Abstract
The Hand Blink Reflex (HBR) is a subcortical defensive response, elicited by the electrical stimulation of the median nerve. HBR increases when the stimulated hand is inside the defensive peripersonalspace (DPPS) of the face. However, the presence of a screen protecting the face could reduce the amplitude of this response. This work aimed to investigate whether the learning of a posture intended to protect the head could modulate the HBR responses. Boxing athletes learn a defensive posture consisting of blocking with arms opponent’s blow towards the face. Two groups were recruited: 13 boxers and 13 people naïve to boxing. HBR response was recorded and elicited in three hand positions depending on the distance from the face. A suppression of HBR enhancement in the static position close to the face was observed in boxer group, contrary to the control group. Also, the higher years of practice in boxing, the higher suppression occurred. However, this suppression was not observed when boxers were asked to move the hand up-to/down-from the face. These findings might suggest that the sensorimotor experience related to a previously learnt protective posture can modify the HBR and thus shape the dimension of the DPPS.
Highlights
The peripersonal space (PPS) is the space directly surrounding the body at grasping distance[1]
Since this sport situation can be considered the ecological counterpart of the Hand Blink Reflex (HBR) experiment, we investigated whether this “shield effect” in boxers can shape the defensive peripersonal space surrounding the face
A group of boxers with different years of practice were enrolled and compared with a group of 13 age-matched control subjects during a static HBR experiment hypothesizing that the expected HBR enhancement in the position close to the face would not be present in boxers, and that the years of practice could have a role in this modulation
Summary
The peripersonal space (PPS) is the space directly surrounding the body at grasping distance[1]. The intensity of responses increases when the hand moves towards the face bringing the threat near to the subject, but decreases when the hand moves away from the face[5] This shows that in dynamic conditions HBR modulation depends by the actual position of the stimulated hand, and by the final position where the hand is expected to be at the end of the movement. At a first glance the hands are inside the DPPS of the face, boxers are confident to use their hands as a shield to protect the face from an external threatening stimulus Since this sport situation can be considered the ecological counterpart of the HBR experiment, we investigated whether this “shield effect” in boxers can shape the defensive peripersonal space surrounding the face.
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