9 months: Layer 3c and layer 4 cortical neurons are functional {brain development, 9 months}. Sensory tracts between thalamus and primary sensorimotor cortex are ready. Motor tracts between motor cortex and cerebellum are ready. Thalamus and lower gyrus-cinguli layers are in intraorganismic short circuit. Brain-wave waking and sleeping patterns are like adult.
9 months: Infants know other's wishes or intentions in shared things, and mother's purposes and experiences become primary {cognition development, 9 months}.
9 months: Forefinger grasping ends {reflex development, 9 months}.
9 to 12 months: Reaching-behavior control allows infants to reach anywhere, not just along sightlines {physical development, 9 to 12 months}.
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Date Modified: 2022.0225