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

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 min rest (baseline), followed by 1 min of motor paradigm (T1), and a 1.5 min recovery (T2). Transcranial Doppler 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 and critical closing pressure were observed at T1 compared to baseline, followed by an increase at T2 (p< 0.05). HR showed significant changes, while resistance area product, ABP, and ETCO2remained 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.