05; Table S1). Therefore, the periods with high delta power did

not coincide with those of TPSM expression. Moreover, even when coexpressed, there was no correlation between the phases of delta and TPSM oscillations (Table S1). Altogether, these results suggest that TPSM is distinct from delta modulation of theta power. Because previous observations suggested that theta power was correlated with running speed (Czurkó et al., 1999; DeCoteau et al., 2007; McFarland et al., 1975; Montgomery et al., 2009; Rivas et al., 1996; Shen et al., 1997; Whishaw and Vanderwolf, 1973), cyclic changes in theta Screening Library molecular weight power might result from systematic changes in running speed. Overall, we indeed observed that theta power globally correlated with running speed when selecting periods of several seconds with relatively constant running speed (p < 0.05, paired Student t test, open field, n = 9 sessions from 4 animals; maze, n = 10 sessions from 3 animals; wheel, n = 8 sessions from 3 animals; Figure 3A). But finer analysis considering instantaneous running speed

at a time scale closer to that of theta oscillations (see Experimental Procedures) revealed no systematic correlation of running speed or acceleration with theta power (p > 0.05, Pearson linear correlation; Figure 3B) or TPSM phase (p > 0.05, circular-linear correlation analysis [Berens, 2009] and Rayleigh test; Figure 3C). This is most striking for maze/track recordings, in which although our results are in agreement with the recent report that globally faster runs were Rutecarpine associated with larger average theta power estimated on a run per run basis (Hinman Venetoclax ic50 et al., 2011), visual inspection

of theta power and running speed within individual runs clearly shows a lack of correlation between these two variables (in Figure 1C, instantaneous speed displays two clear cycles of fluctuation while TPSM shows 4 cycles during the same 4 s running period). More systematic comparison of speed and theta power autocorrelograms confirmed that even though both parameters can occasionally oscillate at similar frequency, they most often show pretty different profiles (Figure 4). Altogether, these results indicate that theta power modulation by running speed or acceleration does not account for TPSM. During sleep, transient increases of theta power have been described as “phasic REM” sleep (Karashima et al., 2005; Montgomery et al., 2008; Sano et al., 1973). Sleep-related TPSM is rather related to tonic REM because (1) it was not associated with the increased theta frequency and the increased power of high-frequency components which accompany phasic REM, (2) it could occur in a continuous manner during several seconds, and (3) it was expressed throughout REM sleep (see Experimental Procedures; n = 4 animals), while phasic REM episodes typically last for about one second and represent around 4% of REM sleep (Montgomery et al.