IPSPs in layer V cells are strongly coherent with LFPs in the beta range.

<p>(A) Concurrent LFPs from layers V and II, and intracellularly recorded membrane potential (Vm) from a cell in layer V. Oscillations and IPSPs (at −80 mV, optimised for IPSPs) are blocked following application of GABA_A receptor antagonist bicuculline (right panel). (B) Power spectral densities (PSD) of LFPs from layers V and II, and of Vm (with IPSPs), showing 99% significance levels (above red lines) at beta frequencies, and harmonics thereof, which (right panels) are blocked by bicuculline. Vertical dashed lines indicate 27 Hz for reference. Same recordings as (A). (C), upper panel: cross-correlograms of LFPs from layers II (blue) and V (red) with Vm from same recordings as in (A) and (B). Lower panel: normalised, cross-correlated data (means+SEM) between Vm (displaying IPSPs) and LFPs in layer V (red) and layer II (blue) pooled from all 20 recordings showing significant IPSP-LFP coherence in 15–40 Hz range. The IPSP leads layer V peak (red dashed line) by 7.2 ms and layer II peak (blue dashed line) by 20.5 ms. (D) Left column: coherence between each of layer II and layer V LFP (top row), layer II LFP and IPSPs (middle row), and layer V LFP and IPSPs (bottom row) in each case demonstrates single significant (>99%) peaks at beta frequencies, and harmonics thereof, which is abolished by bicuculline (right panels). Same recordings as A, B and C. (E) and (F), data pooled from all recordings within 3 frequency ranges (demarked by vertical dashed lines, with mean ± SEM in red, n in parentheses) showing (E) the distribution of the single largest significant (>99%) power spectrum peaks for Vm (optimised for IPSPs), and (F) peak frequencies of coherence between LII, LV, and Vm (IPSPs).