Neurovascular coupling dynamics assessed via transcranial doppler: a comparative study between motor paradigms in healthy individuals

<p dir="ltr">Introduction: Neurovascular coupling (NVC) represents multiple mechanisms that adapt cerebral blood flow to neural activity. This study hypothesized that two NVC paradigms (active hand movement; AHM and active elbow flexion; AEF) would elicit similar hemodynamic responses. Methods: Seventeen healthy subjects (9 females, mean age: 34 ± 3 years) performed both motor paradigms. Each session began with a 1.5-minute rest (baseline), followed by 1 minute of motor paradigm (T1), and a 1.5-minute recovery (T2). Transcranial Doppler (TCD) was used to monitor cerebral blood velocity (CBv) in middle cerebral artery. Arterial blood pressure (ABP), heart rate (HR), and end-tidal CO₂ (EtCO₂) were continuously monitored. Data were analyzed using two-way repeated measures ANOVA (p < 0.05). Results: Both AEF and AHM elicited significant increases in CBv over time (p < 0.05), with similar temporal profiles between paradigms. For AEF, CBv in the dominant hemisphere increased from 100% ± 1 at baseline to 104% ± 4 at T1 (p < 0.05) and returned to 98% ± 4 at T2. Similarly, AHM increased CBv from 100% ± 1 at baseline to 105% ± 6 at T1 (p < 0.05) and 98% ± 4 at T2. Significant reductions in cerebrovascular resistance (CVR) and critical closing pressure (CrCP) were observed at T1 compared to baseline, followed by an increase at T2 (p < 0.05). Heart rate showed significant changes, while resistance area product (RAP), ABP, and ETCO₂ remained stable throughout the experiment. Conclusion: AHM produced hemodynamic responses comparable to AEF, with an increase in CBv through vasodilation via non-myogenic responses. In this study we demonstrated that the maneuver is a valid alternative to AEF in NVC studies.</p>