Self-Controlled Feedback and Learner Impulsivity in Sequential Motor Learning.

Many studies have attributed self-controlled feedback benefits associated with motor learning to learners' greater information processing during practice. However, individual learner characteristics like their impulsivity can also influence how people engage cognitively during learning. We investigated possible dissociations between the types of interaction in self-controlled knowledge of results (KR) and learner impulsivity levels in learning a sequential motor task. Ninety volunteers responded to the self-restraint section of the Barkley deficits in executive functioning scale, and those 60 participants with the highest ( n = 30) and lowest ( n = 30) impulsivity scores practiced a motor task involving sequential pressing of four keys in predetermined absolute and relative times. We further divided participants into four experimental groups by assigning the high- and low-impulsivity groups to two forms of KR-self-controlled absolute and yoked. Study results showed no interaction effect between impulsivity and self-controlled KR, and, contrary to expectation, self-controlled KR did not benefit learning, independently of impulsivity. However, low-impulsivity participants performed better than high-impulsivity participants on the absolute dimension of the transfer task, while high-impulsivity learners were better at the relative dimension. Cognitive characteristics of automatic and reflexive processing were expressed by the strategies used to direct attention to relative and absolute task dimensions, respectively. Low-impulsivity learners switched their attention to both dimensions at the end of practice, while high-impulsivity learners did not switch their attention or directed it only to the relative dimension at the end of the practice. These results suggest that the cognitive styles of high- and low-impulsive learners differentially favor learning distinct dimensions of a motor task, regardless of self-controlled KR.

Aprendizaje serial de secuencias basadas en la posición y dimensión de sus componentes / Serial learning of sequences based on the position and dimension of its components

El objetivo de esta investigación fue evaluar el aprendizaje serial empleando el método de recuerdo de secuencias de tres componentes. Uno de los componentes de las secuencias fue la posición mientras los otros dos variaron en propiedad dimensional: colores y/o números. El Experimento 1 evaluó las diferencias en el aprendizaje y recuerdo de una secuencia de colores o números. Los resultados mostraron que la secuencia de números se aprendió más rápido que la de colores. El Experimento 2 buscó aislar el efecto del aprendizaje inicial de la secuencia de posiciones sobre el aprendizaje y recuerdo posterior de una secuencia de colores o números superpuesta a la secuencia de posiciones ya aprendida. Los resultados mostraron que aprender inicialmente la secuencia de posiciones facilitó el aprendizaje de los componentes posteriores de la secuencia. El análisis se orienta a la identificación de un gradiente de posición como factor explicativo del aprendizaje de este tipo de secuencias; además se propone la existencia de un efecto de la dimensión de los componentes de las secuencias en su aprendizaje y recuerdo. Finalmente, se analizan las funciones atípicas obtenidas en las curvas de posición serial de los dos experimentos

Serial learning was evaluated using the recall method. Three-component sequences were used. One of the components was the position of the element, while the other two varied in the dimensional property: colors or numbers. Experiment 1 evaluated differences in learning and remembering a sequence of colors or numbers. The results showed the numerical sequence was learned faster than the colors sequence; Experiment 2 isolate the effect of initial learning of positions on learning and subsequent recall of superimposed sequences of colors or numbers. The results showed that learn the positions facilitated the learning of sequence. The analysis identified a position gradient as an explanatory factor of sequence learning; We also discuss about the item dimension effect on learning and recall sequences. Finally, the atypical serial position curves obtain were analyzed

Aberrant connections between climbing fibres and Purkinje cells induce alterations in the timing of an instrumental response in the rat.

