Effects of focal cortical cooling on somatosensory evoked potentials in rats

Mizuho Gotoh; Shinnosuke Dezawa; Ichiro Takashima; Shinya Yamamoto

doi:10.1016/j.brainres.2024.148995

Effects of focal cortical cooling on somatosensory evoked potentials in rats

Brain Res. 2024 May 10:148995. doi: 10.1016/j.brainres.2024.148995. Online ahead of print.

Authors

Mizuho Gotoh¹, Shinnosuke Dezawa², Ichiro Takashima³, Shinya Yamamoto⁴

Affiliations

¹ Department of Information Technology and Human Factors, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan; Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba Japan; Department of Rehabilitation for Brain Functions, Research Institute of National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Japan.
² Department of Information Technology and Human Factors, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan; Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba Japan; Faculty of Medical and Health Sciences, Tsukuba International University, Tsuchiura, Japan.
³ Department of Information Technology and Human Factors, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan; Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba Japan; Department of Informatics and Electronics, Daiichi Institute of Technology, Tokyo, Japan.
⁴ Department of Information Technology and Human Factors, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan; Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba Japan. Electronic address: yamamoto-s@aist.go.jp.

PMID: 38735427
DOI: 10.1016/j.brainres.2024.148995

Abstract

Although the focal brain cooling technique is widely used to examine brain function, the effects of cortical temperature at various levels on sensory information processing and neural mechanisms remain underexplored. To elucidate the mechanisms of temperature modulation in somatosensory processing, this study aimed to examine how P1 and N1 deflections of somatosensory evoked potentials (SEPs) depend on cortical temperature and how excitatory and inhibitory inputs contribute to this temperature dependency. SEPs were generated through electrical stimulation of the contralateral forepaw in anesthetized rats. The SEPs were recorded while cortical temperatures were altered between 17-38 °C either without any antagonists, with a gamma-aminobutyric acid type A (GABA_A) receptor antagonist (gabazine), with aminomethylphosphonic acid (AMPA) receptor antagonist (NBQX), or with N-Methyl-D-aspartic acid (NMDA) receptor antagonist ([R]-CPP). The effects of different gabazine concentrations (0, 1, and 10 µM) were examined in the 35-38 °C range. The P1/N1 amplitudes and their peak-to-peak differences plotted against cortical temperature showed an inverted U relationship with a maximum at approximately 27.5 °C when no antagonists were administered. The negative correlation between these amplitudes and temperatures of ≥ 27.5 °C plateaued after gabazine administration, which occurred progressively as the gabazine concentration increased. In contrast, the correlation remained negative after the administration of NBQX and (R)-CPP. These results suggest that GABAergic inhibitory inputs contribute to the negative correlation between SEP amplitude and cortical temperature around the physiological cortical temperature.

Keywords: Electrophysiology; Focal brain cooling; Gamma-aminobutyric acid; Rat; Somatosensory evoked potential; Temperature.