Figure 3.

Combined light stimulation and multi-site extracellular recordings from the PFC of neonatal mice in vivo. (Ai) Diagrams illustrating the surgery for electrophysiology in vivo in neonatal mice. The skin is removed from the top of the head and dental cement is applied to strengthen the fragile skull and serve as “glue” for two plastic tubes that enable head fixation. (ii) Photograph showing a head-fixed P10 mouse during combined light stimulation and extracellular recordings in vivo. (Bi) Extracellular recordings (unfiltered local field potentials (LFP), band-pass filtered LFP and MUA) from the PFC of a P10 mouse transfected with ChR2(ET/TC) by IUE at E15.5 in response to light pulses (473 nm, 3 ms) of different intensities. (ii) Same as (i) for a mouse transfected with an opsin-free construct. (Ci) Representative band-pass filtered (1–400 Hz) LFP signals recorded in response to 30 trains of pulsed stimuli (473 nm, 3 ms, 14 mW/mm²) before (Alive) and after a lethal injection of ketamine-xylazine (Dead, Dead scaled) from a neonatal mouse transfected by IUE with ChR2(ET/TC). The LFP trace after removal of photoelectric artifacts was obtained by subtraction of the scaled artifact (Alive-Dead scaled). (ii) Same as (i) for an opsin-free mouse. For (B,C) individual traces are shown in black, averages are shown in gray.