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PubMed2004

Learning of ambiguous versus hybrid sequences by patients with Parkinson's disease.

Implicit motor learning as indexed by the serial reaction time (SRT) task has been shown to be impaired in patients with Parkinson's disease (PD). This has only been conclusively demonstrated for sequences that require learning of second-order sequential information (ambiguous sequences). This study examines implicit learning of ambiguous sequences as well as sequences which contain first-order information (hybrid sequences) in a sample of 12 early to middle stage Parkinson's disease patients and matched controls. The study used dual-task methodology in order to prevent strategic/attentional learning of second-order information. The results showed that while ambiguous sequences were not learned by either group, both patient and control groups demonstrated learning of the hybrid sequence under dual-task conditions. This suggests that first-order associations may be learned by people with Parkinson's disease, even under attentionally demanding conditions. This may be interpreted as providing evidence for a non-attentional learning mechanism which is relatively intact in Parkinson's disease.

Aged↗
PubMed2006

Myosin light chain kinase regulates synaptic plasticity and fear learning in the lateral amygdala.

Learning and memory depend on signaling molecules that affect synaptic efficacy. The cytoskeleton has been implicated in regulating synaptic transmission but its role in learning and memory is poorly understood. Fear learning depends on plasticity in the lateral nucleus of the amygdala. We therefore examined whether the cytoskeletal-regulatory protein, myosin light chain kinase, might contribute to fear learning in the rat lateral amygdala. Microinjection of ML-7, a specific inhibitor of myosin light chain kinase, into the lateral nucleus of the amygdala before fear conditioning, but not immediately afterward, enhanced both short-term memory and long-term memory, suggesting that myosin light chain kinase is involved specifically in memory acquisition rather than in posttraining consolidation of memory. Myosin light chain kinase inhibitor had no effect on memory retrieval. Furthermore, ML-7 had no effect on behavior when the training stimuli were presented in a non-associative manner. Anatomical studies showed that myosin light chain kinase is present in cells throughout lateral nucleus of the amygdala and is localized to dendritic shafts and spines that are postsynaptic to the projections from the auditory thalamus to lateral nucleus of the amygdala, a pathway specifically implicated in fear learning. Inhibition of myosin light chain kinase enhanced long-term potentiation, a physiological model of learning, in the auditory thalamic pathway to the lateral nucleus of the amygdala. When ML-7 was applied without associative tetanic stimulation it had no effect on synaptic responses in lateral nucleus of the amygdala. Thus, myosin light chain kinase activity in lateral nucleus of the amygdala appears to normally suppress synaptic plasticity in the circuits underlying fear learning, suggesting that myosin light chain kinase may help prevent the acquisition of irrelevant fears. Impairment of this mechanism could contribute to pathological fear learning.

Amygdala↗
PubMed2004

Learning and adult neurogenesis: survival with or without proliferation?

Recent high quality papers have renewed interest in the phenomenon of neurogenesis within the adult mammalian brain. Many studies now show that neurogenesis can be modulated by environmental factors including physical activity, stress, and learning. These findings have considerable implications for neuroscience in general, including the study of learning and memory, neural network plasticity, aging, neurodegeneration, and the recovery from brain injury. Although new light has been shed on this field, many contradictory findings have been reported. Here we propose two principle issues which underlie these inconsistencies, with particular focus on the interaction between learning and neurogenesis. The first issue relates to the basic methodology of measuring the generation of new brain cells, i.e., proliferation, as compared to survival of the newly made cells. Mostly, measures of neurogenesis reported are a combination of proliferation and survival, making it impossible to distinguish between these separate processes. The second aspect is in regards to the role of environmental factors which can affect both proliferation and survival independently. Especially the interaction between stress and learning is of importance since these might counteract each other in some circumstances. Reviewing the literature while taking these issues into account indicates that, in contrast to some findings, cell proliferation in the dentate gyrus of the hippocampus as a result of learning cannot be ruled out yet. On the other hand, increased survival of granule cells in the dentate gyrus as a result of hippocampal-dependent learning has been clearly demonstrated. Moreover, this learning-induced survival of granule cells, which were born before the actual learning experience, might provide a molecular mechanism for the 'use it or lose it' principle.

Animals↗
PubMed2006

Estrogen modulates place learning through estrogen receptors in the hippocampus.

