Figure 5: Generation of discontinuous patterns of oscillatory activity in the neonatal prelimbic cortex in response to optogenetic activation of layer II/III pyramidal neurons in vivo.

(a) Characteristic light-induced (ramp stimulus, 473 nm, 3 s) discontinuous oscillatory activity from a P10 mouse after transfection of layer II/III pyramidal neurons with ChR2(ET/TC) by IUE. The LFP is displayed before (top) and after band-pass filtering (4–100 Hz) (middle) together with the corresponding colour-coded wavelet spectrum at identical timescale. (b) Bar diagrams displaying the LFP power during the first half (1.5 s), the second half (1.5 s) and after (post, 1.5 s) ramp stimulus when normalized to the power before stimulation (pre, 1.5 s). Network activity in theta (θ, 4–12 Hz), beta (β, 12–30 Hz) and gamma (γ, 30–100 Hz) frequency bands (n=9 pups) was considered. (c) Polar plots displaying the phase-locking of light-triggered (blue, stimulation 3 s, post 3 s) and spontaneous (grey) MUA to oscillatory activity from layer II/III ChR2(ET/TC)-transfected mice (n=21 recording sites from 9 pups). Bar diagrams display the locking strength. (d) Same as (c) for SUA (n=50 units from 9 pups). For (b) individual values corresponding to pups with light-induced oscillations are displayed as black crosses. For (c,d) the values from individual units are shown as blue and grey dots, whereas the arrows correspond to the mean resulting group vectors. Data are presented as mean±s.e.m. *P<0.05, **P<0.01, two-sided t-tests and circular statistics toolbox.