English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Open

We examine the properties of the transfer function F_T = V_m / V_{LFP}between the intracellular membrane potential (V_m) and the local fieldpotential (V_{LFP}) in cerebral cortex. We first show theoretically that, inthe subthreshold regime, the frequency dependence of the extracellular mediumand that of the membrane potential have a clear incidence on F_T. Thecalculation of F_T from experiments and the matching with theoreticalexpressions is possible for desynchronized states where individual currentsources can be considered as independent. Using a mean-field approximation, weobtain a method to estimate the impedance of the extracellular medium withoutinjecting currents. We examine the transfer function for bipolar (differential)LFPs and compare to simultaneous recordings of V_m and V_{LFP} duringdesynchronized states in rat barrel cortex in vivo. The experimentally derivedF_T matches the one derived theoretically, only if one assumes that theimpedance of the extracellular medium is frequency-dependent, and varies as1/sqrt(omega) (Warburg impedance) for frequencies between 3 and 500 Hz. Thisconstitutes indirect evidence that the extracellular medium is non-resistive,which has many possible consequences for modeling LFPs.

Evidence for frequency-dependent extracellular impedance from the transfer function between extracellular and intracellular potentials