Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Discrimination Learning”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,369 records · Page 76Linked to original sources
PubMed1979

Visual discrimination impairments after lesions in zona incerta or lateral terminal nucleus of accessory optic tract.

Possible visual functions of zona incerta (ZI) and lateral terminal nucleus of the accessory optic tract (LTN) in rats were investigated by comparing the effects of localized lesions on a series of discrimination learning tasks. In Experiment 1 animals with ZI lesions were impaired on a simultaneous black versus white (BW) discrimination but not on a simultaneous horizontal versus vertical (HV) task. Animals with LTN lesions were impaired on HV but not on BW. Rats with ZI lesions were impaired on a successive bright versus dim but not a successive HV discrimination when subsequently tested in Experiment 2. Animals with LTN lesions were impaired on both tasks. The results are related to the possibility that visual intensity information gains access to the motor system through a pathway running from the ventral lateral geniculate nucleus to the basal ganglia via ZI. Since LTN lesions impaired acquisition of a HV discrimination, a task highly susceptible to the effects of geniculostriate ablation, it is suggested that such lesions impair the use of visual information without distroying the sensory channels mediating the discrimination.

Animals↗
PubMed1992

A specific form of cognitive rigidity following excitotoxic lesions of the basal forebrain in marmosets.

The effects of N-methyl-D-aspartate-induced lesions of the basal forebrain were studied on performance of a series of visual discrimination tests that examined a range of cognitive functions in the marmoset. These included the ability to attend to the various dimensional properties of stimuli and to use just one of these properties in order to solve a discrimination (intra-dimensional shift); to switch attention from one dimension to another (extra-dimensional shift); to learn the reinforcement value of specific exemplars within a dimension (new learning); and to relearn their reinforcement value following reversal of the reward contingencies (serial reversals). Lesions of the basal forebrain did not impair the ability either to attend selectively to the dimensional properties of the stimuli or to switch attention from one dimension to the other. However, the lesion did affect various aspects of associative learning including a transient impairment of new learning and a marked disruption of serial reversal learning. The reversal deficit could be characterised as a tendency to perseverate on the previously correct stimulus and as a failure to to show the formation of a reversal learning set. In addition, the lesion prevented disruption of performance of a well-learned discrimination when novel exemplars from the irrelevant dimension were introduced (probe test). It is suggested that the functional effects of the basal forebrain lesion reflect impaired learning of stimulus-reward associations and behavioural rigidity. The finding, however, that there was no effect of the lesion on attentional set-shifting suggests that any loss of inhibitory control was specific to the level of stimulus-response or stimulus-reward associations, inhibitory control at the level of attentional selection remaining intact. The similarity of the effects of damage to the basal forebrain to those seen following damage to the orbitofrontal cortex and the amygdala are discussed in the context of the close anatomical and functional relationships that exist among these three structures.

Animals↗
PubMed1976

Relations between birth weight and learning ability in young rabbits.

Performance on visual discrimination learning was studied in 41 rabbit pups mainly in relation to their birth weight, but also as functions of their neonatal motor development and weight gain between birth and training time. Partial placental vascular ligation was performed on some fetuses to increase the number of small-for-gestational-age pups. No relation was found between learning ability and either birth weight or rate of motor development. Low birth weight showed some association with slightly delayed motor development, but resulted in no lasting motor handicap. Between two subgroups of low birth weight pups, those who showed substantial weight gain by training time learned faster than those who remained relatively small.

Animals↗
PubMed1984

Ejaculatory incompetence: a theoretical formulation and case illustration.

Three theoretical formulations of ejaculatory incompetence have been proposed in the literature. They include: (1) aversive conditioned inhibition of the ejaculatory reflex, (2) an "autosexual" orientation associated with discrepant levels in the cognitive and physiological dimensions of sexual arousal, and (3) a discriminative learning model. These three models are discussed in relation to their theoretical and therapeutic implications. Clinical data supporting the discriminative view is presented.

Adult↗
PubMed1987

Characteristics of memory impairment in cerebral embolized rats at the chronic stage.

