Figure 7.
Loss of higher-firing complex spiking cells but normal theta coupling in aged tg mice
(A) Left, distribution charts of complex spiking (CS) and non-CS units for ntg and tg mice (pooled data; one high-firing outlier removed from the ntg non-CS group). Genotype effect: CS, p = 0.3072; non-CS, p = 0.2532. Right, PDF. Red autocorrelograms feature units from a tg mouse (case TO124, 23 months).
(B) As in (A) but separated by region (ProS/SUB and CA1) for CS units only. Genotype-region effect: p = 0.0428.
(C) Two place cells from case TO124: unit (u) 4017 most active toward start of virtual linear track, whereas u3770 most active following reward (Δ) at end of track. Color bars, 1%–99% of linearized firing rate (blue minimum [min.], red maximum [max.]). Insets, theta-phase histogram (20° bins; 180° corresponds to peak shown by red sinusoid).
(D) Spike trains from 6 units (case TO124); non-CS units in bold. Note u1586 and u3770 are rhythmically synchronized after reward. “Teleport,” re-initialization of linear track (new trial). Also note coupling to LFP theta cycles, and spikes corresponding to place field of u4017 from (C).
(E) Distribution chart of coupling strength (vector length, r) for all units. Genotype effect: CS, p = 0.580; non-CS, p = 0.987.
(F) Firing rate during theta versus vector length for individual units. Black, ntg mice; green, tg mice.