AUTHOR=Nuernberger Matthias , Schaller Denise , Klingner Carsten , Witte Otto , Brodoehl Stefan 

TITLE=Acoustic Stimuli Can Improve and Impair Somatosensory Perception

JOURNAL=Frontiers in Neuroscience

VOLUME=Volume 16 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2022.930932

DOI=10.3389/fnins.2022.930932

ISSN=1662-453X

ABSTRACT=The integration of stimuli from different sensory modalities forms the basis for human perception. While the relevant impact of visual stimuli on the perception of other sensory modalities is recognized, much less is known about the impact of auditory stimuli on general sensory processing. This study aims to investigate the effect of acoustic stimuli on the processing of somatosensory stimuli using real (i.e., unpleasant everyday noise) and neutral white noise. To this purpose, we studied 20 healthy human subjects between 20 and 29 years of age (mean: 24, SD: ±1.9 years sex ratio 1:1). Somatosensory perception was evaluated using mechanical detection threshold (MDT) of the skin on the back of the dominant hand. To investigate the underlying mechanisms in the brain, fMRI was performed while applying acoustic stimulation (real and white noise) and tactile stimulation of the dominant hand. Here we show that acoustic stimulation with noise alters the perception of touch on the skin. We found that the effect of real noise and white noise differed. Real noise leads to an improved tactile perception, whereas white noise impaired tactile perception. These perceptual changes go along with significant changes in brain activity and connectivity. White noise is associated with a significant increase in brain activity in multiple brain areas such as the auditory and somatosensory cortex, parietal association cortex, and the thalamus compared to real noise. With tactile stimulation of the skin, the flow of information in these brain areas changes. While with real noise the information flow from the thalamus to the somatosensory cortex is prominent, the network activity pattern changes under white noise revealing an increase in interaction between multiple networks. Unpleasant noise inhibits the multisensory integration and enables a more efficient unimodal perception in the somatosensory system, improving perception. Whether this is to be interpreted as a temporary increase in phasic alertness or by a stronger filter function of the thalamus with a preference for unimodal stimuli is still open for debate.