title: Active, passive, and motor imagery paradigms: component analysis to assess neurovascular coupling.
abstract: The association between neural activity and cerebral blood flow (CBF) has been used to assess neurovascular coupling (NVC) in health and diseases states, but little attention has been given to the contribution of simultaneous changes in peripheral covariates. We used an innovative approach to assess the contributions of arterial blood pressure (BP), PaCO2, and the stimulus itself to changes in CBF velocities (CBFv) during active (MA), passive (MP), and motor imagery (MI) paradigms. Continuous recordings of CBFv, beat-to-beat BP, heart rate, and breath-by-breath end-tidal CO2 (EtCO2) were performed in 17 right-handed subjects before, during, and after motor-cognitive paradigms performed with the right arm. A multivariate autoregressive-moving average model was used to calculate the separate contributions of BP, EtCO2, and the neural activation stimulus (represented by a metronome on-off signal) to the CBFv response during paradigms. Differences were found in the bilateral CBFv responses to MI compared with MA and MP, due to the contributions of stimulation (P < 0.05). BP was the dominant contributor to the initial peaked CBFv response in all paradigms with no significant differences between paradigms, while the contribution of the stimulus explained the plateau phase and extended duration of the CBFv responses. Separating the neural activation contribution from the influences of other covariates, it was possible to detect differences between three paradigms often used to assess disease-related NVC. Apparently similar CBFv responses to different motor-cognitive paradigms can be misleading due to the contributions from peripheral covariates and could lead to inaccurate assessment of NVC, particularly during MI.
authors: Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom. asms2@le.ac.uk
authors: Angela S M
authors: AS
authors: Salinet
authors: Thompson G
authors: TG
authors: Robinson
authors: Ronney B
authors: RB
authors: Panerai
mesh_terms: D001132:Arm / Q000294:innervation; D062186:Arterial Pressure / Q000502:physiology; D001783:Blood Flow Velocity / Q000502:physiology; D001921:Brain / Q000098:blood supply* / Q000378:metabolism / Q000502:physiology*; D002245:Carbon Dioxide / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D009046:Motor Neurons / Q000378:metabolism / Q000502:physiology; D012119:Respiration
chemical_list: D002245:Carbon Dioxide
keywords: cerebral hemodynamics; neurovascular coupling; transcranial Doppler ultrasound