Visuomotor Task Performance Research Articles

Cognitive performance is associated with glucose regulation in healthy elderly persons and can be enhanced with glucose and dietary carbohydrates

A glucose drink has been shown to improve memory in persons with poor glucose regulation and poor cognition. The objective of this study was to determine 1) whether an association between cognition and glucose regulation is apparent in healthy seniors and 2) the effects of dietary carbohydrates on cognition. After an overnight fast, 10 men and 10 women (aged 60-82 y) consumed 50 g carbohydrate as glucose, potatoes, or barley or a placebo on 4 separate mornings. Cognitive tests were administered 15, 60, and 105 min after ingestion of the carbohydrate. Plasma glucose and serum insulin were measured. In a multiple regression analysis, poor baseline (placebo) verbal declarative memory (immediate and 20-min delayed paragraph recall and word list recall) and visuomotor task performance were predicted by poor beta cell function, high incremental area under the glucose curve, low insulin resistance, and low body mass index. The difference in plasma glucose after food consumption [glucose > potatoes > barley > placebo (P: < 0.03)] did not predict performance. Although overall performance did not differ with consumption of the different test foods, baseline score and beta cell function correlated with improvements in immediate and delayed paragraph recall for all 3 carbohydrates (compared with placebo); the poorer the baseline memory or beta cell function, the greater the improvement (correlation between beta cell function and improvement in delayed paragraph recall: r > -0.50, P: < 0.03). Poor beta cell function correlated with improvement for all carbohydrates in visuomotor task performance but not on an attention task. Glucose regulation was associated with cognitive performance in elderly subjects with normal glucose tolerance. Dietary carbohydrates (potatoes and barley) enhanced cognition in subjects with poor memories or beta cell function independently of plasma glucose.

Neurophysiological and behavioral indices of time pressure effects on visuomotor task performance

Using a video game format, this study examined the effects of time pressure (TP) on behavioral and electrocortical indices. The behavioral results were consistent with previous time pressure research in that TP reduced time to perform a task and increases behavioral errors. In addition, electroencephalogram (EEG) measures showed distinctive patterns associated with TP in the theta, mu, and gamma bands along the midline. Site specific changes in the success vs. failure trials were also seen in midline theta at Fz, gamma at Fz, and mu at Cz. Right parietal alpha also differentiated TP and success vs. failure trials. In specific TP (1) increased frontal midline theta activity and (2) increased gamma at midline (frontal, central, and partietal) and in right frontal areas. The results of these findings are discussed in terms of the formation of specific neurocognitive strategies as evidenced by the topographic distribution of task-related modulation of the EEG within certain frequency bands. It is suggested that the effect of TP on visuomotor performance is mediated by adopting either task-relevant or task-irrelevant neurocognitive strategies as evidenced by successful or failed trials, respectively. Whether these strategies are formulated prior to performance or appear spontaneously during task performance remains unclear and is awaiting further experimentation.

Evaluation of two new soft contact lenses for correction of presbyopia: the Focus Progressives multifocal and the Acuvue Bifocal

The clinical performance of Focus Progressives multifocal contact lenses and Acuvue Bifocal contact lenses was evaluated in a group of 42 presbyopes, with equal numbers of individuals having low, medium, and high spectacle add requirements. Following visual performance assessment with an optimal sphero-cylinder spectacle refractive correction, each individual wore each of the two types of contact lenses in successive random order. Each type of lens was used in a daily-wear mode for a period of 7 to 12 days, with follow-up and/or refitting visits occurring after 2 to 5 days, and again after 4 to 7 days of attempted wear. Testing for all three forms of refractive correction encompassed Snellen acuities at distance and near, Bailey-Lovie acuities under high and/or low ambient illumination conditions at near, intermediate, and far viewing distances, stereoacuity, a timed visuomotor task (needle threading), apparent glare/flare, and the nearwork range of subjectively clear binocular vision. The contact lenses also were evaluated for handling, comfort, distance and near ghosting, subjective visual quality, acceptability for common tasks (e.g., using a phone directory), and personal preferences. As might be expected, distance and near acuity, stereoacuity, and visuomotor task performance were somewhat better with sphero-cylinder spectacle correction than with either of the two types of contact lenses. However, several performance differences between the multifocal and bifocal lenses were noted. The Focus Progressives lenses provided significantly better distance acuity under both high and low illumination conditions, and received significantly higher ratings for visual quality (overall and at distance), comfort, and handling. The Focus Progressives lenses were preferred 5:1 over the Acuvue Bifocal lenses. No differences existed between the lenses with respect to near visual acuities, the perceived quality of the near vision, the nearpoint binocular range, stereoacuity, or the acceptability of vision for common nearwork tasks. The results suggest that although both types of lenses afford presbyopes a viable alternative to spectacles, the Focus Progressives lens is superior in many ways to the Acuvue Bifocal lens.

Increased gamma-range activity in human sensorimotor cortex during performance of visuomotor tasks

Objective: We documented changes in spectral power of human electrocorticograms (ECoG) during performance of sensorimotor tasks.Methods: In 6 human subjects, ECoGs were recorded simultaneously from 14 subdural cortical sites in forearm sensorimotor cortex. The subjects performed 3 visuomotor tasks: tracking a moving visual target with a joystick-controlled cursor, threading pieces of tubing, and pinching the fingers sequentially against the thumb. Control conditions consisted of passive resting and active extension of the wrist. For each site the spectral power of the ECoG during these behaviors was computed for 5 10 Hz ranges between 10 and 60 Hz.Results: All subjects showed power decreases in the range of 11–20 Hz and power increases in the 31–60 Hz range during performance of the visuomotor tasks, at sites in forearm sensorimotor cortex and adjacent areas. Simple wrist movements often produced little change in power. Three subjects showed episodes of explicit gamma oscillations during the visuomotor tasks. Different sites showed increases in gamma-range power for different tasks, indicating that the spatial distribution of the gamma activity is specific to the tasks. Cross-spectra showed that gamma activity could become synchronized between separate sites during particular tasks.Conclusions: Synchronized gamma-range activity in human sensorimotor cortex increases with performance of manipulative visuomotor tasks, supporting the hypothesis that coherent gamma oscillations may play a role in sensorimotor integration or attention.

Some observations on the performance of squinters and non-squinters on the Wechsler Intelligence Scale for Children.

30 children with and without squint were tested on the WISC. Non-squinters performed significantly better only on the Information subtest. However, children with alternating squint scored significantly less well on the Performance Scale than children with uniocular squint. This result is consistent with the hypothesis that alternating vision is a handicap in the performance of visuo-motor tasks.