Affiliations: Experimental and Biological Psychology, Philipps-University Marburg, Marburg, Germany
Note: [] Corresponding author: Katja Fiehler, Philipps-University
Marburg, Department of Experimental and Biological Psychology, Gutenbergstr.
18, D-35032 Marburg, Germany. Tel.: +49 (0)6421 2823619; Fax: +49 (0)6421
2828948; E-mail: [email protected]
Abstract: The dorsal stream has been proposed to compute vision for space
perception and for the control of action. However, perceiving space and guiding
movements is not only based on vision but also on other sensory modalities such
as proprioception and kinesthesia. Blind people who lost vision early in life
provide an exceptional example to study the plasticity of dorsal stream
functions. Using fMRI and psychophysical methods, action control and space
perception was investigated in congenitally blind and sighted adults while
performing active and passive hand movements without visual feedback. The
functional imaging data showed largely overlapping activation patterns for
kinesthetically guided hand movements in congenitally blind and sighted
participants covering regions of the dorsal stream. In contrast to the sighted
participants, congenitally blind participants additionally activated the
extrastriate cortex and the auditory cortex. The psychophysical results
revealed a significant correlation between proprioceptive spatial
discrimination acuity of the blind and the age when they had attended an
orientation and mobility training, i.e., an extensive non-visual spatial
training. The earlier the blind acquired such a spatial training the more
accurate and the more precise was their space perception in later life. Our
findings suggest a multisensory network of movement control that develops on
the basis of sensorimotor feedback rather than being under the exclusive
control of vision. Thus, visual deprivation seems to result in both cross-modal
and compensatory intra-modal plasticity. The present findings further imply
that dorsal stream functions are shaped by non-visual spatial information
during early development.
Keywords: dorsal stream, kinesthesia, motor control, posterior parietal cortex, proprioception, space perception