The effect of cerebral embolization on learning and memory in rats was studied at the chronic stage (8 weeks or more after embolization). At the chronic stage, embolized rats showed no significant change in emotional behavior, but exhibited an increase in ambulation in the open-field test. Rats with cerebral embolization exhibited marked impairment of the response was observed at the chronic stage. In a two-way active avoidance task, embolized rats showed accelerated acquisition of the avoidance response in comparison with a sham-operated control group. However, at the chronic stage, embolized rats exhibited marked impairment of light-dark discrimination learning. Spatial memory impairment was also observed in embolized rats, as demonstrated by a significant decrease in initial correct responses and an increase in total errors in the radial maze task. Upon microscopic examination, multi-focal necroses were detected in several brain regions, being particularly obvious in the hippocampus and internal capsule of the embolized hemisphere. These results demonstrate that embolized rats show definite impairment of memory and learning at the chronic stage, and suggest that the impairment may be qualitatively different from that observed at the early stage.

Animals↗
PubMed1980

Interaction of laminae of the cingulate cortex with the anteroventral thalamus during behavioral learning.

Neurons in deep laminae of the rabbit cingulate cortex develop discriminative activity at an early stage of behavioral discrimination learning, whereas neurons in the anteroventral nucleus of thalamus and neurons in the superficial cortical laminae develop such activity in a late stage of behavioral learning. It is hypothesized that early-forming discriminative neuronal activity, relayed to anteroventral neurons via the corticothalamic pathway, contributes to the construction of changes underlying the late-forming neuronal discrimination in the anteroventral nucleus. The resultant late discriminative activity in the anteroventral nucleus is then relayed via the thalamocortical pathway back to the superficial cortical laminae, promoting disengagement of cortex from further task-processing.

Animals↗
PubMed1992

Effects of intra-hippocampal scopolamine injections in a repeated spatial acquisition task in the rat.

The involvement of hippocampal cholinergic synapses in spatial discrimination learning was evaluated by locally administering scopolamine into the hippocampus. Sixteen 16-month-old male Lewis rats received bilaterally implanted cannulae aimed at the dorsal part of the hippocampus. The rats were trained on a repeated acquisition test in the Morris water-escape task. In this procedure the invisible platform is randomly moved from day to day to one of four possible locations. Thus, the rat has to learn to localize the platform from day to day. On each day the rats received four pairs of trials. Scopolamine injections (35 micrograms in 1 microliter per hippocampus) were given to one group (n = 8) on days 5 and 7. On days 6 and 8 all rats received saline injections. Place learning was retarded in the scopolamine-treated rats during the first swims of pairs of trials. During second swims the scopolamine-treated rats showed a general performance deficit, indicating that first and second swims were differentially affected. The data support the hypothesis that cholinergic neurotransmission in the dorsal hippocampus is involved in spatial learning processes.

Analysis of Variance↗
PubMed1984

Activity of neurons in monkey posterior temporal cortex during multidimensional visual discrimination tasks.

Unit activity was recorded from the posterior temporal cortex (PTE) of awake, behaving rhesus monkeys while they performed a series of visual discrimination tasks involving colored checkerboard patterns. The activity of 130 (91%) of 143 PTE units was altered by the presentation of a visual discriminandum; 112 of these cells (86%) exhibited a significant increase in firing after presentation of the stimulus while the remainder gave an inhibitory response. Over half (64%) the PTE units exhibited differential activity between discriminanda, i.e. they were selective for color and/or form. Six of 10 neurons, recorded when the monkey was required to shift attention from one stimulus feature to another, exhibited a difference in poststimulus neural activity even though the discriminandum remained the same. Three neurons were recorded from when the stimuli were altered by changing the check size although the relevant (i.e. rewarded) dimension (color) was left the same; two showed an invariant response to the altered stimuli and one gave the same response to one of the altered stimuli but a different response to the other. These data support the role of posterior temporal cortex in visual discrimination learning and visual attention.

Animals↗
PubMed2002

High-probability stimulus control topographies with delayed S+ onset in a simultaneous discrimination procedure.

Experimenters and teachers use discrimination learning procedures to encourage reliable attending to stimulus differences defined as relevant for their purposes. Put another way, the goal of discrimination training is to establish high-probability stimulus control topographies that are coherent with experimenter or teacher specifications. The present research was conducted to investigate a novel procedure for encouraging stimulus control topography coherence. Participants were 13 adolescents with severe intellectual handicaps. During an initial Condition A, all were exposed to a simultaneous discrimination procedure. Participants could select a form alternating with a black field (S+) or an identical form that did not alternate (S-). Accuracy scores were typically low, and there was little evidence of coherent stimulus control topographies. Subsequently, the procedure was changed. During Condition B, every trial initially presented two identical nonalternating S- forms (Trial State 1). If the participant made no selection for 5 s, one of the forms began to alternate with the black field, and he or she could make the S+/S- discrimination (Trial State 2). Selections during Trial State I prolonged the delay to Trial State 2 until there had been no response for 5 s. During Condition B, S+/S- discrimination accuracy scores improved rapidly and markedly for most participants. Reinstating Condition A often resulted in diminished accuracy scores. This study thus (a) demonstrated a novel procedure for encouraging stimulus control topography coherence and (b) provided support for the interpretation that intermediate accuracy scores may be due to different topographies of stimulus control that co-occur in the same discriminative baseline.

