Visual experience differentially impacts the egocentric and allocentric coding of touch and motor sequence

Crollen, Virginie [UCL] Albouy, Geneviève [Université de Montréal] Lepore, Franco [Université de Montréal] Collignon, Olivier [Université de Trento]

The foundation of our sensory-motor experience is based on two spatial frames of reference: a representation built upon egocentric (body-centered) coordinates and a goal-directed representation built upon allocentric (world-centered) coordinates. It has been demonstrated that early visual deprivation prevents the automatic use of an external frame of reference for touch. Whether visual experience also affects the allocentric representation of space in the motor field remains to be explored. To examine this issue, early blind (EB) and sighted control participants (SC) took part in two experiments. In experiment 1 we used a temporal order judgment task (TOJ), targeting touch processing, in which participants were required to determine, either with their hands in parallel or crossed over the body midline, the temporal order of two tactile stimuli, one applied to each hand. Crossing the hands led to a significant decrement in performance in SC but did not affect EB. In experiment 2, the same participants were trained to perform a sequence of five-finger movements. After the training session, participants were tested on their ability to produce, with the same hand but with the keypad turned upside down, the learned (egocentric condition) or the mirror sequence (allocentric condition). In this task, EB and SC both experienced significant transfer of motor sequence knowledge irrespective of whether the representation of the sequence was allocentric or egocentric. These results therefore demonstrated that visual experience differentially impacts the egocentric and allocentric coding of touch and motor action.