A dual-task study of interference between mental activity and control of balance.
ABSTRACT This study aimed to examine interference between mental activity and control of balance.
In a mixed design, dual-task study, the performance of patients and healthy control subjects was compared on computerized dynamic posturography, on a visuospatial mental task, and when performing the mental task while balancing.
The study was performed at a tertiary referral outpatient neuro-otology clinic.
The patient group comprised 24 patients seen consecutively at the clinic because of vertigo and dizziness. The control group consisted of 24 subjects with no complaint or medical history of dizziness or balance disorder, matched with the patients for age and gender.
Performance on a visuospatial mental task and on the computerized dynamic posturography test (conditions 4 and 5) was measured.
Balancing on the posturography test resulted in a deterioration in performance on the mental task for both patients and control subjects. The effect was more marked when subjects had their eyes closed. Results on the balance test showed that normal subjects and patients with normal balance also swayed more when performing the mental task, whereas patients who had failed the posturography test swayed less when performing the mental task.
These results show that mental performance deteriorates when performing a demanding balance task. In addition, in both normal subjects and patients, balance also may be affected by mental activity in complex and varied ways that merit further investigation.
Article: The influence of cognitive tasks on vestibular-induced eye movements in young and older adults.[show abstract] [hide abstract]
ABSTRACT: The purpose of this study was to further investigate the mechanism of the influence of concurrent cognitive tasks on eye movements induced by earth-vertical axis rotation (EVAR) in young and older participants. Ten young (ages 21-34), ten young-old (ages 65-74) and nine older participants (ages 75-84) each performed five different cognitive tasks during sinusoidal EVAR in darkness at 0.02 Hz for three cycles, 0.05 Hz for four cycles, and 0.1 Hz for five cycles, all at a peak velocity of 50 degrees per second. The five tasks differed from one another in terms of their inherent sensory and motor components and were designed to provide insight into the effect of cognitive processing on VOR dynamics. Tasks included auditory frequency and lateralization disjunctive reaction time (DRT) tasks, silent and audible backward counting, and a question-response clinical standard task. For the DRT trials, tones were presented to the participant through earphones. Participants were instructed to respond as accurately and as quickly as possible. Eye movements were recorded with electro-oculography and calibrations were performed before and after every five rotations in all subjects. Participants had an increase in VOR phase lead while performing DRT tasks as compared to the clinical standard and counting tasks. The effect was most noticeable at the 0.02 Hz frequency and was present in all age groups. In addition, we observed a decrease in VOR gain while subjects performed auditory DRT tasks during EVAR at 0.02 Hz, 0.05 Hz and 0.1 Hz as compared to the clinical standard and counting tasks. These results suggest cognitive task-dependent interference between central auditory processing and vestibular processing primarily at the sensory rather than at the motor level.Journal of Vestibular Research 02/2008; 18(4):187-95. · 1.35 Impact Factor
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ABSTRACT: Vestibular patients show slower and unsteady gait; they have also been shown to need greater cognitive resources when carrying out balance and cognitive dual tasks (DT). This study investigated DT interference during gait in a middle-aged group of subjects with dizziness and unsteadiness after unilateral vestibular neuronitis and in a healthy control group. Fourteen individuals with subacute unilateral vestibular impairment after neuronitis and seventeen healthy subjects performed gait and cognitive tasks in single and DT conditions. A statistical gait analysis system was used and spatio-temporal parameters were considered. The cognitive task, consisting of backward counting by three, was tape recorded and the number of right figures was then calculated. Both patients and controls showed a more conservative gait during DT and between groups significant differences were not found. A significant decrease in cognitive performance during DT was found only in the vestibular group. Results suggest that less attentional resources are available during gait in vestibular patients compared to controls, and that a priority is given in keeping up the motor task to the detriment of a decrease of the cognitive performance during DT.Journal of NeuroEngineering and Rehabilitation 01/2010; 7:47. · 3.26 Impact Factor
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ABSTRACT: Postural control in quiet stance although simple still requires some cognitive resources; dual cognitive tasks influence further postural control. The present study examines whether or not dyslexic teenagers experience postural instability when performing a Stroop dual task for which their performances are known to be poor. Fifteen dyslexics and twelve non-dyslexics (14 to 17 years old) were recruited from the same school. They were asked to perform three tasks: (1) fixate a target, (2) perform an interference Stroop test (naming the colour or the word rather than reading the word), (3) performing flexibility Stroop task: the subject performed the interference task as in (2) except when the word was in a box, in which case he had to read the word. Postural performances were measured with a force platform. The results showed a main task effect on the variance of speed of body sway only: such variance was higher in the flexibility task than for the other two tasks. No group effect was found for any of the parameters of posture (surface, mediolateral and anteroposterior sway, variance of speed). Further wavelet analysis in the time-frequency domain revealed an increase in the spectral power of the medium frequency range believed to be related to cerebellum control; an accompanying increase in the cancellation time of the high frequency band related to reflexive loops occurred for non-dyslexics only. These effects occurred for the flexibility task and could be due to its high cognitive difficulty. Dyslexics displayed shorter cancellation time for the medium frequency band for all tasks, suggesting less efficient cerebellar control, perhaps of eye fixation and attention influencing body sway. We conclude that there is no evidence for a primary posture deficit in 15 year old teenagers who come from the general population and who were recruited in schools.PLoS ONE 01/2011; 6(4):e19272. · 4.09 Impact Factor