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At least 19 recordsLinked to original sources
PubMed1991

Spatial learning, discrimination learning, paw preference and neocortical ectopias in two autoimmune strains of mice.

NZB and BXSB mice were given a battery of behavioral tests including paw preference, water escape, Lashley III maze, and discrimination learning. Their brains were then evaluated for cortical ectopias. The incidence of ectopias was 40.5% in NZBs and 48.5% in BXSBs. In the NZB strain left-pawed ectopic mice (both male and female) had the fastest swimming time in the water escape test, while right-pawed ectopics were the slowest. The same findings were obtained for left- and right-pawed ectopic BXSB males, but not for the females. However, on discrimination learning the BXSB males had the exact opposite pattern: right-pawed ectopics were the best learners while left-pawed ectopics were the worst. Male BXSBs and both male and female NZBs were manifesting autoimmune disease at the time of testing, while female BXSBs were not, suggesting that autoimmunity is a necessary background condition for the differential expression of ectopias and paw preference upon learning processes. The finding that the left-pawed ectopic BXSB mice, who were the poorest learners in the non-spatial discrimination learning test, learned best in the spatial water escape test is in agreement with the Geschwind hypothesis that pathological events during brain development may, in some instances, produce superiority of function.

Animals↗
PubMed2001

Lesions in the central nucleus of the amygdala: discriminative avoidance learning, discriminative approach learning, and cingulothalamic training-induced neuronal activity.

The amygdala is critically involved in discriminative avoidance learning. Large lesions of the amygdala block discriminative avoidance learning and abolish cingulothalamic training-induced neuronal activity. These results indicated that amygdalar processing is critical for cingulothalamic plasticity. The larger lesions did not allow differentiation of the specific functioning of various amygdalar nuclei. Anatomical analysis showed that damage in the central (CE) nucleus of the amygdala was correlated with the severity of the behavioral deficit. The present study was carried out to determine whether smaller lesions, centered in the CE nucleus, would impair discriminative avoidance learning and block cingulothalamic plasticity. In addition, the possible role of the CE nucleus in appetitively motivated discriminative approach learning was examined for the first time. New Zealand White rabbits with CE nuclear lesions were first trained in the discriminative approach task. After attaining asymptotic performance, discriminative avoidance training sessions were alternated with continuing approach training sessions, one session each day. The rabbits with lesions were severely impaired in avoidance learning but showed no impairment of approach learning. Surprisingly, the attenuating effects of the lesions on cingulothalamic training-induced neuronal activity were more prevalent during approach learning than during avoidance learning. These results indicated that avoidance learning can be impaired by lesions centered in the CE nucleus that leave cingulothalamic plasticity largely intact and that the CE nucleus is involved in extra-cingulothalamic learning processes.

Amygdala↗
PubMed1998

Reward-produced memories regulate memory-discrimination learning, extinction, and other forms of discrimination learning.

In memory-discrimination learning, reward-produced memories are differentially rewarded such that they are the only stimuli available to support discriminative responding. Memory-discrimination learning was used in this study as follows: Reward-produced memories that were assumed to regulate instrumental performance in previously reported extinction and discrimination learning investigations were isolated and explicitly differentially reinforced (prior to a shift to extinction) in each of 4 runway investigations with rats. Results obtained here in the explicit discrimination learning stage and in the subsequent extinction stage were consistent with the prediction of the memory view and with prior discrimination learning and extinction findings. The memory interpretation was applied to memory-discrimination learning, to extinction, and to 2 other types of discrimination learning. It appears that a theory must use reward-produced memories to explain all 4 types of discrimination learning.

Animals↗
PubMedDate not supplied

Drug effects on sucessive discrimination learning in young chickens.

Chicks were trained to avoid pecking either a red or a blue bead in a one-trial avoidance task by coating one bead with methy anthranilate. They avoided the aversant bead on retention tests 10 to 180 min or 24 hr after learning, but not the neutral bead. Intracranial administration of ouabain or cycloheximide (CXM) 5 min before learning resulted in decay in retention after 10 and 30 min respectively following learning, discrimination being effective prior to those times. In a second experiment, chicks were trained on three physically distinct beads, two of which were made aversive during the learning period, the training trials separated by an hour. Saline-treated chickens retained memory of both aversive beads on retention trials 180 min later. CXM- and ouabain-treated chickens showed loss of memory for the bead associated with the drug but showed retention of the task which was not associated with the drug.

