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Results for “Time Perception”

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At least 469 records · Page 26Linked to original sources
PubMed1997

Disruption of short-duration timing associated with damage to the suprachiasmatic region of the hypothalamus.

The neural bases of circadian rhythmicity have been demonstrated in a variety of animal species, including primates. Yet, the brain mechanisms underlying time experience and the timing of behaviors of shorter duration are still not well understood. In the present study, we demonstrate disruption of short-duration timing capacity in AH, a patient with damage to the suprachiasmatic (SCN) region of the hypothalamus. AH exhibited extreme inconsistency in her rate of tapping production on a motor continuation paradigm. Her inter-response intervals (IRIs) were extremely large compared with normal control subjects and were similar to those previously reported in patients with cerebellar dysfunction. Increased variability of both central timing and motor implementation processes was evident compared with both age-matched and elderly normal control subjects. Severe impairment of time perception was also evident on duration discrimination, whereas auditory loudness discrimination was intact. These findings suggest that a hierarchic relationship between long-duration (circadian) and short-duration timing exists, and that in addition to the cerebellum, intact hypothalamic functioning is necessary for short-duration timing.

Adult↗
PubMedDate not supplied

[Sex and age differences in the subjective assessment of time by preschoolers].

Time perception was studied in children under school age from 2.5 to 6 years. Using cross-modal matching, the children assessed durations of 1-, 3-, 5-, 7-, and 10-sec sound signals. It was found out that children under school age, irrespective of sex, more accurately estimated the extreme durations in the internal range (1 and 10 sec). In contrast to girls, boys reveal a clear-cut tendency to minimize the variability of assessments with age. Nevertheless, this tendency is not related with the attention level.

Acoustic Stimulation↗
PubMedDate not supplied

[THe characteristics of the autonomic reactions of healthy adolescents and of those with lowered intellectual productivity].

Present research is devoted to psychophysiological study of the mechanisms of functional state control in normal and educationally disabled children using EEG, neuropsychological, and heart rate data obtained during different types of mental activity, including performance of arithmetic, verbal, spatial, and time-perception tests. Attention index and one-minute time interval production in the group of educationally disabled patients were found to be statistically lower than in the normal children. Heart rate level in this group was also lower than in the normal children of the same age. Increase of heart rate indices during perception of instruction and transition to its realization was statistically higher in the group of normal children. The differences between the groups can be explained by disfunction of the functional state regulation mechanisms, deficit of sympathetic influence and prevalence of parasympathetic ones, as well as by the weakness of the functions of the nervous system which causes disadaptation in educationally disabled children.

Adolescent↗
PubMedDate not supplied

Monkey versus human performance in the NCTR Operant Test Battery.

A battery of operant behavioral tasks, designed to monitor complex "cognitive" functions in monkeys, was adapted for use in children. Adaptations were then incorporated into the monkey battery so that monkeys and children performed exactly the same tasks. Food pellets served as reinforcers for monkeys; nickels for children. Correct responding in a task is thought to depend upon relatively specific brain functions including short-term memory and attention, learning, time perception, motivation, and color and position discrimination. Eight 4-year-old rhesus monkeys served as subjects, and groups (n = 10 to 20) of 4- to 8-year-old children were recruited if they were not known to have any neurological, academic or behavioral problems. In performance of only the learning task was there any significant difference between monkeys and children. This difference was in response rate (not accuracy), with the monkeys responding faster than children. This lone difference in operant responding between monkeys and children was likely due to the fact that monkeys generally use all four appendages to respond whereas children generally do not.

Animals↗
PubMedDate not supplied

Psychedelic effects of a subanesthetic concentration of nitrous oxide.

The subjective effects of nitrous oxide were examined by administering questionnaires to volunteers (16 men and 16 women) breathing 30% nitrous oxide or 100% oxygen. Nitrous oxide produced a variety of subjective effects, including some that are characteristic of psychedelic drugs, such as happy, euphoric mood changes, changes in body awareness and image, alterations of time perception, and experiences of a dreamy, detached reverie state. The subjective effects, including those of a psychedelic nature, were very similar to the subject effects we observed in a previous study of nitrous oxide. However, euphoric mood changes were more pronounced, and adverse effects were less pronounced, in the present study, possibly due to the shorter duration of gas inhalation or the minimal tests of performance involved. Some other differences in subjective effects between the present and previous studies were identified by a discriminant analysis and seemed related to specific differences in experimental conditions. This suggests that the environment can influence which drug effects emerge, or at least their relative prominence. Clinicians should be familiar with the range of subjective effects that patients inhaling nitrous oxide may experience.

Adult↗
PubMed2005

Chronic drug exposures during development in nonhuman primates: models of brain dysfunction in humans.

This review of our work presents three specific examples of how nonhuman primates (rhesus monkeys, Macaca mulatta) have been used to study the effects of chronic drug exposures on brain function during different stages of development. In all cases, exposure levels similar to those experienced by humans were employed and the focus was on long-term--not acute--effects. In the case of the marijuana studies, exposures occurred during the adolescent period; for the cocaine studies, exposures occurred in binge-like fashion entirely before birth (in utero); and for the remacemide studies, exposures occurred daily in juveniles, prior to adolescence. An automated battery of behavioral tasks, the National Center for Toxicological Research Operant Test Battery (NCTR OTB), designed to assess aspects of motivation, visual discrimination, time perception, short-term memory, and learning, was used to monitor treatment effects. Chronic marijuana smoke exposure resulted in an 'amotivational' syndrome--even in weekend-only smokers--that resolved within three months of exposure cessation. In utero cocaine exposure was shown to cause behavioral rigidity or lack of plasticity as evidenced by the difficulty of subjects to adjust to rules changes for some OTB tasks. These effects were seen in adult subjects suggesting that the effects of gestational cocaine exposure are long-term or permanent. In addition, animals exposed to cocaine in utero were less sensitive to the behaviorally-disrupting effects of cocaine as adults. Remacemide caused profound and long-lasting, perhaps permanent, changes in learning task performance and because performance of this same task by children is significantly correlated with traditional measures of intelligence (IQ), these data suggest that such treatment may provide a valuable model of chemically-induced mental retardation.

Animals↗
PubMed1978

The use of numerical and graphical statistical methods in the analysis of data on learning to see complex random-dot stereograms.

Several numerical and graphical statistical methods are illustrated in an analysis of data from an experiment that investigated a hypothesis of Julesz that giving a person a priori information about the structure of a complex random-dot stereogram reduces the time needed to perceive it when it is viewed. The data are divided into two groups, one consisting of those observers who received no cue or verbal cues (NV) and the other consisting of those who received verbal-visual cues (VV). A quantile-quantile plot shows that the NV times (mean = 7.6) are longer than the VV times (mean =5.6). By using probability plots, it is shown that the perception times have an exponential probability distribution. A hypothesis test based upon this distribution is used to show that the difference between the NV and VV times has significance slightly below 0.05.

Cues↗
PubMed2001

Quantitative modeling of perception and production of time intervals.

The accurate perception/production of durations in the seconds and minutes range is important in a number of everyday activities, but the lack of direct experimental evidence on the neural circuits that could be involved has precluded the detailed elucidation of the underlying physiological mechanisms. We show, using a basic biophysical model of a timekeeping system and experimental data on time intervals produced or estimated under different conditions, that experimental values, variability, and distributions can be quantitatively explained in terms of a background synaptic activity such as that generated by attention. The model provides a plausible neural substrate for encoding time intervals, and the findings suggest how it may interplay at the single neuron level with the attentional system, to elaborate a subjective representation of the elapsing time.

Humans↗