Postoperative Recovery and Stability of Chronic Intracranial Multielectrode Electroencephalography Recording in Rats

Intracranial multi-electrode implantation enables simultaneous acquisition of neural signals across brain regions but introduces post-surgical perturbations that can affect data quality and experimental timing. This protocol describes a standardized workflow for chronic multi-site intracranial EEG electrode implantation and structured post-implantation assessment in Sprague-Dawley rats. Tungsten wire electrodes are stereotactically implanted at three predefined intracranial sites (anterior cingulate cortex, hippocampus CA1, and entorhinal cortex) using a surgical strategy designed to minimize tissue disruption. Following implantation, the protocol specifies longitudinal evaluation across five domains: electrode localization accuracy, local field potential integrity, pain-related behavior, feeding behavior, and neuroinflammatory markers. Electrophysiological and behavioral assessments are conducted at predefined postoperative time points (baseline and postoperative days 1, 4, 7, 10, and 13) to support consistent monitoring of early post-surgical effects (n = 3). Histological analyses are used to characterize local tissue responses at the end of the study (n = 3 per time point). Operational criteria and assessment intervals are provided to guide decisions regarding experimental readiness and initiation of long-term recordings. This protocol provides a structured approach to post-implantation monitoring and informs the appropriate timing of downstream neurophysiological experiments.