Combined exercise and visual gaze training improves stepping accuracy in people with diabetic peripheral neuropathy

Publisher's version (útgefin grein)Introduction: Patients with diabetes and diabetic peripheral neuropathy (DPN) place their feet with less accuracy whilst walking, which may contribute to the increased falls-risk. This study examines the effects of a multi-faceted intervention on stepping accuracy, in patients with diabetes and DPN. Methods: Forty participants began the study, of which 29 completed both the pre and post-intervention tests, 8 patients with DPN, 11 patients with diabetes but no neuropathy (D) and 10 healthy controls (C). Accuracy of stepping was measured pre- and post-intervention as participants walked along an irregularly arranged stepping walkway. Participants attended a one-hour session, once a week, for sixteen weeks, involving high-load resistance exercise and visual-motor training. Results: Patients who took part in the intervention improved stepping accuracy (DPN: +45%; D: +36%) (p < 0.05). The diabetic non-intervention (D-NI) group did not display any significant differences in stepping accuracy pre- to post- the intervention period (−7%). Discussion: The improved stepping accuracy observed in patients with diabetes and DPN as a result of this novel intervention, may contribute towards reducing falls-risk. This multi-faceted intervention presents promise for improving the general mobility and safety of patients during walking and could be considered for inclusion as part of clinical treatment programmes.This work was supported by a Clinical Research Grant from the European Foundation for the Study of Diabetes (EFSD).Peer Reviewe

A comparison of self-focus versus attentional explanations of choking

This study examined attentional processes underlying skilled motor performance in threatening situations. Twenty-four trained participants performed a simulated rally driving task under conditions designed either to direct the focus of attention toward the explicit monitoring of driving or a distracting secondary task. Performance (lap time) was compared with a “driving only” control condition. Each condition was completed under nonevaluative and evaluative instructional sets designed to manipulate anxiety. Mental effort was indexed by self-report and dual-task performance measures. The results showed little change in performance in the high-threat explicit monitoring task condition, compared with either the low-threat or the high-threat distraction conditions. Mental effort increased, however, in all high- as opposed to low-threat conditions. Performance effectiveness was therefore maintained under threat although this was at the expense of reduced processing efficiency. The results provide stronger support for the predictions of processing efficiency theory than self-focus theories of choking

Mechanisms of synchronous activity in cerebellar Purkinje cells

Complex spike synchrony is thought to be a key feature of how inferior olive climbing fibre afferents make their vital contribution to cerebellar function. However, little is known about whether the other major cerebellar input, the mossy fibres (which generate simple spikes within Purkinje cells, PCs), exhibit a similar synchrony in impulse timing. We have used a multi-microelectrode system to record simultaneously from two or more PCs in the posterior lobe of the ketamine/xylazine-anaesthetized rat to examine the relationship between complex spike and simple spike synchrony in PC pairs located mainly in the A2 and C1 zones in crus II and the paramedian lobule. PC pairs displaying correlations in the occurrence of their complex spikes (coupled PCs) were usually located in the same zone and were also more likely to exhibit correlations in the timing of their spontaneous simple spikes and associated pauses in activity. In coupled PCs, synchrony in both complex spike and simple spike activity was enhanced and the relative timing in the occurrence of complex spikes could be altered by peripheral stimulation. We conclude that the functional coupling between PC pairs in their complex spike and simple spike activity can be significantly modified by sensory inputs, and that mechanisms besides electrotonic coupling are involved in generating PC synchrony. Synchronous activity in multiple PCs converging onto the same cerebellar nuclear cells is likely to have a significant impact on cerebellar output that could form important timing signals to orchestrate coordinated movements

The role of effort in moderating the anxiety - performance relationship: testing the prediction of processing efficiency theory in simulated rally driving

