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Block Phenomena During Electric Micro-Stimulation of Pyramidal Cells and Retinal Ganglion Cells
Electric micro-stimulation of the nervous system is a means to restore various body functions. The stimulus amplitude necessary to generate action potentials, the lower threshold (LT), is well characterized for many neuronal populations. However, electric overstimulation above an upper threshold (UT...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Frontiers Media S.A.
2021
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8663762/ https://www.ncbi.nlm.nih.gov/pubmed/34899192 http://dx.doi.org/10.3389/fncel.2021.771600 |
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author | Sajedi, Sogand Fellner, Andreas Werginz, Paul Rattay, Frank |
author_facet | Sajedi, Sogand Fellner, Andreas Werginz, Paul Rattay, Frank |
author_sort | Sajedi, Sogand |
collection | PubMed |
description | Electric micro-stimulation of the nervous system is a means to restore various body functions. The stimulus amplitude necessary to generate action potentials, the lower threshold (LT), is well characterized for many neuronal populations. However, electric overstimulation above an upper threshold (UT) prevents action potential generation and therefore hinders optimal neuro-rehabilitation. Previous studies demonstrated the impact of the UT in micro-stimulation of retinal ganglion cells (RGCs). The observed phenomenon is mostly explained by (i) reversed sodium ion flow in the soma membrane, and (ii) anodal surround block that hinders spike conduction in strongly hyperpolarized regions of the axon at high stimulus intensities. However, up to now, no detailed study of the nature of these phenomena has been presented, particularly for different cell types. Here, we present computational analyses of LT and UT for layer 5 pyramidal cells (PCs) as well as alpha RGCs. Model neurons were stimulated in close vicinity to the cell body and LTs and UTs as well as the ratio UT/LT were compared. Aside from a simple point source electrode and monophasic stimuli also realistic electrode and pulse configurations were examined. The analysis showed: (i) in RGCs, the soma contributed to action potential initiation and block for small electrode distances, whereas in PCs the soma played no role in LTs or UTs. (ii) In both cell types, action potential always initiated within the axon initial segment at LT. (iii) In contrast to a complete block of spike conductance at UT that occurred in RGCs, an incomplete block of spiking appeared in PC axon collaterals. (iv) PC axon collateral arrangement influenced UTs but had small impact on LTs. (v) Population responses of RGCs change from circular regions of activation to ring-shaped patterns for increasing stimulus amplitude. A better understanding of the stimulation window that can reliably activate target neurons will benefit the future development of neuroprostheses. |
format | Online Article Text |
id | pubmed-8663762 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | Frontiers Media S.A. |
record_format | MEDLINE/PubMed |
spelling | pubmed-86637622021-12-11 Block Phenomena During Electric Micro-Stimulation of Pyramidal Cells and Retinal Ganglion Cells Sajedi, Sogand Fellner, Andreas Werginz, Paul Rattay, Frank Front Cell Neurosci Neuroscience Electric micro-stimulation of the nervous system is a means to restore various body functions. The stimulus amplitude necessary to generate action potentials, the lower threshold (LT), is well characterized for many neuronal populations. However, electric overstimulation above an upper threshold (UT) prevents action potential generation and therefore hinders optimal neuro-rehabilitation. Previous studies demonstrated the impact of the UT in micro-stimulation of retinal ganglion cells (RGCs). The observed phenomenon is mostly explained by (i) reversed sodium ion flow in the soma membrane, and (ii) anodal surround block that hinders spike conduction in strongly hyperpolarized regions of the axon at high stimulus intensities. However, up to now, no detailed study of the nature of these phenomena has been presented, particularly for different cell types. Here, we present computational analyses of LT and UT for layer 5 pyramidal cells (PCs) as well as alpha RGCs. Model neurons were stimulated in close vicinity to the cell body and LTs and UTs as well as the ratio UT/LT were compared. Aside from a simple point source electrode and monophasic stimuli also realistic electrode and pulse configurations were examined. The analysis showed: (i) in RGCs, the soma contributed to action potential initiation and block for small electrode distances, whereas in PCs the soma played no role in LTs or UTs. (ii) In both cell types, action potential always initiated within the axon initial segment at LT. (iii) In contrast to a complete block of spike conductance at UT that occurred in RGCs, an incomplete block of spiking appeared in PC axon collaterals. (iv) PC axon collateral arrangement influenced UTs but had small impact on LTs. (v) Population responses of RGCs change from circular regions of activation to ring-shaped patterns for increasing stimulus amplitude. A better understanding of the stimulation window that can reliably activate target neurons will benefit the future development of neuroprostheses. Frontiers Media S.A. 2021-11-26 /pmc/articles/PMC8663762/ /pubmed/34899192 http://dx.doi.org/10.3389/fncel.2021.771600 Text en Copyright © 2021 Sajedi, Fellner, Werginz and Rattay. https://creativecommons.org/licenses/by/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. |
spellingShingle | Neuroscience Sajedi, Sogand Fellner, Andreas Werginz, Paul Rattay, Frank Block Phenomena During Electric Micro-Stimulation of Pyramidal Cells and Retinal Ganglion Cells |
title | Block Phenomena During Electric Micro-Stimulation of Pyramidal Cells and Retinal Ganglion Cells |
title_full | Block Phenomena During Electric Micro-Stimulation of Pyramidal Cells and Retinal Ganglion Cells |
title_fullStr | Block Phenomena During Electric Micro-Stimulation of Pyramidal Cells and Retinal Ganglion Cells |
title_full_unstemmed | Block Phenomena During Electric Micro-Stimulation of Pyramidal Cells and Retinal Ganglion Cells |
title_short | Block Phenomena During Electric Micro-Stimulation of Pyramidal Cells and Retinal Ganglion Cells |
title_sort | block phenomena during electric micro-stimulation of pyramidal cells and retinal ganglion cells |
topic | Neuroscience |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8663762/ https://www.ncbi.nlm.nih.gov/pubmed/34899192 http://dx.doi.org/10.3389/fncel.2021.771600 |
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