Age-related changes in carbachol-induced gamma oscillations.

A. Coherent gamma oscillations recorded from stratum pyramidale of CA3c (black) and mid-distal CA1 (blue-adult; magenta-aged) of hippocampal slices exposed to bath-applied carbachol (10 µM) for 45–90 minutes. The traces were recorded from three different mice per age group. B. Power spectral density in CA3 (top) and CA1 (bottom). Power was significantly reduced in area CA3, but not area CA1, of aged slices. C. Magnitude squared coherence (MSC) estimates revealed significantly reduced gamma coherence as well as an increased CA3–CA1 phase difference in slices from aged mice. The Inset shows phase coherence in the 20–50 Hz frequency band, with mean MSC as the vector lengths and circular mean phase coherence as the vector angles. Dashed line represents the 95% significance threshold (r = 0.12). Error bands are SEM or circular SEM.