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 1,027 records · Page 57Linked to original sources
PubMed1996

Neural substrates of discriminative avoidance learning and classical eyeblink conditioning in rabbits: a double dissociation.

In a previous study, lesions of the deep cerebellar nuclei blocked classical eyeblink conditioning, but did not impair discriminative avoidance learning in rabbits. Here, was also found previously, lesions of the anterior and medial dorsal thalamic nuclei severely impaired discriminative avoidance learning. However, these lesions had no impact on discriminative eyeblink conditioning or reversal learning. These results complete the demonstration of a double dissociation, indicating distinct neural substrates for the acquisition of these learned behaviors. It is proposed that the two learning circuits identified by these studies mediate, respectively, acquisition of specific adaptive reflexes and whole-body, voluntary goal-directed movements.

Animals↗
PubMed1982

Interhemispheric transfer of visual pattern discriminations: evidence for a bilateral storage of the engram.

The present experiment was carried out to determine whether the memory trace of a pattern discrimination learned with one hemisphere is also transmitted to the second hemisphere via the corpus callosum or whether the trace is limited to the trained hemisphere and becomes accessible to the second during recall via this route. Split-chiasma cats learned two pattern discriminations with one eye (and hemisphere), then were subjected to a mid-sagittal transection of their corpus callosum, followed by learning with the other untrained eye (and hemisphere). Ten cats were separated into two groups: one group learned the discrimination to criterion (the non-overtrained group) while the other received 1600 overtraining trials over and beyond those needed to reach criterion (the overtrained group). Results indicated that there was little bilateral storage in the non-overtrained group (as determined by the number of trials needed to attain criterion with the second eye). Most subjects from the overtrained group showed chance performance during the first transfer session but learned the pattern discrimination much more rapidly with the second eye than with the first. These results are taken as indicating that memory transcription is possible through the callosum but that this route is slower and its readout is possibly contaminated by secondary non-specific factors which affect the initial utilization of the trace.

Animals↗
PubMed1992

Amnesia for Complex Naturalistic Scenes and for Objects Following Fornix Transection in the Rhesus Monkey.

Rhesus monkeys (Macaca mulatta) were trained to discriminate among many complex naturalistic scenes. The scenes were still frames from a cinema film. They were presented as the discriminative stimuli in a concurrent discrimination learning task in which each discriminative stimulus was presented on one trial each day. Learning of this task was severely impaired by fornix transection. The same animals were also deficient in a similar concurrent discrimination learning task, with each discriminative stimulus presented on one trial each day, but with objects, not complex scenes, as the stimulus material. The impairment in object discrimination learning in the present experiment is attributable to an interaction of object discrimination learning with scene discrimination learning, and can be understood as an effect of interference in long-term memory. In contrast to these impairments in long-term memory, a test of within-session learning of complex scenes, in which the average interval between successive presentations of the same stimulus was < 3 min, was performed without significant impairment by the fornix-transected animals. These results show that long-term memory for complex naturalistic scenes reveals analogues in the monkey of human episodic memory and its impairment in amnesia.

Journal Article↗
PubMedDate not supplied

Effect of prenatal heat stress on brain growth and serial discrimination reversal learning in the guinea pig.

Exposure of pregnant guinea pigs to an environmental temperature of 42 degrees C for 1 hr daily on Days 20-24 of gestation resulted in a significant reduction in the birthweight and brainweight of newborn offspring. These deficits persisted to early maturity and were still evident at 250 days of age following behavioral testing. Although some degree of postnatal neurogenesis and brain growth had occurred, this was not sufficient to compensate for the retarding influence of prenatal hyperthermia. Heat stress was also observed to seriously impair learning performance on the original discrimination task and this tendency persisted over the subsequent 4 reversals for both initial and perseverative errors. Impaired learning performance was related to reduction in brainweight. Animals with lower brainweights made significantly more initial, perseverative and total number of errors over the 5 problems. In addition, 12 of the 14 behaviorally tested stressed progeny had brainweights that were at least 2 standard deviations below the mean of the controls and as a result were classified as micrencephalic. Although heat stressed animals showed a significant reduction in the number of amacrine synapses in the inner plexiform layer of the retina, performance differences were not atrributed to changes in synaptic organisation of the retinal circuitry or to visual or other ophthalmic defects, but brain function. Animals with higher mean maternal poststressing core temperatures gave birth to progeny which had smaller whole and part wet-brainweights. Examination of the effect of poststressing core temperature on brainweight revealed that brain growth, independent of bodyweight, was retarded when this temperature elevated above 41.5 degrees C. This represented a rise of approximately 2.1 degrees C above normal and for each 1 degree C rise above this temperature, brainweight was reduced by 0.4227 g of the control value. Analysis of the atmospheric content of the incubator during stressing sessions ruled out the possibility that changes in level of oxygen and carbon dioxide may have contributed to the retarding influence on fetal development and learning ability in the guinea pig.

