Biomedical subjects

N I Barber

Publications and source records attributed to N I Barber.

8 recordsLinked to original sources

PubMed1996

Objective measurement of hyperactivity and attentional problems in ADHD.

OBJECTIVE: To precisely describe movement abnormalities in seated children with attention-deficit hyperactivity disorder (ADHD) while they were engaged in a continuous performance task (CPT). METHOD: Diagnoses were made by using structured interviews (Schedule for Affective Disorders and Schizophrenia for School-Age Children-Epidemiologic Version) and DSM-IV criteria. Movement patterns of 18 boys with ADHD (9.3 +/- 2.4 years) and 11 normal controls (8.6 +/- 1.8 years) were recorded using an infrared motion analysis system that tracked the position of four markers 50 times per second to a resolution of 0.04 mm. RESULTS: Boys with ADHD moved their head 2.3 times more often than normal children (p < .002), moved 3.4 times as far (p < .01), covered a 3.8-fold greater area (p < .001), and had a more linear and less complex movement pattern (p < .00004). They responded more slowly and with greater variability on the CPT. Complexity of head movement and variability in response latency significantly correlated with teacher ratings. A predefined composite of movement and attention discriminated 16 of 18 patients from 11 of 11 controls. CONCLUSIONS: The relative inability of boys with ADHD to sit still can be objectively verified, and "fidgeting" appears to consist of more frequent, larger amplitude, whole body movements.

Attention Deficit Disorder with Hyperactivity↗

PubMed1993

Developmental differences in acute nigrostriatal and mesocorticolimbic system response to haloperidol.

Dose-dependent effects of haloperidol (2.66 nmol/kg to 79.8 mmol/kg, IP) on levels of dopamine, homovanillic acid (HVA) and dihydroxyphenylacetic acid (DOPAC) were assessed in the corpus striatum, nucleus accumbens, and medial prefrontal cortex (PFCTX) of 18-, 30-, and 110-day-old rats. Eighteen-day-old rats were 35% and 63% more sensitive than adults to the effects of haloperidol on striatal and accumbens turnover and had steeper dose-response curves. The dose-response function in the PFCTX was similar to striatum at 18 days, but became shallower and nonsigmoidal with age. Maximally effective doses of haloperidol produced, at all ages, a comparable percent rise in DOPAC levels in all regions. With maturation, the percent rise in HVA progressively outstripped DOPAC response in nucleus accumbens and striatum. Overall, prominent developmental differences emerged in these regions in their sensitivity and response to haloperidol, which are consistent with previously reported differences in behavioral sensitivity.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1990

COSIFIT: an interactive program for simultaneous multioscillator cosinor analysis of time-series data.

A BASIC program for the Macintosh family of computers has been developed that provides an iterative nonlinear least-squares analysis of biological rhythm data using Marquardt's modification of the Gauss-Newton algorithm. A cosinor model is used, and multiple cosine functions can be fit simultaneously to any equi- or unequispaced time-series data. The program computes optimal frequency, mesor, amplitude, and phase, with standard errors of measurement and both parametric and nonparametric estimates of goodness-of-fit. Multiple time-series can be analyzed simultaneously, allowing one to test for shared characteristics between series. Statistical differences between parameter values of select curves are ascertained by ANOVA. The program is interactive and designed to be user-friendly for the scientist or clinician.

Adult↗

PubMed1989

Effects of selective monoaminergic reuptake blockade on activity rhythms in developing rats.

Developing rats display prominent ultradian rhythms of locomotor activity when separated from the litter. A pharmacological analysis was undertaken to provide preliminary data on the role of monoaminergic neurotransmitter systems in the modulation or manifestation of this fundamental biological rhythm. Twenty-four hour activity profiles were monitored in 15-day-old rats, tested in darkness, after intraperitoneal treatment with desipramine (DMI), zimelidine (ZMI), or GBR-13069 (GBR), selective uptake inhibitors of norepinephrine, serotonin, and dopamine, respectively. Time series data were analyzed by low-resolution variance spectral analysis. DMI significantly diminished ultradian (greater than 1 cycle per day; cpd) rhythmicity, and enhanced the circadian rhythm. Equimolar doses of ZMI had little effect on the ultradian band (7-15 cpd), but slightly reduced the circadian peak. The effects of acute GBR administration were complex, as this agent produced prominent effects on basal activity. In a second study these agents were administered continuously over a 5-day period, using subcutaneously implanted Alzet osmotic minipumps, to avoid the confounding effects of acute administration. Continuously-infused DMI virtually eliminated characteristic ultradian rhythms in the 9-15 cpd bandwidth. ZIM diminished ultradian oscillations only in the 14-15 cpd range, and GBR-12909 had little effect on ultradian rhythms throughout the usually prominent 7-16 cpd domain. All three reuptake inhibitors increased the prominence of slow ultradian rhythms with frequencies of 3-4 cpd. Continuous reuptake blockade had no significant effects on circadian amplitude or phase, as determined by cosinor analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Increased activity and phase delay in circadian motility rhythms in geriatric depression. Preliminary observations.

