Introduction
neurological damage, neurologic signs, damages, ataxia
CONSTRICTION, SENSORY DISTURBANCE, AUDITORY DISTURBANCES, SENSORY DISTURBANCES
Methylmercury (MeHg) is a major environmental neurotoxicant that damages the central nervous system depending on the dose and duration of exposure (MD is classified based on the onset time as acute/subacute MD (manifestation during the heavy contamination of seafood with MeHg in the Minamata Bay) and chronic MD (manifestation following the cessation of MeHg excretion). Acute or subacute MD is characterized by marked sensory disturbances in the distal parts of the extremities (“glove and stocking type” sensory disturbance), concentric constriction of visual fields, ataxia, and auditory disturbances. Except for sensory disturbance, neurologic signs are milder and less frequent in chronic MD than in acute or subacute MD (Given that chronic exposure mercury and its compounds can cause irreversible neurological damage and recent increases in environmental mercury emissions, the Minamata Convention on Mercury was held in August 2017, aiming to issue guidance on protecting human health and decreasing anthropogenic mercury emissions (The Clinically, sensory disturbance appears initially (As the “glove and stocking type” sensory disturbances frequently observed in MD (MEG can detect magnetic fields generated by neural currents with marginal distortion owing to differences in conductance at a millisecond temporal resolution (In this study, we aimed to develop a highly sensitive objective assessment for detecting central somatosensory disturbance in patients with chronic MD. We intended to perform single-trial analysis of SEFs using MEG to clarify the pathophysiological mechanisms underlying central somatosensory disturbances in chronic MD. Single-trial epochs were classified into three categories (N20m, non-response, and P20m epochs) based on the cross-correlation between average sensor SEFs and individual epochs. Further, we compared the characteristics of N20m between patients with MD and healthy controls given previous reports of stable N20m latency and amplitude in healthy participants (