Medicine and Health Sciences Commons^™

Effects Of Acute Ethyl Alcohol Consumption On A Psychophysical Measure Of Lateral Inhibition In Human Vision., Kevin D Johnston, Brian Timney

Brain and Mind Institute Researchers' Publications

Acute consumption of ethyl alcohol affects a variety of visual functions. However, there have been few systematic attempts to investigate the neural mechanisms underlying these effects. Here, we employed the Westheimer paradigm to investigate the hypothesis that alcohol reduces lateral inhibition within human "perceptive fields", the psychophysical analogue of physiological receptive fields. Westheimer functions obtained under alcohol and no-alcohol conditions at photopic, mesopic, and scotopic levels of adaptation showed changes consistent with an alcohol-induced decrease in lateral inhibition. We conclude that this decrease in lateral inhibition may be responsible for some of the changes in visual perception that result from …

Human Parietal "Reach Region" Primarily Encodes Intrinsic Visual Direction, Not Extrinsic Movement Direction, In A Visual Motor Dissociation Task., Juan Fernandez-Ruiz, Herbert C Goltz, Joseph F X Desouza, Tutis Vilis, J Douglas Crawford

Brain and Mind Institute Researchers' Publications

Posterior parietal cortex (PPC) participates in the planning of visuospatial behaviors, including reach movements, in gaze-centered coordinates. It is not known if these representations encode the visual goal in retinal coordinates, or the movement direction relative to gaze. Here, by dissociating the intrinsic retinal stimulus from the extrinsic direction of movement, we show that PPC employs a visual code. Using delayed pointing and event-related functional magnetic resonance imaging, we identified a cluster of PPC regions whose activity was topographically (contralaterally) related to the direction of the planned movement. We then switched the normal visual-motor spatial relationship by adapting subjects to …

Alcohol Slows Interhemispheric Transmission, Increases The Flash-Lag Effect, And Prolongs Masking: Evidence For A Slowing Of Neural Processing And Transmission., Sarah A Khan, Brian Timney

Brain and Mind Institute Researchers' Publications

While the alcohol literature is extensive, relatively little addresses the relationship between physiological effects and behavioural changes. Using the visual system as a model, we examined alcohol's influence on neural temporal processing as a potential means for alcohol's effects. We did this by using tasks that provided a measure of processing speed: Poffenberger paradigm, flash-lag, and backward masking. After moderate alcohol, participants showed longer interhemispheric transmission times, larger flash-lags, and prolonged masking. Our data are consistent with the view that alcohol slows neural processing, and provide support for a reduction in processing efficiency underlying alcohol-induced changes in temporal visual processing.

Representation Of Head-Centric Flow In The Human Motion Complex., Jeroen Goossens, Sean P Dukelow, Ravi S Menon, Tutis Vilis, Albert V Van Den Berg

Brain and Mind Institute Researchers' Publications

Recent neuroimaging studies have identified putative homologs of macaque middle temporal area (area MT) and medial superior temporal area (area MST) in humans. Little is known about the integration of visual and nonvisual signals in human motion areas compared with monkeys. Through extra-retinal signals, the brain can factor out the components of visual flow on the retina that are induced by eye-in-head and head-in-space rotations and achieve a representation of flow relative to the head (head-centric flow) or body (body-centric flow). Here, we used functional magnetic resonance imaging to test whether extra-retinal eye-movement signals modulate responses to visual flow in …

Gaze-Centered Updating Of Visual Space In Human Parietal Cortex., W Pieter Medendorp, Herbert C Goltz, Tutis Vilis, J Douglas Crawford

Brain and Mind Institute Researchers' Publications

Single-unit recordings have identified a region in the posterior parietal cortex (PPC) of the monkey that represents and updates visual space in a gaze-centered frame. Here, using event-related functional magnetic resonance imaging, we identified an analogous bilateral region in the human PPC that shows contralateral topography for memory-guided eye movements and arm movements. Furthermore, when eye movements reversed the remembered horizontal target location relative to the gaze fixation point, this PPC region exchanged activity across the two cortical lobules. This shows that the human PPC dynamically updates the spatial goals for action in a gaze-centered frame.

