Effect of mechanical tactile noise on the amplitude 1 of visual evoked potentials : Multisensory 2 stochastic resonance

40 The present investigation documents the electrophysiological occurrence of 41 multisensory stochastic resonance in the human visual pathway elicited by tactile 42 noise. We define multisensory stochastic resonance of brain evoked potentials as 43 the phenomenon in which an intermediate level of input noise of one sensory 44 modality enhances the brain evoked response of another sensory modality. Here 45 we examined this phenomenon in visual evoked potentials (VEP) modulated by the 46 addition of tactile noise. Specifically, we examined whether a particular level of 47 mechanical Gaussian noise applied to the index finger can improve the amplitude 48 of the VEP. We compared the amplitude of the positive P100 VEP component 49 between zero noise (ZN), optimal noise (ON) and high mechanical noise (HN). The 50 data disclosed an inverted U-like graph for all the subjects, thus demonstrating the 51 occurrence of a multisensory stochastic resonance in the P100 VEP. 52