Neuroscience 2005 Abstract
| Presentation Number: | 56.11 |
|---|---|
| Abstract Title: | The initial burst of the human automatic postural response scales with the perturbation acceleration and velocity during quiet stance. |
| Authors: |
Welch, T. D. J.*1
; Ting, L. H.1
1Dept of Biomedical Engineering, Georgia Inst. of Technology/Emory Univ., Atlanta, GA |
| Primary Theme and Topics |
Sensory and Motor Systems - Kinematics and EMG -- Posture |
| Session: |
56. Posture: Sensory Effects Poster |
| Presentation Time: | Saturday, November 12, 2005 3:00 PM-4:00 PM |
| Location: | Washington Convention Center - Hall A-C, Board # X16 |
| Keywords: | POSTURE, MOTOR CONTROL, FEEDBACK, SENSORIMOTOR |
The neural basis governing the temporal formation of the human postural response is not well understood. It has been shown that postural control can be modeled using a simple feedback controller (Kuo 1995) and that the entire timecourse of EMG activity can be reconstructed using feedback on CoM kinematics in cats (Lockhart et al. 2005, SfN abstract). Specifically, acceleration and velocity feedback are important in the temporal formation of the EMG waveform during postural responses in cats. Our goal was to determine whether similar sensory feedback pathways are responsible for the temporal patterning of postural responses in humans. We hypothesize that the initial burst of EMG activity is formed by feedback on perturbation acceleration (acc) and velocity (vel). Since these characteristics typically covary, we attempted to delineate their individual effects. Subjects were perturbed during quiet stance with three different sets of anterior-posterior support surface translations with distinguishable acc and vel characteristics – one where acc and vel covary and two in which each characteristic is varied independently. EMGs from sixteen muscles were recorded. Cross correlations show that the shape of the initial burst of EMG activity is similar to that of a weighted sum of the perturbation acc and vel (r > 0.87). Similarly, the slope of EMG onset and those of acc and vel onset are correlated (R² > 0.99). Further, when acc and vel are varied together, integrated EMG of the initial burst in two representative muscles (tibialis anterior and medial gastrocnemius) scales with both acc and vel (R² > 0.6). When varied separately, the first 75 ms of integrated EMG scale with acc magnitude (R² > 0.5), while the next 75 ms scale with vel (R² > 0.5). These results suggest that the initial burst of EMG activity in response to postural disturbances may be formed using feedback on both acc and vel of the perturbation rather than by a feedforward mechanism.
Supported by Whitaker RG-02-0747, NIH HD046922-01S1
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2005 Neuroscience Meeting Planner. Washington, DC: Society for Neuroscience, 2005. Online.
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