Spectral and source structural development of mu and alpha rhythms from infancy through adulthood.

OBJECTIVE: To assess the developmental trajectory of spectral, topographic, and source structural properties of functional mu desynchronization (characterized during voluntary reaching/grasping movement), and investigate its spectral/topographic relation to spontaneous EEG in the developing alpha band.

METHODS: Event related desynchronization (ERD) and power spectral density spectra/topography are analyzed in 12 month-old infants, 4 year-old children, and adults. Age-matched head models derived from structural MRI are used to obtain current density reconstructions of mu desynchronization across the cortical surface.

RESULTS: Infant/child EEG contains spectral peaks evident in both the upper and lower developing alpha band, and spectral/topographic properties of functionally identified mu rhythm strongly reflect those of upper alpha in all subject groups. Source reconstructions show distributed frontoparietal patterns of cortical mu desynchronization concentrated in specific central and parietal regions which are consistent across age groups.

CONCLUSIONS: Peak frequencies of mu desynchronization and spontaneous alpha band EEG increase with age, and characteristic mu topography/source-structure is evident in development at least as early as 12 months.

SIGNIFICANCE: Results provide evidence for a cortically distributed functional mu network, with spontaneous activity measurable in the upper alpha band throughout development.