Moderate elevations in circulating estradiol enhance learning in tasks that tap place learning strategies such as those requiring the use of extramaze cues. Use of place learning strategies is particularly impaired by damage to the hippocampus, a structure shown to be sensitive to estrogen treatments. We have shown that direct estrogen infusions into the dorsal hippocampus, and not the dorsolateral striatum, enhance place learning, suggesting that the hippocampus may be an important modulatory site for the effects of estrogen on place learning. The current experiment tested whether the hippocampus is indeed a critical site of estrogen modulation through classical estrogen receptors. Young adult female Sprague-Dawley rats were ovariectomized for 21 days and given systemic injections (0.1 ml) of sesame oil (OIL) or 10 microg of 17beta-estradiol-benzoate (E2), 48 and 24 h before being trained on a place task. Twenty-four hours prior to the first systemic injection, separate groups of rats received bilateral hippocampal implants of either the antiestrogen ICI 182,780 (ICI) or cholesterol vehicle. Implants were maintained until and throughout training. Intrahippocampal ICI reversed the enhancement in place learning seen with systemic E2 treatment. Unexpectedly, intrahippocampal ICI in OIL-treated rats also enhanced place learning. These data suggest that ICI may have some mixed agonist and antagonist effects in the hippocampus and that estrogen enhances place learning through activation of estrogen receptors located in the hippocampus.

Animals↗
PubMed2006

Neural activation during successful and unsuccessful verbal learning in schizophrenia.

Successful and unsuccessful intention to learn words was assessed by means of event-related functional MRI. Eighteen patients with schizophrenia and 15 healthy control participants were scanned while being given two word lists to read and another seven to learn with immediate recall. Neural activation patterns were segregated according to whether words were subsequently recalled or forgotten and these conditions were contrasted with each other and reading. Compared to controls, patients with schizophrenia showed deficits with regard to neural recruitment of right hippocampus and of cerebellar structures during successful verbal learning. Furthermore, a reversal of activated structures was evident in the two groups: Controls showed activation of right frontal and left middle temporal structures during the unsuccessful intention to learn. During successful learning, there was additional activation of right superior parietal lobule. In contrast, patients showed activation of right superior parietal lobule during unsuccessful and successful intention to learn. There were additional frontal and left middle temporal lobe activations during successful learning. We conclude that increased parietal activity may reflect a mechanism which compensates for the lack of hippocampal and cerebellar contributions to verbal learning in schizophrenia.

Adult↗
PubMed2006

Studying primate learning in group contexts: Tests of social foraging, response to novelty, and cooperative problem solving.

Learning commonly refers to the modification of behavior through experience, whereby an animal gains information about stimulus-response contingencies from interacting with its physical environment. Social learning, on the other hand, occurs when the same information originates, not from the animal's personal experience, but from the actions of others. Socially biased learning is the 'collective outcome of interacting physical, social, and individual factors' [D. Fragaszy, E. Visalberghi, Learn. Behav. 32 (2004) 24-35.] (see p. 24). Mounting interest in animal social learning has brought with it certain innovations in animal testing procedures. Variants of the observer-demonstrator and cooperation paradigms, for instance, have been used widely in captive settings to examine the transmission or coordination of behavior, respectively, between two animals. Relatively few studies, however, have examined social learning in more complex group settings and even fewer have manipulated the social environment to empirically test the effect of group dynamics on problem solving. The present paper outlines procedures for group testing captive non-human primates, in spacious arenas, to evaluate the social modulation of learning and performance. These methods are illustrated in the context of (1) naturalistic social foraging problems, modeled after traditional visual discrimination paradigms, (2) response to novel objects and novel extractive foraging tasks, and (3) cooperative problem solving. Each example showcases the benefits of experimentally manipulating social context to compare an animal's performance in intact groups (or even pairs) against its performance under different social circumstances. Broader application of group testing procedures and manipulation of group composition promise to provide meaningful insight into socially biased learning.

Animals↗
PubMed1998

Learning style influences student examination performance.

BACKGROUND: The Kolb Learning Style Inventory (LSI) measures preference for each of four learning orientations: abstract conceptualization, concrete experience, active experimentation, and reflective observation. These orientations define four learning styles: convergence, divergence, assimilation, and accommodation. METHODS: To determine if learning style correlates with objective multiple-choice and clinical measures of performance, the learning styles of third-year medical students (n = 227) were evaluated using the LSI. Performance was assessed using the United States Medical Licensing Examination step 1 (USMLE 1), the National Board of Medical Examiners (NBME) multiple-choice surgical subject examination (MCQ), and NBME computer-based case simulations (CBX). RESULTS: The data showed a significant (P < or = 0.05) relationship between learning style and performance on the USMLE 1. There was a significant (P < or = 0.05) and direct correlation between an abstract orientation and performance on the USMLE 1 (r = 0.33) and MCQ (r = 0.20). There was no relationship between learning style and clinical performance measured using the CBX. CONCLUSIONS: These data demonstrate that performance on objective measures of academic achievement is influenced by learning style, while application of that knowledge in the management of clinical situations may require additional skills beyond those measured.

