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At least 343 records · Page 19Linked to original sources
PubMed1972

Visual receptive fields sensitive to absolute and relative motion during tracking.

Some neurons in the visual cortex of awake monkeys visually tracking a moving target showed receptive fields that were excited only by stimulus motion relative to a background, while other neurons responded to any kind of stimulus motion. This result was found with two methods, one in which tracking eye movements were identical in both relative-motion and absolute-motion conditions, and another in which stimulus motions on the retina were identical in both conditions. This response pattern can differentiate translation of the retinal image during eye movement from motion of objects in the world.

Animals↗
PubMed1981

Meprobamate reduces accuracy of physiological detection of deception.

Normal male subjects attempted to deceive an experimenter recording electrodermal, respiratory, an cardiovascular activity. Those who had ingested a placebo or nothing were detected with statistically significant frequency on the basis of their phasic electrodermal responses, which clearly distinguished them from truthful suspects. That was not the case with deceptive subjects who had ingested 400 milligrams of meprobamate, nor did the examiner detect which subjects had received the drug.

Blood Pressure↗
PubMed1990

Learning a unimanual motor skill by partial commissurotomy patients.

A series of motor tests on four Chinese partial commissurotomy patients is reported. The single-stage commissurotomy in all four patients included the anterior commissures and two-thirds or four-fifths section of the corpus callosum with sparing of the splenium. There was no demonstrable ability to transfer hand posture in these patients. This was the major evidence for functional deconnexion. A newly learned task of one-hand knotting revealed right hand impairment in all four patients. There was no dyspraxia in the right hand for over-learned object-handling tasks in these patients. It is suggested that there might be right hemisphere specialisation for the initial acquisition of unimanual object-handling skills and that the spared callosal fibres in the splenium alone are insufficient to mediate task control under these conditions. This is supported by the finding that one of these patients, who was the only one who had a right parietal lesion, was unable to perform the newly learned task with either hand.

Adolescent↗
PubMed1976

Trial sequence of changed unit activity in auditory system of alert rat during conditioned response acquisition and extinction.

1. The activity of units in the auditory system of alert, freely moving rats was studies during the acquisition and extinction of a tone-signaled, appetitive classically conditioned response. Responses of neurons in inferior colliculus (N = 28), medial geniculate (N = 32), posterior nucleus of thalamus (N = 28), pretectal region (N = 19), and cortex (N = 100) were studies in 74 rats across 10-trial blocks. 2. During behavioral acquisition, neurons in posterior nucleus of thalamus were the first to show response increments to CS+ onset. They were followed by neurons in cortex, pretectal region, medial geniculate, inferior colliculus and by movement behavior. 3. Prestimulus background rates during acquisition showed significant decrements in cortical neurons. These background decrements began to be evidenced in the trial series before the response increases in posterior nucleus. These data strengthened the suggestion of a previous study that posterior nucleus responses could be dependent on tonic modulation from cortex. 4. Extinction appeared to be largely a reverse of acquisition. Cortex and behavior showed response decrements first in the trial series. They were followed by medial geniculate, pretectal region, posterior nucleus, and inferior colliculus neurons. 5. The hypothesis was advanced that the auditory lemniscal adjunct afferent system may play a primary role in the early phases of auditory conditioned-response acquisition.

Acoustic Stimulation↗
PubMed1992

Responses of monkey dopamine neurons during learning of behavioral reactions.

1. Previous studies have shown that dopamine (DA) neurons respond to stimuli of behavioral significance, such as primary reward and conditioned stimuli predicting reward and eliciting behavioral reactions. The present study investigated how these responses develop and vary when the behavioral significance of stimuli changes during different stages of learning. Impulses from DA neurons were recorded with movable microelectrodes from areas A8, A9, and A10 in two awake monkeys during the successive acquisition of two behavioral tasks. Impulses of DA neurons were distinguished from other neurons by their long duration (1.8-5.0 ms) and low spontaneous frequency (0.5-7.0 imp/s). 2. In the first task, animals learned to reach in a small box in front of them when it opened visibly and audibly. Before conditioning, DA neurons were activated the first few times that the empty box opened and animals reacted with saccadic eye movements. Neuronal and behavioral responses disappeared on repeated stimulus presentation. Thus neuronal responses were related to the novelty of an unexpected stimulus eliciting orienting behavior. 3. Subsequently, the box contained a small morsel of apple in one out of six trials. Animals reacted with ocular saccades to nearly every box opening and reached out when the morsel was present. One-third of 49 neurons were phasically activated by every door opening. The response was stronger when food was present. Thus DA neurons responded simultaneously to the sight of primary food reward and to the conditioned stimulus associated with reward. 4. When the box contained a morsel of apple on every trial, animals regularly reacted with target-directed eye and arm movements, and the majority of 76 DA neurons responded to door opening. The same neurons lacked responses to a light not associated with task performance that was illuminated at the position of the food box in alternate sessions, thus demonstrating specificity for the behavioral significance of stimuli. 5. The second task employed the operant conditioning of a reaction time situation in which animals reached from a resting key toward a lever when a small light was illuminated. DA neurons lacked responses to the unconditioned light. During task acquisition lasting 2-3 days, one-half of 25 DA neurons were phasically activated when a drop of liquid reward was delivered for reinforcing the reaching movement. In contrast, neurons were not activated when reward was delivered at regular intervals (2.5-3.5 s) but a task was not performed.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1976

