Figure 7.

Weak modulation of subicular unit firing by theta oscillations. (A) Representative 5-s snapshot during a choice trial of the NOR task showing, from top to bottom, an epoch of novel object exploration (N), and epoch of familiar object exploration (F), the unfiltered neural activity (Raw), the band-pass (4–12 Hz) neural activity (Filtered), and raster plots for the firing of five single DS cells. (B) Rose diagram showing the firing of a DS unit with respect to theta phase, collected during a 5-min choice trial. In this diagram, 90° is the theta trough and 270° is the theta peak. This unit exhibits a highly dispersed theta phase distribution with a mean of 195 ± 118° (Rayleigh test; Z = 0.12, p = 0.89), indicating poor phase locking to the theta oscillation. (C) Distribution of spike times across theta phases (mean ± SEM) for a representative DS cell over multiple trials indicates weak phase locking.