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Updated: Jul 9, 2026
09:15
Ex Vivo Pressurized Hippocampal Capillary-Parenchymal Arteriole Preparation for Functional Study
Published on: December 18, 2019
Functional reactivity of cerebral capillaries
Bojana Stefanovic1, Elizabeth Hutchinson, Victoria Yakovleva
1Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland 20892-1065, USA. stefanovicb@ninds.nih.gov
Summary
Cerebral capillaries show significant functional reactivity during brain stimulation, with increased blood flow and volume. These microcirculatory adjustments in capillaries are crucial for understanding brain imaging signals.
Area of Science:
- Neuroscience
- Microcirculation
- Cerebral Blood Flow
Background:
- Functional neuroimaging relies on hemodynamics, but capillary-level responses are poorly understood.
- Capillaries are the vessels closest to active neurons, yet their role in functional hyperemia is unclear.
Purpose of the Study:
- To investigate the spatiotemporal evolution of cerebral microcirculatory adjustments in individual capillaries during functional brain stimulation.
- To determine the contribution of capillary geometry changes to the hemodynamic response.
Main Methods:
- Two-photon laser scanning microscopy
- Intracranial electrophysiology
- Intravital video microscopy in an anesthetized rodent model
Main Results:
- Forepaw stimulation caused decreased vascular transit times (-20%) and capillary dilatation (+10.9%).
- Red blood cell speed (+33%) and flux (+19.5%) significantly increased in capillaries.
- Capillary dilatation contributed ~18% to focal cerebral blood volume changes, exceeding that of larger vessels.
Conclusions:
- Cerebral capillaries exhibit strong functional reactivity, with significant changes in geometry and flow during neuronal activation.
- Capillary geometric changes are important contributors to the overall hemodynamic response to brain activity.
- Findings highlight the critical role of microcirculation in hemodynamically weighted neuroimaging signals.
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