LAYER-SPECIFIC ECOG BIOMARKERS OF COLUMNAR INPUT-OUTPUT STAGES SHIFT WITH COGNITIVE ENGAGEMENT

How is sensory information transferred and broadcast across cortical areas? We investigated the mechanisms of perceptual readout from primary sensory cortex by combining patterned whisker stimulation, mesoscale µECoG recordings (~columnar resolution), and optogenetic perturbations in mice. In the first series of experiments, we optogenetically suppressed superficial (L2/3) or deep (L5) populations of pyramidal neurons during whisker-evoked responses. L5 inhibition strongly reduced the high-gamma (65–170 Hz) component of early sensory responses, whereas L2/3 inhibition primarily attenuated theta-beta (4–30 Hz) activity. This indicates a frequency-specific segregation of columnar input (low-frequency) and output (high-frequency) processes in ECoG signals. In ongoing work, we relate mesoscale ECoG dynamics to behavioral readout. Mice integrate sequential whisker inputs over a temporal window of ~150 ms, beyond which delayed inputs fail to summate perceptually. In awake mice, ECoG signals show state-dependent shifts from low- to high-frequency activity with increasing cognitive engagement, coupled with enhanced sensory-evoked high gamma. We are investigating whether these state changes reflect transitions from input to output processing modes.