Independent control of the digits: changes in perceived heaviness over a wide range of force.
Perceived heaviness of a weight lifted by flexion of the distal joint of one digit increases when an adjacent digit concurrently lifts a weight. The present study confirmed this finding for relatively low weights (representing 3-5% maximal voluntary force) and a method was adapted to show that this effect occurs for much larger weights (20-25% maximal force). Thus, the increase in perceived heaviness is likely to operate over a wide range of muscle force generated by the hand. As perceived heaviness is biased by the magnitude of the central motor commands, these findings may reflect a lack of complete independence of motor commands to the long flexor muscles acting on the digits.
Kilbreath
S L
SL
Department of Clinical Neurophysiology, Prince Henry Hospital, Sydney, Australia.
Gandevia
S C
SC
D005385:Fingers / Q000502:physiology*; D006225:Hand / Q000502:physiology; D006801:Humans; D013933:Thumb / Q000502:physiology; D014892:Weight Perception / Q000502:physiology*