Sensory enhancement - learning a new sense
Final Report Abstract
The ultimate goal of this proposal was to test enactive theories of conscious perception by an investigation of new sensorimotor contingencies. For this purpose we developed an innovative sensory augmentation device, the feelSpace belt. We then tested behavioural, physiological, and perceptual changes induced by extended training. Specifically, we developed an fMRI compatible belt, supplying the orientation relative to magnetic north by a tactile signal. This belt was built in two versions, one suitable for training and the other compatible with fMRI scanning. A total of 14 subjects (nine with belt, five without) trained for seven weeks. A navigation task, an turning angle discrimination task, sleep-EEG measurements, fMRI scanning and evaluation of subjective experiences were performed before and after the training period. Additionally, sleep-EEG (twice) and measurements of subjective experiences (daily and weekly) were obtained during the training period as well. The results in a turning angle discrimination task in a virtual environment revealed limited integration of visual and tactile signals with vestibular information. Performance in the navigation task demonstrated a small reduction in systematic inward bias and a moderate reduction of the stochastic homing error. Sleep EEG revealed an increase of the amount of REM sleep early in training in subjects training with the belt. This was accompanied by reduction of the fraction of stage 1 sleep and a reduction of sigma power in stage 2. These changes indicate intensified procedural learning in the early training phase. The fMRI measurements conducted in a complete factorial design revealed main effects involving specific areas in frontal (MFG, SMA), parietal (S1, S2, A5, A7) and insular (Rolandic) cortex. The important 2-way interactions with usage of the belt involve SMA, MFG, A5 and A7. This argues for specific neuronal plasticity in cortical areas processing information relative to egocentric space. The evaluation of subjective experiences document that all but one of the subjects trained with the belt report remarkable changes in perception, e.g. “Es ist ein wirkliches Raumgefühl, unvermittelt durch Sinne wie Sehen und Hören, oder Propriozeption (...). Irgendwie stellt sich auch ein Gefühl für Fernpräsenz ein: Sehen und Hören vermitteln nur Nahes/Anwesendes der Gürtel aber auch Abwesendes von Sehen & Hören.”; “Zuvor waren die Karten eher aus Vogelperspektive, während nun die Karten aus Ego-Perspektive auf das erlebte Sehen projiziert sind. (…) Auch sind es weniger klare Karten als Wege. Ich kann nur noch schwer mentale Karten bilden. (…) Stattdessen navigiere ich nach Gefühl.” (subjects fS13 and fS31 resepectively). None of the controls reported comparable changes. This is supported by quantitative questionnaires and a statistical evaluation of diaries and weekly interviews. The tactile signal recedes into the background and a direct effect on spatial perception is reported. This is accompanied by a feeling of increased security. These results on the psychophysical, physiological, and perceptual level are compatible with enacted theories of conscious perception and simultaneously highlight that predictions with respect to performance are non trivial. A speculative all encompassing explanation stresses the enlargement of egocentric space on a high level with ensuing consequences for action and perception.
Publications
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(2012) Donders Discussion Properties and mechanisms of sensory enhancement – An fMRI study, 25.-26. Oktober 2012
Wache et al.
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(2012) Properties and mechanisms of sensory enhancement (An fMRI study). KogWis, 1.-3. Oktober 2012
Wache et al.
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(2012) Properties and mechanisms of sensory enhancement. Spatial Cognition, 31. August-3. September 2012, Kloster Seoon
König et al.
