title: Microscale inhomogeneity of brain tissue distorts electrical signal propagation.
abstract: 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.
authors: 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. matthew.nelson@icm-institute.org
authors: Matthew J
authors: MJ
authors: Nelson
authors: Clémentine
authors: C
authors: Bosch
authors: Laurent
authors: L
authors: Venance
authors: Pierre
authors: P
authors: Pouget
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology; D001808:Blood Vessels / Q000502:physiology; D001921:Brain / Q000166:cytology / Q000502:physiology*; D003712:Dendrites / Q000502:physiology; D004558:Electric Stimulation; D055724:Electrophysiological Phenomena / Q000502:physiology*; D005110:Extracellular Space / Q000502:physiology; D005260:Female; D007091:Image Processing, Computer-Assisted; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D009412:Nerve Fibers / Q000502:physiology; D009457:Neuroglia / Q000502:physiology; D018408:Patch-Clamp Techniques; D051381:Rats