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PubMed2006

Intermittent practice facilitates stable motor memories.

Humans adaptively control reaching movements to maintain good performance in the presence of novel forces acting on the arm. A recent study suggested that motor memories of different force conditions are not transformed from fragile to stable states, but rather are always vulnerable to interference from newly learned conditions (Caithness et al., 2004). This is contrary to the results of previous studies (Brashers-Krug et al., 1996; Shadmehr and Brashers-Krug, 1997), although all of these studies followed similar methods. Here, we show that a seemingly insignificant and inconsistently applied methodological detail may reconcile this discrepancy. Catch trials, in which the novel forces are removed, may be randomly interspersed among the more frequent force trials to assess how a subject is learning to predict the pattern of forces. In the absence of an interfering condition, subjects retained their learning until retest a day later regardless of whether they experienced catch trials. But in the presence of an interfering condition, only the subjects who had experienced forces intermittently retained their learning and thereby showed resistance to the interference. Thus, intermittent rather than constant practice conditions appear to be critical for dynamic motor memory stabilization.

Adaptation, Physiological↗
PubMed2001

Context-dependent memory under stressful conditions: the case of skydiving.

Two experiments examined the effect of differing levels of emotional arousal on learning and memory for words in matching and mismatching contexts. In Experiment 1, experienced skydivers learned words either in the air or on the ground and recalled them in the same context or in the other context. Experiment 2 replicated the stimuli and design of the first experiment except that participants were shown a skydiving video in lieu of skydiving. Recall was poor in air-learning conditions with actual skydiving, but when lists were learned on land, recall was higher in the matching context than in the mismatching context. In the skydiving video experiment, recall was higher in matching learn-recall contexts regardless of the situation in which learning occurred. We propose that under extremely emotionally arousing circumstances, environmental and/or mood cues are unlikely to become encoded or linked to newly acquired information and thus cannot serve as cues to retrieval. Results can be applied to understanding variations in context-dependent memory in occupations (e.g., police, military special operations, and Special Weapons and Tactics teams) in which the worker experiences considerable emotional stress while learning or recalling new information.

Adolescent↗
PubMed2004

Active navigation and orientation-free spatial representations.

In this study, we examined the orientation dependency of spatial representations following various learning conditions. We assessed the spatial representations of human participants after they had learned a complex spatial layout via map learning, via navigating within a real environment, or via navigating through a virtual simulation of that environment. Performances were compared between conditions involving (1) multiple- versus single-body orientation, (2) active versus passive learning, and (3) high versus low levels of proprioceptive information. Following learning, the participants were required to produce directional judgments to target landmarks. Results showed that the participants developed orientation-specific spatial representations following map learning and passive learning, as indicated by better performance when tested from the initial learning orientation. These results suggest that neither the number of vantage points nor the level of proprioceptive information experienced are determining factors; rather, it is the active aspect of direct navigation that leads to the development of orientation-free representations.

Adolescent↗
PubMed1993

Medical decision making based on inductive learning method.

Medical decision making based on inductive learning has been studied in order to collect experience necessary for practical use of such methods in clinical and epidemiological work. The decision trees have been constructed by using the modified Quinlan's approach based on choosing relevant attributes according to their informativity. An inductive learning software tool, ASSISTANT Professional, has been used for experimenting. The variability in results has been studied under varying learning conditions. Two sets of data have been chosen for learning experiments: from a study on rheumatoid factors in patients with rheumatoid arthritis, and from an epidemiological investigation of aging. The results of this study indicate the necessity to determine inductive learning parameters for each particular problem. The pruning procedure is always recommended as it eliminates redundant elements in the tree. In problems with greater number of attributes, however, pruning itself is not guaranteeing satisfactory solutions. Interventions like the change of the minimal weight threshold might improve the situation. If these precautions are met, the method of inductive learning seems to be a useful guide in practical clinical and epidemiological decisions.

Aging↗
PubMed1983

Luck and learning: feedback contingencies and initial success in verbal discrimination learning.

