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At least 1,405 records · Page 78Linked to original sources
PubMed1992

[Role of N-methyl-D-aspartate receptor in the maintenance of learning-dependent long-term potentiation in rat hippocampal CA3 area].

The effect of microinjection of 2-amino-5-phosphonovaleric acid (APV), a selective NMDA receptor antagonist, into the rat hippocampal CA3 area on the synaptic efficacy and related conditioned behavior during the acquisition and consolidation of discrimination learning behavior was examined. The results showed: (1) After population spike (PS) amplitude had just increased to the maximum through training i.e. learning-dependent LTP had just formed, APV 1 microliter (2 mmol/L) was injected into CA3 area, then the rats were trained during the time of efficacy of the drug in every experimental block. The result demonstrated that the PS amplitude could not be maintained at the highest level but decreased to the pre-experiment level after 8 blocks. Correct response percentage of rats could not be consolidated with further training but decreased to less than 10%. (2) After the PS amplitude had kept up at the highest level, APV 1 microliter (2 mmol/L) was injected into CA3 area, then the rats were trained during the time of efficacy of the drug in every experimental block, in which case the PS amplitude also could not be maintained at the highest level but decreased to the pre-experiment level after 14 blocks. Correlatively, when the correct response percentage of rats decreased gradually to less than 10%, the conditioned response of the animals extinguished, but its extinction speed was slower than it was in result (1). These results suggest that the NMDA receptor in CA3 area plays an important role in the maintenance of the learning-dependent long-term potentiation.

2-Amino-5-phosphonovalerate↗
PubMed1991

Effects of a high-linoleate and a high-alpha-linolenate diet on the learning ability of aged rats. Evidence against an autoxidation-related lipid peroxide theory of aging.

This study examined the effect of dietary alpha-linolenate (18:3n-3)/linoleate (18:2n-6) balance on brain lipid compositions and brightness-discrimination learning ability in aged rats. An alpha-linolenate-rich diet with a peroxidizability index (PI) of 142 and a linoleate-rich diet with a PI value of 80 were used. Long-term feeding of these diets induced a significant difference in the n-3/n-6 ratios of highly unsaturated fatty acids in brain, but the PI values and the conjugated diene contents were similar between the two dietary groups. Rats fed the alpha-linolenate-rich diet had a longer mean survival time and an increased learning ability in senescence. These results contradict an autoxidation-related lipid peroxide theory of aging, and indicate that the aging process must also be considered in terms of n-3/n-6 balance of dietary fats.

Aging↗
PubMed1997

Effects of telencephalic ablation on short-term memory and attention in goldfish.

Two hypotheses regarding the functions of the teleost telencephalon (short-term memory and nonspecific arousal hypotheses) were examined by using a Y-maze training paradigm. A delayed reinforcement method, which allowed the separation of choice process (a process in which choice responses are evoked) and reward process (a process in which choice responses are reinforced), showed that normal fish can acquire clear learned responses to choice stimuli under different stimulus conditions between the choice process and the reward process, while telencephalon-ablated fish showed greatly impaired learning performance. Neither normal nor telencephalon-ablated fish could acquire learned responses to choice stimuli under neutral stimulus conditions in the reward process with respect to choice stimuli in the choice process. These results suggest that the telencephalon facilitates extratelencephalic short-term memory function essential for memory retention of choice stimuli and evoked choice responses until reinforcement, and support the supplementary function of the telencephalon suggested previously [Ohnishi, K., Telencephalic function implicated in food-reinforced colour discrimination learning in the goldfish, Physiol. Behav., 46 (1989) 707-712 and Savage, G.E., Temporal factors in avoidance learning in normal and forebrainless goldfish (Carassius auratus), Nature, 218 (1968) 1168-1169]. In addition, it was shown that cue information in the reward process is very important for the fixation of short-term memory of choice stimuli and choice responses. Furthermore, telencephalon-ablated fish also showed clear visual aspect selection, as did normal fish, when they were reinforced to a visual compound stimulus containing heterogeneous aspects (pattern and colour). This result shows that the telencephalon-related arousal or attentional function is not critical for aspect selection in goldfish. It seems that visual aspect selection in goldfish is performed without paying telencephalon-related 'selective attention' to an aspect.

Animals↗
PubMed1992

Behavior, ectopias and immunity in BD/DB reciprocal crosses.

