The influence of scopolamine on motor control and attentional processes

PeerJ. 2016 May 5;4:e2008. doi: 10.7717/peerj.2008. eCollection 2016.

Abstract

Background: Motion sickness may be caused by a sensory conflict between the visual and the vestibular systems. Scopolamine, known to be the most effective therapy to control the vegetative symptoms of motion sickness, acts on the vestibular nucleus and potentially the vestibulospinal pathway, which may affect balance and motor tasks requiring both attentional process and motor balance. The aim of this study was to explore the effect of scopolamine on motor control and attentional processes.

Methods: Seven subjects were evaluated on four different tasks before and after a subcutaneous injection of scopolamine (0.2 mg): a one-minute balance test, a subjective visual vertical test, a pointing task and a galvanic vestibular stimulation with EMG recordings.

Results: The results showed that the reaction time and the movement duration were not modified after the injection of scopolamine. However, there was an increase in the center of pressure displacement during the balance test, a decrease in EMG muscle response after galvanic vestibular stimulation and an alteration in the perception of verticality.

Discussion: These results confirm that low doses of scopolamine such as those prescribed to avoid motion sickness have no effect on attentional processes, but that it is essential to consider the responsiveness of each subject. However, scopolamine did affect postural control and the perception of verticality. In conclusion, the use of scopolamine to prevent motion sickness must be considered carefully because it could increase imbalances in situations when individuals are already at risk of falling (e.g., sailing, parabolic flight).

Keywords: Attentional processes; EMG; GVS; Motion sickness; Parabolic flights; Postural control; Scopolamine.

Grant support

This work was supported by the Centre National d‘Etudes Spatiales (CNES). It is based on ground observations parallels to the VP92, VP95 and VP102 campaign. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.