragulus-membraneaceus treated groups were set up. RESULT: In model group, caspase-3 mRNA showed an increase at 6h, with maximum arrivimg at 24 h - 48 h after HI. In astragulus-membraneaceus treated group, neurons death rate and caspase-3 mRNA were significantly reduced by astragulus membraneaceus, and discrimination learning ability of developed rats were improved obviously. CONCLUSION: Astragulus membraneaceus has a strong protective effect on neuronal damage in the immature rat hippocampus, which is ralated reducing caspase-3 expression.

Animals↗
PubMed1998

Visual control of the arm, the wrist and the fingers: pathways through the brain.

Sperry and his colleagues had shown that section of the corpus callosum blocks the normally strong interocular transfer of visual learning in chiasma sectioned monkeys. Although interhemispheric transfer of learning was blocked, monkeys could be readily trained to use any combination of eye and hand in a task that required rapid visually guided responses. Sperry suggested that there must be a subcortical pathway linking sensory to motor areas of the brain. We tested monkeys in a task which required them to orient their wrist and fingers correctly in order to remove a morsel of food from a slotted disc. Animals in which we made lesions of the dorsal extrastriate visual areas of the parietal lobe were profoundly impaired in performing this task, but showed no deficit in visual discrimination learning. A monkey with an extensive lesion of the ventral, temporal lobe extrastriate areas showed no deficit in the visuomotor task but was profoundly impaired in visual discrimination learning. Lesions of peri-arcuate cortex, a major cortical target of parietal lobe visual areas, produced only a mild deficit which was motor in character. We suggest that the visuomotor deficit caused by parietal lobe lesions is brought about by depriving the cerebellum of its cortical visual input.

Animals↗
PubMed2000

The effects of aminotriazole and acetaldehyde on an ethanol drug discrimination with a conditioned taste aversion procedure.

The present study was designed to investigate whether acetaldehyde shares stimulus properties with ethanol using the conditioned taste aversion (CTA) baseline of drug discrimination learning. Animals were trained to discriminate ethanol (0.8 g/kg, i.p.) from saline using 11 consecutive cycles consisting of a pairing day and three nonpairing days. On pairing days, all animals were injected with ethanol 30 min prior to a 20-min limited access to a saccharin solution (0.1% w/v) and then immediately injected with either LiCl (0.15 M, 1.8 meq) or distilled water. On the three following nonpairing days, animals were injected with saline and 30 min later presented with the same saccharin solution for 20 min. No injections followed on these nonpairing days. Results showed that animals acquired discriminative stimulus control for ethanol after seven pairings. Pretreatment with the catalase inhibitor did not alter the discriminative control for ethanol. Generalization tests revealed that acetaldehyde substituted for ethanol at a dose of 0.3 g/kg. The results of the present study suggest that catalase inhibition did not reverse or alter the discriminative stimulus effects of ethanol. However, generalization tests showed that acetaldehyde (0.3 g/kg) will substitute for ethanol suggesting that these two drugs share some similar properties.

Acetaldehyde↗
PubMed1967

Phenylketonuria: enduring behavioral deficits in phenylketonuric rats.

The behavioral deficit in rats made "phenylketonuric" by ingestion of L-phenylalanine was evaluated 23 to 65 days following cessation of treatment. Animals treated from birth to 60 days showed significant deficit on reasoning and discrimination learning tests but not on discrimination reversal sets. Animals treated from 30 to 60 days showed significant deficit only on the reasoning test.

Animals↗
PubMed1986

Behavioral functions and hippocampal cell types: evidence for two nonoverlapping populations in the rat.

Extracellular recordings of individual hippocampal neurons in behaving rats were classified by several different electrophysiological criteria as theta (theta-) or complex spike cells. The firing characteristics of each cell were studied in two different behavioral contexts, each of which contained experimental conditions in which firing correlates of these cells have been demonstrated previously. Forty-eight theta-cells and 68 complex spike cells were classified and studied electrophysiologically as animals performed an operant auditory discrimination task or freely explored an open platform environment for water reward. Spontaneous discharge characteristics, as well as electrically evoked firing patterns following stimulation of hippocampal fiber pathways, consistently differentiated theta-cells from complex spike cells. In agreement with previous reports, these results indicate that theta-cells and complex spike cells represent electrophysiologically and possibly morphologically different types of hippocampal neurons. A clear dichotomy also emerged between the firing correlates of identified theta-cells and complex spike cells in the two behavioral tests. During auditory-discrimination learning and performance, time-locked theta-cell discharges to tone onset were correlated with the emergence of conditioned behavioral responding. Increased activity of theta-cells was also observed during locomotion in the spatial exploration task. Time-locked increases in firing to the tone stimulus were restricted to identified theta-cells. Complex spike cells, in contrast to theta-cells, did not increase activity during any phase of tone-discrimination learning or performance. The same cells, however, fired at markedly increased rates coincident with the animals' presence in specific spatial locations during exploration of the platform but did not fire during other overt behaviors on the platform such as grooming, drinking, or locomotion. Complex spike cells qualified on the basis of positive collision tests and antidromic criteria as hippocampal output neurons. "Spatial firing" was unique to complex spike cells and was not observed from theta-cells recorded from the same animal. Twenty-one theta-cells and 31 complex spike cells studied in both behavioral contexts showed mutually exclusive and nonoverlapping electrophysiological firing correlates. No cell was observed in either category which exhibited spatial and tone discrimination related firing correlates.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1984

Hypothesis-testing and nonlinguistic symbolic abilities in language-impaired children.