In a previous study, in which fertilized DBA ova were transferred into an autoimmune female, and NZB ova were transferred into a non-autoimmune female, we found that (1) the maternal environment affected the degree of autoimmunity, (2) the incidence of cortical ectopias was not affected by the maternal environment (3) DBA and NZB females had greater paw asymmetry if reared in an autoimmune uterus, and (4) avoidance learning scores were inversely related to degree of autoimmunity. In the present experiment, reciprocal crosses of DBA and BXSB mice were studied to confirm and extend the original findings. DB mice (DBA female x BXSB male) had greater immune activity than the BD animals, had poorer avoidance learning, but were better on black-white discrimination learning and the Lashley III maze. The BD mice had greater paw asymmetry. Only one of 38 animals had a cortical ectopia. The results lead to the following conclusions: (1) there is an inverse relationship between amount of immune activity and active avoidance learning; (2) some uterine factor in autoimmune mice causes females to have greater paw asymmetry; (3) cortical ectopias are under genetic control; and (4) the lesser immune activity of the BD mice suggests that they developed a suppressor system following early exposure to autoimmunity in the uterine/maternal environment.

Animals↗
PubMed1997

Triple dissociation of anterior cingulate, posterior cingulate, and medial frontal cortices on visual discrimination tasks using a touchscreen testing procedure for the rat.

Four experiments examined effects of quinolinic acid-induced lesions of the anterior cingulate, posterior cingulate, and medial frontal cortices on tests of visual discrimination learning, using a new "touchscreen" testing method for rats. Anterior cingulate cortex lesions impaired acquisition of an 8-pair concurrent discrimination task, whereas posterior cingulate cortex lesions facilitated learning but selectively impaired the late stages of acquisition of a visuospatial conditional discrimination. Medial frontal cortex lesions selectively impaired reversal learning when stimuli were difficult to discriminate; lesions of anterior and posterior cingulate cortex had no effect. These results suggest roles for the anterior cingulate, posterior cingulate, and medial frontal cortex in stimulus-reward learning, stimulus-response learning or response generation, and attention during learning, respectively.

Animals↗
PubMed1980

Visual acuity following binocular deprivation in the cat.

Threshold visual acuity for three cats which were reared from birth to 4--12 months of age with bilateral lid closure was measured and compared to visual acuity in three cats which had the use of a non-deprived eye. The results indicate that binocular deprivation (BD) results in significant deficits in visual acuity which are proportional to the duration of deprivation. Threshold visual acuities were 3.7 cycles/deg. following 4 months of BD, 3.25 cycles/deg. following 7 months of BD and 2.55 cycles/deg. following 12 months of BD compared to acuities of 6.0, 6.5 and 6.8 cycles/deg9 for cats using a non-deprived eye. All BD cats had recovered from the initial visuomotor deficits, seen in these cats and reported in the literature, following lid-parting. The implication of such deficits in visual acuity on visual discrimination learning in BD cats is discussed.

Animals↗
PubMed1989

Synaptic plasticity and learning: selective impairment of learning rats and blockade of long-term potentiation in vivo by the N-methyl-D-aspartate receptor antagonist AP5.

This paper reports a series of 5 experiments concerned with a possible role for N-methyl-D-aspartate (NMDA) receptors in certain types of learning. The results show that chronic intraventricular infusion of the NMDA receptor antagonist D,L-2-amino-5-phosphonopentanoic acid (D,L-AP5) caused an impairment of spatial but not of visual discrimination learning in rats. Such selectivity of the learning impairment occurred despite widespread distribution of the drug throughout the CNS. AP5 sometimes caused a disturbance of sensorimotor function during learning, but one experiment addressing whether this disturbance could be responsible for the spatial learning impairment established that it was statistically independent. Another experiment showed that AP5 did not affect the retention of previously acquired spatial information. These behavioral effects were all obtained with a concentration of AP5 that, in a final study, was found to be sufficient to block hippocampal long-term potentiation (LTP) in vivo without affecting normal synaptic transmission. Taken together, these observations (1) implicate NMDA receptors in certain types of learning, and (2) extend recent work showing that saturation of LTP causes an anterograde spatial amnesia (McNaughton et al., 1986). A preliminary report of parts of this work has been published (Morris et al., 1986a).

Animals↗
PubMed1995

Protein kinase C in the hippocampus is altered by spatial but not cued discriminations: a component task analysis.

The exact role of the mammalian hippocampus in memory formation remains essentially as an unanswered question for cognitive neuroscience. Experiments with humans and with animals indicate that some types of mnemonic associative processes involve hippocampal function while others do not. Support for the spatial processing hypothesis of hippocampal function has stemmed from the impaired performance of rats with hippocampal lesions in tasks that require spatial discriminations, but not cued discriminations. Previous procedures, however, have confounded the interpretation of spatial versus cued discrimination learning with the number and kinds of irrelevant stimuli present in the discrimination. An empirical set of data describing a role of protein kinase C (PKC) in different mnemonic processes is similarly being developed. Recent work has implicated the activation of this serine-threonine kinase in a variety of learning paradigms, as well as long-term potentiation (LTP), a model system for synaptic plasticity which may subserve some types of learning. The present study employs the principles of component task analysis to examine the role of membrane-associated PKC (mPKC) in hippocampal-dependent memory when all factors other than the type of learning were equivalent. The results indicate that hippocampal mPKC is altered by performance in hippocampally-dependent spatial discriminations, but not hippocampally-independent cued discriminations and provide a general experimental procedure to relate neural changes to specific behavioral changes.

