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Results for “Reversal Learning”

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At least 1,405 records · Page 78Linked to original sources
PubMed1983

Hippocampectomy selectively disrupts discrimination reversal conditioning of the rabbit nictitating membrane response.

The effects of hippocampal lesions were tested on two-tone discrimination reversal conditioning of the rabbit nictitating membrane response. Results showed that hippocampectomized animals learned the initial two-tone discrimination at rates equivalent to operated control animals and animals with neocortical lesions. During reversal conditioning, however, animals with hippocampal lesions were severely impaired relative to both other groups. Neocortical lesions were without effect on reversal learning. An additional study revealed that the hippocampectomized animals' failure at reversal could not be attributed to a lesion-induced increased resistance to extinction. Results are discussed with respect to several theories of hippocampal function, and with respect to changes in the activity of hippocampal pyramidal neurons which occur during classical conditioning of the nictitating membrane response.

Animals↗
PubMed2003

Behavioral training increases local astrocytic metabolic activity but does not alter outcome of mild transient ischemia.

Functional neurological outcome after transient ischemia might be improved by timely therapeutic intervention. To determine if restorative behavioral therapy influences damage, improves task learning, or alters astrocyte metabolic activity after ischemia, rats (food-restricted to 85% of free-feeding weight) were (a) first trained to respond on one of two levers under a fixed-ratio 20 schedule of food presentation (FR20), then (b) subjected to sham manipulation of carotid arteries or 10 min ischemia by four-vessel occlusion, followed by (c) 4 days of operant testing or inactivity, (d) then all rats were tested under a FR20 lever reversal task for 4 weeks, and (e) 3 days after the last behavioral session astrocyte metabolism was assayed by local uptake of [2-14C]acetate. Mild loss of hippocampal neurons occurred in ischemic rats with or without training after ischemia. Glial fibrillary acidic protein-positive astrocytes were present in similar numbers throughout brains of sham control and ischemic rats. Mild ischemia did not impair learning, and no changes in FR20 reversal learning were detected in sham vs. ischemic rats. Net [14C]acetate uptake was unaffected by ischemia but [14C]acetate uptake increased 15-24% (P<0.05; n=12-15/group) in specific structures (caudate, primary motor and sensorimotor cortex, CA1 hippocampus, subcortical white matter) in the pooled groups of rats that had 4 days FR20 testing vs. inactivity before reversal learning. 'Behavioral therapy' (operant testing on the 4 days immediately following either sham manipulation or ischemia) did not alter ischemic outcome, but was associated with higher acetate utilization in regions involved in motor activities.

Acetic Acid↗
PubMed1983

Behavioral effects of intracerebral injections of renin and captopril in intact and brain-damaged rats.

Rats with, or without, bilateral lesions of the caudate nucleus received intracaudate injection of either renin or renin plus Captopril (SQ 14225). Following such treatment, animals were impaired on a spatial reversal task compared to controls. We concluded that the putative renin contaminant of nerve growth factor (NGF) does not contribute to behavioral recovery from brain damage observed after NGF injections in other studies. Furthermore, angiotensin II might play a possible role in mediating footshock learning and spatial reversal performance.

Animals↗
PubMed1975

Learning deficits produced by chronic and reversible lesions of the corpus striatum in rats.

In a first experiment it was found that the reversible disruption of the normal activity of the corpus striatum (CN) of rats by microinjections of potassium chloride produced a marked impairment on the acquisition of a one-trial passive avoidance task. Two additional experiments showed the same performance deficits on the acquisition as well as on the retention of the task when the CN was electrolytically lesioned. Since two different methods of disrupting the functional integrity of the striatum were used, it can be concluded that the results are not due to the pecularities of a single method. These results further support the hypothesis of critical involvement of the CN in the integration and storing of learned information.

Animals↗
PubMed1989

Effects of excitotoxic lesions of the substantia innominata, ventral and dorsal globus pallidus on visual discrimination acquisition, performance and reversal in the rat.

Rats received infusions of ibotenic acid into the substantia innominata, in the region of the nucleus basalis of Meynert (nbM), before and after training on simple (simultaneous) and conditional visual discriminations. The ibotenate infusions reduced cortical choline acetyltransferase (ChAT) levels by about 20%, destroyed many ChAT-immunoreactive neurons in the nbM, but also caused the loss of many neurons in the substantia innominata and adjacent areas. These lesions did not impair the acquisition and performance of a simple visual discrimination, but did impair reversal of the discrimination and the performance of a conditional visual discrimination. However, the degree of impairment was unrelated to the degree of cortical ChAT loss. Ibotenic acid lesions to the dorsal globus pallidus also impaired reversal of discrimination but left acquisition and performance unaffected. Striatal dopamine depletion produced by 6-hydroxydopamine (6-OHDA) infusions into the mid-ventral caudate nucleus impaired performance of the simultaneous visual discrimination. Cortical noradrenaline depletion produced by 6-OHDA lesions of the dorsal noradrenergic bundle either alone or in combination with ibotenic acid lesions of the substantia innominata had no effect on acquisition of the discrimination. It is concluded that ibotenic acid lesions of the substantia innominata or to the dorsal globus pallidus affect learning and performance of conditional visual discrimination performance and impair reversal learning without affecting the capacity to discriminate visual events. These results are compared to those following cortical noradrenaline depletion or striatal dopamine loss.