Ninety undergraduate volunteers learned a 12-pair, low frequency, verbal discrimination list. The independent variables were feedback (positive only, negative only, or both) and initial success (17%, 50%, or 83% correct on trial one). With the total errors on nine trials as the dependent variable, the main effect of feedback was found to be not significant. The main effect of initial success was significant. Subjects who started at 50% correct had the most difficulty learning the list and subjects in the 83% correct condition learned quickest. The predicted interaction between feedback and initial success was not significant, even though the means for the three types of feedback at the 17% correct starting level reflect the expected differences. The results are interpreted as supporting the rule-use component of frequency theory. The relationship between initial success and subsequent performance appears to be curvilinear, rather than linear, as many theorists have assumed.

Discrimination Learning↗
PubMed2006

Name and face learning in older adults: effects of level of processing, self-generation, and intention to learn.

Many older adults are interested in strategies to help them learn new names. We examined the learning conditions that provide maximal benefit to name and face learning. In Experiment 1, consistent with levels-of-processing theory, name recall and recognition by 20 younger and 20 older adults was poorest with physical processing, intermediate with phonemic processing, and best with semantic processing. In Experiment 2, name and face learning in 20 younger and 20 older adults was maximized with semantic processing of names and physical processing of faces. Experiment 3 showed a benefit of self-generation and of intentional learning of name-face pairs in 24 older adults. Findings suggest that memory interventions should emphasize processing names semantically, processing faces physically, self-generating this information, and keeping in mind that memory for the names will be needed in the future.

Adult↗
PubMed2003

Alexithymia and incidental learning of emotional words.

Alexithymia is thought to reflect a deficit in the cognitive capacity to process emotions. Prior research suggests that emotional valence has a memory enhancing effect in poor conceptual learning conditions. This study addressed the question of whether incidental learning of emotional words is a function of alexithymic tendencies. Incidental learning is unintentional learning that results from other activities. The 20-item Toronto Alexithymia Scale (TAS-20) and measures of depression and verbal intelligence were administered to 30 nonclinical subjects (15 women, 15 men) whose mean age was 35.5 yr. (SD = 8.6) along with a sequential word-word evaluation task. Partial correlations indicated that the TAS-20 subscale, Difficulties identifying feelings was negatively correlated with recall of positive distractor words but not with recall of neutral distractors or recall of positive or negative target words. Emotional valence appears to have less organizational power in the memory of individuals with difficulties in recognizing their feelings.

Adult↗
PubMed1975

Conditioned drinking as avoidance learning.

Blocking the robust conditioned drinking response following conditioning eliminates the isotonic procaine conditioned response (CR) but not the hypertonic procaine CR. Rats allowed to drink in the box during conditioning form a larger CR than rats merely injected with hypertonic or isotonic procain who are prevented from drinking in the box: response blocking during extinction eliminated if no experience of drinking water in the box occurs either during baseline or during conditioning. Blocking the drinking response, like blocking shock avoidance, markedly reduces its high resistance to extinction. This suggests that rats overdrink to avoid anticipated illness, and fail to extinguish partially because they are never exposed to the fact that no illness will occur even if no drinking occurs.

Animals↗
PubMed1990

Effect of reserpine on retention of the conditioned NK cell response.

The effect of reserpine and 6-hydroxydopamine on the learned conditioned natural killer (NK) cell response was investigated in mice. Reserpine given at 2.5 mg/kg, 24 hr prior to reexposure to camphor-conditioned stimulus on days 6 and 8 blocked the recall of conditioned NK cell response to a significant extent. In other words, the NK cell activity of conditioned mice, treated with reserpine and reexposed to the conditioned stimulus, was similar to the nonconditioned (NC) group. A conditioned increase in NK cell response was still evident in mice treated with 6-OHDA.

Animals↗
PubMed1989

Establishing conditional discriminations: concurrent versus isolation-intermix instruction.