Animals↗
PubMed2001

Model for olfactory discrimination and learning in Limax procerebrum incorporating oscillatory dynamics and wave propagation.

We extend our model of the procerebral (PC) lobe of Limax, which is comprised of a layer of coupled oscillators and a layer of memory neurons, each layer 4 rows by 20 columns, corresponding to the cell body layer (burster cells) and neuropil layer (nonburster cells) of the PC lobe. A gradient of connections in the layer of model burster cells induces periodic wave propagation, as measured in the PC lobe. We study odor representations in the biological PC lobe using the technique of Kimura and coworkers. Lucifer yellow injection into intact Limax after appetitive or aversive odor learning results in a band or patch of labeled cells in the PC lobe with the band long axis normal to the axis of wave propagation. Learning two odors yields two parallel bands of labeled PC cells. We introduce olfactory input to our model PC lobe such that each odor maximally activates a unique row of four cells which produces a short-term memory trace of odor stimulation. A winner-take-all synaptic competition enabled by collapse of the phase gradient during odor presentation produces a single short-term memory band for each odor. The short-term memory is converted to long-term memory if odor stimulation is followed by activation of an input pathway for the unconditioned stimulus (US) which presumably results in release of one or more neuromodulatory amines or peptides in the PC lobe.

Animals↗
PubMed1984

Prenatal monosodium glutamate (MSG) treatment given through the mother's diet causes behavioral deficits in rat offspring.

The present study reports various developmental and behavioral changes in the offspring of rat dams that received monosodium glutamate (MSG) in the drinking water all through the second and third trimesters of pregnancy. Three main effects were observed in the MSG exposed offspring: (1) juvenile obesity; (2) reduced general activity levels; (3) a specific type of learning disability in discrimination learning involving choice between simultaneously present positive and negative stimuli.

Animals↗
PubMed2005

Polydrug abusers display impaired discrimination-reversal learning in a model of behavioural control.

Long-term cocaine and alcohol use is associated with neuropsychological impairments that implicate poor inhibitory mechanisms of behavioural control. This study tested acquisition and discrimination-reversal learning in a group of polydrug users (n 20) with a history of cocaine and heavy alcohol use and a group of age-matched controls (n 20). A cued go/nogo task measured subjects' ability to learn stimulus-response associations that involved the quick activation and sudden inhibition of responses. Compared with controls, drug users displayed similar acquisition, but impaired discrimination-reversal learning of both inhibitory and activational responses. The results suggest that some drug-related neuropsychological deficits might reflect specific impairments of the ability to inhibit interference from prior learning. The findings contribute to growing evidence that suggests cocaine and alcohol use could produce broad inhibitory impairments that increase the risk for learning deficits and poor impulse control.

Adolescent↗
PubMed1975

Effects of diagnostic ultrasound irradiated during foetal stage on emotional and cognitive behaviour in rats.

Our previous work demonstrated that the prenatally irradiated ultrasound of even a low-intensity might affect the functional development of the brain of offspring in rats. In the present study, in order to investigate the emotional and cognitive behaviour of offspring of rats that received the irradiation of a diagnostic ultrasound on the 9th day of gestation, the following three experiments were carried out: 1) The emotional reactivity of the offspring was measured by the open-field technique. 2) The same reactivity was further evaluated in terms of the excape response from electroshock. 3) The cognitive function of the offspring was assessed through the discrimination learning and the discrimination reversal learning. The offspring of irradiated rats showed significantly more distinct vocalization response to handling in the open-field test and significantly more distinct escape response from the electroshock, when compared with the two control rats (untreated control and sham-irradiated control). From these findings it may be suggested that the emotional behaviour in rats can be influenced by a low-intensity ultrasound irradiated during foetal stage. On the other hand, as for the cognitive behaviour, the results of the present study suggest no adverse effect on it.

