BACKGROUND: A variety of evidence suggests that frontostriatal dysfunction is involved in obsessive-compulsive disorder (OCD). This evidence includes both neuroimaging findings and results from studies using neuropsychological assessments. Previous studies have documented nonverbal memory deficits in individuals with OCD, whereas verbal learning and memory were less affected. METHODS: The present study examined both verbal and nonverbal memory in a sample of 17 untreated outpatients with OCD. We also evaluated the effects of encoding strategies which are believed to be mediated by frontostriatal system functioning. RESULTS: OCD patients were significantly impaired in both verbal and nonverbal memory performance. This deficit was correlated with impairments in organizational and semantic clustering strategies at the time of encoding. CONCLUSIONS: Deficits in organizational strategies are consistent with frontostriatal dysfunction models in OCD.

Adult↗

PubMedDate not supplied

Information processing and interhemispheric transfer in left- and right-handed adults.

Two experiments are reported using simple reaction time (SRT) and visual evoked potentials (VEP) to measure information processing and interhemispheric transfer time (IHTT) in left- and right-handed subjects. Study 1 used an SRT procedure to estimate IHTT in 30 left-handed and 30 right-handed subjects. No differences in IHTT were indicated, but left- and right-handers were found to have opposite visual field advantages on the SRT task, indicating possible hemispheric differences in visual information processing. Study 2 was designed to test hypotheses generated in Study 1, using a VEP procedure to provide additional measures of visual information processing and IHTT. VEPs were collected during an SRT procedure in 20 left-handers and 20 right-handers, and SRT response hand and visual field advantages were replicated among right-handers only. Left-handers in Study 2 demonstrated no significant response hand or visual field effects on SRT. Analysis of the VEP N160 latency data indicated no significant laterality, hemisphere, or visual field effects, except for a robust hemisphere by visual field interaction, which reflects IHTT. The significant SRT left visual field advantage in right-handers was not reflected by hemispheric asymmetries in VEP N160 latency. It is concluded that left-handers and right-handers do not differ in IHTT in two functional regions of the corpus callosum, nor do they vary in simple visual receptive processing. Results are more consistent with variability in SRT resulting from differences in complex heteromodal processes beyond the striate and extrastriate visual cortex.

Adult↗

PubMedDate not supplied

Tourette's disorder and related problems: a review and update.

Tourette's disorder is a complex, multifaceted condition of neurological origin with psychiatric symptomatology characterized by multiple motor and vocal tics. It begins during childhood and has a waxing and waning course. Coexisting obsessive-compulsive symptoms, attentional problems, and other behavioral features are common. Pathophysiology involves dysfunction in basal ganglia and related corticothalamic circuits. Many patients who present in clinical settings have mild to moderate symptoms and require only education, monitoring, and long-term follow-up. Those with more-severe symptoms require treatment, typically including both pharmacotherapy and nonmedication approaches. In addition to traditional neuroleptic treatment, a variety of agents such as clonidine, serotonin-reuptake inhibitors, and tricyclic antidepressants can be used. Further investigation is needed in a variety of areas, including longitudinal follow-up studies of children, adolescents, and adults with Tourette's disorder; systematic investigation of psychiatric comorbidity and the heterogeneity of the disorder; clarification of the phenomenological similarities and differences between Tourette's disorder and obsessive-compulsive disorder; and neuroimaging and neuropsychological studies of Tourette's disorder and related problems.

Antidepressive Agents, Tricyclic↗

PubMedDate not supplied

Pulsed plasma discharge polymer coatings.

The authors studied a pulsed radiofrequency glow discharge polymer film deposition method (pRFGD) on polyethylene terephthalate (PET), silicon (Si), and potassium chloride (KCl) surfaces, with the aim of better controlling film uniformity and homogeneity. A pulse generator was used to control a conventional 13.56 MHz RFGD circuit to provide plasma on and off times throughout a wide range of duty cycles. Starting monomers included fluorocarbon monomers (C8F16O and C3F6O) and more conventional unsaturated monomers [acrylonitrile (C3H3N) and vinyl trimethyl silane (C5H12Si)]. With each of these monomers progressive, large scale changes in the molecular structure of the plasma deposited films were noted with systematic variations in the RF duty cycle. Film characterizations were performed using electron spectroscopy for chemical analysis (ESCA) and fourier transform infrared (FTIR) analysis. In the case of fluorocarbon (FC) films, systematically decreasing plasma on time at a constant off time resulted in enhanced CF2 and CF3 content compared with that seen with the less highly fluorinated groups. There was virtually no oxygen atom incorporation in the FC films obtained from the oxygen containing monomers. Overall, a dramatic decrease in cross-linking of the FC polymer films was observed with decreasing RF duty cycles. A highly ordered Teflon-like structure was obtained for the lowest duty cycles. In the silane experiments, a systematic variation in the ratio of Si-H/Si-CH3 groups was observed, with this ratio increasing as the RF duty cycle decreased. Experiments with C3H3N revealed an increasing surface density of -CN groups with decreasing RF duty cycle.(ABSTRACT TRUNCATED AT 250 WORDS)

Biocompatible Materials↗