Mismatch negativity-like responses in nitroglycerin-elicited migraine model.

Mismatch negativity (MMN) is an endogenous event-related potential that reflects automatic information processing of the brain and exhibits alterations in latency and amplitude across various pathological conditions. The investigation of MMN-like responses in animal models has provided significant insights into the neural underpinnings of aberrant change-detection mechanisms. This study aims to investigate MMN-like responses in rat models of nitroglycerin (NTG)-induced migraine, to determine whether these responses resemble MMN alterations observed in migraine patients, and to explore novel tools for assessing cortical function in animal models of migraine. Male Wistar rats were assigned to two groups: an NTG-treated group, which received intermittent intraperitoneal injections of nitroglycerin to induce a migraine-like state, and a control group, which received equal volumes of saline. The classical oddball paradigm was employed as the stimulation protocol, and electroencephalography (EEG) signals were recorded concurrently. The latency and amplitude of MMN-like responses were compared between the NTG and control groups. During modeling, the mechanical threshold of rats in the NTG group gradually decreased over time, indicating the development of nociceptive hypersensitivity. Moreover, the mechanical threshold was significantly different from that of the control group on days 3, 5, 7, and 9 of drug administration. The latency in the NTG group exhibited an overall trend toward shortening compared with the control group, with significant differences observed between the second and third assays. The amplitude showed an overall upward trend compared with the control group, with significant differences detected in the third assay. Rats in the NTG group exhibited accelerated information processing and heightened cortical excitability during auditory stimulation, a finding consistent with observations in migraine patients.