PubMed Health⌕ Search

Biomedical subjects

D B Lindsley

Publications and source records attributed to D B Lindsley.

At least 19 recordsLinked to original sources
PubMed1981

Slow potential shifts of human brain during forewarned reaction.

The slow brain potentials observed during the 4 sec interstimulus interval (ISI) of a CNV paradigm were investigated by a factorial manipulation of the parameters that have been identified as affecting the CNV at ISIs of 1 or 2 sec. Subjects performed choice and simple reaction time (RT) tasks under all possible combinations of auditory and visual warning (S1) and imperative (S2) stimuli. The choice task involved easy or difficult intensity discriminations at S2, which were forewarned by S1s that cued the subject as to the level of difficulty for that trial. Principal components analysis (PCA) of the data revealed two negative afterwave factors and a late positive component (LPC) related to warning stimulus variables, and a late negative shift preceding S2 that was related to motor preparation. The negative afterwave components were enhanced in the choice RT task, and the earlier of the two components showed a modality-specific distribution. The LPC factor was also enhanced in the choice task and was further enhanced by S1s signaling difficult discriminations. Additionally, the LPC was larger for visual S1s. The S1-related components are interpreted in terms of orienting, while the later shift is identified with the readiness potential and motor preparation. The results support the notion that the conventionally recorded CNV consists of S1 evoked and response-related potentials rather than non-specific and modality-specific anticipatory potentials.

Action Potentials↗
PubMed1980

Synthesis of the contingent negative variation brain potential from noncontingent stimulus and motor elements.

Slow shifts in brain potential (commonly called the contingent negative variation), obtained during a warned reaction-time task with a foreperiod of 1 second, were compared with waveforms synthesized by the addition of separately obtained potentials associated with individual (nonpaired) sensory stimuli and self-initiated motor movements. The synthesized waveforms match closely the actual contingent negative variation, suggesting that it is constituted largely of separate, noncontingent elements related to sensory and motor processes.

Auditory Perception↗
PubMed1980

Pulvinar neuron responses to spontaneous and trained eye movements and to light flashes in squirrel monkeys.

Single unit responses were recorded in the pulvinar nucleus of the squirrel monkey (Saimiri sciureus) while awake and alert, with the head fixed but free to make eye movements. Peri-saccadic time histograms revealed only post-saccadic responses to eye movements made spontaneously in the dark or in a uniformly illuminated field (Ganzfeld), or to trained eye movements made in response to a spot of light in the periphery. Of 120 pulvinar neurons that responded to eye movements in the light, approximately one-quarter was responsive to eye movements in the dark. In one group of monkeys about half of the eye movement-responsive cells in the light were responsive to light flash in the dark; in another group approximately half of the eye movement-responsive cells in the light were also responsive to trained eye movements. Of particular interest is the fact that pulvinar neurons responsive to eye movements were located within a restricted region oriented vertically and cutting across lateral and inferior pulvinar, rostrally, and lateral and medial pulvinar, caudally. The results have been interpreted as supporting the concept of convergence and integration of visual and oculomotor input in the pulvinar and also its potential role in the mediation of visual attention.

Animals↗
PubMed1979

Cortical slow negative waves following non-paired stimuli: effects of modality, intensity and rate of stimulation.

Using a simple stimulus counting task, negative after-waves following single (unpaired) stimuli were investigated under a variety of stimulus conditions. Responses were obtained to tones at 3 intensities, to light flashes at 3 intensities, and to tones at 3 rates of presentation. The acoustic stimuli led to a negative after-wave that peaked at frontal sites around 500 or 600 msec, and then trailed off to a more central scalp representation. This negative after-wave was increased in amplitude by slowing the rate of stimulus presentation. In comparison, no appreciable or sustained after-wave was elicited by visual stimuli. No significant effects in the negative after-wave were associated with intensity, either for visual or for acoustic stimuli. When analyzed by Principal Components Analysis, the negative after-waves were shown to comprise in all cases two underlying factors, although the factors contributed less to the total wave form for visual stimuli than for acoustic stimuli. Two interpretations for the negative after-wave were contrasted, one considering it to be an integral feature of the auditory evoked potential. A second interpretation, more compatible with the data obtained here, links the negative after-wave with non-specific activation processes.

