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PubMed1997

Comparative effects of alcohol and marijuana on mood, memory, and performance.

This study compared subjective and behavioral effect profiles of alcohol and smoked marijuana using technology that controlled puffing and inhalation parameters. Male volunteers (n = 5) with histories of moderate alcohol and marijuana use were administered three doses of alcohol (0.25, 0.5, or 1.0 g/kg), three doses of marijuana [4.8, or 16 puffs of 3.55% delta 9-tetrahydrocannabinol (THC)], and placebo in random order under double blind conditions in seven separate sessions. Blood alcohol concentration (10-90 mg/dl) and THC levels (63-188 ng/ml) indicated that active drug was delivered to subjects dose dependently. Alcohol and marijuana produced dose-related changes in subjective measures of drug effect. Ratings of perceived impairment were identical for the high doses of alcohol and marijuana. Both drugs produced comparable impairment in digit-symbol substitution and word recall tests, but had no effect in time perception and reaction time tests. Alcohol, but not marijuana, slightly impaired performance in a number recognition test. These data are useful for understanding the relative performance impairment produced by alcohol and marijuana at the delivered doses and the relationship between their subjective and behavioral effects.

Adolescent↗
PubMed1984

The relationship between space and time in the perception of stimuli moving behind a slit.

When a shape defined by a set of dots plotted along its contour is presented in a sequence of frames within the boundaries of a slit, and in each frame only one dot (featureless frame) or two dots (feature frame) are displayed, a whole moving dotted shape is perceived. Masking techniques and psychophysical measures have been used to show that a dynamic random-dot mask interferes with shape identification, provided the interframe interval is greater than about 15 ms, and there are no stimulus features for recognition in individual frames. A similar pattern of results was obtained when the observer had only to detect the movement of a single dot or a pair of dots against a dynamic-noise background. It is concluded that the visual system can resolve the correspondence problem in both apparent movement (one moving dot) and aperture viewing (featureless-frame condition) by extracting motion before the extraction of features in each frame. However, the results also show that where feature identification in each frame is possible, it can also be used to identify the moving targets.

Female↗
PubMed1999

Maternal perception of lactogenesis time: a clinical report.

A study evaluating the time between delivery and the surge in milk production (lactogenesis time) determined whether lactogenesis time (LT) is affected by parity, factors in pregnancy and delivery, and especially cesarean section. Forty-six primiparous mothers and 81 multiparous mothers reported the time of sensation of milk production after delivery. The mean LT in the entire sample was 50 +/- 15 hours. The mean LT in 46 primiparous mothers was 59 +/- 14 hours, and in 81 multiparous mothers 45 +/- 12 hours (by student t test, p < 0.01). Mean LT did not decrease as parity increased in the multiparous mothers. By multivariate analysis, mean LT was 44 hours in multiparous mothers who delivered vaginally without medication, 11 hours longer if primiparous, 6 hours longer if delivery by cesarean section, and 13 hours longer if sedative or pain medication were given during labor.

Adult↗
PubMed1979

Variations in perception of short time intervals during menstrual cycle.

The hypothesis that women experience heightened sensitivity and responsivity premenstrually was tested by asking 10 women to produce short time intervals at four phases of the menstrual cycle. 10 men were assigned to "pseudo-cycles" and tested as a control. The test was based on the assumption that a greater sensitivity to stimuli is reflected in a "slowing down" of subjective time. The women produced the shortest time intervals three to four days before menses, confirming the hypothesis.

Adult↗
PubMed1979

Carbon monoxide and human time discrimination: failure to replicate Beard-Wertheim experiments.

Beard and Wertheium described a dose-related deficit in human time perception during low level CO exposure. Two other laboratories were unable to replicate this finding, although methodological differences could explain these failures. This study more precisely repeated the original experiment, but failed again to obtain any CO-related deficit. The bulk of evidence, therefore, does not indicate any adverse effect of low level CO exposure on time perception in healthy young adults.

Acoustic Stimulation↗
PubMed1993

Temporal bisection in rats: the effects of high-peak-power pulsed microwave irradiation.

