Biomedical subjects

John J Chelonis

Publications and source records attributed to John J Chelonis.

8 recordsLinked to original sources

PubMed2004

Effect of methylphenidate on time perception in children with attention-deficit/hyperactivity disorder.

The effects of methylphenidate (MPH) on performance of a time-production task were studied in 17 children with attention-deficit/hyperactivity disorder who participated in 1 test session on and 1 off MPH. Participants held a response lever down for at least 10 but no longer than 14 s. Administration of MPH had no effect on the number of correct responses or on the mean duration of lever holds. MPH administration significantly decreased timing response variability, increased holds of 10- to 11-s duration, and decreased lever holds of extremely short durations. These results indicate that administration of MPH resulted in more precise timing performance without changing the mean duration of lever holds, suggesting an enhancement in working memory.

Adolescent↗

PubMed2004

Stimulation of the semicircular canals via the rotary chair as a means to test pharmacologic countermeasures for space motion sickness.

OBJECTIVE: Space motion sickness is currently treated pharmacologically with the empiric use of the H1 antihistamine promethazine, but use of this intervention is limited by the side effect of significant sedation. This creates a dilemma, as full cognition is particularly important during the same conditions likely to exacerbate the symptoms of space motion sickness. Using overstimulation of the semicircular canals with a rotary chair as a paradigm for space motion sickness, we evaluated four medications, commonly used for the treatment of terrestrial motion sickness and vertigo, for their efficacy in alleviating the simulated symptoms of space motion sickness. STUDY DESIGN: Randomized, prospective, double-blind study. SETTING: Tertiary referral center. PATIENTS: Healthy male and female volunteers, 18 years of age or older, without history of neurologic or psychiatric disorders, and with no known allergies or any previous adverse reactions to the drugs used. INTERVENTIONS: Lorazepam 1 mg, meclizine 25 mg, promethazine 25 mg, scopolamine 0.4 mg, or placebo. MAIN OUTCOME MEASURE: The ability of each treatment to control the nausea and vomiting associated with our paradigm for space motion sickness was evaluated by measuring time of rotation pre- and posttreatment and time of symptom onset pre-and posttreatment. RESULTS: Only scopolamine effected a mean change in duration of rotation that reached statistical significance when compared with placebo (p <0.008), with a greater than 40% increase in rotation time. Results with promethazine were not statistically significant. CONCLUSION: Results showed a rank order of efficacy of scopolamine > promethazine > placebo > meclizine > lorazepam. Scopolamine significantly increased rotation time, but none of the treatments resulted in a significant delay to onset of symptoms.

Adolescent↗

PubMed2002

Stimulant medication improves recognition memory in children diagnosed with attention-deficit/hyperactivity disorder.

The effect of stimulant medication on recognition memory was examined in 18 children with attention-deficit/hyperactivity disorder (ADHD). Recognition memory was assessed using a delayed matching-to-sample task at 6 delays ranging from 1 to 32 s. Each child was tested on 2 separate occasions, once 60 to 90 min after taking stimulant medication and the other at least 18 hr after taking medication. Children performed significantly better on medication than off. Stimulant administration significantly increased accuracy and the number of nickel reinforcers earned. Decreases in observing response latency and correct choice response latency occurred after taking stimulant medication. The results indicate that stimulant medication improved recognition memory for children with ADHD.

Attention Deficit Disorder with Hyperactivity↗

PubMedDate not supplied

Developmental aspects of timing behavior in children.

This research examined the association of age, sex, and intelligence on the performance of a time production (temporal response differentiation, TRD) task. Variations of this task have been used extensively with both animals and humans to study factors that affect aspects of timing ability. The participants in this study (720 children, ages 5 to 13 years) were required to hold down a response lever for at least 10 s, but no more than 14 s, to receive a nickel. Older children made more correct lever holds and exhibited less variability in the duration of their lever holds than did the younger children. Boys and girls performed similarly on this task, whereas children with higher IQs made more correct lever holds. Young children with below average IQs exhibited increased variability in lever hold duration compared with young children with average and above average IQs. The results of this study illustrate that both age and intelligence influence timing ability. The use of this timing task in children, which also has been widely used in animal models, provides unique opportunities for interspecies comparisons.

Age Factors↗

PubMedDate not supplied

Effects of drug countermeasures for space motion sickness on working memory in humans.

