Visual experience and the establishment of spatial and tactile maps in the brain

Abstract

Visual experience is necessary for the normal development of spatial cognition. Although some aspects of spatial processing in an egocentric reference frame are well preserved in the case of congenital blindness, it appears the lack of vision influences processing in an allocentric reference frame. Here I will first report our finding that visual experience biases congenitally blind participants to rely on an egocentric reference frame for spatial cognition tasks, rather than an allocentric reference frame that is favoured by late blind and sighted participants. This suggests that visual experience can influence the neural basis of spatial representations, given the importance of vision for normal multisensory processing. A previous study discovered an area in human parietal cortex with aligned maps of tactile and visual stimuli. We investigated whether visual experience is necessary for the development of tactile maps in multisensory areas, such as the putative human ventral intraparietal (VIP) area reported previously. Congenital and late blind participants underwent functional magnetic resonance imaging while exposed to facial air-puffs of varying polar angle. Phase-encoding of the facial air-puffs allowed for tactile mapping that revealed full face maps in the posterior parietal cortex of the late blind participants, as reported previously for sighted participants. The congenitally blind participants however did not have the same representation of the face map as those with visual experience. Retinotopic maps are ideal for characterizing an allocentric representation of the environment and might be necessary as the basis for representing and aligning the neural representation of space as seen in the somatotopic maps examined here.