The effects of high-peak-power, pulsed microwaves on a time perception and discrimination task were studied in rats. Exposures were performed with the TEMPO exposure system, which produces an 80 nanosecond pulse with peak-power levels in excess of 700 megawatts. The ability to expose animals to such fields within a controlled environment is unique. As determined by calorimetry, a maximal, whole-body-averaged, specific-absorption rate of 0.072 W/kg was produced. Thus exposures were well below a recommended SAR limit of 0.4 W/kg. Power levels of transmitted microwaves were varied over a 50 dB range to obtain ascending and descending dose-response functions for each of the behavioral measures. Measures of time perception, response bias, and total trials did not change with power level. Dose-response effects were observed for discriminability (ability to distinguish between durations), session time, and trial completions (null responses, failures to respond on a trial). Covarying sound and X-ray exposures produced by TEMPO did not reliably correlate with the observed microwave effects. The observation of repeatable dose-response effects on discriminability and null responses indicates that the microwave exposures were affecting cognitive function in the rats, particularly the decision-making process.

Animals↗
PubMed1991

Effects of morphine sulfate on operant behavior in rhesus monkeys.

The acute effects of morphine sulfate were assessed using a battery of complex food-reinforced operant tasks that included temporal response differentiation (TRD, n = 5), delayed matching-to-sample (DMTS, n = 6), progressive ratio (PR, n = 9), incremental repeated acquisition (IRA, n = 9), and conditioned position responding (CPR, n = 7) tasks. Performance in these tasks is thought to depend upon specific brain functions such as time perception (TRD), learning (IRA), short-term memory and attention (DMTS), color and position discrimination (CPR), and motivation to work for food (PR). Morphine sulfate (0.1-5.6 mg/kg IV), given 15 min presession, produced significant dose-dependent decreases in the number of reinforcers obtained in each task. Response accuracy was significantly decreased at doses greater than or equal to 1.0 mg/kg for TRD when compared to saline injections. Accuracy was not consistently affected in any other task in the test battery. Response rates decreased or response latencies increased significantly at doses of 1.0 mg/kg and above for the PR task, at 3.0 mg/kg and above for the IRA and TRD tasks, and only at the highest dose 5.6 mg/kg in the CPR and DMTS tasks. Percent task completed was decreased following doses of 1.0 mg/kg and higher for the IRA, PR and TRD tasks, at doses of 3.0 mg/kg and higher for the DMTS task, and at the high dose of 5.6 mg/kg for the CPR task. These results indicate that in monkeys, the performance of operant tasks designed to model learning ability (IRA), time perception (TRD) and motivation (PR) are more sensitive to the disruptive effects of morphine than is performance in tasks designed to model short-term memory and attention (DMTS). The task which models color and position discrimination (CPR) was the least sensitive to disruption by morphine.

Animals↗
PubMed1978

The clinical utility of the hand-held tachistoscope.

A hand-held tachistoscope for use at the bedside was constructed and used to examine 40 normal controls and 170 psychiatric and neurological patients. This instrument quickly provided an index (perception time) which distinguished between idiopathic psychiatric illness and delirium, and between cortical and subcortical neuropathology. Slow perception time was seen in patients with delirium or cortical neuropathology.

Adolescent↗
PubMed1993

Acute effects of pentobarbital in a monkey operant behavioral test battery.

The effects of acute pentobarbital treatment were assessed using a complex operant test battery containing five tasks in which correct performance is thought to depend upon processes associated with short-term memory and attention [delayed-matching-to-sample (DMTS)], color and position discrimination [conditioned position responding (CPR)], motivation [progressive ratio (PR)], time perception [temporal response differentiation (TRD)], and learning [incremental repeated acquisition (IRA)]. Adult, male rhesus monkeys were tested 15 min after IV injection of saline or pentobarbital (1, 3, 5.6, 10, or 15 mg/kg). Behavioral endpoints measured included percent task completed, response rate or latency, and response accuracy. The order of task sensitivity to disruption by PBT was TRD > IRA = DMTS = PR > CPR, in which sensitivity was defined as a significant disruption in any aspect of task performance. PBT slowed response rates at 10.0 and/or 15.0 mg/kg in all tasks. Accuracy was decreased in the TRD task at > or = 5.6 mg/kg but doses of > or = 10.0 mg/kg were required to decrease accuracy in the IRA, DMTS, and CPR tasks. Thus, behavior thought to model time perception (TRD) was more sensitive than behavior modeling learning (IRA), short-term memory and attention (DMTS), and motivation (PR). CPR was the least sensitive behavior. Because pentobarbital exerts its effects at least in part via GABA systems, the effects in the current study were compared with those of a previous study of the acute effects of diazepam. The two compounds exerted fundamentally different effects on operant test battery performance.