Adolescent↗
PubMed1973

The analysis of habituation.

Using the "method of continuous data" a detailed, quantitative description of the "action-program" of rats introduced into new environment make it possible to derive indices of the intensity of behavior which correlate closely with hippocampal "theta" activity. Using these indices a mathematical analysis of the course of habituation was attempted. Both uninterrupted and interrupted habituation can be divided into two parts: the activation and disactivation (habituation) curves. The theoretical habituation curve may be represented by a negative (usually) exponential growth function on which intrinsic damped oscillations with exponentially increasing wavelengths and decreasing amplitudes are superimposed (Fig. 11). The activation curve has the inverse characteristics (Fig. 15). The course of positive learning seems to be intimately related to the activation curve. Since the dependence of both the rate of habituation and the rate of discrimination learning on the individual excitability level are of the same nature (inverted U-shaped curves), habituation can hardly be accepted as the simplest kind of learning. For habituation to occur, intervals between stimuli are critical; novelty or absence of reinforcement may be secondary.

Animals↗
PubMed1997

Substance P facilitates memory in goldfish in an appetitively motivated learning task.

The aim of this study was to investigate if the neuropeptide substance P (SP) can improve learning and memory in goldfish (Carassius auratus). Four groups of fish were trained for seven days to find food in one out of two compartments until discrimination was achieved. On the last training day, they were injected (intra-abdominal) with haloperidol or vehicle before the training, and with SP or vehicle immediately after the training session. Each group of fish received either: (1) vehicle+vehicle (n = 18); (2) vehicle + SP, (n = 20, SP 50 mg/kg); (3) haloperidol+ vehicle (n = 15, haloperidol 2 mg/kg); or (4) haloperidol+ SP (n = 14, haloperidol 2 mg/kg, SP 50 mg/kg). Twenty-four hours later, the time spent to find the food was recorded. Reversal training was done for four consecutive days after this post-injection test and the time spent to find the food was recorded again. The results indicate that only the group treated with vehicle + SP needed more time to reach reversal training than control fish (Mann-Whitney U-test, P = 0.0009). It is suggested that SP can enhance memory in fish and that this effect may have a dopaminergic mediation in discrimination learning task.

Animals↗
PubMed1968

The fine structure of puromycin-induced changes in mouse entorhinal cortex.

Bitemporal intracerebral injections of puromycin in mice suppress indefinitely expression of memory of avoidance-discrimination learning. Ultrastructural studies of the entorhinal cortex of puromycin-treated mice revealed the following: (a) Abnormalities were not observed in presynaptic terminals and synaptic clefts; many postsynaptic dendrites or somas contained swollen mitochondria. (b) Dispersion of polyribosomes into single units or condensation of ribosomes into irregular aggregates with loss of "distinctiveness" was noted in a few neurons 7-27 hr after puromycin treatment. (c) Cytoplasmic aggregates of granular or amorphous material were frequently noted within otherwise normal neuronal perikarya. (d) Mitochondria in many neuronal perikarya and dendrites were swollen. Mitochondria in axons, presynaptic terminals, and glial cells were unaltered. The relationships between these lesions and the effect of puromycin on protein synthesis and memory are examined. It is suggested that the disaggregation of polysomes is too limited to explain the effect of puromycin on memory. Special emphasis is given to the swelling of mitochondria. The possible mechanisms and the significance of this lesion are discussed.

Animals↗
PubMed1976

Evidence for dimensional independence in short-term memory of retarded individuals.

This experiment was designed to assess the relative importance of dimensional similarity between test and interpolated problems and absolute difficulty of interpolated material as variables influencing short-term retention in the discrimination learning of retarded persons. Twenty moderate-to-borderline retarded individuals were taught a mixed series of two-trial discriminations consisting of: (a) relatively easy multidimensional ("junk") problems and (b) more difficult, form-relevant dotpattern discriminations. Test problems and interpolations were either dimensionally similar (both junk or both dot-pattern problems) or dissimilar (train one type of problem, interpolate the other). The major finding was that short-term forgetting occurred only when test and interpolated stimuli were dimensionally similar. Absolute difficulty of interpolations had no effect on retention. These results were interpreted as supporting Fisher and Zeaman's (1973) assumption of dimensional independence of memory processes in retarded persons. A secondary finding was that performance on dot-pattern discriminations varied with intelligence.

