Fluctuations and stimulus-induced changes in blood flow observed in individual capillaries in layers 2 through 4 of rat neocortex

Kleinfeld, D., Mitra, P. P., Helmchen, F., Denk, W. (1998) Fluctuations and stimulus-induced changes in blood flow observed in individual capillaries in layers 2 through 4 of rat neocortex. Proceedings of the National Academy of Sciences of the United States of America, 95 (26). pp. 15741-15746. ISSN 00278424 (ISSN)

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URL: https://www.ncbi.nlm.nih.gov/pubmed/9861040
DOI: 10.1073/pnas.95.26.15741


Cortical blood flow at the level of individual capillaries and the coupling of neuronal activity to flow in capillaries are fundamental aspects of homeostasis in the normal and the diseased brain. To probe the dynamics of blood flow at this level, we used two-photon laser scanning microscopy to image the motion of red blood cells (RBCs) in individual capillaries that lie as far as 600 μm below the pia mater of primary somatosensory cortex in rat; this depth encompassed the cortical layers with the highest density of neurons and capillaries. We observed that the flow was quite variable and exhibited temporal fluctuations around 0.1 Hz, as well as prolonged stalls and occasional reversals of direction. On average, the speed and flux (cells per unit time) of RBCs covaried linearly at low values of flux, with a linear density of ≃70 cells per mm, followed by a tendency for the speed to plateau at high values of flux. Thus, both the average velocity and density of RBCs are greater at high values of flux than at low values. Time-locked changes in flow, localized to the appropriate anatomical region of somatosensory cortex, were observed in response to stimulation of either multiple vibrissae or the hindlimb. Although we were able to detect stimulus-induced changes in the flux and speed of RBCs in some single trials, the amplitude of the stimulus- evoked changes in flow were largely masked by basal fluctuations. On average, the flux and the speed of RBCs increased transiently on stimulation, although the linear density of RBCs decreased slightly. These findings are consistent with a stimulus-induced decrease in capillary resistance to flow.

Item Type: Paper
Additional Information: PubMed ID: 9861040
Uncontrolled Keywords: animal experiment article blood flow velocity brain blood flow capillary flow erythrocyte hindlimb laser microscopy male neocortex nonhuman pia mater priority journal rat sensory stimulation vibrissa Animals Brain Mapping Capillaries Cerebrovascular Circulation Erythrocytes Neurons Rats Rats Sprague-Dawley Regional Blood Flow Vibrissae
Subjects: organs, tissues, organelles, cell types and functions > organs types and functions > brain
physics > fluid dynamics
Investigative techniques and equipment > microscopy
organism description > animal > mammal > rodent > rat
organism description > animal > mammal > rodent > rat
Investigative techniques and equipment > optical devices > lasers > two-photon excitation laser scanning
CSHL Authors:
Communities: CSHL labs > Mitra lab
Depositing User: CSHL Librarian
Date: 1998
Date Deposited: 04 Apr 2012 20:11
Last Modified: 11 Sep 2019 16:22
Related URLs:
URI: https://repository.cshl.edu/id/eprint/25841

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