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Tracking performance with sinusoidal and irregular targets under different conditions of peripheral feedback
I Cathers1, N O'Dwyer, P Neilson
1Department of Biomedical Sciences, Faculty of Health Sciences, University of Sydney, Lidcombe, NSW, Australia. i.cathers@cchs.su.edu.au
Experimental Brain Research
|October 1, 1996
Summary
Investigating forearm tracking, this study found that perturbational feedback significantly enhances voluntary tracking of sinusoidal movements up to 7 Hz. However, this feedback offered minimal advantage for tracking irregular signals, suggesting different control mechanisms.
Area of Science:
- Neuroscience
- Human Motor Control
- Biomedical Engineering
Background:
- Muscle stretch reflexes and muscle tone assessment require subjects to avoid tracking stimuli, which contaminates results.
- Voluntary responses to limb perturbations can occur with latencies similar to reflexes, potentially enabling faster tracking.
- Perturbational feedback, comprising cutaneous and proprioceptive signals from limb displacement, is crucial for understanding motor control.
Purpose of the Study:
- To investigate the forearm's tracking frequency response to sinusoidal and irregular target signals.
- To determine the effect of perturbational feedback on voluntary tracking performance.
- To explore the underlying mechanisms of rapid voluntary tracking.
Main Methods:
- Subjects voluntarily tracked perturbations applied to a manipulandum under two conditions: with and without perturbational feedback.
- Sinusoidal and irregular target signals were used to assess tracking frequency response.
- Tracking performance was evaluated based on the ability to follow target signals at various frequencies.
Main Results:
- Perturbational feedback significantly improved tracking performance for sinusoidal signals, with some subjects achieving 7 Hz tracking.
- Tracking performance without perturbational feedback was considerably lower, typically around 2 Hz.
- For irregular signals, perturbational feedback provided only a marginal advantage, with no improvement in maximum tracking frequency.
Conclusions:
- Perturbational feedback enhances voluntary tracking of predictable, sinusoidal movements by allowing synchronization with internally generated motor commands.
- The limited benefit of perturbational feedback for irregular signals suggests that different neural pathways or control strategies are employed for unpredictable movements.
- The study provides no evidence for a shorter-latency, same-limb displacement response underlying rapid voluntary tracking of irregular targets.