Cerebellar participation in timing and sensory-motor sequences has been supported by several experimental and clinical studies. A relevant role of the cerebellum in timing of conditioned responses in the range of milliseconds has been demonstrated, but less is known regarding the role of the cerebellum in supra-second timing of operant responses. A dissociated role of the cerebellum and striatum in timing in the millisecond and second range had been reported, respectively. The climbing fibre-Purkinje cell synapse is crucial in timing models; thus, the aberrant connection between these cellular elements is a suitable model for evaluating the contribution of the cerebellum in timing in the supra-second range. The aberrant connection between climbing fibres and Purkinje cells was induced by administration of the antagonist of NMDA receptors MK-801 to Sprague-Dawley rats at postnatal days 7-14. The timing of an operant response with two fixed intervals (5 and 8 s) and egocentric sequential learning was evaluated in 60-day-old adult rats. The aberrant connections caused a reduced accuracy in the timing of the instrumental response that was more evident in the 8-s interval and a reduced number of successive correct responses (responses emitted in the correct second without any other response between them) in the 8-s interval. In addition, an inability to incorporate new information in a sequence previously learned in egocentric-based sequence learning was apparent in rats with aberrant CF-PC synapses. These results support a relevant role for the cerebellum in the fine-tuning of the timing of operant responses in the supra-second range.

Choice between contingencies of variation: effects of the requirement of variation upon preference.

The present study investigated whether choices between contingencies of variation are affected by the degree of variability required. For such, five pigeons were exposed to a concurrent chain schedule. In the initial links, responses in one key initiated the terminal link with the most stringent variation requirement while responses in the other key initiated the terminal link with the least stringent variation requirement. In both terminal links, four-responses sequences were reinforced according to a variation criterion, which favored less frequent and less recent sequences. The probability of reinforcement in the terminal link with the least stringent criterion was manipulated in order to generate similar percentage and rate of reinforcers in both terminal links. Choices for the terminal link with the least stringent criterion were more frequent than choices for the terminal link with the most stringent criterion. It is possible that situations that demand lower levels of behavior variability are chosen due to the lower response cost correlated to those situations.

Serial conditional discrimination and temporal bisection in rats selectively lesioned in the dentate gyrus.

In positive serial conditional discrimination, animals respond during a target stimulus when it is preceded by a feature stimulus, but they do not respond when the same target stimulus is presented alone. Moreover, the feature and target stimuli are separated from each other by an empty interval. The present work aimed to investigate if two durations (4 or 16s) of the same feature stimulus (light) could modulate the operant responses of rats to different levers (A and B) during a 5-s target stimulus (tone). In the present study, lever A was associated with the 4-s light, and lever B was associated with the 16-s light. A 5-s empty interval was included between the light and the tone. In the same training procedure, the rats were also presented with the 5-s tone without the preceding light stimuli. In these trials, the responses were not reinforced. We evaluated the hippocampal involvement of these behavioral processes by selectively lesioning the dentate gyrus with colchicine. Once trained, the rats were submitted to a test using probe trials without reinforcement. They were presented with intermediate durations of the feature stimulus (light) to obtain a temporal bisection curve recorded during the exposure to the target stimuli. The rats from both groups learned to respond with high rates during tones preceded by light and with low rates during tones presented alone, which indicated acquisition of the serial conditional discrimination. The rats were able to discriminate between the 4- and 16-s lights by correctly choosing lever A or B. In the test, the temporal bisection curves from both experimental groups showed a bisection point at the arithmetic mean between 4 and 16s. Such processes were not impaired by the dentate gyrus lesion. Thus, our results showed that different durations of a feature stimulus could result in conditional properties. However, this processing did not appear to depend on the dentate gyrus alone.

Serial position effects in social transmission of food preference: retention/demonstration intervals.

The effects of retention and demonstration intervals on serial position were evaluated in two experiments with Long-Evans rats. A list of 3 demonstrators that had eaten one of three flavored foods was presented to naive observers. In Experiment 1, there were four groups, three groups with a retention interval compared with one group with a zero retention interval or no retention interval. In Experiment 2, the demonstration interval was reduced. Intervals of 15, 5, 2, and 1 min were used. In Experiment 1, primacy decreased gradually in the four groups as the retention interval was increased in duration. In Experiment 2, primacy also decreased gradually, and recency occurred with the 1-min demonstrator interval. The increase in the duration of the retention interval reduced primacy. The reduction in the duration of the demonstration interval decreased primacy and produced recency.

