Reaction time and diazepam plasma concentration in subjects with normal gastric pH

The present study investigated the relationship of reaction time with the plasma concentration of four different formulations of diazepam (liquid, original, new, and generic). On four separate days, over a 4-month period, subjects with normal gastric pH (N=7) were administered each of the diazepam formulations. Blood samples were obtained prior to each dose and at subsequent intervals. Likewise, reaction times were evaluated prior to dosing and then at ten different intervals post-dosing. As hypothesized, reaction time performance was associated with plasma diazepam concentration, regardless of formulation type. This suggests that reaction time is a sensitive measure of cerebral functioning for individuals who are treated with diazepam. In addition to providing a measure of drug effects on cognitive functioning, the results of this study have implications concerning possible hazards of operating machinery or driving motor vehicles for individuals being treated with diazepam.     

Effect of diazepam on visuomotor reaction time

20 male and 10 female adult, normal, healthy subjects, whose mean age was 26.34 yr., participated in a double-blind study of the effect of a single dose (0.2 mg./kg. of body weight) of diazepam on visuomotor reaction time. Reaction time was measured before drug administration, and 60 min., and 120 min. after administration. Separate reaction times for the dominant and nondominant hand were recorded. There were no significant differences between the diazepam and placebo group at each of the three time intervals. Diazepam in the single dose employed does not appear to affect adversely visuomotor reaction time of relatively young, normal, healthy adults. For both groups the difference in visuomotor reaction time between the dominant hand and the nondominant hand was statistically significant as expected.     

Diazepam-stress interactions in the rat: effects on autoanalgesia and a plus-maze model of anxiety

On six occasions spaced at least a week apart, two groups of rats were subjected to a variety of stressful conditions consisting of a restraint/bright light complex, either alone or in combination with a tail pinch, whole-body inversion, or partial immersion in cold water. One of these groups was injected with diazepam (2.0 mg/kg) 30 min prior to the stressors, while the other group experienced the drug in their home cages the following day. A third group also received the diazepam but was not exposed to the stressors. In three test sessions all animals were injected with either diazepam or saline and were then exposed to a novel stressor: a plus-maze used as a screening device for anxiolytic drugs. This was immediately followed by a tail-flick measure of analgesia. The longest tail-flick latencies, indicating stress-induced analgesia ("autoanalgesia"), were observed in the group that had not been exposed to stress prior to testing. The other two groups exhibited substantially shorter latencies but did not differ from one another, thus showing a "stress inoculation" effect that was uninfluenced by diazepam. In the plus-maze, diazepam tends to increase the amount of time rats will spend in the two exposed arms of the maze relative to the two enclosed arms. This effect was significantly attenuated in the group that had previously experienced the variety of stressors after a diazepam injection, suggesting a learned association between drug and stress that resulted in a diminution of the drug's anxiolytic property.     

Traumatic Brain Injury in School-Age Children Academic and Social Outcome

School-aged children with a traumatic brain injury (TBI) require extraordinary effort and energy from individuals in their school, home, and community. The purpose of this study was to examine the academic, behavioral, and social outcomes of a cohort of children and adolescents following TBI. A comprehensive assessment of cognitive functioning, achievement, and adaptive behavior was administered to 43 school-aged children 2 years after their TBI. Premorbid functioning for each participant was obtained from state-mandated test scores assessed prior to the TBI. The predictive utility of premorbid functioning, TBI severity, and age at injury were examined. Findings revealed that premorbid functions were significant predictors of reading and spelling achievement and adaptive functioning. Severity of injury was predictive of adaptive functioning. Implications of findings include program development, reintegration into school, and educating parents and teachers.     

Health,social comparisons,and psychological well-being: Their cross-time relationships

The purposes of this short-term longitudinal study were to investigate (a) stability and change in social comparisons across time; (b) the relationship between physical health and the use of social comparisons across time; (c) whether psychological well-being is best predicted by prior or concurrent social comparisons; and (d) the moderating effects of social comparisons. Community-dwelling elderly women (N=149) completed self-report instruments designed to measure social comparisons, psychological well-being, and physical health at two times, 2 years apart. Worse health at Time 1 predicted more frequent and less positive social comparisons at Time 2. Concurrent, but not prior, social comparisons contributed to a number of domains of psychological well-being. Further, the effects of prior health status on subsequent psychological functioning (Time 2) were moderated by social comparison processes. Women in poorest health who engaged in positive social comparisons showed less depression and anxiety and more positive relations with others at Time 2. Little support was found for the influence of prior psychological functioning on subsequent physical health.     

