説明
Publisher Summary With the development of techniques for recording from single afferents in conscious cats and monkeys, evidence has mounted that for most movements, variations in muscle length are apparently more powerful than fusimotor action in modulating spindle firing. This chapter presents an argument that these views are not contradictory if it is assumed that for muscle velocities in excess of 0.2 resting lengths (RL)/sec, spindle firing is mainly modulated by the length variations, whereas for muscle velocities less than 0.2 RL/sec, fusimotor action may often predominate. The discharge trains of single, identified muscle receptors may be recorded during voluntary movements of different speeds in cats. The firing rates of both primary and secondary muscle spindles were modulated strongly by the length variations when these involved muscle velocities in excess of 0.2 resting lengths/sec. For movements involving muscle velocities lower than 0.2 resting lengths/sec, there was evidence that fusimotor action could be the predominant modulatory influence.