Adolescent↗
PubMed2006

Deficits across multiple cognitive domains in a subset of aged Fischer 344 rats.

Rodent models of cognitive aging routinely use spatial performance on the water maze to characterize medial temporal lobe integrity. Water maze performance is dependent upon this system and, as in the aged human population, individual differences in learning abilities are reliably observed among spatially characterized aged rats. However, unlike human aging in which cognitive deficits rarely occur in isolation, few non-spatial learning deficits have been identified in association with spatial impairment among aged rats. In this study, a subset of male aged Fischer 344 rats was impaired both in water maze and odor discrimination tasks, whereas other aged cohorts performed on par with young adult rats in both settings. The odor discrimination learning deficits were reliable across multiple problems. Moreover, these deficits were not a consequence of anosmia and were specific to olfactory learning, as cognitively impaired aged rats performed normally on an analogous non-olfactory discrimination task. These are among the first data to describe an aging model in which individual variability among aged rat cognition occurs across two independent behavioral domains.

Aging↗
PubMed1982

Effects of posttrial vasopressin injections on appetitively motivated learning in rats.

Sixty male rats, maintained on 23-hr food deprivation were trained on two types of appetitive tasks: bar pressure responding under a CRF schedule, and under a differentially reinforced (light+, dark-) schedule. Performance of rats treated with lysing vasopressin, injected immediately after each training session, was compared to that of control animals injected with saline. In the CRF stage, treated animals reached learning criterion significantly later than did control rats, and made significantly fewer bar presses. During acquisition and extinction of a light-dark discrimination, learning and retention were not altered by vasopressin, though the number of bar presses was significantly decreased, and a differential effect was found according to previous CRF performance. The results are discussed considering the hypothesis of a facilitatory effect of vasopressin on memory processes.

Animals↗
PubMed1967

Brain lesions in birds: effects on discrimination acquisition and reversal.

Bobwhite quail (Colinus virginianus) with lesions of the cortex and the dorsal portion of the hyperstriatum (or " wulst") showed a considerable deficit in ability to reverse a learned discrimination between horizontal and vertical stripes. Two birds that had been run on 25 such reversals before ablation showed the same result. Lesioned birds did not, however, differ from controls in the Original acquisition of the discrimination. Analysis of performance indicated that the reversal deficit was not due to difficulties in discrimination, interference with motor ability, or lack of motivation. The deficit appeared to be based on perseveration of response to the previous positive stimulus during reversal training.

Animals↗
PubMed1978

Further evidence of impaired tactile learning after removals of the second somatic sensory projection cortex (SII) in the monkey.

Four rhesus monkeys with bilateral removals of SII and five unoperated monkeys were trained on tests of tactile equivalence, weight discrimination and generalization, tactile discrimination learning (including concurrent learning and serial reversal) and inter-manual transfer of tactile learning. Lesioned animals were impaired on almost all tactile learning tasks and on inter-manual transfer but not on the test of tactile equivalence nor on the propioceptive tasks. The results are considered in the context of previous studies of somatosensory and parietal cortex.

Animals↗
PubMed1996

The role of performance factors in the active avoidance-conditioning deficit in autoimmune mice.

Prior studies with autoimmune mice demonstrated deficits in 2-way active avoidance conditioning that correlated with the degree of autoimmunity. In this study, autoimmune female NZB x NZW F1 hybrid (B/W) mice were tested in shock-motivated discrimination learning, 1-way avoidance conditioning, and a modified 2-way avoidance task and compared to nonautoimmune female NZW mice. The discrimination and 1-way conditioning results indicated that B/W mice can learn shock-motivated tasks that involve minimal fatigue and no conflict. B/W mice were also able to learn the 2-way avoidance task when it was made easier by increasing conditioned-stimulus cue salience, clarifying contingencies, and increasing trial spacing to decrease possible cognitive, emotional, and physical fatigue. Thus, poor performance in 2-way avoidance appears to be a consequence of altered attention, motivation, or emotionality and can be overcome by altering task parameters.

Animals↗