Executive Functioning and Delay Discounting of Four Different Outcomes in University Students

The study investigated a potential relationship between level of executive functioning and rates of delay discounting (i.e., the subjective decrease in the value of an outcome if its delivery is delayed). University students completed an executive-functioning questionnaire and then a delay-discounting task involving four different outcomes (money, cigarettes, dating partner, body image). Results showed that the overall measure of executive functioning was a significant predictor of rates of discounting of three of the four outcomes, and approached significance for the fourth outcome. Further, different subscales of executive functioning were significantly correlated with discounting of different outcomes. These results suggest that executive functioning plays a role in discounting of delayed outcomes and that procedures designed to affect either executive function or delay discounting might result in concomitant changes in the other measure.     

Evaluating Three Models of Intimate Relationships

The purpose of this study was to evaluate three models of intimate relationships: attachment, elementary pragmatic, and selfhood. These models were evaluated with three instruments respectively constructed to evaluate the validity of each model. One convenience group of functioning individuals and three experimental groups of inpatients and outpatients were administered the three instruments. All three instruments showed relatively high internal consistency and discriminated among the four groups. Significant correlations were found among the measure of attachment with measures of the pragmatic elementary and selfhood models. These correlations indicate that all three instruments were measuring similar aspects of intimate relationships. Clinical and preventive implications and applications of these models are briefly discussed.     

Attentional biases in dysphoria: An eye-tracking study of the allocation and disengagement of attention

This study looked for evidence of biases in the allocation and disengagement of attention in dysphoric individuals. Participants studied images for a recognition memory test while their eye fixations were tracked and recorded. Four image types were presented (depression-related, anxiety-related, positive, neutral) in each of two study conditions. For the simultaneous study condition, four images (one of each type) were presented simultaneously for 10 seconds, and the number of fixations and the total fixation time to each image was measured, similar to the procedure used by Eizenman et al. (2003) and Kellough, Beevers, Ellis, and Wells (2008). For the sequential study condition, four images (one of each type) were presented consecutively, each for 4 seconds; to measure disengagement of attention an endogenous cuing procedure was used (Posner, 1980). Dysphoric individuals spent significantly less time attending to positive images than non-dysphoric individuals, but there were no group differences in attention to depression-related images. There was also no evidence of a dysphoria-related bias in initial shifts of attention. With respect to the disengagement of attention, dysphoric individuals were slower to disengage their attention from depression-related images. The recognition memory data showed that dysphoric individuals had poorer memory for emotional images, but there was no evidence of a conventional mood-congruent memory bias. Differences in the attentional and memory biases observed in depressed and dysphoric individuals are discussed.     

Multidimensional sequence learning in patients with focal basal ganglia lesions

Parkinson's patients have been found to be impaired in learning movement sequences. In the current study, patients with unilateral basal ganglia lesions due to stroke were tested on a serial reaction time task in which responses were based on the spatial location of each stimulus. The spatial locations either followed a fixed sequence or were selected at random, with learning operationalized as the difference in reaction time between these two conditions. In addition, three response-to-stimulus intervals were used, and these either followed a fixed sequence or were randomized. Compared to control participants, the patients showed normal learning of the spatial and temporal sequences, as well as normal cross-dimensional learning. This was true for performance with either the contralesional or ipsilesional hand. Sequence learning was not correlated with maximum tapping rate, a simple measure of motor impairment. These results raise questions concerning the use of Parkinson's disease as a model for studying basal ganglia dysfunction.     

Effects of diazepam on approach, self-reported fear and psychophysiological responses in snake phobics

The effects of diazepam was assessed on a number of measures of phobic anxiety. Snake-phobic subjects underwent two sessions on either diazepam or placebo in a crossover design. In addition to a habituation series, a slide with the phobic object was displayed as well as a live snake which subjects were asked to approach. The anxiolytic effect of diazepam was manifest in only one measure of fear, namely self-rated fear at the point of closest approach when it also attained the highest level. The result would indicate that diazepam has an anxiolytic only on high levels of subjective anxiety. The magnitude of the phasic cardiac reaction to the slide was highly and positively correlated with self-rated fear of the slide.     