Generalization of behaviour therapy with psychotics.

Generalization of improvement in the behavioural treatment of psychotic patients must be planned in after-care settings, and for durability over time. The transfer of clinical gains is not an automatic by-product of treatment with severely and chronically impaired mental patients. Treatment strategies that facilitate generalization from hospital to community are illustrated in a case study using empirical data. Systematic and specific treatment programmes were co-ordinated between a state hospital ward and a community-based day hospital. Setting step-wise and limited goals is a feature of successful outcomes. Maintaining consistency in reinforcement contingencies from hospital to community settings, using natural reinforcers, pinpointing functional behaviours as therapeutic goals, over-learning, and training natural caregivers are methods that promote generalization.

Activities of Daily Living↗
PubMed1981

Identifying the educative and suppressive effects of positive practice and restitutional overcorrection.

Two major features of the overcorrection procedure, restitution and positive practice, were analyzed for their educative and suppressive properties in the treatment of profoundly retarded adults. Positive practice techniques that were topographically similar and dissimilar to the target behavior were studied. Eating behavior and puzzle performance were observed. Restitutional overcorrection and both forms of positive practice were effective for suppressing inappropriate behaviors. Even when appropriate behaviors had been acquired by positive practice, restitution and dissimilar positive practice were generally ineffective for increasing their rate of occurrence. However, topographically similar positive practice was successful as a means of teaching new appropriate behaviors.

Adult↗
PubMed1968

Cue-producing behavior in the Capuchin monkey during reversal, extinction, acquisition, and overtraining.

In a two-choice discrimination situation, a cue-producing response produced the discriminanda for 0.05 sec. The cue-producing responses beyond those normally necessary to identify the discriminanda thus provided only redundant information. Two of the four Capuchin monkeys studied showed a large increase in cue-producing responses during reversal learning and extinction, and they reversed much faster than the two whose cue-producing responses showed little increase. During acquisition of a difficult discrimination, the cue-producing responses of the first two subjects reached a high level and during overtraining gradually reduced to their initial low level. The results were related to Wyckoff's theory of observing behavior and to the notions of uncertainty, reduction, and lack of information as extensions of the concepts of reinforcement and motivation.

Animals↗
PubMed1976

Are two hands better than one? assessing information acquired from one- and two-handed haptic exploration of random forms.

15 male undergraduates were presented with 10-sided random forms which they explored visually, or one-handed haptically, or two-handed haptically. Forms were exposed for various durations and subjects were required to draw each form immediately after its removal. The results indicated that 30 sec. of one-handed exploration and 20 and 30 sec. of two-handed exploration produced performance comparable to just 2 sec. of visual exploration. Two-handed exploration was significantly superior to one-handed exploration only at the 20-sec. exposure duration. These results illustrate the disparity in the information-gathering capabilities between the visual and haptic systems.

Form Perception↗
PubMed1976

Visual serial search across number and letter sets.

To discover whether visual serial search time for numbers differed significantly from time for letters, a repeated-measurements design was used with 24 undergraduate women. Performance on number targets 0 to 9 was significantly moe rapid than performance on the letter targets A to J, I to R, or Q to Z. By controlling confounding effects due to redundancy, the possibility that the outcomes might be related to the balance of linear and curvi-linear target features was strengthened.

Discrimination, Psychological↗
PubMed1994

The Trail Making Test A and B: a technical note on structural nonequivalence.

The major structural aspect of the Trail Making Test, length of drawn lines needed to complete the tests, was measured and compared for the adult and school-aged child versions. Trail Making B is a markedly longer test than Trail Making A, 32% for adults and 27% for school-aged children. The interpretive assumptions that Trail Making B differs from Trail Making A only in terms of the cognitive skills needed to complete the test and the implicit interpretive bias toward minimizing the motor component of the tests were challenged in this technical note.

Adult↗