Distinct neocortical mechanisms underlie human SI responses to median nerve and laser-evoked peripheral activation

• DOI: 10.1162/imag_a_00095
• Publication Date: 2024-02-06T00:32:31Z
• Authors: Ryan V. Thorpe; Christopher J. Black; David A. Borton; Li Hu; Carl Y. Saab; Stephanie R. Jones
• Keywords: 03 medical and health sciences; 0302 clinical medicine

Abstract Magneto- and/or electro-encephalography (M/EEG) are non-invasive clinically relevant tools that have long been used to measure electromagnetic fields in the somatosensory cortex evoked by innocuous and noxious stimuli. Two commonly applied stimulation paradigms produce distinct responses primary (SI) linked sensations electrical median nerve (MN) cutaneous laser-evoked (LE) dorsum of hand, respectively. Despite their prevalence, physiological mechanisms stereotypic macroscale MN LE yet be fully articulated, limiting utility understanding brain dynamics associated with non-painful painful somatosensation. Through a literature review, we detailed features source-localized SI robust reproducible across studies. We showed first peak response at ~20 ms post-stimulus (i.e., N1) corresponds upward-directed deep-to-superficial current flow through cortical laminae, which is followed downward-directed ~30 P1). In contrast, initial occurs later ~170 directed downward opposite direction N1. then examined neocortical circuit contributing each using Human Neocortical Neurosolver (HNN) neural modeling software tool (Neymotin et al., 2020). Using HNN as hypothesis development testing tool, model results predicted can simulated sequence layer-specific thalamocortical cortico-cortical synaptic drive similar previously reported for tactile (S. R. Jones 2007; Neymotin 2020), novel discovery an early excitatory input supragranular layers essential mechanism P1. Model further N1 was generated burst repetitive gamma-frequency (~40 Hz) layers, consistent prior reports activity. These make multiscale predictions about dynamic laminar underlying temporal spectral guide investigations follow-up Ultimately, these findings may help targeted therapeutics pathological somatosensation, such somatic sensitivity acute neuropathic pain.