We tested some of the key predictions of processing efficiency theory using a simulated rally driving task. Two groups of participants were classified as either dispositionally high or low anxious based on trait anxiety scores and trained on a simulated driving task. Participants then raced individually on two similar courses under counterbalanced experimental conditions designed to manipulate the level of anxiety experienced. The effort exerted on the driving tasks was assessed though self-report (RSME), psychophysiological measures (pupil dilation) and visual gaze data. Efficiency was measured in terms of efficiency of visual processing (search rate) and driving control (variability of wheel and accelerator pedal) indices. Driving performance was measured as the time taken to complete the course. As predicted, increased anxiety had a negative effect on processing efficiency as indexed by the self-report, pupillary response and variability of gaze data. Predicted differences due to dispositional levels of anxiety were also found in the driving control and effort data. Although both groups of drivers performed worse under the threatening condition, the performance of the high trait anxious individuals was affected to a greater extent by the anxiety manipulation than the performance of the low trait anxious drivers. The findings suggest that processing efficiency theory holds promise as a theoretical framework for examining the relationship between anxiety and performance in sport

Rehearsal by eye movement improves visuomotor performance in cerebellar patients

In order to assess the effect of rehearsal by eye movement alone on visuomotor performance, the eye movements and visually guided stepping of two cerebellar patients were monitored before and after a first and second batch of eye-movement rehearsals, in which patients made saccadic eye movements to the first 6 footfall targets (in a sequence of 18) whilst standing stationary at the start of the walkway. There was a marked improvement in oculomotor and locomotor performance following the second batch of eye-movement rehearsal. Both patients showed reduced occurrence of saccadic dysmetria, evident as a significant increase in the proportion of single to multi-saccadic eye movements (from 46 to 77% for DB and from 75 to 94% for TP). This was accompanied by increased regularity and accuracy of stepping in both patients, and decreased stance and double support phase durations (one patient only). Separate testing confirmed that these improvements in eye movements and stepping did not result from simple repetition of the task. This is the first demonstration of a technique – rehearsal by eye movement – that improves the visuomotor performance of cerebellar patients. It is compelling evidence for our proposal that during visually guided stepping the locomotor control system is dependent on assistance from the oculomotor control system

An internal model of a moving visual target in the lateral cerebellum

In order to overcome the relatively long delay in processing visual feedback information when pursuing a moving visual target, it is necessary to predict the future trajectory of the target if it is to be tracked with accuracy. Predictive behaviour can be achieved through internal models, and the cerebellum has been implicated as a site for their operation. Purkinje cells in the lateral cerebellum (D zones) respond to visual inputs during visually guided tracking and it has been proposed that their neural activity reflects the operation of an internal model of target motion. Here we provide direct evidence for the existence of such a model in the cerebellum by demonstrating an internal model of a moving external target. Single unit recordings of Purkinje cells in lateral cerebellum (D2 zone) were made in cats trained to perform a predictable visually guided reaching task. For all Purkinje cells that showed tonic simple spike activity during target movement, this tonic activity was maintained during the transient disappearance of the target. Since simple spike activity could not be correlated to eye or limb movements, and the target was familiar and moved in a predictable fashion, we conclude that the Purkinje cell activity reflects the operation of an internal model based on memory of its previous motion. Such a model of the target's motion, reflected in the maintained modulation during the target's absence, could be used in a predictive capacity in the interception of a moving object

Alcohol badly affects eye movements linked to steering, providing for automatic in-car detection of drink driving

Driving is a classic example of visually guided behavior in which the eyes move before some other action. When approaching a bend in the road, a driver looks across to the inside of the curve before turning the steering wheel. Eye and steering movements are tightly linked, with the eyes leading, which allows the parts of the brain that move the eyes to assist the parts of the brain that control the hands on the wheel. We show here that this optimal relationship deteriorates with levels of breath alcohol well within the current UK legal limit for driving. The eyes move later, and coordination reduces. These changes lead to bad performance and can be detected by an automated in-car system, which warns the driver is no longer fit to drive