With the 1.27mm diameter of DBS electrodes often leading to the development of scar tissue, and evidence that electrodes with diameters near the size of neurons, approximately 30 microns, are less likely to induce such scaring, can stimulating electrodes of that size or smaller be expected to perform as well as current DBS electrodes? Is there a minimum optimal diameter for neural stimulating electrodes?
http://news.mit.edu/2017/making-brain-implants-smaller-prolong-lifespan-0516
Hi Cody Crutchfield
The size of the electrode alone prevents a precise stimulation of only the appropriate neurons. Since most neurons are about 20 µm in diameter, a stimulatory electrode larger than this size will stimulate multiple neurons and nearby axons. The large size also limits the number of electrodes that can be placed in the brain and increases the risk of brain haemorrhaging at the site of insertion.
The body’s foreign-body response compounds complications as inflammatory cells adhere to and ultimately encapsulate the electrode in proteins and fibrous scar tissue. scar tissue both disrupts the electrode’s intended electrolytic functions and inhibits neurite growth in the surrounding area. (see page 296).
Also, a small (600 nm diameter) platinum electrodes is inserted into the bloodstreams and gets carried to the brain intravascularly. (see page 297).
For more details Please See this book, page 296 and 297
Biomedical Nanosensors
Edited by Joseph M.Irudayaraj
Also,
Smaller diameter electrodes (500 µm) were more selective for recording from local cells over passing axons, with the opposite true for larger diameters (1500 µm). Changes in electrode dimensions had phase-dependent effects on Evoked compound action potentials (ECAP) characteristics, and generally had small effects on the local field potentials (LFP) magnitude.
Please see this reference
Analysis of deep brain stimulation electrode characteristics for neural recording.
J Neural Eng. 2014 Aug;11(4):046010. doi: 10.1088/1741-2560/11/4/046010. Epub 2014 Jun 12.
Kent AR1, Grill WM.
Thank you
Look into Buitenweg JR 1998 Med Biol Eng comput 36: 630-637, Rutten WLC 1999 IEEE engin med biol magazine 18: 47-55. Buitenweg JR IEEE engin med biol 2000 pp 46-52 and Rutten WLC Proc IEEE 89 : 1013-1029.
or contact Jan Buitenweg: J [email protected]
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