Effects Of Ethanol On Anti-Saccade Task Performance., Sarah A Khan, Kristen Ford, Brian Timney, Stefan Everling

Brain and Mind Institute Researchers' Publications

It has been shown that saccade-related neurons in the superior colliculus (SC) display an increased level of prestimulus activity and a higher stimulus-related burst in action potentials preceding direction errors in the anti-saccade task compared with correct anti-saccades. From this, it has been hypothesized that errors occur when the incoming visual signal in the SC passes a threshold and triggers a reflexive saccade. This hypothesis predicts that an attenuated visual signal will reduce the number of direction errors. Since ethanol has been shown to have a suppressive effect on cortical visual event-related potentials (ERPs), the purpose of the present study …

Eye Position Signal Modulates A Human Parietal Pointing Region During Memory-Guided Movements., J F Desouza, S P Dukelow, J S Gati, R S Menon, R A Andersen, T Vilis

Brain and Mind Institute Researchers' Publications

Using functional magnetic resonance imaging, we examined the signal in parietal regions that were selectively activated during delayed pointing to flashed visual targets and determined whether this signal was dependent on the fixation position of the eyes. Delayed pointing activated a bilateral parietal area in the intraparietal sulcus (rIPS), rostral/anterior to areas activated by saccades. During right-hand pointing to centrally located targets, the left rIPS region showed a significant increase in activation when the eye position was rightward compared with leftward. As expected, activation in motor cortex showed no modulation when only eye position changed. During pointing to retinotopically identical …

Intimate Partner Violence Among Men And Women In South Carolina, 1998, Ann L. Coker, Christina Derrick, Julia L. Lumpkin, Robert Oldendick, R H. Potter

CRVAW Faculty Journal Articles

Few studies provide population-based estimates of intimate partner violence (IPV) for men and women, especially at the state level. IPV may result in adverse health effects for victims and perpetrators (1-3). To estimate the lifetime incidence of IPV by type of violence (e.g., physical, sexual, and perceived emotional abuse) and to explore demographic correlates of reporting IPV among men and women, the South Carolina Department of Health and Environmental Control and the University of South Carolina conducted a population-based random-digit-dialed telephone survey of adults in the state. This report summarizes the results of the survey, which indicated that approximately 25% …

Secular Trends In The Incidence Of Anorexia Nervosa: Integrative Review Of Population-Based Studies, Kevin M. Gorey

Social Work Publications

OBJECTIVE AND METHOD: Aggregating across retrospective cohort samples, this integrative review synthesizes the findings of 12 cumulative incidence studies (45 hypotheses) on anorexia nervosa secular trends.

RESULTS: (1) The female/male anorexia incidence rate ratio was estimated to be 8.20, 18.46 versus 2.25 cases per 100,000 per year, p < .05; (2) female teenagers experienced anorexia at a rate fivefold greater than other women, 50.82 versus 10.37 incident cases per 100,000 per year, p < .001; (3) no secular trend or change in the incidence of anorexia was observed among teenagers, while a near threefold increase was observed over the past 40 years among women in their 20s and 30s, 6.28 (1950-1964) versus 17.70 (1980-1992) cases per 100,000 per year, p < .05; and (4) the two cohort characteristics of age, and the age by year interaction accounted for nearly two thirds of the variability among anorexia incidence estimates, R2 = .614, F(2,27) = 21.49, p < .001. After the two factors of age and the Age x Year interaction were accounted for, none of the other study characteristics, including study year(s), were found to be significantly associated with anorexia incidence, that is, a main effect of time was not observed.

DISCUSSION: The integrative evidence across the population-based epidemiologic studies covering 40 years in this field suggests strongly that, overall, the incidence of anorexia nervosa, particularly among those very young women at greatest risk of experiencing it, has not increased significantly. However, the risk does seem to have increased significantly among women in …