Microscale Inhomogeneity of Brain Tissue Distorts Electrical Signal Propagation
Journal of Neuroscience. 2013-02-13; 33(7): 2821-2827
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1. J Neurosci. 2013 Feb 13;33(7):2821-7. doi: 10.1523/JNEUROSCI.3502-12.2013.
Microscale inhomogeneity of brain tissue distorts electrical signal propagation.
Nelson MJ(1), Bosch C, Venance L, Pouget P.
(1)Centre de Recherche de l’Institut du Cerveau et de la Moelle Epinière, Inserm
UMRS 975, CNRS 7225, Université Pierre et Marie Curie, Hôpital de la Salpêtrière,
75651 Paris, France.
Interpretations of local field potentials (LFPs) are typically shaped on an
assumption that the brain is a homogenous conductive milieu. However, microscale
inhomogeneities including cell bodies, dendritic structures, axonal fiber bundles
and blood vessels are unequivocally present and have different conductivities and
permittivities than brain extracellular fluid. To determine the extent to which
these obstructions affect electrical signal propagation on a microscale, we
delivered electrical stimuli intracellularly to individual cells while
simultaneously recording the extracellular potentials at different locations in a
rat brain slice. As compared with relatively unobstructed paths, signals were
attenuated across frequencies when fiber bundles were in between the stimulated
cell and the extracellular electrode. Across group of cell bodies, signals were
attenuated at low frequencies, but facilitated at high frequencies. These results
show that LFPs do not reflect a democratic representation of neuronal
contributions, as certain neurons may contribute to the LFP more than others
based on the local extracellular environment surrounding them.
PMID: 23407941 [Indexed for MEDLINE]