Abstract
The multisensory FULCRUM principle describes a ubiquitous phenomenon in humans [1,2]. This principle can be interpreted within an energy and frequency model of multisensory neurons' spontaneous activity. In this context, the sensitivity transitions represent the change from spontaneous activity to a firing activity in multisensory neurons. Initially the energy and frequency content of the multisensory neurons' activity (supplied by a weak signal) is not enough to be detected but when the facilitation signal (for example auditory noise or another deterministic signal) enters the brain, it generates a general activation among multisensory neurons of different regions, modifying their original activity. The result is an integrated activation that promotes sensitivity transitions and the signals are then perceived. For instance, by using psychophysical techniques we demonstrate that auditory or tactile noise can enhance the sensitivity of visual system responses to weak signals. Specifically, we show that the effective tactile noise significantly decreased luminance modulated visual thresholds. Because this multisensory facilitation process appears universal and a fundamental property of sensory/perceptual systems, we will call it the multisensory FULCRUM principle. A fulcrum is one that supplies capability for action and we believe that this best describes the fundamental principle at work in these multisensory interactions. [1] Lugo E, Doti R, Faubert J (2008) Ubiquitous Crossmodal Stochastic Resonance in Humans: Auditory Noise Noise Facilitates Tactile, Visual and Proprioceptive Sensations. PLoS ONE 3(8): e2860. doi:10.1371/journal.pone.0002860 [2] Lugo J E, Doti R, Wittich W, Faubert J (2008) Multisensory Integration: Central processing modifies perypheral systems. Psychological Science 19 (10): 989-999.
NSERC-Essilor Chair and NSERC.