Fig 1.
Monthly spectral profiles at motor cortices.
Each color-coded curve presents averaged relative power density from sessions of the same monthly age. Shaded areas show standard deviations for each monthly age with corresponding colors. Left inset shows geodesic locations of each electrode on the scalp, and green ones are selected to evaluate spectral profiles in motor cortices. Right inset provides a zoom-in view of spectral profiles in 6–9 Hz.
Table 1.
Likelihood ratio test of changes in mean alpha coherence across chronological age in days, reaching skill, fine motor and gross motor scores, for all 18 electrode pairs.
A cutoff value of 0.05/18 (adjusted by number of electrode pairs) is selected for the statistical tests and p-values smaller than it are marked in bold and italic.
Fig 2.
Topographies of alpha band power for each monthly age.
First row shows spatial patterns of alpha band power from 1 to 4 months of age. Second row shows those for 5–7 months of age.
Fig 3.
Correlation of alpha band power with chronological age in days.
Each cross represents magnitude of alpha band power from one session. Dashed line shows the least-squares fitted line along maturation. The r and p values denote correlation test results.
Fig 4.
Changes in mean alpha coherence along maturation.
(A) Changing trends of mean alpha coherence for each electrode pair. In each subplot, blue crosses denote magnitudes of mean alpha coherence for all sessions, and dashed lines are the least-squares fitted lines. (B) Electrode pairs with significance in likelihood ratio tests. Electrode pairs with significance are connected with blue lines.
Fig 5.
Changes in mean alpha coherence across different reaching skill scores.
(A) Changing trends of mean alpha coherence for each electrode pair. In each subplot, bars present mean magnitudes of mean alpha coherence for sessions of the same reaching skill score, with corresponding standard deviation added on top. (B) Electrode pairs with significance in likelihood ratio tests. Electrode pairs with significance are connected with blue lines.
Fig 6.
Changes in mean alpha coherence across fine motor scores from the Bayley test.
(A) Changing trends of mean alpha coherence for each electrode pair. In each subplot, blue crosses denote magnitudes of mean alpha coherence for all sessions, and dashed lines are the least-squares fitted lines. (B) Electrode pairs with significance in likelihood ratio tests. Electrode pairs with significance are connected with blue lines.
Fig 7.
Changes in mean alpha coherence across gross motor scores from the Bayley test.
(A) Changing trends of mean alpha coherence for each electrode pair. In each subplot, blue crosses denote magnitudes of mean alpha coherence for all sessions, and dashed lines are the least-squares fitted lines. (B) Electrode pairs with significance in likelihood ratio tests. Electrode pairs with significance are connected with blue lines.