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Abstract:
Enacted theories of consciousness conjecture that perception and cognition arise from an active experience of the regular relations that tie together sensory stimulation and associated motor actions [1,2]. By employing the technique of sensory substitution [3] and sensory augmentation [4] previous experiments explored this assumption. In this study
a sensory augmentation device delivered global orientation information by mapping directional information of a compass to a set of vibrators around the waist, activating the element pointing north (feelSpace belt) [4]. Here we use it to investigate the impact on cortical plasticity sensory
processing, and spatial cognition. Therefore we want to answer the questions how the brain is able to integrate and use new sensory input, where this processing takes place and whether the newly supplied directional information can be used by the subjects for enhanced orientation and navigation leading to many useful applications. Out of fourteen subjects (age 19–32y, seven female, five controls) nine
were wearing the belts during all waking hours over a period of six weeks. We compared belt-on and belt-off conditions in a series of measurements including homing, fMRI, and subjective methods before, during and after training.
(1) In the homing task using polygons of varying complexity we observed a slight reduction of the systematic error and a larger reduction of the stochastic error in belt-on condition after the training period.
(2) Most areas that were reported in a previous fMRI study on navigation [5] could be replicated in our subjects. Furthermore, we observed widespread cortical activation induced by the belt in the pretraining baseline measurements which is more localized and less intense after training. (3) Subjective reports indicate that by training with the
feelSpace belt the scope of perceived space grows wider and includes areas that are not within reach or directly visible; subjects feel more secure in known as well as previously unknown environments; and navigational
abilities improve and emphasize an egocentric reference frame. The data provide evidence for an integration of the newly supplied signals in sensory integration (homing), cortical processing (fMRI) and spatial cognition (subjective methods). However, further analysis is needed to elucidate significant individual variations.