Animals↗
PubMed2001

Measuring maximum holding times and perception of static elevated work and forward bending in healthy young adults.

The objectives of this study were to investigate the maximum holding times (MHT) of two highly stressful postures: standing in a forward bend position and performing elevated work in a standing position. The relationship between perceived exertion and MHT was also studied. Subjects were 44 young adults, age 20-29 years (25 female, 19 male). A test-retest design was used to establish reliability. Mean maximum holding times for forward bending and elevated work were respectively 14.51 and 16.18 min with large interindividual variations. A logarithmic rather than a linear relation between perceived exertion and performance is found. It is not possible to reliably predict MHTs from subjective data. Test-retest correlation is high (n = 19, r = 0.716 and 0.813, p < 0.001), and the scores did not differ significantly (p < 0.005), indicating a reliable procedure. The average holding times of the population studied are higher than expected from literature. Neither generic formulas, curve estimations, or predictions can reliably predict an individual's MHT. An individual's MHTs are best tested through performance based testing.

Adult↗
PubMed2000

Changes of the neurotransmitter serotonin but not of hormones during short time music perception.

We studied the impact of the perception of pleasant and unpleasant music, as rated by healthy subjects with a psychometric scale, on the hormones prolactin and ACTH. In addition, the neurotransmitter serotonin (5-HT) was studied using the platelet model for central neurotransmission of 5-HT. We did not observe any significant changes of prolactin and ACTH during the perception of different kinds of music. The 5-HT content of platelets, however, was higher during the perception of pleasant music as compared to the perception of unpleasant music indicating an increased release of 5-HT during unpleasant music (748 ng/10(9) platelets vs. 699 ng/10(9) platelets; p<0.014). The difference of the 5-HT level was significantly correlated to the score of unpleasantness as rated by the subjects. Our data suggest that perception of unpleasant music induces increased release and decreased peripheral and possibly also central intracellular content of 5-HT.

Adrenocorticotropic Hormone↗
PubMed1986

Regularity, exposure time and perception of numerosity.

Two experiments are described. In Exp. 1, subjects compared the apparent numerosity of two kinds of dot patterns, regular vs irregular, with two different exposures (160 vs 2000 msec.). In Exp. 2, the subjects had to estimate the numerosity of the same patterns, presented one at a time. Analysis showed a relative overestimation of the regular patterns in Exp. 1 but not in Exp. 2. In general an overestimation occurred with an increase in exposure. Such results support our hypothesis of two separate processes as the basis of the two kinds of performance (estimating vs comparison).

Attention↗
PubMed1978

Methadone maintenance: an assessment of potential fluctuations in behavior between doses.

Thirty methadone maintenance outpatients were measured 1 and 25 hours after ingestion of methadone on auditory threshold, distance perception, simple and differential reaction time, time perception, attention span, and short-term memory. The results revealed a small but statistically significant difference between the two tests for distance perception. In addition, treatment interacted with preparatory interval on differential reaction time and with sex on attention span.

Adolescent↗
PubMed1996

Ethnic differences in temporal orientation and its implications for hypertension management.

Research indicates that health beliefs and perceptions are shaped and organized by life experiences. Time perception, also structured by life experiences, can systematically alter individuals' perceptions of disease and evaluations of treatment options. Using the Health Belief Model (HBM), this study examines the effects of ethnicity and hypertension temporal orientation on the health perceptions of 300 African Americans and White Americans with hypertension. Results revealed that African Americans were more present-oriented than White Americans regarding their daily experiences with managing hypertension. Compared to more future-oriented respondents, present-oriented people perceived themselves to be less susceptible to the consequences of hypertension, believed more in the benefits of home remedies and negative aspects of prescribed medication, and believed less in the benefits of prescribed medication and negative aspects of home remedies. We concluded that ethnicity influences hypertension temporal orientation and that hypertension temporal orientation affects perceptions about hypertension and its management. Implications for health and medical care are addressed.

Black or African American↗
PubMed2001

Interneurons, spike timing, and perception.

Rhythmic gamma oscillations at 30-70 Hz in cortical and hippocampal slices depend on a maintained excitation and on interactions between interneurons and pyramidal cells. These interactions include gap-junctional connections between inhibitory cells and fast excitatory and inhibitory chemical synapses. Spike timing with precision in the range of several ms may be assured by biphasic signaling mechanisms operating at these different connections. Such temporal precision may be important in cognitive processing.

Action Potentials↗