FIGURE 10.2. Point source paradigm for diffusion studies.

FIGURE 10.2

Point source paradigm for diffusion studies. Glass micropipette (source micropipette) is filled with extracellular probe molecules that are released to the ECS by passing current (iontophoretic delivery of small charged molecules) or by pressure injection (any molecule). The diameter of micropipette tip is small, ≈3–6 μm; the micropipette therefore is a good approximation of point source (large black circle). Released molecules diffuse through the ECS (lines with arrowheads) around cellular elements and possibly other diffusion barriers. Some molecules may be removed from the ECS at uptake sites (black dots). The diffusion of molecules is recorded by appropriate sensors (see text for details). (Reproduced from Nicholson and Syková, E., Trends Neurosci., 21, 207–215, 1998.)

From: Chapter 10, Biophysical Properties of Brain Extracellular Space Explored with Ion-Selective Microelectrodes, Integrative Optical Imaging and Related Techniques

Cover of Electrochemical Methods for Neuroscience
Electrochemical Methods for Neuroscience.
Michael AC, Borland LM, editors.
Boca Raton (FL): CRC Press/Taylor & Francis; 2007.
Copyright © 2007, Taylor & Francis Group, LLC.

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