Cerebral potentials evoked by balance perturbations.
Published: 2006
Language: eng
Number of pages: 189
ISBN-13: 9780494219782
Description: To investigate the role of the cerebral cortex in human compensatory postural control, electroencephalography was used to record perturbation-evoked cerebral potentials (PEPS). Previous studies have identified a large negative cerebral potential termed the N1 response (peak latency being 100-200 ms with respect to the perturbation onset), which was accompanied by a positive cerebral potential termed the P2 response (peak latency being 200-500 ms with respect to the perturbation onset). As these studies provided a limited understanding of the role of PEPS in compensatory postural control, the main thesis goals were: (1) to further explore N1 and its relation to sensory processing of the postural perturbation, and (2) to determine whether P2 represented sensorimotor events associated with the control of the postural response. N1 and P2 responses were examined in four interconnected studies which involved: (1) determining whether N1 represented sensory inputs related to the perturbation or sensorimotor events related to the control of evoked balance responses, (2) determining the influence of altered attention on N1 by comparing conditions that featured the presence and absence of a concurrent cognitive task, (3) examining the influence of stimulus predictability on N1, and (4) altering the later components of balance responses in order to establish influence over P2. Based on these studies, there were several important findings that have led to a better understanding of these potentials. Firstly, N1 appeared to represent sensory events related to the perturbation that were independent of ankle automatic postural reactions (APRs). Secondly, N1 appeared to be modulated by altered attention. Thirdly, as opposed to a simple reflection of sensory volume or perturbation intensity, N1 appeared to represent a 'mismatch event detector' that alerted the CNS to unpredictable changes in the perturbation. Lastly, P2 did not appear to represent sensorimotor events related to ankle APRs, suggesting that the control of ankle APRs could mainly reside within subcortical structures. Future work will determine whether the cerebral cortex uses sensory information about the perturbation in order to influence immediate or future postural reactions. Future studies will also examine whether P2 responses might reflect cognitive events associated with postural control.
Notes: Source: Dissertation Abstracts International, Volume: 68-01, Section: B, page: 0124.

Thesis (Ph.D.)--University of Toronto, 2006.

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