This paper describes an investigation comparing the effectiveness and efficiency (sessions to criterion, errors to criterion, minutes of instructional time) of concurrent and isolation-intermix instruction in teaching four preschool children to read words found in community and school environments. Two students were taught words using constant time delay and two progressive time delay across the two different conditions. Concurrent instruction consisted of two sessions per day where two words were randomly presented within each session until criterion was reached and a conditional discrimination was established. The isolation-intermix condition involved two sessions per day where each word was taught in separate daily sessions until criterion was reached and a simple discrimination was established (isolation instruction); followed by random presentation of both words within each daily session until the conditional discrimination was acquired (intermix). Concurrent instruction resulted in students learning conditional discriminations in fewer trials and minutes of instructional time. These data suggest that teachers should structure their instruction to teach conditional discriminations from the beginning rather than teaching simple discriminations.

Attention↗
PubMed2005

The contribution of implicit and explicit memory to the effects of errorless learning: a comparison between young and older adults.

There is evidence that the prevention of errors during learning might be helpful in improving an impaired memory performance, both in amnesia as well as in normal age-related memory decline. Although errorless learning is a promising technique for use in rehabilitation practice, the underlying mechanisms are unclear. That is, it has been suggested that the beneficial effects of errorless learning operate through implicit memory, whereas others implicate that it is explicit memory that is responsible for the enhanced memory performance after errorless learning. The current study examined the contribution of implicit and explicit memory function to the memory performance after errorless and errorful learning using the process-dissociation procedure. A group of young adults (N=40) was compared to a matched group of older individuals (N=40) on a spatial memory task (i.e., learning the locations of everyday objects in a room). The results clearly show age-related decline in explicit spatial memory, while implicit spatial memory was unaffected. Furthermore, the young group benefited from errorless learning compared to errorful learning, while the older group did not show a difference between the two learning conditions. Also, it was found that the effects of errorful learning were related to explicit memory function, and not implicit processing, corroborating and extending recent findings.

Adult↗
PubMed2004

Dorsal striatum and stimulus-response learning: lesions of the dorsolateral, but not dorsomedial, striatum impair acquisition of a stimulus-response-based instrumental discrimination task, while sparing conditioned place preference learning.

While some evidence suggests that the dorsal striatum is important for stimulus-response learning, disagreement exists about the relative contribution of the dorsolateral and dorsomedial striatum to this form of learning. In the present experiment, the effects of lesions of the dorsolateral and dorsomedial striatum were investigated on two tasks that differentially require the development of stimulus-response learning. The first task utilized an operant conditional discrimination task, which is likely to rely heavily upon stimulus-response learning. The second task looked conditioned place preference learning, a task that is unlikely to require the development of stimulus-response associations. Animals with lesions of the dorsolateral striatum were impaired on the operant conditional discrimination task, but retained the ability to learn the conditioned place preference task. In contrast, animals with lesions of the dorsomedial striatum were not found to be impaired on either task used in the present experiment. These results suggest that the dorsolateral striatum is necessary for the successful acquisition of tasks that place a demand upon stimulus-response learning, while the dorsomedial striatum is not involved in this type of learning.

Amygdala↗
PubMed2004

Challenge point: a framework for conceptualizing the effects of various practice conditions in motor learning.

The authors describe the effects of practice conditions in motor learning (e.g., contextual interference, knowledge of results) within the constraints of 2 experimental variables: skill level and task difficulty. They use a research framework to conceptualize the interaction of those variables on the basis of concepts from information theory and information processing. The fundamental idea is that motor tasks represent different challenges for performers of different abilities. The authors propose that learning is related to the information arising from performance, which should be optimized along functions relating the difficulty of the task to the skill level of the performer. Specific testable hypotheses arising from the framework are also described.

Biofeedback, Psychology↗
PubMed2000

Verbal learning strategies in Parkinson's disease.

Word-list learning was studied in patients with Parkinson's disease (PD) and normal control (NC) participants by means of the selective-reminding procedure of H. Buschke and P. A. Fuld (1974) in 3 learning conditions using semantically unrelated items; semantically related items, whose implicit categorical structure had to be spontaneously guessed; and semantically related items, whose explicit categorical structure was known in advance. The PD patients displayed poor learning in all 3 conditions. To identify the functional locus of the PD patients' deficits, the authors performed a stochastic Markov chain analysis, which allowed individual measurements of encoding, retrieval, and category clustering abilities. PD patients were never significantly impaired in encoding word engrams; their impairment was confined to automatic and intentional retrieval and to the ability to benefit from explicit semantic clues.