The Effect of Paired Muscle Stimulation on Preparation for Movement

Paired muscle stimulation is used clinically to facilitate the performance of motor tasks for individuals with motor dysfunction. However, the optimal temporal relationship between stimuli for enhancing movement remains unknown. We hypothesized that synchronous, muscle stimulation would increase the extent to which stimulated muscles are concurrently prepared for movement. We validated a measure of muscle-specific changes in corticomotor excitability prior to movement. We used this measure to examine the preparation of the first dorsal interosseous (FDI), abductor digiti minimi (ADM), abductor pollicis brevis (APB) muscles prior to voluntary muscle contractions before and after paired muscle stimulation at four interstimulus intervals (0, 5, 10, and 75 ms). Paired muscle stimulation increased premovement excitability in the stimulated FDI, but not in the ADM muscle. Interstimulus interval was not a significant factor in determining efficacy of the protocol. Paired stimulation, therefore, did not result in a functional association being formed between the stimulated muscles. Somatosensory potentials evoked by the muscle stimuli were small compared to those commonly elicited by stimulation of peripheral nerves, suggesting that the lack of functional association formation between muscles may be due to the small magnitude of afferent volleys from the stimulated muscles, particularly the ADM, reaching the cortex.     

Adolescent depressed mood and young adult functioning: A longitudinal study

The present study examined two aspects of depressed mood in adolescence: (1) stability across the adolescent years and (2) ability to predict functioning in young adulthood. Participants included 82 Caucasian individuals (46 females and 36 males) who were assessed one time per year for 4 consecutive years during adolescence (mean age at initial assessment = 13.5 years) and again during young adulthood (mean age = 19). The results indicated that depressed mood, as measured by the Children's Depression Inventory (CDI), remained relatively stable across at least 3 consecutive years of data collection during adolescence. In addition, adolescent CDI scores predicted young adult functioning in each of four areas: prosocial competence, self-esteem, externalizing problems, and internalizing problems.This study was supported, in part, by the William T. Grant Foundation and the University of Georgia's Institute for Behavioral Research.     

Temporal changes in visual and acoustic codes in a letter-matching task

The objective of the present experiment was to examine the nature of the coding process in a letter-matching task. Letter pairs that were either visually confusable or acoustically confusable or both visually and acoustically confusable were presented tachistoscopically with a variable interval between the first letter and the comparison letter. The dependent measure was RT for the “different” responses to the three types of confusable items which were each assessed at four interstimulus intervals ranging from 0 to 2 sec. The results indicate that a visual code appears to be emphasized for approximately 1 sec, after which an acoustic code seems to be dominant. There is also evidence which indicates that the acoustic code does not immediately replace the visual code and that both may coexist for a brief period of time.     

Extremely long-term persistence of the McCollough effect.

The question has been raised whether an associative mechanism is responsible for the persistence of the McCollough effect. Since current estimates of its rate of decay are derived from procedures in which subjects are repeatedly tested, it was hypothesized that the measured effects might be attenuated by the testing process. Accordingly, a comparison was made between repeated testing and time-elapse testing. A conventional group of 16 subjects had repeated testing at 0, 8, 24, 56, and 120 hr. after induction. Five other groups of 16 were run, each at one of the time delays, with no intervening tests; an additional measure was taken where appropriate at 120 hr. A magenta-green nulling procedure was used to assess the aftereffect. The repeated-test group showed a linear decrease of effect against the stated delays, reaching zero at 120 hr. In contrast, the time-elapse groups showed little decline up to 120 hr. Those groups retested at 120 hr. showed declines due to prior testing. When four more groups were subsequently tested at intervals up to 2,040 hr., the effect remained at better than half strength.     

Acute neuropsychological changes in hemodialysis and peritoneal dialysis patients.

This study examined the impact of different dialysis treatments on the neuropsychological (NP) functioning of 145 end-stage renal disease patients. Hemodialysis (HD) and peritoneal dialysis (PD) patients were administered an NP test battery and measures of mood on 2 consecutive days (pre- and 24 hr postdialysis). Biochemistry was assessed at each session. Results indicated significant improvements in NP functioning (attention, concentration, verbal and visual memory, and psychomotor speed) in HD patients 24 hr postdialysis. No such fluctuations were found in PD patients. Although biochemical changes were found in the HD patients at the same time points, these were not consistently related to the NP changes.     

