2D vs 3D visualization modalities and their effects on motor related potentials

Abstract

Objective: When pathways for normal motor function are interrupted (e.g. after stroke), brain-computer interfaces (BCI) can be used as an alternative channel for communication by translating brain signals measured with electroencephalography (EEG) [1] and/or to influence brain plasticity processes to induce recovery of normal motor control [2]. Especially after neural injury local cortical connections are continuously reorganized and sensorimotor rhythm-based BCIs might be able to guide newly sprouting axons to the appropriate cortical regions by repetitive motor imagery practice [3]. This study investigated if feedback (2D vs. 3D visualisation) can amplify motor related potentials during motor imagery. We hypothesize that three dimensional, sensory richer feedback might be more effective during instrumental conditioning, resulting in more pronounced event related desynchronisation (ERD) of the mu (10-12Hz) and beta (20 Hz) bands over the sensorimotor cortex. Methods: 15 healthy, BCI nïve participants were instructed to watch attentively videos of seven different left and right arm movements on a True3Di monitor (2D and 3D, using stereoscopic glasses) and to replicate these movements subsequently by motor imagery. EEG signals were recorded from a grid of 40 Ag/AgCl scalp electrodes. Results: In Fig. 1 Left and Right, increased ERD peaks are present during motor imagery after 3D feedback at electrode position CP3 and CP4. Largest desynchronisation in the mu band power was elicited after 3D feedback (left:-8.3 dB; right: -8.5 dB from baseline; 2D left: -4.9 dB; right: -8.3 from baseline, Fig. 1 Middle). Conclusion: Motor imagery offers a promising technique for motor rehabilitation [4]. These results support the hypothesis that the choice of feedback modality can have significant effects on motor-related potentials. By inducing changes in the features of brain activity, 3D BCI protocols might be able to guide plasticity to promote recovery of motor function [5].

Meeting abstract presented at VSS 2014