This study sought to clarify further the cognitive abilities of language-impaired children by examining their hypothesis-testing and nonlinguistic symbolic abilities. A discrimination learning task and a concept formation task were used to measure hypothesis-testing abilities, and a haptic (touch) recognition task was used to assess nonlinguistic symbolic abilities. Subjects were 10 language-impaired and 10 language-normal children matched for performance Mental Age. Measures of expressive and receptive language were also obtained from each child. The language-impaired children were found to perform significantly poorer than their MA controls on the haptic recognition task and on a portion of the discrimination learning task. No differences were found between the two groups' concept formation abilities. Correlational analyses revealed a particularly strong positive relationship between performance on the Peabody Picture Vocabulary Test and the haptic recognition tasks. It was speculated that this relationship was motivated by the symbolic demands of these tasks. One implication of this speculation is that a symbolic representational deficit might better explain the receptive language deficit than the expressive one.

Age Factors↗
PubMed1980

[Neurobehavioral and systemic effects in lead-exposed rats after an exposure-free interval of four months duration (author's transl)].

This experiment was designed to study the degree of recovery from lead-induced neuro-behavioral deficit after normalization of blood lead-level (PbB). Female Wistar-rats were given a diet containing lead-acetate (2260 ppm Pb) for 60 d until mating, giving rise to a PbB-increase from 53 microgram/d1 (before mating) to 84 microgram/d1 (after weaning). Lead-exposure of their male offspring was continued for 4 months with their PbB levelling off at 40 microgram/d1 (table 1). Lead-feeding was discontinued thereafter for another 4 months, PbB declining to a final level of 12 microgram/d1 (table 1). These animals were then compared for neurobehavioral functions to age-matched controls with respect to discrimination-learning (Lashley jumping-stand) and motor activity (open field-test). In addition recovery from initial loss of body-weight after partial food-deprivation was measured, known to be retarded at elevated PbB. The results may be summarized as follows: Formerly Pb-treated animals subsequently raised on a lead-free diet resulting in PbB-normalization within 4 months as compared to untreated controls exhibit (1) significant retardation of recovery from initial loss of body-weight (fig 4), (2) significant increase of error-repetitions in discrimination-learning (table 4; fig. 5) indicating disturbances of learning-performance without a change in learning-speed, and (3) significant hypoactivity (ambulation) without a significant change of other variables of open field-behavior (table 5; fig. 6). These results demonstrate, that some neurobehavioral and systemic symptoms of Pb-related dysfunction persist even after normalization of PbB, thus indicating partial irreversibility of Pb-induced damage.

Animals↗
PubMed1994

Dissociated effects of perirhinal cortex ablation, fornix transection and amygdalectomy: evidence for multiple memory systems in the primate temporal lobe.

Four experiments were performed with macaque monkeys (rhesus, Macaca mulatta, and cynomolgus, M. fascicularis). In experiment 1 six rhesus monkeys learned pre-operatively to perform delayed matching-to-sample, with complex naturalistic scenes as the stimulus material. Three of these monkeys then received bilateral ablations of the perirhinal cortex, while the other three received fornix transection. Both groups showed an impairment postoperatively, but the effect of perirhinal cortex ablation was significantly more severe than the effect of fornix transection. In experiment 2 the same animals, together with three normal, control rhesus monkeys, which had a similar training history, performed simple, spatial discrimination learning in a Wisconsin General Test Apparatus. The animals with fornix transection were impaired, but the animals with ablations of perirhinal cortex were not. In experiment 3 the nine animals from experiment 2 were tested for the acquisition of systematic preferences among four novel foods (apple, lemon, olive, meat). Their results were compared with those from a previously published experiment with normal and amygdalectomized cynomolgus monkeys which had been given the same food preference test. Amygdalectomy produced a significant disruption of food preference learning but the other two lesions (fornix transection and perirhinal cortex ablation) did not. In experiment 4, 16 rhesus monkeys (9 normal controls, 4 with perirhinal cortex ablation, and 3 with fornix transection) learned to discriminate among complex naturalistic scenes, in a task in which each scene was presented only once per day in the main part of the experiment. The two operated groups were impaired, and there was no significant difference between the severity of the impairments. Thus, the effects of perirhinal cortex ablation can be doubly dissociated from the effects of fornix transection (experiments 1 and 2) and both can be dissociated from the effects of amygdalectomy (experiment 3). Furthermore, the results of experiment 4 show that the effects of perirhinal cortex ablation are not limited to tasks of memory over short retention intervals. On the basis of the presently reported data and other known effects of perirhinal cortex ablation, it is suggested that this ablation produces an impairment in knowledge (semantic memory) about objects.

Amygdala↗
PubMed2002

Transfer of learning across durations and ears in auditory frequency discrimination.

Frequency-discrimination thresholds (FDTs) for 1-kHz tone pips with durations of 40, 100, and 200 msec were measured in the left and right ears of 10 normal-hearing listeners, before and after six 2-h frequency-discrimination training sessions involving, exclusively, the 200-msec duration and the right ear. In the trained ear, highly significant improvements in FDTs were observed at all durations. Further inspection of the data suggested complete generalization between 200 and 100 msec, but not at 40 msec. Posttraining FDTs were not found to differ between the two ears for the two untrained durations, but proved significantly smaller in the right (trained) than in the left (untrained) ear at the trained (200-msec) duration only. A control experiment involving 10 additional subjects allowed us to establish the absence of intrinsic differences in pretraining FDTs between the right and left ears. Overall, these findings indicate that frequency-discrimination learning generalizes widely across stimulus durations and across ears, but that part of the improvement is specific to the range of durations and to the ear used in training.

Adult↗