Aged↗
PubMed1999

Spatial knowledge acquisition from maps and from navigation in real and virtual environments.

In this study, the nature of the spatial representations of an environment acquired from maps, navigation, and virtual environments (VEs) was assessed. Participants first learned the layout of a simple desktop VE and then were tested in that environment. Then, participants learned two floors of a complex building in one of three learning conditions: from a map, from direct experience, or by traversing through a virtual rendition of the building. VE learners showed the poorest learning of the complex environment overall, and the results suggest that VE learners are particularly susceptible to disorientation after rotation. However, all the conditions showed similar levels of performance in learning the layout of landmarks on a single floor. Consistent with previous research, an alignment effect was present for map learners, suggesting that they had formed an orientation-specific representation of the environment. VE learners also showed a preferred orientation, as defined by their initial orientation when learning the environment. Learning the initial simple VE was highly predictive of learning a real environment, suggesting that similar cognitive mechanisms are involved in the two learning situations.

Adolescent↗
PubMed2006

Frontal-temporal disconnection abolishes object discrimination learning set in macaque monkeys.

Two previous studies have shown that frontal-temporal disconnection in monkeys, produced by unilateral ablation of frontal cortex in one hemisphere and of visual inferior temporal cortex in the opposite hemisphere is entirely without effect on visual object-reward association learning in concurrent discrimination tasks. This is a surprising finding in light of the severe impairments that follow frontal-temporal disconnection in many other tests of visual learning and memory, including delayed matching-to-sample and several conditional learning tasks. To explore the limits of this preserved object-reward association learning, we trained monkeys on visual object discrimination learning set (DLS) prior to frontal-temporal disconnection. As a result of training with single object-reward associations, the monkeys acquired a proficient learning set, evidenced by the rapid learning of new single object-reward association problems. This rapid learning was not affected by unilateral ablations of either inferior temporal cortex alone or frontal cortex alone but was severely impaired after final surgery to complete the disconnection. Moreover, each individual monkey now learned single object-reward association problems at the slow rate at which that individual had learned such problems before the formation of learning set. This result shows that frontal-temporal disconnection abolishes visual learning set.

Animals↗
PubMed2005

Cognitive disruption and altered hippocampus synaptic function in Reelin haploinsufficient mice.

The heterozygote reeler mouse (HRM) shows many neuroanatomical and biochemical features that are also present in some human cognitive disorders, such as schizophrenia. In the present study, hippocampal dependent plasticity and cognitive function of the HRM were characterized in detail in an attempt to reveal phenotypic functional differences that result from Reelin haploinsufficiency. The HRM and wild type mice show similar levels of overall activity, coordination, thermal nociception, startle responses, and anxiety-like behavior. In addition, both genotypes show similar shock threshold, identical cued freezing behavior and comparable spatial learning in Morris water maze tasks. However, a significant reduction in contextual fear conditioned learning was observed in the HRM. Electrophysiological studies in hippocampal CA1 synapses revealed a plethora of differences between genotypes. The HRM exhibits reduced field excitatory postsynaptic potentials in responses to similar synaptic inputs, lowered paired pulse facilitation ratio and impaired long-term depression and tetanus-induced long-term potentiation (LTP). Also, deficits were detected in LTP elicited by theta burst stimulation or by a whole cell pairing protocol. These physiologic differences could not be accounted for by changes in the overall amount of glutamate receptor subunits. In addition, it was determined that network-driven excitatory and inhibitory activities recorded in CA1 pyramidal neurons showed that the HRM had comparable amplitude and frequency of spontaneous excitatory postsynaptic currents, but a marked reduction in spontaneous inhibitory postsynaptic currents. Thus, the HRM exhibits a specific hippocampal-dependent learning deficit accompanied with a pronounced impairment of hippocampal plasticity and functional inhibitory innervation.

Animals↗