Sensory substitution is a new concept in neurosciences. It assumes that the information from a defective sensory system (e.g.) a TV camera and "translated" into another physical stimulus that can be used by an intact sensory system (e.g. smoothes) and carried to the brain via the corresponding pathways (e.g. tactile nerve pathways). Visio-tactile and visual-auditory sensory substitution systems are both designed to code spatial information normally provided by vision. Utilising brain imaging techniques (FMRI and PET) and behavioural experimental techniques, we propose to analyse:
(a) the ongoing brain changes and
(b) the links between sensory and cognitive brain representation due to the utilisation off that perceptual modality that is totally artificial and new to the subjects.
1) EXPERIMENTAL PSYCHOLOGY: To try to understand the specific role of the vision in the sensory substitution perception, sighted blindfolded subjects were compared with congenital and total blind subjects. They were submitted to extensive training with the sensory substitution systems: half of the population were trained with the visuo auditory (PSVA) system and half with the visuo tactile (pneumatic TVSS) system (see WP2). Then, perceptual effects of sensory substitution were assessed three times (naïve subjects at the very first utilisation of the sensory substitution system, at the middle of the extensive training and at the end of the training) by three categories of tasks: kinematics analysis of aimed movements, analysis of intermodal transfer (natural and artificial perceptual modalities), and induction of visual illusions by sensory substitution systems;
2) NEUROIMAGING : brain plasticity was assessed by two brain imaging techniques. The population trained with the PSVA was assessed with the PET scanner (H2O15, see WP4) technique and the population trained with the pneumatic TVSS was assessed with the fMRI (2 T, EPI, see WP5) technique.
Several data acquisitions were done with each of the blindfolded sighted and blind subjects: (a) with naïve subjects at the very first utilisation of the sensory substitution system, (b) at the middle of the extensive training and (c) at the end of the training. Furthermore, an additional acquisition was done with all subjects in a cross check modality: the blind and sighted subjects trained with the PSVA were assessed with the fMRI technique and the blind and sighted subjects trained with the pneumatic TVSS were assessed with the PET technique. 3) BIOMEDICAL ENGINEERING: a TVSS prototype suited for operation in the high magnetic field of fMRI was not commercially available. Consequently, a totally non magnetic stimulator, with 64 tactors, operated via pneumatic tubes was developped (PTD). Furthermore, the very last version of the TVSS, an electronic miniaturized device using a 3x3cm array, with144 tactors, explored with the tongue (TDU), proved that it can also be safely used in the fMRI environment.
Funding SchemeCSC - Cost-sharing contracts