Performance on a measure of category fluency in cognitively impaired elderly

ABSTRACT

Measures of verbal fluency are widely used in the assessment of cognitive functioning of the elderly. However, limited research has evaluated patterns (across specific timed intervals) of performance on tasks of language fluency in different forms of dementia. The current study investigated semantic fluency in 488 elderly individuals (249 with Alzheimer's dementia, 97 Vascular dementia, 97 Mild Cognitive Impairment and 45 cognitively intact) across 15-second intervals in an animal naming task using retrospective chart review. Normal controls produced significantly more exemplars and AD patients produced fewer animal names than the other groups. After the first 15- second time interval, the demented groups produced significantly fewer exemplars than the non-demented. At the end of 30 seconds it was possible to differentiate normal aging from MCI who no longer differed from the VaD group. Overall, it appears that the greatest and most clinically meaningful differences between the diagnostic groups were detected in the first three 15-second intervals. The present findings support the use of time intervals and total scores on tasks of verbal fluency in clinical settings and for research purposes.     

Performance on a measure of category fluency in cognitively impaired elderly

Measures of verbal fluency are widely used in the assessment of cognitive functioning of the elderly. However, limited research has evaluated patterns (across specific timed intervals) of performance on tasks of language fluency in different forms of dementia. The current study investigated semantic fluency in 488 elderly individuals (249 with Alzheimer's dementia, 97 Vascular dementia, 97 Mild Cognitive Impairment and 45 cognitively intact) across 15-second intervals in an animal naming task using retrospective chart review. Normal controls produced significantly more exemplars and AD patients produced fewer animal names than the other groups. After the first 15- second time interval, the demented groups produced significantly fewer exemplars than the non-demented. At the end of 30 seconds it was possible to differentiate normal aging from MCI who no longer differed from the VaD group. Overall, it appears that the greatest and most clinically meaningful differences between the diagnostic groups were detected in the first three 15-second intervals. The present findings support the use of time intervals and total scores on tasks of verbal fluency in clinical settings and for research purposes.     

Walking patterns change rapidly following asymmetrical lower extremity loading

The purpose of this study was to determine the amount of time needed for individuals to become well accommodated to asymmetrical changes in lower extremity inertial properties. Participants walked at 1.57 m s(-1) during four separate data collection sessions over the period of eight days. On days 1 and 7, participants completed a 60 min treadmill protocol consisting of both overground (motion and ground reaction force recorded) and treadmill (vertical ground reaction force recorded) walking. On day 1, 1.95 kg was attached distally to one shank prior to the start of the 60 min treadmill protocol and was not removed until day 7. On day 7, the load was permanently removed prior to the 60 min treadmill protocol. On days 2 and 8 participants completed three overground walking trials and walked on the treadmill for approximately 5 min. Stance and swing time asymmetries appeared immediately and were complete following initial assessment after the load was attached. Net joint moments at the knee and hip were altered and continued to change beyond initial exposure to the load, but these changes were complete within 5 min. Overall, results suggest that changes in walking symmetry due to asymmetrical lower extremity loading are immediate and complete within 5 min of exposure to the load. We recommend that at least 5 min of walking or other normal activity be used to accommodate individuals to novel asymmetrical lower extremity loading.     

The Temporal Dimension of Social Episodes: Position Effect in Time Judgments of Unfilled Intervals

An experiment was conducted to test the prediction, derived from field theory, that unfilled intervals at the core of a social episode (in-process) are perceived to last longer than unfilled intervals at the beginning (preprocess) or toward the end of the social episode (postprocess). As expected, individuals who judged in-process unfilled intervals overestimated their duration and judged them to last longer than individuals who judged preprocess or postprocess unfilled intervals. Moreover, this finding was observed in both immediate and delayed time duration estimates, and the overestimation effect for in-process intervals was stronger in the remote than in the immediate estimates. Relations to prior research on delays in services and implications for the management of services are discussed.     

Study of neuromotor reaction times under the influence of thyrotropin-releasing hormone

Neuromotor reaction times (simple, choice, and decision) were measured when Thyrotropin-releasing hormone (TRH) was administered intravenously to nine healthy men in a double-blind study. Measurements were made of simple reaction time, choice reaction time, and decision time for each subject at various intervals over a 54-hr. period. Given the observed inherent interaction of the drug with the long time used (54 hr.), most analyses were conducted across separate time epochs. Injected subjects showed inhibition in the normal improvement of simple reaction time (which occurs with practice), and they reduced the time required to make a decision. Choice reaction time, however, remained unchanged across the drug-nondrug experimental conditions.