Animals↗
PubMed2006

Learning-memory deficit with aging in APP transgenic mice of Alzheimer's disease and intervention by using tetrahydroxystilbene glucoside.

OBJECTIVE: To investigate learning-memory deficit in different ages of AD-like APP transgenic mice and to observe the protective effects of 2,3,5,4'-tetrahydroxystilbene-2-O-beta-D-glucoside (TSG), which is the main component of Polygonum multiflorum, on learning-memory abilities. METHODS: PDAPPV717I transgenic (Tg) mice were randomly divided into 3 model groups (4, 10 and 16 months old mice) and TSG treated (at doses 120 and 240 micromol/kg/d) groups. TSG was administered to some Tg mice with an age range 4-10 months. In untreated 10 months old Tg mice, the TSG was administrated to those falling in the age range 10-16 months. For the control group we adopted the same age and background C57BL/6J mice. The learning-memory ability was measured by applying Morris water maze (MWM) and object recognition test (ORT). RESULTS: In the 4 months old PDAPPV717I Tg mice, the learning-memory deficit was detected. The escape latency in MWM was prolonged, and the discrimination index decreased in ORT. In the 10 months old Tg mice, the learning-memory deficit was aggravated. TSG improved all spatial learning-memory impairment in MWM as well as the object recognition impairment in ORT. In the 16 months old Tg mice, the learning-memory deficit remained to exist but abated a lot. TSG showed significant improvement in learning-memory ability in both MWM and ORT. CONCLUSION: PDAPPV717I transgenic mice with an age range 4-16 months revealed the existence of learning-memory deficit compared with the control group. Tetrahydroxystilbene glucoside not only prevents, i.e. at an early stage, the learning-memory deficit in AD-like model, but also can reverse the learning-memory deficit in the late stage of AD-like model. Thus, TSG could be considered among the future therapeutic drugs indicated for the treatment of AD.

Age Factors↗
PubMed1993

Effects of traditional and reversed bandwidth knowledge of results on motor learning.

The effects of two types of bandwidth (BW) knowledge of results (KR) were investigated on the acquisition and immediate retention of a timing task. Traditional and reversed BW KR groups were compared with two yoked control groups. Forty-eight randomly assigned subjects completed 60 acquisition trials and 20 no-KR retention trials. Acquisition analysis indicated a greater timing accuracy for the traditional BW group in comparison to the reversed BW group. During retention, less absolute constant error was found for both BW groups than for their yoked controls. Absolute performance changes were analyzed to further differentiate the contributions of quantitative and qualitative KR available in both types of BW conditions. This analysis revealed a significant KR x Trial Type interaction. Reliable changes in performance were observed after quantitative trials for the traditional BW group, whereas for the reversed BW group, reliable changes were observed after qualitative trials. This reversed BW group finding, along with the retention accuracy findings, indicated that the qualitative information was used to learn the timing task.

Female↗
PubMed1991

Tetrahydroaminoacridine alleviates medial septal lesion-induced and age-related spatial reference but not working memory deficits.

This study examined the effects of tetrahydroaminoacridine (THA, an anticholinesterase) on water-maze (WM) spatial reference (stable platform location during training) and spatial working memory (reversal of platform location) learning in young intact/medial septal (MS)-lesioned and aged rats. THA (1 or 3 mg/kg, IP) had no effect on reference or working memory performance of young intact rats. MS lesions decreased cholineacetyltransferase activity in the hippocampus and also impaired spatial reference and working memory. THA at 3 mg/kg stabilized MS lesion-induced reference memory performance deficit (path length increase), but was ineffective at 1 mg/kg. THA had no effect on the working memory performance of MS-lesioned rats. Aged rats were impaired in spatial reference and working memory tasks. THA at 3 mg/kg partially stabilized the age-induced spatial reference memory deficits, but was ineffective at 1 mg/kg. THA at either 1 or 3 mg/kg did not alleviate the age-related deficit in the working memory version of WM. The present results suggest that some of the age-related WM deficits may be related to the degeneration of the MS-hippocampus cholinergic system and that THA may be effective in stabilizing the reference memory deficits induced by hippocampal cholinergic dysfunction.

Aging↗
PubMed2005

A comparison of wild-caught wood mice and bank voles in the Intellicage: assessing exploration, daily activity patterns and place learning paradigms.

Our previous work has revealed very high baseline neurogenesis in the dentate gyrus of wood mice as compared particularly to bank voles; a difference which may be related to learning capacity. This study explored whether the newly-developed Intellicage system could be used to compare these species in simple spatial learning paradigms. The Intellicage is essentially a group-housing cage that also allows continuous automatic recording of each individual's behaviour. Seven wild-caught bank voles (Clethrionomys glareolus) were compared with seven wild-caught long-tailed wood mice (Apodemus sylvaticus) in the Intellicage system over 9 days. During the first 90 min after entering the cage, the wood mice were substantially more exploratory than the bank voles (P = 0.003). Over subsequent days, both species showed nocturnal activity increases with voles being 3.7 times more active overall. In the spatial learning paradigms, there were significant species-by-time interactions with wood mice outperforming bank voles on both place learning (P = 0.027) and subsequent reversal (P = 0.006). Conclusions are firstly that the wood mice show superior learning abilities in this paradigm, and secondly that the Intellicage serves as a valuable cognitive testing arena for small wild rodents, or for circumstances where cognition must be compared independent of different responses to handling or novel environments.

Activity Cycles↗