The relations between development of humans’ manipulative skills and physiological signals of brain and hand

The relations between development of humans’ manipulative skills and physiological signals of brain and hand

  Two studies report the physiological signals of brain and hand that change as a human develops one"s manipulative skills. In Study 1, we investigated the activation of the brain in Brodmann"s area 46 of the frontal lobe in drawing tasks to examine whether Near-Infrared Spectroscopy (NIRS) can measure the changes of the DLPFC (dorsolateral prefrontal cortex) activation as a human develops motor skills. Participants performed a mirror drawing task and a square drawing task using their non-dominant hand. The change in oxy-Hb concentration decreased as the participant repeated the drawing task in most participants, suggesting that the activation of DLPFC decreases when a human develops manipulative skills. In Study 2, we investigated the phenomenon of micro？slips or non-smooth hand movements in relation to humans" skill development in coffee making. Seven right-handed participants were asked to make coffee ten times consecutively by their left hand. Each micro-slip was coded about its severity with a 5-point-scale and total frequency and a micro-slip score were calculated that we defined as the sum of micro-slip level multiplied by frequency for observed micro-slips in each cup of coffee. Results showed that frequency and micro-slip score decreased when the participants developed the coffee- making skills. We also tried to detect micro-slips by a physical measurement method of analyzing hand"s acceleration data. We showed that time-frequency characteristics of hand"s acceleration show characteristic patterns when micro-slips occur. Based on these results, we presented that physiological signals show characteristic changes as humans develop manipulative skills and suggest that such data could be a useful source of information for construction of human adaptive mechatronics (HAM).