Stochastic Resonance within the Somatosensory System: Effects of Noise on Evoked Field Potentials Elicited by Tactile Stimuli

Abstract

Stochastic resonance (SR) is commonly understood to be the enhancement, by noise, of the response of a system to a weak input signal. The aim of this study was to demonstrate the occurrence of SR in spinal and cortical evoked field potentials (EFPs) elicited by periodic tactile stimuli in the anesthetized cat. The electrodes were positioned in spinal and cortical somatosensory regions in which the largest negative EFPs were detected. The periodic tactile stimuli consisted of local skin displacements on the central pad of the hindpaw. Two series of experiments were performed. First, periodic tactile stimuli and the noisy tactile stimuli were applied with the same indenter. Second, noisy tactile stimuli were applied with an additional indenter placed on the glabrous skin of the third hindpaw digit. This last protocol ensured that the signal and noise were mixed not in the skin but in the somatosensory regions of the CNS. All cats showed distinct SR behavior at the spinal and cortical stages of the sensory encoding. Such SR was abolished in the cortical but not in the spinal recording after sectioning of the dorsal columns and the ipsilateral dorsolateral funiculus. This suggests that the spinal neurons may also contribute to the SR observed at the cortical level. To the best of our knowledge, this is the first documented evidence that such a remarkable phenomenon embodies electrical processes of the spinocortical somatosensory system itself.

Effect of mechanical tactile noise on amplitude of visual evoked potentials: multisensory stochastic resonance

“…Our present study as well as other studies published by Lugo et al (2012), Mendez-Balbuena et al (2012), Trenado et al (2014a, 2014b), and Malacuso et al (2000 suggest that in the near future it will be possible to develop and design new devices that enable the use of multisensory SR in the visuotactile modality for human sensorimotor enhancement and rehabilitation purposes. For instance, Mendez-Balbuena et al (2012) and Trenado et al (2014a) suggested that multisensory SR could be employed to improve visuomotor human performance in easy, noninvasive ways.…”

“…We employed a sample of eight subjects, as in our previous study (Mendez-Balbuena et al 2012), because the results obtained here were also clear and consistent within and across subjects. To exclude cyclic ovarian effects on cortical excitability and oscillatory cortical activity, the female subjects were in different menstrual phases (Smith et al 2002).…”

“…The output of a noise generator (model 132, Wavetek, San Diego, CA) provided input to a closed-loop mechanical stimulator-transducer (Chubbuck 1966), which allowed measurements of the force and displacement of the applied stimuli. This method of tactile stimulation was previously reported by our laboratory (Manjarrez et al 2002(Manjarrez et al , 2003.…”

“…SR-type effects have been demonstrated in physical and biological systems (Moss et al 2004). Commonly, SR has been studied in diverse sensory systems in which the signal and noise applied were of the same sensory modality (Aihara et al 2010;Collins et al 1996;Lindner et al 2004;Long et al 2004;Manjarrez et al 2002Manjarrez et al , 2003Mori and Kai 2002;Segundo et al 1994;Simonotto et al 1997;Winterer et al 1999;Zeng et al 2000); however, there are a few studies addressing the influence of noise within one sensory modality on the responses elicited by stimuli of another modality. The purpose of the present study was to analyze changes in the amplitude of visual evoked potentials (VEPs) when a continuous tactile noise was applied on the index finger.…”

“…In our recent studies, we demonstrated that an optimum level of tactile noise applied on the finger can improve the performance of a visuomotor task in which the subjects had to compensate a target force isometrically in order to keep a visual feedback (Mendez-Balbuena et al 2012;Trenado et al 2014a). A question derived from these studies is whether a multisensory SR in the visual and tactile modalities is also involved.…”