Occasion setting in Pavlovian ambiguous target discriminations.

Rats were trained in a Pavlovian serial ambiguous target discrimination, in which a target cue was reinforced if it was preceded by one stimulus (P-->T+) but was not reinforced if it was preceded by another stimulus (N-->T-). Test performance indicated that stimulus control by these features was weaker than that acquired by features trained within separate serial feature positive (P-->T+, T-) and serial feature negative (N-->W-, W+) discriminations. The form of conditioned responding and the patterns of transfer observed suggested that the serial ambiguous target discrimination was solved by occasion setting. The data are discussed in terms of the use of retrospective coding strategies when solving Pavlovian serial conditional discriminations, and the acquisition of special properties by both feature and target stimuli.

Effects of semantic relations, repetition of words, and list length in word list recall of Alzheimer's patients.

INTRODUCTION: Semantic relations among words and repetition enhance free recall, but it is unknown if these facilitating factors are effective in dementia. METHOD: Alzheimer's patients (MILD-Alz, MOD-Alz) were compared to healthy elderly. Fifteen-word lists were read out to the subjects. In four sets of lists the words in intermediary input positions were semantically related or not, or the midlist words were repeated, or they were repeated and semantically related. RESULTS: The usual third peak of recall of semantically related words was not observed in MOD-Alz, repetition of words did not increase recall of the patients, and the combination of relatedness and repetition benefited only MID-Alz. In a second experiment, with related or unrelated midlist words, and list length shortened from 15 to 9 words, semantic facilitation was observed in mild and moderate Alzheimer s patients, although diminished compared to controls. CONCLUSION: Progression of dementia turns facilitating factors of recall less effective.

Effects of semantic relations, repetition of words, and list length in word list recall of Alzheimer's patients / Efeitos da relação semântica, repetição de palavras e extensão das listas na recordação de pacientes com doença de Alzheimer

INTRODUCTION: Semantic relations among words and repetition enhance free recall, but it is unknown if these facilitating factors are effective in dementia. METHOD: Alzheimer's patients (MILD-Alz, MOD-Alz) were compared to healthy elderly. Fifteen-word lists were read out to the subjects. In four sets of lists the words in intermediary input positions were semantically related or not, or the midlist words were repeated, or they were repeated and semantically related. RESULTS: The usual third peak of recall of semantically related words was not observed in MOD-Alz, repetition of words did not increase recall of the patients, and the combination of relatedness and repetition benefited only MID-Alz. In a second experiment, with related or unrelated midlist words, and list length shortened from 15 to 9 words, semantic facilitation was observed in mild and moderate Alzheimer´s patients, although diminished compared to controls. CONCLUSION: Progression of dementia turns facilitating factors of recall less effective.

INTRODUÇÃO: Relacionamento semântico e repetição facilitam a recordação livre mas não se sabe se esses fatores continuam efetivos na demência. MÉTODO: O desempenho de pacientes com doença de Alzheimer (MILD-Alz e MOD-Alz) foi comparado com o de idosos sadios na recordação livre de listas de 15 palavras, utilizando quatro diferentes conjuntos de listas que continham ou não palavras relacionadas nas posições intermediárias, palavras repetidas, ou ainda palavras repetidas e semanticamente relacionadas. RESULTADOS: O terceiro pico usual na recordação das palavras semanticamente relacionadas não foi observado em MOD-Alz; a repetição não aumentou a recordação dos pacientes; a combinação de relacionamento e repetição beneficiou apenas MILD-Alz. Em outro experimento, com palavras intermediárias relacionadas ou não, e em que a extensão das listas foi reduzida para 9 palavras, observou-se facilitação semântica em MILD-Alz e MOD-Alz. CONCLUSÃO: A progressão da demência diminui a eficácia de fatores facilitadores da recordação.

Effects of paradoxical sleep deprivation on the performance of rats in a model of visual attention.

