Sensing form - finger gaiting as key to tactile object exploration: A data glove analysis of a prototypical daily task

Abstract

Background Motor hand skill with associated dexterity is an important facility in meeting the challenges of daily activity and an important resource post-stroke. In this context, the present study investigated the finger movements of right-handed subjects during tactile manipulation of a cuboid, a prototypical component of tactile exploration. Methods For both hands of 22 subjects, we acquired the time series of consecutive multifinger cuboid manipulations using a digital data glove consisting of 29 sensors. Of these, 16 recorded the bending of metacarpo-phalangeal (MCP) and proximal interphalangeal (PIP) joints of the fingers, MCP and interphalangeal IP joints of the thumb, palm arch and carpo-metacarpal (CMC) joint of the thumb, and abduction between fingers. Results Using principle component analysis we decomposed the short action into motor patterns related to successive manipulations of the cuboid. The fraction of variance described by the principal components indicated that three components described the salient features of the single motor acts for each hand. Striking in the finger patterns was the prominent and varying roles of the MCP and PIP joints of the fingers, and the CMC joint of the thumb. An important aspect of the three components was their representation of distinct finger configurations within the same motor act. Principal component and graph theory analysis confirmed modular, functionally synchronous action of the involved joints. The computation of finger trajectories in one subject illustrated the workspace of the task, which differed for the right and left hands. Conclusion The study substantiates finger gaiting, described until now only in artificial systems, as the principal mechanism underlying this prototypical task, which is ubiquitous in daily object shape recognition.