The role of mechanical resonance in physiological tremor

Vernooij, Carlijn Andrea (2014). The role of mechanical resonance in physiological tremor. University of Birmingham. Ph.D.

Preview

Vernooij14PhD.pdf
PDF - Redacted Version
Download (6MB)

Abstract

The origin of physiological tremor has been studied for many years. Several central and spinal mechanisms which provide an oscillatory input to the muscles have been proposed. Nevertheless, any neural control signal inevitably has to work upon a resonant peripheral system involving the series-coupled elastic muscle-tendon complex and the inertia of the limb.
In this thesis I look into the potential role for mechanical resonance to explain tremor. First, I show that the resonant component of hand tremor depends on the velocity of hand movement. Movement reduces muscle stiffness (a process called muscle thixotropy) and the tremor frequency falls. Second, I demonstrate that rhythmic tremor is abolished when eliminating resonance by recording tremor in isometric conditions. Third, I replaced EMG by an artificial drive. This generated tremor which behaved similarly to physiological postural and dynamic tremor. Finally, I studied the relationship between EMG and tremor in the transition from posture to movement. Muscle converts EMG into acceleration differently for static and moving limbs.
These findings suggest that there is a key role for mechanical resonance in the generation of physiological tremor. A frequency-specific neural input is not necessary to produce any of the characteristic peaks in postural or dynamic tremor.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):