Education, Medical, Undergraduate↗
PubMed1997

Vicarious learning revisited: a contemporary behavior analytic interpretation.

Beginning in the 1960s, social learning theorists argued that behavioral learning principles could not account for behavior acquired through observation. Such a viewpoint is still widely held today. This rejection of behavioral principles in explaining vicarious learning was based on three phenomena: (1) imitation that occurred without direct reinforcement of the observer's behavior; (2) imitation that occurred after a long delay following modeling; and (3) a greater probability of imitation of the model's reinforced behavior than of the model's nonreinforced or punished behavior. These observations convinced social learning theorists that cognitive variables were required to explain behavior. Such a viewpoint has progressed aggressively, as evidenced by the change in name from social learning theory to social cognitive theory, and has been accompanied by the inclusion of information-processing theory. Many criticisms of operant theory, however, have ignored the full range of behavioral concepts and principles that have been derived to account for complex behavior. This paper will discuss some problems with the social learning theory explanation of vicarious learning and provide an interpretation of vicarious learning from a contemporary behavior analytic viewpoint.

Cognition↗
PubMed2003

192 IgG-saporin lesions to the nucleus basalis magnocellularis (nBM) disrupt acquisition of learning set formation.

Rats with bilateral 192 IgG-saporin lesions to the nucleus basalis magnocellularis (nBM) were tested on olfactory discrimination learning set (ODLS), olfactory discrimination reversal learning set (DRLS), and open field activity. Control animals demonstrated learning set in both the ODLS and DRLS tasks. The nBM-lesioned animals showed initial acquisition impairment in learning set in the ODLS task but eventually demonstrated learning set in both ODLS and DRLS tasks. There were no group differences in open-field activity. Results suggest that removal of the nBM cholinergic system through 192 IgG-saporin lesions impairs early acquisition of learning set compared to control animals, but does not prevent later use of learning set formation. Implications for the non-cholinergic basal forebrain cells in learning set are discussed.

Acetylcholinesterase↗
PubMed1998

Water maze learning and hippocampal synaptic plasticity in streptozotocin-diabetic rats: effects of insulin treatment.

Streptozotocin-diabetic rats express deficits in water maze learning and hippocampal synaptic plasticity. The present study examined whether these deficits could be prevented and/or reversed with insulin treatment. In addition, the water maze learning deficit in diabetic rats was further characterized. Insulin treatment was commenced at the onset of diabetes in a prevention experiment, and 10 weeks after diabetes induction in a reversal experiment. After 10 weeks of treatment, insulin-treated diabetic rats, untreated diabetic rats and non-diabetic controls were tested in a spatial version of the Morris water maze. Next, hippocampal long-term potentiation (LTP) was measured in vitro. To further characterize the effects of diabetes on water maze learning, a separate group of rats was pre-trained in a non-spatial version of the maze, prior to exposure to the spatial version. Both water maze learning and hippocampal LTP were impaired in diabetic rats. Insulin treatment commenced at the onset of diabetes prevented these impairments. In the reversal experiment, insulin treatment failed to reverse established deficits in maze learning and restored LTP only partially. Non-spatial pre-training abolished the performance deficit of diabetic rats in the spatial version of the maze. It is concluded that insulin treatment may prevent but not reverse deficits in water maze learning and LTP in streptozotocin-diabetic rats. The pre-training experiment suggests that the performance deficit of diabetic rats in the spatial version of the water maze is related to difficulties in learning the procedures of the maze rather than to impairments of spatial learning.

Animals↗
PubMed1989

How do old dogs learn new tricks: teaching a technological skill to brain injured people.

Little is known about the way people learn technological skills. This investigation was carried out to see how 100 brain injured, 50 controls and two amnesic patients performed on a task requiring them to learn a six-step programme for an electronic memory aid. Performance was correlated with other measures of memory to determine whether the technological skill was similar to a procedural learning task, a spatial memory task, a visual task, a verbal task or an amalgam of these. All controls but only 59 percent of the patients learned the task within three trials. The two amnesic patients also failed to learn the new skill. There was a high correlation between overall performance on a standardized test of everyday memory (the Rivermead Behavioural Memory Test) but little evidence that the technological skill was similar to a procedural learning task; nor was it specifically related to visual, verbal or spatial memory. It is concluded that a combination of skills is required to learn the technological task. Implications for the concept of procedural learning are discussed.