Space motion sickness (SMS) is a problem during the first 72 h of space flight and during transitions from different gravity environments. There currently are no effective drug countermeasures for SMS that also accommodate the retention of optimal cognitive function. This creates a dilemma for astronauts because cognitive skills are particularly important during gravity transitions (e.g., take-off and landing). To quantify the cognitive side effects of potential drug countermeasures, an automated delayed matching-to-sample (DMTS) procedure was used to assess visual working memory before and after drug countermeasures (meclizine 25 mg, scopolamine 0.4 mg, promethazine 25 mg, or lorazepam 1 mg, given orally approximately 45 min prior to testing) and/or the induction of SMS by vestibular stimulation in a rotary chair (spinning). Sixty-seven normal healthy volunteers (mean age, in years, 26.6+/-4.8 S.D.; 24 females and 43 males) each participated in two test sessions, one 'off' drug and one 'on' drug. Spinning by itself significantly decreased task accuracy (Acc) and choice response speed, especially at longer recall delays. Meclizine alone had no effect on Acc or speed with or without spinning. Scopolamine alone decreased Acc, and with spinning, slowed speed. Promethazine alone had no adverse effect, but combined with spinning, decreased Acc and speed. Lorazepam alone decreased speed, and with spinning, decreased Acc. The data suggest that, at clinically useful doses, the rank order of the drugs with the best cognitive profiles is meclizine>scopolamine>promethazine>lorazepam.

Adult↗

PubMedDate not supplied

The effects of prenatal cocaine exposure on reversal learning using a simple visual discrimination task in rhesus monkeys.

The purpose of this research was to determine if adult animals that were exposed to cocaine prenatally would be able to adapt to changes in the rules of reinforcement for a simple discrimination task. Treatment groups included 0.0, 1.0, and 3.0 mg cocaine/kg/day and an escalating-dose group that began treatment at 3.0 mg cocaine/kg/day, after which the dose was increased by 0.5 mg cocaine/kg/day every 2 weeks throughout the pregnancy. All animals performed a color and position discrimination task for food reinforcers for approximately 6 years before the present study. For this task, subjects were presented with colored stimuli that determined the correctness of subsequent position choices: left for red or yellow and right for blue or green. At 7 years of age, the rules for obtaining reinforcement were reversed. Animals exposed to all doses of cocaine showed impaired reversal performance. Further, animals exposed to the escalating doses of cocaine continued to show this impairment for over 285 sessions (about 21/2 years). The number of sessions required by subjects to master these contingency changes indicated that, using a task with which they have an extensive history, cocaine-exposed animals have greater difficulty in adapting to important changes in their environment.

Age Factors↗

PubMedDate not supplied

Time perception differences in children with and without ADHD.

INTRODUCTION: The purpose of this study was to compare time perception in children with and without attention deficit hyperactivity disorder (ADHD) with use of a time reproduction task. METHODS: The sample consisted of 60 children (30 with ADHD and 30 without ADHD) ranging in age from 9 to 12 years. Children were asked to watch a light, verbally estimate how long the light was illuminated, and hold a lever in a depressed position for the same amount of time they thought the light was on. Each child participated in 16 trials of 3, 6, 12, or 24 seconds for a total of 64 trials. RESULTS: Children with ADHD had significantly greater absolute discrepancy scores on the time reproduction task (F(1,58) = 10.878; P <.01) than did children in the control group. In addition, children with ADHD had greater increases in absolute discrepancy scores across time intervals (F(3,174) = 82.08; P <.01). DISCUSSION: Poor time perception affects the performance of social skills and other adaptive behaviors such as health consciousness and concerns for safety. The findings of this study indicate that children with ADHD have impaired time perception compared with children who do not have ADHD.

Adaptation, Psychological↗

PubMedDate not supplied

The relationship between behavioral inhibition and time perception in children.

PURPOSE: To test one component of Barkley's (1997) model of executive functions by examining the relationship between behavioral inhibition and time perception in children. METHOD: Correlation analysis was used to determine the relationships between measures of behavioral inhibition and time perception for the entire sample, and for boys (n = 34) and girls (n = 26) separately. FINDINGS: For both parent and child measures, behavioral inhibition and time perception scores were correlated for the total group and for girls. Child measure of behavioral inhibition and time perception were not correlated for boys. CONCLUSIONS: The findings of this study support Barkley's theory and indicate a relationship between poor behavioral inhibition and poor time perception in children.

Attention Deficit Disorder with Hyperactivity↗