In 57 mice, LFP Granger influence in visual cortex went from lower to higher anatomical areas in all bands from 3 to 120 Hz; beta was not a feedback band

Question: does the primate rule that gamma carries feedforward and beta carries feedback influence apply to the mouse visual hierarchy? We used Allen Visual Coding Neuropixels LFP from 57 mice (LGd, six visual cortical areas, LP) in gray-screen, drifting-grating and natural-movie conditions. We measured pairwise spectral Granger causality on 80 um local bipolar signals and compared the directed asymmetry index (DAI) with the Harris et al. (2019) anatomical hierarchy. For all pairs, DAI from the lower to the higher area was above zero in all 15 band x condition tests (p <= 0.007 across mice). Within visual cortex, DAI was 0.23 to 0.33 in gratings (3 to 80 Hz) and increased with hierarchy distance (rho about +0.2). The rank of the six areas by received DAI was exactly the anatomical order in five gratings or movie tests (exact p = 0.003). Beta had a larger feedforward asymmetry than gamma; no band showed net feedback. Running decreased theta to beta asymmetry but not gamma asymmetry. Shuffle, time-reversal, same-layer and no-V1 controls kept the result. LGd and LP did not follow their anatomical scores. Main limitation: unipolar LFP gave feedback-like beta DAI in spontaneous activity, and a CSD-like derivation gave DAI near zero, so the result depends on the signal derivation.

Granger causality · visual hierarchy · feedforward · feedback · beta oscillation · gamma oscillation · local field potential · Allen Brain Observatory · Neuropixels · mouse visual cortex · structure-function