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bioRxiv · 10.1101/2020.04.23.056655

Multi-day rTMS exerts site-specific effects on functional connectivity but does not influence associative memory performance

Hendrikse, J. J.·Coxon, J. P.·Thompson, S.·Suo, C.·Fornito, A.·Yucel, M.·Rogasch, N.
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Abstract

Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation technique with the capacity to modulate brain network connectivity and cognitive function. Recent studies have demonstrated long-lasting improvements in associative memory and resting-state connectivity following multi-day repetitive TMS (rTMS) to individualised parietal-hippocampal networks. We aimed to assess the reproducibility and network- and cognitive-specificity of these effects following multi-day rTMS. Participants received four days of 20 Hz rTMS to a subject-specific region of left lateral parietal cortex exhibiting peak functional connectivity to the left hippocampus. In a separate week, the same stimulation protocol was applied to a subject-specific region of pre-supplementary motor area (pre-SMA) exhibiting peak functional connectivity to the left putamen. We assessed changes to associative memory before and after each week of stimulation (N = 39), and changes to resting-state functional connectivity before and after stimulation in week one (N = 36). We found no evidence of long-lasting enhancement of associative memory or increased parieto-hippocampal connectivity following multi-day rTMS to the parietal cortex, nor increased pre-SMA-putamen connectivity following multi-day rTMS to pre-SMA. Instead, we observed some evidence of site-specific modulations of functional connectivity lasting [~]24 hours, with reduced connectivity within targeted networks and increased connectivity across distinct non-targeted networks. Our findings suggest a complex interplay between multi-day rTMS and network connectivity. Further work is required to develop reliable rTMS paradigms for driving changes in functional connectivity between cortical and subcortical regions.

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Hendrikse, J. J., Coxon, J. P., Thompson, S., Suo, C., Fornito, A., Yucel, M., Rogasch, N.. 2020-04-25. Multi-day rTMS exerts site-specific effects on functional connectivity but does not influence associative memory performance. https://doi.org/10.1101/2020.04.23.056655

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