title: Bi-phasic activation of the primary motor cortex by pain and its relation to pain-evoked potentials - an exploratory study.
abstract: The primary motor cortex (M1) is a known target for brain stimulation aimed at pain alleviation in chronic pain patients, yet the mechanisms through which analgesia occurs, and the exact pain-motor interrelations are not fully understood. We used noxious contact heat evoked potentials (CHEPs) and cortical source analysis to further explore the relevance of M1 in pain processing. Twenty-four healthy young females received brief noxious heat stimuli to their left non-dominant volar forearm, simultaneously with CHEPs recordings. Thereafter, the pain-evoked activity of M1 and a control area in the occipital cortex (OC) was analyzed and estimated using sLORETA (standardized low-resolution brain electromagnetic tomography). This analysis revealed two phases of M1 pain-evoked activation (phase 1: the peak at 261.5±25.7ms; phase 2: the peak at 381.3±28.3ms). Canonical correlations revealed that M1, but not the OC, was the main factor contributing to the relation with the CHEPs components. In detail, the activity magnitude of M1 first and second phases was related to the N2 and P2 amplitude, respectively. The latency of the second phase was associated with both N2 and P2 latencies. In relation to pain, the latency of M1's first activity phase was positively correlated with pain ratings, suggesting pain interference to synchronized activity in M1. Our results confirm the established relevance of the primary motor cortex to pain processing.
authors.affiliation: Department of Psychology, University of Haifa, Haifa, Israel.
authors.forename: Lee-Bareket
authors.initials: LB
authors.lastname: Kisler
authors.affiliation: Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa, Israel.
authors.forename: Irit
authors.initials: I
authors.lastname: Weissman-Fogel
authors.affiliation: Department of Neurology, Rambam Health Care Campus, Haifa, Israel; Department of Neurosurgery, Rambam Health Care Campus, Haifa, Israel.
authors.forename: Alon
authors.initials: A
authors.lastname: Sinai
authors.affiliation: Department of Neurology, Rambam Health Care Campus, Haifa, Israel.
authors.forename: Elliot
authors.initials: E
authors.lastname: Sprecher
authors.affiliation: Department of Neurosurgery, Rambam Health Care Campus, Haifa, Israel; Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Andrei V
authors.initials: AV
authors.lastname: Chistyakov
authors.affiliation: Department of Psychology, University of Haifa, Haifa, Israel.
authors.forename: Simone
authors.initials: S
authors.lastname: Shamay-Tsoory
authors.affiliation: Department of Psychology, University of Haifa, Haifa, Israel.
authors.forename: Nadav
authors.initials: N
authors.lastname: Moscovitz
authors.affiliation: Laboratory of Clinical Neurophysiology, Technion Faculty of Medicine, Haifa, Israel; Department of Neurology, Rambam Health Care Campus, Haifa, Israel. Electronic address: y_granovsky@rambam.health.gov.il.
authors.forename: Yelena
authors.initials: Y
authors.lastname: Granovsky
mesh_terms: D000328:Adult; D004569:Electroencephalography; D005071:Evoked Potentials; D005260:Female; D006358:Hot Temperature; D006801:Humans; D009044:Motor Cortex / Q000503:physiopathology*; D009778:Occipital Lobe / Q000503:physiopathology; D010146:Pain / Q000503:physiopathology*; D010147:Pain Measurement; D058748:Pain Perception / Q000502:physiology*; D011601:Psychophysics; D055815:Young Adult
keywords: Canonical correlation; Contact heat evoked potentials (CHEPs); Pain psychophysics; Primary motor cortex (M1); Standardized low-resolution brain electromagnetic tomography (sLORETA)