Evidence for an eye-centered spherical representation of the visuomotor map.
(1/2056)
During visually guided movement, visual coordinates of target location must be transformed into coordinates appropriate for movement. To investigate the representation of this visuomotor coordinate transformation, we examined changes in pointing behavior induced by a local visuomotor remapping. The visual feedback of finger position was limited to one location within the workspace, at which a discrepancy was introduced between the actual and visually perceived finger position. This remapping induced a change in pointing that extended over the entire workspace and was best captured by a spherical coordinate system centered near the eyes. (+info)
Disrupted temporal lobe connections in semantic dementia.
(2/2056)
Semantic dementia refers to the variant of frontotemporal dementia in which there is progressive semantic deterioration and anomia in the face of relative preservation of other language and cognitive functions. Structural imaging and SPECT studies of such patients have suggested that the site of damage, and by inference the region critical to semantic processing, is the anterolateral temporal lobe, especially on the left. Recent functional imaging studies of normal participants have revealed a network of areas involved in semantic tasks. The present study used PET to examine the consequences of focal damage to the anterolateral temporal cortex for the operation of this semantic network. We measured PET activation associated with a semantic decision task relative to a visual decision task in four patients with semantic dementia compared with six age-matched normal controls. Normals activated a network of regions consistent with previous studies. The patients activated some areas consistently with the normals, including some regions of significant atrophy, but showed substantially reduced activity particularly in the left posterior inferior temporal gyrus (iTG) (Brodmann area 37/19). Voxel-based morphometry, used to identify the regions of structural deficit, revealed significant anterolateral temporal atrophy (especially on the left), but no significant structural damage to the posterior inferior temporal lobe. Other evidence suggests that the left posterior iTG is critically involved in lexical-phonological retrieval: the lack of activation here is consistent with the observation that these patients are all anomic. We conclude that changes in activity in regions distant from the patients' structural damage support the argument that their prominent anomia is due to disrupted temporal lobe connections. (+info)
Behavioral and physiological effects of remifentanil and alfentanil in healthy volunteers.
(3/2056)
BACKGROUND: The subjective and psychomotor effects of remifentanil have not been evaluated. Accordingly, the authors used mood inventories and psychomotor tests to characterize the effects of remifentanil in healthy, non-drug-abusing volunteers. Alfentanil was used as a comparator drug. METHODS: Ten healthy volunteers were enrolled in a randomized, double-blinded, placebo-controlled, crossover trial in which they received an infusion of saline, remifentanil, or alfentanil for 120 min. The age- and weight-adjusted infusions (determined with STANPUMP, a computer modeling software package) were given to achieve three predicted constant plasma levels for 40 min each of remifentanil (0.75, 1.5, and 3 ng/ml) and alfentanil (16, 32, and 64 ng/ml). Mood forms and psychomotor tests were completed, and miosis was assessed, during and after the infusions. In addition, analgesia was tested at each dose level using a cold-pressor test. RESULTS: Remifentanil had prototypic micro-like opioid subjective effects, impaired psychomotor performance, and produced analgesia. Alfentanil at the dose range tested had more mild effects on these measures, and the analgesia data indicated that a 40:1 potency ratio, rather than the 20:1 ratio we used, may exist between remifentanil and alfentanil. A psychomotor test administered 60 min after the remifentanil infusion was discontinued showed that the volunteers were still impaired, although they reported feeling no drug effects. CONCLUSIONS: The notion that the pharmacodynamic effects of remifentanil are extremely short-lived after the drug is no longer administered must be questioned given our findings that psychomotor effects were still apparent 1 h after the infusion was discontinued. (+info)
Postoperative behavioral outcomes in children: effects of sedative premedication.
(4/2056)
BACKGROUND: Although multiple studies document the effect of sedative premedication on preoperative anxiety in children, there is a paucity of data regarding its effect on postoperative behavioral outcomes. METHODS: After screening for recent stressful life events, children undergoing anesthesia and surgery were assigned randomly to receive either 0.5 mg/kg midazolam in 15 mg/kg acetaminophen orally (n = 43) or 15 mg/kg acetaminophen orally (n = 43). Using validated measures of anxiety, children were evaluated before and after administration of the intervention and during induction of anesthesia. On postoperative days 1, 2, 3, 7, and 14, the behavioral recovery of the children was assessed using the Post Hospitalization Behavior Questionnaire. RESULTS: The intervention group demonstrated significantly lower anxiety levels compared with the placebo group on separation to the operating room and during induction of anesthesia (F[1,77] = 3.95, P = 0.041). Using a multivariate logistic regression model, the authors found that the presence or absence of postoperative behavioral changes was dependent on the group assignment (R = 0.18, P = 0.0001) and days after operation (R = -0.20, P = 0.0001). Post hoc analysis demonstrated that during postoperative days 1-7, a significantly smaller number of children in the midazolam group manifested negative behavioral changes. At week 2 postoperatively, however, there were no significant differences between the midazolam and placebo groups. CONCLUSIONS: Children who are premedicated with midazolam before surgery have fewer negative behavioral changes during the first postoperative week. (+info)
Genomic imprinting: implications for human disease.