Locomotor activity levels and rhythms of eight hospitalized geriatric unipolar depressed patients (DSM-III criteria) were compared with those of eight healthy elderly controls in a similar environment. Activity was measured using a wrist-worn electronic activity monitor with solid-state memory. Depressed patients had a 29% higher mean total 24-hour activity level, with no change in circadian amplitude or frequency. Daily peak activity (acrophase) averaged 2.05 hours later in depressed patients, with no overlap between the groups. The degree of phase delay correlated significantly with the 4 PM postdexamethasone serum cortisol level. These tentative findings suggest that elderly unipolar depressed patients have prominent chronobiological disturbances in the modulation of activity levels and possibly other physiological processes. These differ strikingly from reported disturbances in younger or bipolar depressed patients.

Adult↗

PubMed1988

Amphetamine accelerates and attenuates ultradian activity rhythms in preweanling rats.

Developing rats, studied in environmental isolation, display prominent fluctuations in locomotor activity with a periodicity of about 1-3 hr. This ultradian rhythmic pattern is most marked at 2 weeks of age, and appears to be endogenously mediated. (+)Amphetamine (1 mg/kg) was administered to 2 week old rat pups, and their locomotor activity levels were recorded continuously and stored in 5 min intervals using a sensitive computer-interfaced vibrational activity monitor. Activity was recorded for 12 hr after treatment and resulting time-series data were analyzed by harmonic spectral techniques. During the first 6 hr of testing, amphetamine induced a prominent low frequency perturbation in baseline activity levels corresponding to the expected period of acute drug action. During this time, normally prominent ultradian activity rhythms in the range of 8-12 cycles per day (cpd) were diminished in amplitude, even following low frequency smoothing to remove the changes in baseline. Correspondingly, there was also an increase in ultradian rhythm amplitude in amphetamine-treated pups at higher frequencies (32-40 cpd). During the final 6 hr of testing there was a marked suppression of typical ultradian rhythms in amphetamine-treated pups but not in controls. These results suggest that amphetamine treatment both accelerates and attenuates ultradian activity rhythms in developing rats during the acute period of drug action, and produces a prominent diminution in these rhythms during subsequent rebound and recovery periods.

Activity Cycles↗

PubMed1986

Altered locomotor activity in neuropsychiatric patients.

Movement was monitored continuously for 24-48 hours in representative neuropsychiatric patients, using a wrist-worn portable piezoelectric activity monitor with solid-state memory. Striking differences were observed in both circadian and more rapid (ultradian) rhythms between these patients and normal controls of a similar age. We found a loss of circadian rhythm following stroke, and a marked 4-hour activity rhythm in patients with dementia and brain tumor. These results may provide insights into the neural substrate of activity rhythms and may lead to better care of neuropsychiatric patients.

Affective Disorders, Psychotic↗

PubMed1986

Selective depletion of cerebral norepinephrine with 6-hydroxydopamine and GBR-12909 in neonatal rat.

Specific and extensive neonatal depletions of norepinephrine were produced in 3-day-old rats by combined administration of GBR-12909 (40 mg/kg, i.p.), a specific inhibitor of dopamine uptake, and the neurotoxin 6-hydroxydopamine (125 micrograms, i.c.). Norepinephrine concentrations in prefrontal cortex and hippocampus were reduced by more than 95%, and hypothalamic concentrations were reduced by 57%. Concentrations of dopamine, serotonin, and their respective metabolites were not affected in these regions or in the striatum.

3,4-Dihydroxyphenylacetic Acid↗