Animals↗
PubMed1984

Haloperidol in the treatment of infantile autism: effects on learning and behavioral symptoms.

In this double-blind, placebo-controlled study the administration of haloperidol resulted in significant decreases in behavioral symptoms and in general clinical improvement in 40 autistic children ages 2.33 to 6.92 years. Haloperidol also produced greater facilitation and retention of discrimination learning in the laboratory. No adverse effects were observed at therapeutic doses, which ranged from 0.5 to 3.0 mg/day or 0.019 to 0.217 mg/kg per day.

Autistic Disorder↗
PubMed1976

Effect of different training methods on perceptual learning in impulsive children.

The effectiveness of different training and transfer test conditions in promoting perceptual learning in impulsive kindergarten children was investigated. Interproblem variability was found to be more effective than intraproblem variability, and a differentiation training procedure was found to be more effective than a matching training procedure. The results provide guidelines for designing effective training methods for improving discrimination learning and problem solving in impulsive children.

Child↗
PubMed1988

Prenatal caffeine causes long lasting behavioral and neurochemical changes.

The effects of prenatal exposure to caffeine were studied on later physical development, behavior and brain neurochemistry. Daily doses (150, 300 or 450 mg/L) of caffeine were given to rat dams during the last week of pregnancy. Prenatal caffeine exposure resulted in a number of behavioral and neurochemical changes in the offspring which were long lasting and dose related. The low dose (150 mg/L) of prenatal caffeine caused hyperactivity in an open-field. The high dose of caffeine caused learning disabilities in complex visual and auditory discrimination learning paradigms while simple motor learning or a spatial orientation task were not affected. Both male and female offspring showed some behavioral effects of caffeine exposure. The medium and high doses of caffeine resulted in weight gain that was observable as early as 35 days of age and increased progressively with age. This weight gain was associated with increased food intake. The neurochemical studies carried out at 2-3 months of age revealed an increase in choline uptake in hippocampus, mainly in the animals treated with the lower doses of caffeine and higher protein concentration (microgram/mg wet tissue) in the cortex or hippocampus of offspring exposed to the higher doses of caffeine. At 15 months of age, choline uptake in the frontal cortex was significantly reduced in the animals prenatally exposed to the 300 and 450 mg/L dose.

Animals↗
PubMed1997

Pointing, withholding information, and deception in capuchin monkeys (Cebus apella).

Brown capuchin monkeys, like 4-year-old children and human-socialized chimpanzees, showed communicative and deceptive pointing in experiments in which they benefited by indicating, accurately or falsely, the location of hidden food. All 3 capuchin monkeys tested (13, 19, and 26 years old) pointed communicatively in the presence of a cooperative trainer. One human-reared monkey pointed without any training and frequently gazed at her human respondent; as with apes, extensive exposure to humans may promote some human-like responses in monkeys. Another capuchin withheld pointing when beneficial, whereas the 3rd learned to obtain the hidden food by pointing deceptively in the presence of a competitive trainer. Such deceptive pointing by one monkey and withholding of information by another suggest that primates' deceptive pointing in an experimental situation is explainable in terms of response inhibition and conditional discrimination learning.

Animals↗
PubMed1997

Habituation of ocular following reflex requires corpus callosum for interhemispheric transfer.

In cats, unanesthetized following transection of the brainstem at a level precluding painful sensation, and limiting ocular motility to a vertically oriented course (the pretrigeminal preparation), habituation of the orienting reflex, consisting of ocular fixation and smooth pursuit, readily transferred between moving visual stimuli directed first at one and then the other cerebral hemisphere. Under the same conditions, when the corpus callosum had been transected 2 weeks prior to the habituation, interhemispheric transfer was absent. Thus, despite substantial brainstem involvement and bilateral coordination of ocular motility the neocortex plays an essential role in this habituation, just as it does in the interhemispheric transfer of visual discrimination learning. This suggests that habituation is a fundamental form of learning in the mammalian forebrain.

Animals↗
PubMed2006

Multiple learning modes in the development of performance on a rule-based category-learning task.

