Fig. 5: Thalamocortical evoked synaptic responses in freely behaving animals

(A) AAV-Chr2-mCherry viral expression targeted to dLGN projects to V1. Left, coronal slice showing viral expression in magenta. Right, visual cortex showing neuronal nuclei marked with NeuN and ChR2-mCherry in magenta. (B) Evoked fEPSPs recorded with a linear silicon array show clear layer-specific waveforms consistently with TC afferent location. (C) Current source density heat plot identifies layers; cool colors indicate current sink. (D) FEPSP latency to first negative peak identifies layers. Red circles represent latency of individual events; black line represents mean for each channel. (E) FEPSPs recorded over 3 days in a single freely behaving animal. Amplitude of the response plotted and colored by brain state. Dark periods (lights off) are represented by grey rectangles. (F) fEPSP waveforms by brain state, where each waveform is from a different animal; normalized to QW peak (indicated by dashed line) for each animal. Scale bar, 50% of peak amplitude, 10 ms. (G) FEPSP amplitudes across circadian time, normalized to quiet wake in the light period. N = 4 animals.