Thesis

EEG signatures and directional information in planning and execution of arm isometric exertions

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Awarding institution
  • University of Strathclyde
Date of award
  • 2013
Thesis identifier
  • T13419
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Abstract
  • The motor-related electroencephalographic (EEG) activity pattern in humans during motor behaviour is of interest to provide insight into normal motor control processes and for development of brain-computer interfaces (BCI), brain stimulation and rehabilitation systems. While the patterns preceding brisk voluntary movements, and especially movement execution, are well described, there are few EEG studies that address the cortical activation patterns seen in isometric exertions, and their planning. Furthermore, the effect of exertion direction on EEG signatures needs investigation. This study explores and reports on the time and time-frequency surface EEG signatures in isometric task experiments in normal subjects (n=8). Multichannel EEG is recorded during motor preparation, planning and execution of directional centre-out arm isometric exertions performed at the wrist in the horizontal plane, in response to instruction-delay visual cues. The directional information of surface EEG and modulation of EEG signatures by cue direction are investigated by statistical measures and linear classifiers. The observations suggest that isometric force exertion is accompanied by transient and sustained forms of event-related potentials (ERP) and event-related (de-)synchronisations (ERD/ERS), comparable to those of a movement task. Furthermore, the ERP and ERD/ERS are observed not only during execution, but also during preparation and planning of the isometric task. Transient synchronisation in 2-7 Hz frequency band and both transient and sustained desynchronisation in α (u) and β frequency bands were observed. Low-γ (30-50 Hz) ERD is observed in all areas, except over the parietal region where ERS is seen. While ERP and ERD/ERS are not consistently modulated by task direction, the direction of exertion can be predicted by single-trial classification. Classification rates reach 69% and 83% in planning and execution stages, respectively. As no physical displacement happens during the task, it can be hypothesised that the underlying mechanisms of motor-related ERD/ERS and the directional information do not only depend on limb coordinate change or target coordinates. The results contribute to the current understanding of different brain region functions during voluntary motor tasks and can help to clarify the relationships between invasive brain recordings and large-scale recordings such as EEG in this context. Ultimately, this will contribute to further clinical applications, including (BCI-)rehabilitation and electrical/magnetic brain stimulation research.
Resource Type
DOI
Date Created
  • 2013
Former identifier
  • 990129

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