Acoustic Stimulation↗
PubMed1977

Behavioral and hippocampal electrical changes during operant learning in cats and effects of stimulating two hypothalamic--hippocampal systems.

The electrical activity of the dorsal and ventral hippocampus and of the anterior and posterior neocortex is described and illustrated during the development of trained operant behavior in water-deprived cats learning to bar-press for water reward under three operant conditioning schedules: (a) continuous reinforcement; (b) alternating 10 sec periods of reinforcement and non-reinforcement; and (c) mixed reinforcement and non-reinforcement with special auditory and visual cues. In addition, the contrasting effects of 100 c/sec electrical stimulation of the medial and lateral hypothalamic systems upon hippocampal electrical activity and operantly trained behavior are reported. During the early stages of learning to bar-press for water reward, when close attention to the bar and water-well are required, hippocampal electrical activity manifests synchrony (theta rhythm) and neocortical electrical activity is desynchronized. Subsequently, as bar-pressing performance improves and requires little attention to the manipulanda, the pattern of hippocampal and neocortical electrical activity is one of irregular slow waves mixed with low voltage high frequency activity, characteristic of relative inattention and automatic performance. During alternating or mixed reinforcement and non-reinforcement schedules of operant training differential effects are observed during reinforcement and non-reinforcement periods, the latter being characterized generally by lower voltage, mixed low and high frequency activity, except when orienting and shifting of attention occurred with associated theta rhythm bursts. Stimulation of the medial hypothalamic system has a striking inhibitory effect upon bar-pressing for water reward. Bar-pressing ceases for many minutes but its eventually resumed at the pre-stimulation rate. In contrast, stimulation of the lateral hypothalamic system only interrupts bar-pressing for a matter of seconds. Possible causes of these differential effects, and especially the prolonged inhibition of bar-pressing induced by medial hypothalamic stimulation, are discussed.

Animals↗
PubMed1976

Influences of hypothalamic stimulation upon septal and hippocampal electrical activity in the cat.

Spontaneous patterns of hippocampal EEG and septal cell activity were studied in immobilized cats, and the influences of high frequency stimulation of medial hypothalamus (MH) and lateral hypothalamus (LH) were determined. Septal cells were divided into 3 classes on the basis of their discharge patterns: (1), rhythmic bursting (2), non-rhythmic bursting and (3), non-bursting, and the relationship of these discharge patterns to hippocampal theta rhythm was analyzed. Rhythmic bursting cells displayed close frequency and phase relations to hippocampal theta rhythm and were located chiefly in the diagonal band of Broca. Cells of the other two categories were found both within and outside of the diagonal band region.

Action Potentials↗
PubMed1976

Brain wave components of the contingent negative variation in humans.

In a contingent negative variation paradigm with two stimuli paired at an interstimulus interval of 4 seconds, two distinct waveforms having functional and topographic differences are observed. An early wave is maximal over the frontal cortex and is elicited by the warning stimulus. A later wave, maximal over the motor cortex, precedes the imperative stimulus and is identified with preparation for motor response.

Brain↗
PubMed1976

Cortical and subcortical visual evoked potential correlates of reaction time in monkeys.

The relationships between reaction time (RT) and evoked potentials were investigated in three monkeys (Macaca nemestrina) during the performance of a simultaneous brightness discrimination task. Evoked potentials from the lateral geniculate, medial and inferior pulvinar, midbrain reticular formation, hippocampus, and striate and prestriate cortex were recorded concurrently with RT in response to the discriminative stimuli. An early component of the geniculate response and a late positive wave in striate cortex were found to be related systematically to RT. These components were largest for short RTs and diminished progressively in amplitude as RT lengthened. The statistical significance of these relationships was supported by a detailed analysis of single trials. The increases in amplitude of evoked potentials associated with short RTs were attributed to increased arousal level and were discussed in terms of reticular formation modulation of central excitability levels.

