EEG oscillatory patterns and classification of sequential compound limb motor imagery

Journal of NeuroEngineering and Rehabilitation, Jan 2016

Background A number of studies have been done on movement imagination of motor sequences with a single limb. However, brain oscillatory patterns induced by movement imagination of motor sequences involving multiple limbs have not been reported in recent years. The goal of the present study was to verify the feasibility of application of motor sequences involving multiple limbs to brain-computer interface (BCI) systems based on motor imagery (MI). The changes of EEG patterns and the inter-influence between movements associated with the imagination of motor sequences were also investigated. Methods The experiment, where 12 healthy subjects participated, involved one motor sequence with a single limb and three kinds of motor sequences with two or three limbs. The activity involved mental simulation, imagining playing drums with two conditions (60 and 30 beats per minute for the first and second conditions, respectively). Results Movement imagination of different limbs in the sequence contributed to time-variant event-related desynchronization (ERD) patterns within both mu and beta rhythms, which was more obvious for the second condition compared with the first condition. The ERD values of left/right hand imagery with prior hand imagery were significantly larger than those with prior foot imagery, while the phase locking values (PLVs) between central electrodes and the mesial frontocentral electrode of non-initial movement were significantly larger than those of the initial movement during imagination of motor sequences for both conditions. Classification results showed that the power spectral density (PSD) based method outperformed the multi-class common spatial patterns (multi-CSP) based method: The highest accuracies were 82.86 % and 91.43 %, and the mean values were 65 % and 74.14 % for the first and second conditions, respectively. Conclusions This work implies that motor sequences involving multiple limbs can be utilized to build a multimodal classification paradigm in MI-based BCI systems, and that prior movement imagination can result in the changes of neural activities in motor areas during subsequent movement imagination in the process of limb switching.

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EEG oscillatory patterns and classification of sequential compound limb motor imagery

Yi et al. Journal of NeuroEngineering and Rehabilitation EEG oscillatory patterns and classification of sequential compound limb motor imagery Weibo Yi 0 1 Shuang Qiu 0 1 Kun Wang 1 Hongzhi Qi 1 Feng He 1 Peng Zhou 1 Lixin Zhang 1 Dong Ming 1 0 Equal contributors 1 Department of Biomedical Engineering, College of Precision Instruments and Optoelectronics Engineering, Tianjin University , Tianjin , China Background: A number of studies have been done on movement imagination of motor sequences with a single limb. However, brain oscillatory patterns induced by movement imagination of motor sequences involving multiple limbs have not been reported in recent years. The goal of the present study was to verify the feasibility of application of motor sequences involving multiple limbs to brain-computer interface (BCI) systems based on motor imagery (MI). The changes of EEG patterns and the inter-influence between movements associated with the imagination of motor sequences were also investigated. Methods: The experiment, where 12 healthy subjects participated, involved one motor sequence with a single limb and three kinds of motor sequences with two or three limbs. The activity involved mental simulation, imagining playing drums with two conditions (60 and 30 beats per minute for the first and second conditions, respectively). Results: Movement imagination of different limbs in the sequence contributed to time-variant event-related desynchronization (ERD) patterns within both mu and beta rhythms, which was more obvious for the second condition compared with the first condition. The ERD values of left/right hand imagery with prior hand imagery were significantly larger than those with prior foot imagery, while the phase locking values (PLVs) between central electrodes and the mesial frontocentral electrode of non-initial movement were significantly larger than those of the initial movement during imagination of motor sequences for both conditions. Classification results showed that the power spectral density (PSD) based method outperformed the multi-class common spatial patterns (multi-CSP) based method: The highest accuracies were 82.86 % and 91.43 %, and the mean values were 65 % and 74.14 % for the first and second conditions, respectively. Conclusions: This work implies that motor sequences involving multiple limbs can be utilized to build a multimodal classification paradigm in MI-based BCI systems, and that prior movement imagination can result in the changes of neural activities in motor areas during subsequent movement imagination in the process of limb switching. Sequential compound limb motor imagery; Event-related desynchronization; Phase locking value; Braincomputer interface; Support vector machine Background Motor imagery (MI), defined as the mental rehearsal of a motor act without any overt motor output, can modify the neuronal activity in the primary sensorimotor areas in a manner which is quite similar to motor execution [ 1, 2 ]. MI-based brain-computer interface (BCI) systems could translate the subjective movement consciousness of the users without any inducing factors such as visual stimulus producing steady-state visual evoked potential (SSVEP) or event-related potential (ERP). This provides an alternative communication and control channel for patients with limited motor function to improve the quality of their lives [3]. Therefore, MI-based BCI systems play an important role in the field of rehabilitation engineering. Since Jasper and Penfield’s discovery of brain oscillatory activity induced by MI [ 4 ], MI-based BCI systems have gone through several decades of development. However, a major problem is the limitation of control commands in contrast to other BCI paradigms. Most research on MI-based BCI systems have focused on analyzing EEG rhythms induced by simple limb motor imagery involving a single part of the limbs such as the left hand, the right hand or the foot [ 5, 6 ]. Pfurtscheller et al. studied the reactivity of EEG rhythms in association with the imagination of three kinds of limb movements (right hand, left hand, and foot) with the addition of tongue movement [7]. To implement a twodimensional cursor movement between arbitrary positions, P300 potential was combined with MI (left and right hands) for controlling the horizontal and vertical movements of the cursor, respectively [ 8 ]. Additionally, MI was applied as a brain switch in a hybrid BCI system by detecting the post imagery beta event-related synchronization (ERS) of foot imagery to turn a fourstep electrically driven hand orthosis with two flickering lights on and off to reduce the false positive rate during the resting period [ 9 ]. On the other hand, a significant amount of work have been reported on movement imagination of motor sequences with a single limb such as sequential finger-tothumb opposition tasks [ 10–12 ], sequential dorsiflexion, and plantarflexion of the foot [ 13 ]. Lafleur et al. u (...truncated)


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Weibo Yi, Shuang Qiu, Kun Wang, Hongzhi Qi, Feng He, Peng Zhou, Lixin Zhang, Dong Ming. EEG oscillatory patterns and classification of sequential compound limb motor imagery, Journal of NeuroEngineering and Rehabilitation, 2016, pp. 11, 13, DOI: 10.1186/s12984-016-0119-8