Sleep spindles are considered a hallmark of stage
2 of the sleep electroencephalogram (EEG) and are used both
for sleep staging and for clinical studies of pharmacological
agents. Analyses of sleep spindle topography, as well as
intracranial source investigations provided evidence for the
existence of two distinct sleep spindle types, “slow” and “fast”
spindles at approximately 12 and 14 Hz, respectively. The aim
of the present study was to apply Independent Component
Analysis (ICA) to sleep spindles, for examining the possibility
of extracting, through visual analysis of the spindle EEG and
selection of Independent Components (ICs), spindle
“components” corresponding to separate EEG activity
patterns, and to investigate the sources underlying these
spindle components. The inverse electromagnetic problem was
solved using Low-Resolution Brain Electromagnetic
Tomography (LORETA). Results indicate separability and
stability of sources related to sleep spindle components
reconstructed from separate groups of ICs.