Sleep Spindles as an Electrographic Element: Description and Automatic Detection Methods

Figure 8

(a) Main effects of late slow and early fast spindles. (A–E left) fMRI responses to slow spindles displayed over an individual structural image normalized to the Montreal Neurological Institute space (). The leftmost panels show peristimulus time histograms (PSTHs) depicting the responses in auditory cortices (circled) (A), thalamus (B), anterior cingulate (circled) and midbrain tegmentum (dotted) (C), anterior insula (D), and superior frontal gyrus (E). The PSTH (solid blue line; blue error bars reflect the SEM) depicts the mean response across spindles of the corresponding voxel, irrespective of contrast based on a finite impulse response refit. The fitted response is drawn in black. (F–I center) Conjunction analysis of slow and fast sleep spindles. (J–M right) fMRI responses to fast spindles (). The right most panels show PSTHs depicting the response in superior temporal gyri (J), thalami (K), midcingulate cortex (circled) and SMA (dotted) (L), and anterior insula (M). (b) Differential fMRI activity between fast and slow spindles. Larger brain responses for fast (red) than slow (black) spindles were revealed in the hippocampus (A), mesial prefrontal cortex (B), precentral gyrus (C), and postcentral gyrus (D). Peristimulus time histograms show mean response of the corresponding voxels (dotted lines; error bars show SEM) and the corresponding fitted responses (continuous lines). Modified from [34].

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