Animals↗
PubMed1976

Effect of pulvinar lesions on visual pattern discrimination in monkeys.

This study compares the performance (percent correct responses and reaction times) of three unoperated control monkeys with the postoperative performance of eight monkeys with pulvinar lesions, either inferior pulvinar or medial and lateral pulvinar, on a tachistoscopically presented visual pattern-discrimination task highly demanding of attention. To further emphasize and assess the attentional factor in visual pattern discrimination, all monkeys who attained criterion performance (90% correct response on three consecutive sessions of 100 trials each) were tested for the effects of visually distracting interference stimuli added to the original discriminative stimuli. In addition, retention of postoperatively learned discriminations was tested after a 6-wk interval withou training and compared with the performance of control monkeys. Four monkeys with only inferior pulvinar lesions and one monkey with inferior pulvinar plus medial and lateral pulvinar lesions were markedly impaired in the postoperative learning of a visual pattern discrimination. Three of these monkeys failed to acquire criterion perfromance in 9,000 or more training trials, while two learned to ceiterion level only after prolonged training (7,400 and 6,900 trials). In contrast, monkeys with medial and lateral pulvinar lesions showed no deficit in learning ability compared to unoperated control monkeys. Furthermore, the performance of the two monkeys with inferior pulvinar lesions, who attained the criterion level of learning only with difficulty, was further impaired by the addition of distracting interference stimuli, where the performance of monkeys with medial and lateral pulvinar lesions as well as the control monkeys was only temporarily disrupted by this procedure. None of the monkeys with pulvinar lesions, who were tested for retention of the postoperatively learned discrimination, showed appreciable deficits in comparison to control monkeys. All monkeys, including controls and those uith pulvinar lesions who were able to learn the visual pattern discrimination, showed a common pattern of reaction time (RT) change during the course of the learning; that is, RT was low during change-level performance, increased during learning, and decreased once criterion performance was achieved. Reaction times of monkeys with inferior pulvinar lesions tended to be longer than for controls or for those with medial and lateral pulvinar lesions. These results provide the first behavior evidence that the inferior pulvinar of monkeys is involved in visual pattern discrimination and add further support to the concept of a second visual system in which the inferior pulvinar plays a role. The attentional aspects of the visual pattern-discrimination task employed in this study and the additional effects obtained with distracting stimuli suggest that the impairments arising from inferior pulvinar lesions may be dependent in part on visual attentional factors.

Acoustic Stimulation↗
PubMed1975

Response plasticity of lateral geniculate neurons during and after pairing of auditory and visual stimuli.

Neurons of the lateral geniculate nucleus, responsive only to visual stimulation, show response plasticity during and after pairing of auditory and visual stimuli. Modal response histograms reveal a gradual decrement in the number of spikes at interstimulus pairing intervals of 0 and 100 milliseconds but not 500 milliseconds. This plasticity effect, limited to tonic units, may persist for 2 to 3 minutes after termination of click-flash pairing.

Action Potentials↗
PubMed1975

Development of visually evoked responses and visually guided behavior in kittens: effects of superior colliculus and lateral geniculate lesions.

The development of visually evoked responses (VER's) and visually guided behavior was studied in kittens for 3 months after unilateral lesions of the superior colliculus (SC) or lateral geniculate nucleus (LGN) made at an early age. Of 37 kittens studied, data are presented for 6 which met 3 criteria: survival to at least 90 days of age; adequate lesion size and location; and technically satisfactory VER's and behavioral observations at appropriate intervals. The SC and LGN lesions markedly reduced or eliminated different VER components in infancy, but only the effects of LGN lesions persisted to 3 months of age. Visual field behavior deficits occurred following both types of lesions, but only those following SC lesions persisted to 3 months of age. These results are interpreted in terms of the functional status of the structures mediating the VER's and behavior at the time the lesions were made.

Animals↗