Test-retest reliability of intrahemispheric dorsal premotor and primary motor cortex dual-site TMS connectivity measures

Objective: Investigating the optimal interstimulus interval (ISI) and the 24 -hour test-retest reliability for intrahemispheric dorsal premotor cortex (PMd) - primary motor cortex (M1) connectivity using dual -site transcranial magnetic stimulation (dsTMS). Methods: In 21 right-handed adults, left intrahemispheric PMd-M1 connectivity has been investigated with a stacked -coil dsTMS setup (conditioning stimulus: 75% of resting motor threshold; test stimulus: eliciting MEPs of 1-1.5 mV) at ISIs of 3, 5-8, and 10 ms. Additionally, M1-M1 short -interval intracortical inhibition (SICI) and intracortical facilitation (ICF) were investigated to assess comparability to standard paired -pulse setups. Results: Conditioning PMd led to significant inhibition of M1 output at ISIs of 3 and 5 ms, whereas 10 ms resulted in facilitation (all, p < 0.001), with a fair test-retest reliability for 3 (ICC: 0.47) and 6 ms (ICC: 0.44) ISIs. Replication of SICI (p < 0.001) and ICF (p = 0.017) was successful, with excellent test-retest reliability for SICI (ICC: 0.81). Conclusion: This dsTMS setup can probe the inhibitory and facilitatory PMd-M1 connections, as well as reliably replicate SICI and ICF paradigms. Significance: The stacked -coil dsTMS setup for investigating intrahemispheric PMd-M1 connectivity offers promising possibilities to better understand motor control. (c) 2024 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.