Animals↗
PubMed1994

Postnatal high-peak blood ethanol concentration and external cue-based discrimination learning and reversal in the preweanling rat: comparison with memory-based discrimination learning.

Postnatal exposure to ethanol that produces high-peak blood ethanol concentrations (HP-BEC) in artificially reared infant rats affects hippocampal neuroanatomy and discrimination learning based on memorial cues from a patterned (single) alternation (PA) schedule in preweanling rats (P. L. Greene, J. L. Diaz-Granados, & A. Amsel, 1992). In the present experiments, discrimination by preweanling rats exposed to ethanol in the same way was tested with nonmemorial, external cues. In this external cue-based discrimination and in its reversal, ethanol-exposed rats were not different from normal or artificially reared controls whether the cues were presented in a PA or random manner, although there was some evidence that the memorial cues from the PA schedule contributed to learning a discrimination based on external cues, suggesting that the deficit reported earlier in ethanol-exposed rats is a memorial deficit and not a general discrimination deficit.

Animals↗
PubMed1998

Restricted lesions to ventral prefrontal subareas block reversal learning but not visual discrimination learning in rats.

Previous studies have shown that extensive damage to the medial prefrontal cortex (mPFC) of rats causes reversal learning deficits. The mPFC of rats, however, consists of several subareas that are different from each other in both cytoarchitecture and neural connectivity, suggesting a functional dissociation among the mPFC subareas. In the present study, selective lesions of the mPFC of rats were made with a specially designed microknife whose intracranial placement could be controlled stereotaxically. Restricted lesions were made to each of the 3 parts of the mPFC: the anterior cingulate area (AC) (including the medial precentral area, PrCm), the prelimbic area (PL), and the infralimbic area (IL). One week after surgery, rats were trained in an aversively motivated visual discrimination task in a novel rotating T-maze. After reaching the acquisition criterion, rats were trained in a reversal task in the same maze. No difference was found in acquisition between control and mPFC lesioned rats. However, lesions of either the PL or the IL produced a marked deficit in the reversal task. This behavioral deficit was not found in rats with lesions of the AC. The results indicate that the mPFC of rats is not essential for discrimination learning, but that each of the 2 ventral subareas of the mPFC, PL, and IL, plays a critical role in reversal learning.

Animals↗
PubMed1990

Picture recognition vs. picture discrimination learning in monkeys with medial temporal removals.

Three monkeys with complete ablations of temporal-lobe limbic structures and three unoperated controls were compared in an automated testing apparatus for their ability to remember pictures presented between 1 and 180 seconds previously, as well as to learn picture discriminations in which successive trials with a given pair were separated by either 20 seconds or 24 hours. The operated animals were not impaired in picture discrimination learning under either condition and they were not impaired in picture recognition memory up to about 10 seconds. At 10 seconds and beyond, however, the operated animals showed rapid deterioration of picture memory. The results demonstrate that the limbic system's selective contribution to learning and retention uncovered initially with objects applies equally to pictures, this contribution being essential for recognition memory but not for discrimination habits. The results demonstrate further that, as in humans, temporal-lobe limbic structures are essential for recognition only when the retention test exceeds the immediate memory span of a few seconds.

Animals↗
PubMed1984

Monkeys with combined amygdalo-hippocampal lesions succeed in object discrimination learning despite 24-hour intertrial intervals.

Monkeys with combined amygdalo-hippocampal removal show severe impairments on visual memory tasks after delays of only a minute or two, yet they learn visual discrimination habits about as quickly as normal animals with intertrial intervals of the same duration. In an attempt to resolve this discrepancy between abnormally rapid forgetting and successful retention, tests were conducted to determine whether discrimination learning would be prevented in animals with limbic lesions if intertrial intervals lasted 24 hr. The results showed that as long as the lesion did not encroach on inferior temporal cortex, the operated animals could acquire concurrent sets of 20 object discrimination habits at the same rate as normal animals, in an average of about 10 trials per set. The findings suggest that learning and retention processes are divisible into a mechanism for memory formation that is dependent on the limbic system and a mechanism for habit formation that is not.