Animals↗
PubMed2003

Hemispheric lateralization of memory stages for discriminated avoidance learning in the chick.

Memory formation following the one trial discriminated bead task in the chick falls into three stages (short-term, intermediate and long-term memory) that are defined by susceptibility to different classes of drugs. The stages show sharply timed offsets of sensitivity and loss at specific times after inhibition. Recall of the memory in the chick shows cyclical changes that differ in period between left and right hemispheres, and is marked by a series of brief windows of enhanced recall that recur with periods of about 16 and 25 min in the left and right hemispheres respectively. The timing of these 'retrieval events' corresponds, to a large extent, with the timing of the memory stages seen in the visual discrimination task. Here we examine the effects of left or right hemisphere injection of the main agents (glutamate, ouabain and anisomycin) that have been used to characterize the three stages of memory. We show that memory in the left hemisphere is largely responsible for performance at test and that processes involved in its consolidation generate the phases of memory.

Animals↗
PubMedDate not supplied

Effects of perinatal PCB exposure on discrimination-reversal learning in monkeys.

Monkeys exposed to PCB mixtures during gestation and lactation were tested on two-choice discrimination-reversal learning (DR). In Experiment 1, offspring of mothers fed 1.0 ppm Aroclor 1248, and offspring born 1.5 years after maternal exposure to 2.5 ppm Aroclor 1248 ended did not differ from controls on spatial, color or shape DR problems. In Experiment 2, offspring of mothers fed 0.25 or 1.0 ppm Aroclor 1016 and offspring born 3 years after maternal exposure to 2.5 ppm Aroclor 1248 ended were tested on the same spatial, color and shape problems, but a spatial problem with color and shape as irrelevant cues was inserted after the initial spatial problem. Performance of the high dose Aroclor 1016 offspring was impaired on the initial spatial problem, and facilitated on the shape problem. Performance of the Aroclor 1248 postexposure offspring was facilitated on the shape problem. This apparently facilitatory effect may represent a failure of PCB-exposed monkeys to learn the irrelevancy of the shape cue when it was initially presented.

Adipose Tissue↗
PubMed1990

Therapeutic effect of THA on hemicholinium-3-induced learning impairment is independent of serotonergic and noradrenergic systems.

Tetrahydroaminoacridine (THA: Tacrine) has previously been shown to reverse deficits in spatial discrimination learning induced by hemicholinium-3 (HC-3). In the present experiments the effects of prior depletion of serotonin (5-HT) or noradrenaline (NA) on this reversal were examined. In the first experiment 5-HT lesions were made by injecting 5,7-DHT (2 x 50 micrograms/5 microliters) into the lateral ventricles of rats pretreated with desmethylimipramine (DMI 25 mg/kg IP). A permanently indwelling guide tube was then implanted over the right lateral ventricle. Subsequent testing under drug-free conditions, revealed no effect of the lesion on the number of trials needed to attain criterion (nine consecutive correct choices) in two-platform spatial discrimination learning in a watermaze. Using a latin square design rats were then tested for the effects of HC-3 and THA. HC-3 (5 micrograms/5 microliters ICV) or placebo (CSF) were injected 60 min before the start of a 30-trial training session. THA (4.6, 10 mg/kg SC) or placebo were then injected 15 min before training. Choice accuracy but not choice latency was significantly impaired by HC-3 and the effect was reversed by THA in both sham operated and 5-HT lesioned rats. In the second experiment two injections of DSP-4 (50 mg/kg IP) were given, following cannulation, to deplete forebrain NA. The lesion had no effect on spatial learning under drug-free conditions and failed to block the THA-induced reversal of spatial discrimination learning deficits following HC-3. These results confirm that forebrain Ach depletion by HC-3 impairs spatial discrimination learning and that the deficit is reversed by THA.(ABSTRACT TRUNCATED AT 250 WORDS)

5,7-Dihydroxytryptamine↗