Adolescent↗
PubMed2003

Distinct contribution of the cortico-striatal and cortico-cerebellar systems to motor skill learning.

This review paper focuses on studies in healthy human subjects that examined the functional neuroanatomy and cerebral plasticity associated with the learning, consolidation and retention phases of motor skilled behaviors using modern brain imaging techniques. Evidence in support of a recent model proposed by Doyon and Ungerleider [Functional Anatomy of Motor Skill Learning. In: Squire LR, Schacter DL, editors. Neuropsychology of Memory. New York: Guilford Press, 2002.] is also discussed. The latter suggests that experience-dependent changes in the brain depend not only on the stage of learning, but also on whether subjects are required to learn a new sequence of movements (motor sequence learning) or learn to adapt to environmental perturbations (motor adaptation). This model proposes that the cortico-striatal and cortico-cerebellar systems contribute differentially to motor sequence learning and motor adaptation, respectively, and that this is most apparent during the slow learning phase (i.e. automatization) when subjects achieve asymptotic performance, as well as during reactivation of the new skilled behavior in the retention phase.

Animals↗
PubMed2003

An investigation of errorless learning in memory-impaired patients: improving the technique and clarifying theory.

In rehabilitating individuals who demonstrate severe memory impairment, errorless learning techniques have proven particularly effective. Prevention of errors during acquisition of information leads to better memory than does learning under errorful conditions. This paper presents results of a study investigating errorless learning in three patient groups: those demonstrating mild, moderate, and severe memory impairments. The first goal of the study was to trial a new version of errorless learning, one encouraging more active participation in learning by patients via the use of elaboration and self-generation. This technique led to significantly better memory performance than seen under standard errorless conditions. This finding highlights the value of encouraging active and meaningful involvement by patients in errorless learning, to build upon the benefits flowing from error prevention. A second goal of the study was to clarify the mechanisms underlying errorless learning. Memory performance under errorless and errorful conditions was compared within and across each group of patients, to facilitate theoretical insight into the memory processes underlying performance. The pattern of results observed was equivocal. The data most strongly supported the hypothesis that the benefits seen under errorless learning reflect the operation of residual explicit memory processes, however a concurrent role for implicit memory processes was not ruled out.

Adult↗
PubMed1997

Errorless learning of novel associations in amnesia.

In two experiments involving verbal association learning by people with memory impairments, the effectiveness of errorless learning (EL) was compared with errorful learning (EF). Experiment 1 examined the effectiveness of both methods in learning remotely linked word pairs. There was an advantage for items learned by EL at immediate test which was not sustained over a delay of 1 hr. Learning appeared to be stable over this delay in the EF condition. Analysis of responses at delayed cued recall showed more evidence of spontaneous recovery in EF than in EL. Elimination of these items from analysis resulted in a similar pattern of forgetting in both methods. Experiment 2 examined the effectiveness of EL and EF in teaching novel associations, and showed an advantage for EL at immediate and delayed test. Forgetting was apparently observed following EL, but not EF. As in Experiment 1, this discrepancy was attributed to recovered responses at delayed test in EF. Eliminating these responses showed a similar pattern of forgetting in both methods for items correctly recalled at immediate test. The study shows an advantage for EL techniques in learning novel associations. The two methods also differ in that learning via EF is associated with more spontaneous recovery.

Adult↗
PubMed1998

Are the benefits of errorless learning dependent on implicit memory?

The effectiveness of errorless and errorful learning methods was compared in two experiments in which a group of memory-impaired individuals learned lists of single words. In both experiments, error prevention during learning resulted in higher levels of cued recall performance than trial-and-error learning. Experiment 1 showed that the beneficial effects of the errorless learning method extended over a delay of up to 48 hr and were also observed in free recall. The hypothesis that the benefits of errorless learning rely upon implicit memory was tested in Experiment 2. No evidence was found to support the hypothesis. Implicit memory was observed following both errorless and errorful learning, but there was no indication that enhanced performance in the errorless condition could be accounted for by implicit memory. There was no correlation between performance on a direct test (cued recall) and performance on an indirect test (fragment completion) for the same materials. Furthermore, the extent of priming was no greater for recalled items than non-recalled items in the cued recall test. It is proposed that the benefits of errorless learning in this paradigm stem from the effects of error prevention on residual explicit memory.

Adult↗
PubMed2000

Perceptual learning for a pattern discrimination task.

