Comparing techniques to reduce simulator adaptation syndrome and improve naturalistic behaviour during simulated driving

Electrical stimulation of the vestibular sensory system during virtual environment simulations reduces the incidence of simulator adaptation syndrome (SAS). However, interactions between vestibular stimulation and complex visual scenery can increase oculomotor symptoms. This study examined an alternative technique to reduce symptoms of SAS using the application of galvanic cutaneous stimulation of the neck. The effect of both vestibular and cutaneous stimulation was also evaluated on the naturalistic driving behaviour of curves. Thirty participants drove a rural setting virtual environment with high visual cues. Three groups of ten participants each were used to compare the effect of galvanic vestibular stimulation and galvanic cutaneous stimulation versus a control group on post drive scores of the SSQ (Simulator Sickness Questionnaire) and three driving variables (steering variability, lane position, and vehicular speed). Galvanic cutaneous stimulation while driving resulted in decreased SSQ scores, but did not show an effect on driving behaviour. Conversely, galvanic vestibular stimulation while driving curves resulted in vehicular speeds that were reflective of natural real world driving behaviour and similar SSQ scores to control. These results support the theory that cutaneous stimulation of the neck is a worthy alternative to vestibular stimulation for reducing SAS especially in scenarios requiring complex visual scenes; however, if naturalistic driving behaviour (of curves) is important, vestibular stimulation remains the better choice as it can reduce SAS symptoms (in virtual environments with low visual stimuli) and also promotes naturalistic driving behaviours

Peripheral artery disease and activity-induced shifts in quadriceps median frequency during treadmill walking

Peripheral artery disease (PAD) is associated with altered gait biomechanics. No previous research study has investigated the effect of activity on muscle activation in individuals with PAD. The purpose of this study was to investigate the effect of PAD on muscle activation in response to a ten-minute walking task. METHODS: Ten healthy young adults, ten healthy older adults and ten individuals with PAD performed a ten-minute treadmill walking trial at a self-selected velocity. Surface EMG was recorded from the vastus lateralis and medial gastrocnemius during five steps in the first and tenth minutes of the walking trial. EMG signals were rectified and smoothed using the root mean squared (RMS) with a 20 ms smoothing window. Peak RMS EMG and median frequencies (MdF) were calculated. Mixed-model ANOVAs with Tukey’s post-hoc was used to determine effects of group and activity on peak RMS EMG and MdF. RESULTS: PAD was associated with significantly greater reductions in MdF of the vastus lateralis compared to healthy young and healthy older adults. No significant differences were observed in peak RMS EMG. DISCUSSION: PAD is associated with exaggerated rates of fatigue in the quadriceps but not the gastrocnemius. Efficacy of evidence-based therapeutic interventions should be further investigated. Key words: peripheral art

Simulated visual field loss does not alter turning coordination in healthy young adults

Turning, while walking, is an important component of adaptive locomotion. Current hypotheses regarding the motor control of body segment coordination during turning suggest heavy influence of visual information. The authors aimed to examine whether visual field impairment (central loss or peripheral loss) affects body segment coordination during walking turns in healthy young adults. No significant differences in the onset time of segments or intersegment coordination were observed because of visual field occlusion. These results suggest that healthy young adults can use visual information obtained from central and peripheral visual fields interchangeably, pointing to flexibility of visuomotor control in healthy young adults. Further study in populations with chronic visual impairment and those with turning difficulties are warranted