Figure 3.
Working memory is correlated with 4-Hz modulation of gamma power. (A) Wideband (1 Hz-1250 Hz) and filtered (30-80 Hz) LFP from PFC. Red line indicates the envelope of gamma amplitude fluctuation. Color panels, time-resolved coherence spectra between the LFP and gamma envelope in the working memory and control sessions in a single rat. Right panels, group data of LFP vs gamma envelope coherence in the memory (magenta) and control (green) tasks. Note opposite changes of LFP vs gamma envelope in the 4-Hz and theta bands in both memory and control tasks. Horizontal magenta and green lines above panels, significant group differences (P<0.01 for PFC gamma, P<0.05 for VTA gamma; permutation test; Fujisawa et al., 2008; spurious coupling subtracted). (B) Gamma trough-triggered LFP in the central and side arms in both tasks. Note strongest phase-locking of gamma waves to the ascending phase 4-Hz oscillation in the central arm of the memory task (upper left).