Our goal was to differentiate low and mid level perceptual learning. We used a complex grating discrimination task that required observers to combine information across wide ranges of spatial frequency and orientation. Stimuli were 'wicker'-like textures containing two orthogonal signal components of 3 and 9 c/deg. Observers discriminated a 15% spatial frequency shift in these components. Stimuli also contained four noise components, separated from the signal components by at least 45 degrees of orientation or approximately 2 octaves in spatial frequency. In Experiment 1 naive observers were trained for eight sessions with a four-alternative same-different forced choice judgment with feedback. Observers showed significant learning, thresholds dropped to approximately 1/3 of their original value. In Experiment 2 we found that observers showed far less learning when the noise components were not present. Experiment 3 found, unlike many other studies, almost complete transfer of learning across orientation. The results of Experiments 2 and 3 suggest that, unlike many other perceptual learning studies, most learning in Experiment 1 occurs at mid to high levels of processing rather than within low level analyzers tuned for spatial frequency and orientation. Experiment 4 found that performance was more severely impaired by spatial frequency shifts in noise components of the same spatial frequency or orientation as the signal components (though there was significant variability between observers). This suggests that after training observers based their responses on mechanisms tuned for selective regions of Fourier space. Experiment 5 examined transfer of learning from a same-sign task (the two signal components both increased/decreased in spatial frequency) to an opposite-sign task (signal components shifted in opposite directions in frequency space). Transfer of learning from same-sign to opposite-sign tasks and vice versa was complete suggesting that observers combined information from the two signal components independently.

Adult↗
PubMed1998

Role of vasopressin in learning and memory in the hippocampus.

The involvement of arginine8-vasopressin (VP) in learning and memory in the hippocampus is examined in mice using a discriminative learning task. Bilateral dorsal hippocampal lesion blocks the enhancing effect of intracerebroventricular (i.c.v.) injection of VP on retrieval and relearning processes. An additional study showed that immunoneutralization of dorsal hippocampal endogenous VP inhibited the facilitating effect of i.c.v. injection of VP, suggesting that hippocampus is essential for the expression of VP's behavioral effects. Using in situ microinjection, a greater sensitivity of the ventral part of the hippocampus to the memory enhancing effects of VP has been reported. This effect is mediated by vasopressin V1 type receptors and oxytocin receptors. Then, we examined the effects on behavior of VP applied to the ventral hippocampus, in relation to the time of treatment during learning. When the animals have no previous information about the task to learn, a deleterious effect of VP appears (pre-first session treatment). Regarding memory consolidation, the effects of VP may depend upon the previous level of performance acquired by the animals since, when injected after the first learning session, the peptide slightly delayed performance, whereas when the injection took place after the second learning session, it enhanced learning. Concerning memory retrieval, the effects of VP depend on the quality of the previously stored information. The fact that VP did not generate the same behavioral effects when the treatment was performed at the beginning or in the middle of the learning processes, suggests that mnemonic context is an important factor in understanding the effect of VP on memory in the ventral hippocampus. Finally, the role of hippocampal adrenergic receptors in the enhancing VP effects on memory retrieval has been examined. The facilitatory effects of VP seem to depend upon the functional state of both alpha- and beta-adrenergic receptors, but further studies will be necessary to clarify the role played by each receptor type in retrieval processes, and to determine the relationships that might exist between them.

Animals↗
PubMed2000

Benzodiazepine receptor inverse agonist-induced kindling of rats alters learning and glutamate binding.

Kindling, recognized as a model of epilepsy, can be obtained by applications of repeated nonconvulsive stimulations that finally lead to generalized seizures. Epileptics often show cognitive impairments. The present work analyzed the learning performance of male Wistar rats kindled with a convulsant inverse agonist of the GABA(A)-benzodiazepine receptor complex, methyl beta-carboline-3-carboxylate (beta-CCM). This compound is also known to have an action on learning processes. It was thus interesting to verify if beta-CCM kindling had the same impairing action on learning as other kindling agents, such as pentylenetetrazol (PTZ). A two-way active-avoidance shuttle-box learning task was chosen, because a deficit was found after PTZ kindling in this learning model. On the other hand, hippocampal glutamate binding, has previously been shown to be modified by both seizures and learning. Thus, the level of glutamate binding was also measured in the present study. Results showed that fully kindled rats had poorer learning performance after the third day of test than controls or not fully kindled animals. L-[3H] glutamate binding to hippocampal membrane fractions of the fully kindled animals was significantly higher when compared with controls, whereas L-[3H] glutamate binding of not fully kindled subjects did not differ from that of controls. Neuronal plasticity changes are a possible explanation for the correlation between kindling, learning deficits, and increased glutamate binding.

Animals↗