Amygdala↗
PubMed1996

Object discrimination learning and object-pattern discrimination transfer in visually deprived cats.

We used binocularly deprived cats (BD cats), control cats reared in the laboratory with open eyes (C cats) and normal wild cats (N cats). In stage 1, the cats were trained to discriminate a black ping-pong ball and a 3-dimensional cross of the same size and color for food reward. The BD cats learned slower than N cats. The difference between BD cats and C cats was statistically insignificant. A comparison of these data and previous data on discrimination of corresponding 2-dimensional black patterns (disk and cross) show that in discrimination learning the 3-dimensionality of stimuli is helpful for N cats, but not for BD cats. Thus, the objects and their patterns are for BD cats highly similar. In stage 2, the objects were replaced by corresponding 2-dimensional patterns (disk and cross). Pattern discrimination was learned slower by BD cats than by N cats. Thus, the objects and their patterns are for BD cats certainly not identical and BD cats are deficient in discrimination transfer of even highly similar pairs of visual stimuli.

Animals↗
PubMed2003

Impaired visual discrimination learning in anorexia nervosa.

The primate dopamine system is involved in appetitively motivated behaviours, including certain forms of learning, for example, visual discrimination learning. Furthermore, food restriction in animals and anorexia in humans is associated with impaired dopamine signaling. Based on this, we hypothesized that patients with anorexia nervosa (AN) would show a deficit in visual discrimination learning. In a dynamic categorization task involving the learning of a series of two-alternative forced-choice visual discriminations, conceptually identical to one shown to activate dopamine neurons in primates, and sensitive to dopaminergic manipulations in humans, patients with AN showed a deficit in learning that was most pronounced in the early stages of acquisition. In contrast, AN showed spared performance on a pattern recognition memory test sensitive to medial temporal lobe lesions, but insensitive to dopaminergic manipulations. We conclude that impaired appetitive function in patients with AN extends to include deficits in visual discrimination learning, and that this deficit represents indirect evidence for altered dopaminergic neurotransmission in AN.

Adult↗
PubMed1994

Role of the amygdala in picture discrimination learning with 24-h intertrial intervals.

Six monkeys (Macaca mulatta) learned to discriminate visually between pictures of objects. Each pair of pictures was presented only once per day (24-h intervals between successive trials with the same pair). Choice of the correct picture of a pair produced immediate food reward. One set of 20 pairs was learned before operation and a second set of 20 different pairs was learned after the amygdala had been removed bilaterally in three of the monkeys. The amygdalectomized animals were severely retarded in learning the second set. These results confirm earlier results indicating that amygdalectomy impairs visual discrimination learning in tasks where the discriminanda are directly associated with the incentive value of a primary reward, and they show that, contrary to the indication of some previous results, this impairment extends to the case where each picture is seen only once per day.

Amygdala↗
PubMed1995

Operant discrimination learning in detelencephalated pigeons (Columba livia).

Operant discrimination learning was analyzed in pigeons after massive telencephalic lesions. Twenty-one pigeons were divided into three groups: non-lesioned (N = 6), sham-lesioned (N = 5) and telencephalon lesioned (N = 10). Lesion surgeries were carried out before any experimental training. Learning procedures were run in the same sequence for all groups and under a food deprivation of 80% of the ad libitum weight. Successive discrimination was programmed by the alteration of red and yellow lights in the right key of a standard operant chamber: the red key was correlated with variable-ratio reinforcement; the yellow key was correlated with extinction. Session were run until steady-state key peck rates were obtained. The following results demonstrate discrimination learning by detelencephalated birds. Response shaping and steady-state rates required a larger number of sessions for lesioned pigeons (P < 0.05). They showed increased response rates in red (26.43 +/- 2.59) and yellow (11.17 +/- 2.86) components as compared to the non-lesioned (red: 16.51 +/- 2.0; yellow: 2.02 +/- 0.64) and sham-lesioned (red: 22.84 +/- 1.77; yellow: 4.72 +/- 1.99) groups (P < 0.05). These data show that telencephalic systems are not essential for operant discrimination learning but play a role in the modulation of discriminative behavior. Subtelencephalic systems appear to be functionally important for the organization and storage of learning.

Animals↗