In the present work we sought to evaluate the effects of paradoxical sleep deprivation (PSD) on the performance of rats in the five-choice serial reaction time task, a test designed to assess attentional function. Adult male Wistar rats were trained to detect a brief (1 s) light stimulus randomly presented in one of five locations in a box specially designed for the task. After achieving stable performance, the animals were submitted to 96 h of sleep deprivation by the platform technique, in which the rats are placed on top of small platforms in a tank filled with water. During sleep, particularly during the paradoxical stage, the loss of muscle tone make the animals fall into the water, thus awakening them and so depriving of sleep. Performance in the task was assessed daily during the 96 h deprivation period and also during seven recovery days afterwards. Paradoxical sleep deprivation reduced accuracy on the on the third (72 h) and fourth (96 h) days of sleep deprivation compared to home-cage controls, and this impairment reverted soon after the beginning of the recovery period. Sleep-deprived animals also showed an increase in omissions in the first day of PSD and a reduction on the number of trials started on the fourth day of sleep deprivation. No significant group differences were observed in premature and perseverative responses, correct response latency and reward latency. Our results thus indicate that paradoxical sleep deprivation impairs attentional function.

Bilateral lesion of the cerebellar-dentate nucleus impairs egocentric sequential learning but not egocentric navigation in the rat.

The involvement of the cerebellum in procedural learning is demonstrated in visuomotor-sequence tasks, as lesion of this area impedes the acquisition of new sequences. Likewise, the lateral cerebellum appears to be involved in the acquisition of new sequences, but not in the execution of learned sequences. In contrast, the dentate nucleus participates only in the execution of learned visuomotor sequences. In previous studies, disruption of the procedural elements of spatial navigation following cerebellar or dentate lesions has been reported. However, as praxic strategies (egocentric learning) are included in the procedural elements of the navigation, the participation of the cerebellar-dentate nucleus in egocentric procedural learning processes has not been evaluated. Therefore, using colchicine, bilateral lesions were made in the cerebellar-dentate nucleus of Sprague-Dawley rats, and these rats were given two tasks: egocentric-based motor sequence learning in the radial maze and egocentric navigation in the Morris water maze. The lesioned rats were unable to use the sequential information in the short term and showed delayed long-term acquisition, which was probably due to the inability to detect the sequence. No effects on the egocentric navigation task were observed. Our results indicate that the cerebellar-dentate nucleus is involved in the detection of egocentric sequential information but not in the use of this information in the navigation process. Further, they show differential involvement of the cerebellar-dentate nucleus in the execution of learned visuomotor sequences, as the dentate lesion disrupted the acquisition of new egocentric-motor-based sequences.

Controles ótimos e adaptativo na aquisiçäo de habilidades motoras seriadas / Optimal and adaptive controls in the acquisition of serial motor skills

Habilidades motoras säo mantidas num estado provisório. Por um lado, elas säo estáveis, padronizadas e flexíveis para atingir uma meta imediata. Por outro lado, elas podem se tornar instáveis, desordenadas e inconsistentes quando novas metas necessitam ser alcançadas. A aquisiçäo do primeiro controle ótimo - é restringida pela necessidade do segundo - controle adaptativo. Uma série de estudos foi executada para investigar as seguintes questöes: se o controle ótimo é caracterizado p[or um "timing" relativo invariante; se o controle adaptativo seria beneficiado pela estrutura temporal previamente adquirida; se crianças säo diferentes de adultos nas duas questöes prévias. Oito sujeitos participaram do estudo, cinco adultos e três crianças (6, 8, e 11 anos de idade), numa tarefa motora seriada. O tempo total de resposta e de seus componentes foram medidos. Os resultados indicaram que: (1) o controle ótimo foi adquirido com um "timing" relativo invariante para adultos e crianças; (2) o controle adaptativo foi fortemente baseado nessa estrutura, em todos os sujeitos. O contraste entre a variabilidade dos componentes e a consistêncioa do tempo total de resposta sugere que a variaçäo na micro-estrutura da habilidade pode ser mais importante do que a invariância na macro-estrutura em relaçäo a aquisiçäo de controle adaptativo