Influence of cardiac phase on corticospinal excitability (TMS input-output curves)

• Corticospinal excitability is influenced by cardiac phase; insights come from TMS input-output curves.¹
• The relationship informs brain–body timing and core electrophysiology (NeuroImage, Volume 328).^{1 1}

Gardner updates

• Input-output curves show influence of cardiac phases on cortico-spinal excitability (Di Luzio et al., NeuroImage). ¹

Weekly enrichment (2026-07-20)

• The study (Di Luzio, Perrucci, Ferri & Costantini, NeuroImage vol. 328, 2026) tested whether the cardiac cycle modulates corticospinal excitability by combining electrophysiology with TMS over the left primary motor cortex (lM1) in healthy participants.^{2 3}
• Rather than single-intensity probes, the authors modelled full motor-evoked-potential (MEP) input-output (I/O) curves separately for systole and diastole to characterize excitability across stimulation intensities.^{2 3}
• The I/O curves showed greater inhibition of corticospinal excitability during systole, with decreased MEP amplitudes at maximal stimulation intensities and a diminished corticomotor gain.^{2 3}
• A trial-by-trial analysis linked MEP amplitude negatively to cardiac output strength, indexed by interbeat-interval (IBI) length, indicating heartbeat-to-heartbeat modulation of excitability.^{2 3}
• The authors argue accounting for cardiac phase can reduce variability in TMS and electrophysiology experiments, improving reproducibility of excitability measures.^{2 3}
• Clinically, they suggest timing non-invasive brain stimulation or neurorehabilitation to higher-excitability phases (e.g., diastole) could enhance treatment efficacy and motor recovery, relevant to stroke rehabilitation.^{2 3}
• The systolic-inhibition result aligns with seminal proposals that cardiac-contraction signals dampen brain activity, but contrasts with other TMS work (e.g., a PLOS Biology study) reporting corticospinal excitability is highest during systole, underscoring that the direction of the effect remains debated.^{2 4}
• Prior TMS studies also diverge, with at least one real-time EKG-EMG study finding no significant effect of cardiac phase on MEP amplitude or variability, so the field has not converged on a consistent heart-brain excitability relationship.^{4 5}

Footnotes

1. https://www.sciencedirect.com/science/article/pii/S1053811926001072?dgcid=rss_sd_all ↩ ↩² ↩³ ↩⁴

2. https://doi.org/10.1016/j.neuroimage.2026.121789 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷

3. https://pubmed.ncbi.nlm.nih.gov/41655612/ ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

4. https://doi.org/10.1371/journal.pbio.3002393 ↩ ↩²

5. https://doi.org/10.1016/j.brs.2020.12.009 ↩