(5/2056)
Genomic imprinting refers to an epigenetic marking of genes that results in monoallelic expression. This parent-of-origin dependent phenomenon is a notable exception to the laws of Mendelian genetics. Imprinted genes are intricately involved in fetal and behavioral development. Consequently, abnormal expression of these genes results in numerous human genetic disorders including carcinogenesis. This paper reviews genomic imprinting and its role in human disease. Additional information about imprinted genes can be found on the Genomic Imprinting Website at http://www.geneimprint.com. (+info)
Caregiver behaviors and resources influence child height-for-age in rural Chad.
(6/2056)
The purpose of this study was to identify caregiver characteristics that influence child nutritional status in rural Chad, when controlling for socioeconomic factors. Variables were classified according to the categories of a UNICEF model of care: caregiving behaviors, household food security, food and economic resources and resources for care and health resources. Sixty-four households with 98 children from ages 12 to 71 mo were part of this study. Caregivers were interviewed to collect information on number of pregnancies, child feeding and health practices, influence on decisions regarding child health and feeding, overall satisfaction with life, social support, workload, income, use of income, and household food expenditures and consumption. Household heads were questioned about household food production and other economic resources. Caregiver and household variables were classified as two sets of variables, and separate regression models were run for each of the two sets. Significant predictors of height-for-age were then combined in the same regression model. Caregiver influence on child-feeding decisions, level of satisfaction with life, willingness to seek advice during child illnesses, and the number of individuals available to assist with domestic tasks were the caregiver factors associated with children's height-for-age. Socioeconomic factors associated with children's height-for-age were the amount of harvested cereals, the sources of household income and the household being monogamous. When the caregiver and household socioeconomic factors were combined in the same model, they explained 54% of the variance in children's height-for-age, and their regression coefficients did not change or only slightly increased, except for caregiver's propensity to seek advice during child illnesses, which was no longer significant. These results indicate that caregiver characteristics influence children's nutritional status, even while controlling for the socioeconomic status of the household. (+info)
Saccadic performance characteristics and the behavioural neurology of Tourette's syndrome.
(7/2056)
OBJECTIVE: To better understand the neuropathological correlates of Tourette's syndrome (TS), measures of saccadic eye movement performance were examined among patients with TS. METHODS: A case-control design was used. Twenty one patients with DSM-IV TS (mean age 40.6 years (SD 11.0); 38% female) mainly recruited from UCSD Psychiatry Services, and a community based sample of 21 normal subjects (mean age 34.6 years (SD 13.4); 43% women) participated in this study. Participants were administered ocular motor tasks assessing visual fixation, and the generation of prosaccades, predictive saccades, and antisaccades. Saccadic reaction time, amplitude, duration, and mean and peak velocity were computed. Intrusive saccades during visual fixation and the proportion of correct antisaccade responses were also evaluated. RESULTS: The groups had similar visual fixation performance. Whereas patients with TS generated prosaccades with normal reaction times and amplitudes, their saccade durations were shorter and their mean velocities were higher than in normal subjects. During a prosaccade gap task, patients with TS exhibited an increased proportion of anticipatory saccades (RTs<90). The proportion of "express" saccades (90+info)
Changes in behavioural characteristics of elderly populations of local authority homes and long-stay hospital wards, 1976-7.
(8/2056)
Behavioural characteristics of the elderly populations of seven local authority residential homes and three long-stay hospital wards were assessed in 1976 and 1977 with the Crichton Royal behavioural rating scale. In 1977 the levels of behavioural problems had increased in the residential homes, but declined in the hospital wards. Differences between the homes had decreased as the overall level of problems increased. The findings suggested that the additional burden of caring for increasing numbers of severely disabled elderly people was affecting the balance of institutional care, and a radical reappraisal of present patterns of care may be necessary to meet their future needs. (+info)