Mapping cortical excitability in the human dorsolateral prefrontal cortex

• Published in: bioRxiv
• Main Authors: Gogulski, Juha, Cline, Christopher C, Ross, Jessica M, Truong, Jade, Sarkar, Manjima, Parmigiani, Sara, Keller, Corey J
• Format: Journal Article Paper
• Language: English
• Published: United States Cold Spring Harbor Laboratory Press 20.11.2023; Cold Spring Harbor Laboratory
• Edition: 1.2
• Subjects: EEG; Excitability; Magnetic fields; Mapping; Neuroscience; Prefrontal cortex; Transcranial magnetic stimulation; Transcranial magnetic stimulation (TMS); electroencephalography (EEG); TMS-evoked potentials (TEPs); TMS-EEG; dorsolateral prefrontal cortex (dlPFC)
• ISSN: 2692-8205; 2692-8205
• DOI: 10.1101/2023.01.20.524867

To characterize early TEPs anatomically and temporally (20-50 ms) close to the TMS pulse (EL-TEPs), as well as associated muscle artifacts (<20 ms), across the dlPFC. We hypothesized that TMS location and angle influence EL-TEPs, and that EL-TEP amplitude is inversely related to muscle artifact. Additionally, we sought to determine an optimal group-level TMS target and angle, while investigating the potential benefits of a personalized approach. In 16 healthy participants, we applied single-pulse TMS to six targets within the dlPFC at two coil angles and measured EEG responses. Stimulation location significantly influenced EL-TEPs, with posterior and medial targets yielding larger EL-TEPs. Regions with high EL-TEP amplitude had less muscle artifact, and vice versa. The best group-level target yielded 102% larger EL-TEP responses compared to other dlPFC targets. Optimal dlPFC target differed across subjects, suggesting that a personalized targeting approach might boost the EL-TEP by an additional 36%. Early local TMS-evoked potentials (EL-TEPs) can be probed without significant muscle-related confounds in posterior-medial regions of the dlPFC. The identification of an optimal group-level target and the potential for further refinement through personalized targeting hold significant implications for optimizing depression treatment protocols. Early local TMS-evoked potentials (EL-TEPs) varied significantly across the dlPFC as a function of TMS target.TMS targets with less muscle artifact had significantly larger EL-TEPs.Selection of a postero-medial target increased EL-TEPs by 102% compared to anterior targets.