Behavioral and neuropsychological data suggest that multiple systems are involved in category-learning. In this paper, the existence and the development of multiple modes of learning of a rule-based category structure was examined, and features of different learning processes were identified. Data were obtained in a cross-sectional study by Raijmakers et al. [Raijmakers, M. E. J., Dolan, C. V., & Molenaar, P. C. M. (2001). Finite mixture distribution models of simple discrimination learning. Memory and Cognition, 29, 659-677], in which subjects aged 4-20 years carried out a rule-based category-learning task. Learning models were employed to investigate the development of the learning processes in the sample. The results support the hypothesis of two distinct learning modes, rather than a single general mode of learning with a continuum of appearances. One mode represents sudden rational learning by means of hypothesis testing. In the second, slow learning mode, learning also occurs suddenly as opposed to incrementally. The probability of rational learning increases with age, and seems to be related to dimension preference in the younger age groups. However, the finding of distinct learning modes does not necessarily imply that distinct learning systems are involved. Implications for the interpretation and clinical use of tasks with a category-learning component, such as the Wisconsin Card Sorting Test (WCST [Heaton, R. K., Chelune, G. J., Talley, J. L., Kay, G. G., & Curtis, G. (Eds.). (1993). Wisconsin card sorting test manual: Revised and expanded. Odessa, FL: Psychological Assessment Resources]), are discussed.

Adolescent↗
PubMedDate not supplied

Operant test battery performance in children: correlation with IQ.

The relationship between intelligence and money-(nickel-)reinforced operant behaviors were compared in 115 six year old children. The Operant Test Battery (OTB) consists of tasks thought to engender responses dependent upon specific brain functions that include motivation, color and position discrimination, learning, short-term memory, and time estimation. OTB endpoints were compared with Full Scale, Verbal and Performance IQ scores. Highly significant correlations were noted between several OTB measures (e.g., color and position discrimination accuracy) and IQ scores, but not in others (e.g., motivation task response rate). The results demonstrate the relevance of these measures as metrics of important brain functions. Additionally, since laboratory animals can readily perform these same tasks, these kinds of behaviors in laboratory animals should be useful in studying the effects of neuroactive/neurotoxic compounds on aspects of cognitive function in animals and in predicting adverse effects of such agents on related brain functions in humans.

Brain↗
PubMed1988

Ethanol and Ro 15-4513: behaviour maintained by operant procedures (DRL-72s and PTZ-drug discrimination) in rats.

The proposed amethystic imidazobenzodiazepine Ro 15-4513 and ethanol (ETOH) were examined in rats using two operant procedures, differential reinforcement of low rates of responding (DRL), and drug discrimination learning (DDL). In the first bar-pressing responses occurring 72 s or longer after the last reinforcement were rewarded; responses occurring earlier reset the time schedule. In the latter, animals were trained to discriminate between the effects of the analeptic pentylenetetrazole (PTZ) and the non-drug condition; the schedule of reinforcement was FR-10. Water was the reinforcer. A dose of 1000 mg/kg ETOH decreased the rate of bar pressing in the DRL experiment; doses of 300 and 560 mg/kg ETOH did not. The decrease was not attenuated by Ro 15-4513. No significant deviations from baseline responding occurred with Ro 15-4513 (1, 3 10 mg/kg). The number of reinforcements increased significantly after ETOH (1000 mg/kg), but not after Ro 15-4513. Combinations of the two agents produced increases in the number of reinforcements. Changes in DRL behaviour induced by diazepam (1 and 10 mg/kg) were normalized by 3 mg/kg Ro 15-4513. In DDL, Ro 15-4513 (10 mg/kg) substituted for PTZ; ETOH did not. Diazepam and Ro 15-1788 attenuated the response generalization from Ro 15-4513 to PTZ; ETOH did not. There was a dose-related increase in the time to complete the DDL tests after ETOH treatment; addition of Ro 15-4513 increased the time further. In conclusion, antagonism between Ro 15-4513 and ETOH did not occur in the present studies; data are furthermore consistent with the view that Ro 15-4513 acts as a partial inverse benzodiazepine agonist.

Animals↗
PubMed1982

Hemispheric differences in split-brain monkeys learning sequential comparisons.

Twelve split-brain rhesus monkeys were tested for differences in the abilities of their two cerebral hemispheres to learn discriminations based on the comparison of sequentially-presented visual stimuli. Overall there was no generalized advantage for either the left or right hemisphere. There was, however, a significant correlation between each monkey's handedness and the hemisphere that learned more readily; the more proficient hemisphere tended to be contralateral to the preoperatively preferred hand. This result raises the possibility that handedness in monkeys may be more closely related to cognitive processing than is usually believed.

Animals↗