Figure 1.
Example of recording and scoring of an MA. A, Polygraphic traces of EEG, EMG, and EEG spectrum in a WT mouse. Calibration bars on the right correspond to 0.4 mV. Scoring is performed with three levels: wake, REMS, and NREMS. The transient reduction in EEG power accompanied by a slight EMG activation during NREMS is scored as MA (*). The power spectrum of the EEG (estimated with 256-point fast Fourier transform and using a Hanning window) for 5 sec segments at the times indicated by the shaded area labeled a-e on the EEG trace are plotted on top in the graphs with the corresponding letters. The spectrum during the MA is characteristic of NREMS but has a low power. B, Detail of EEG and EMG for the seconds preceding and following the MA, with low-frequency oscillations of small amplitude during the MA. C, EEG spectral content from a knock-out β2-/- mouse for the three states scored over 24 hr. These spectra are similar to the ones of WT mice (C57BL/6J) used in this study and previously (Franken et al., 1998; Huber et al., 2000). The relative amplitude of the peaks was found to vary from animal to animal, presumably depending on the implantation site.