Figure 1: Amyloid beta peptides inhibit carbachol-induced hippocampal theta oscillatory activity. (a) Representative recordings (left) and the corresponding power spectra (right) of hippocampal population activity recorded in control conditions (upper trace and power spectrum) after bath application of carbachol (Cch 20 µM; middle trace and power spectrum) and after the application of atropine 1 µM (lower trace and power spectrum). The graph on the right shows the quantification of the integrated spectral power from 4 to 12 Hz. Note that the addition of Cch induces atropine-sensitive rhythmic oscillations that increase the power of the hippocampal population activity. (b) Representative recordings (left) and the corresponding power spectra (right) of hippocampal population activity recorded in the presence of carbachol 20 µM (upper trace and power spectrum) and after bath application of 1 µM (lower trace and power spectrum). The graph on the right shows the quantification of the integrated spectral power from 4 to 12 Hz before and after bath application of [0.5 µM] and [1 µM]. Note that a high concentration of inhibits Cch-induced rhythmic theta oscillations and that a lower concentration does not affect this activity. (c) Representative recordings (left) and their corresponding power spectra (right) of hippocampal population activity recorded in the presence of carbachol 20 µM (upper trace and power spectrum) and after bath application of 0.5 µM (lower trace and power spectrum). The graph on the right shows the quantification of the integrated spectral power from 4 to 12 Hz before and after bath application of . Note that inhibits Cch-induced rhythmic theta oscillations. The inset shown on each power spectrum is an autocorrelogram obtained from the corresponding trace. *indicates a significant difference with respect to control (), and ^{#}indicates a significant difference with respect to the carbachol-induced oscillatory activity.