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Auditory stimulation enhances thalamic somatosensory high‐frequency oscillations in healthy humans: a neurophysiological marker of cross‐sensory sensitization?
Author(s) -
Restuccia Domenico,
Coppola Gianluca
Publication year - 2015
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.12873
Subject(s) - somatosensory system , neuroscience , habituation , somatosensory evoked potential , psychology , sensitization , stimulation , sensory system , neurophysiology , stimulus (psychology) , sensory stimulation therapy , psychotherapist
Electrical stimulation of upper limb nerves evokes a train of high‐frequency wavelets (high‐frequency oscillations, HFO s) on the human scalp. These HFO s are related to the influence of arousal‐promoting structures on somatosensory input processing, and are generated in the primary somatosensory cortex (post‐synaptic HFO s) and the terminal tracts of thalamocortical radiations (pre‐synaptic HFO s). We previously reported that HFO s do not undergo habituation to repeated stimulations; here, we verified whether HFO s could be modulated by external sensitizing stimuli. We recorded somatosensory evoked potentials ( SSEP s) in 15 healthy volunteers before and after sensitization training with an auditory stimulus. Pre‐synaptic HFO amplitudes, reflecting somatosensory thalamic/thalamocortical activity, significantly increased after the sensitizing acoustic stimulation, whereas both the low‐frequency N 20 SSEP component and post‐synaptic HFO s were unaffected. Cross‐talk between subcortical arousal‐related structures is a probable mechanism for the pre‐synaptic HFO effect observed in this study. We propose that part of the ascending somatosensory input encoded in HFO s is specifically able to convey sensitized inputs. This preferential involvement in sensitization mechanisms suggests that HFO s play a critical role in the detection of potentially relevant stimuli, and act at very early stages of somatosensory input processing.