From the Research
Normal Neonatal Limb Movements
- Neonatal limb movements are characterized by periodic occurrence, with a 1-hour cycle, and are organized by fluctuations in movement occurrence 1
- These movements are cyclical, with periods consistent with sleep-wake behavioral architecture, and are associated with higher acceleration and a higher proportion of bilateral movements 1
- Limb movements in neonates can be unilateral or bilateral, and may exhibit left-right alternating or synchronous coordination, with variable interlimb coordination and incomplete sensory modulation 2
- Isolated limb movements during active sleep can induce somatotopically distributed alpha-beta oscillations, which decline towards full-term and disappear at 41 corrected gestational weeks 3
- The primary motor cortex drives muscle activity in neonatal spontaneous movements, with corticomuscular coherence and Granger causality indicating functional connectivity between the primary motor cortex and limb muscles 4
Characteristics of Neonatal Limb Movements
- Movement kinematics are organized by fluctuations in movement occurrence, with peaks in movement occurrence associated with higher acceleration and a higher proportion of bilateral movements 1
- Hip position of the blocked limb can affect ipsilateral muscle activities, with hip extension backward engaging hip flexor muscle and hip flexion engaging hip extensors 2
- The sudden release of the blocked limb in the posterior position can elicit the immediate initiation of the swing phase of the limb, with hip flexion and a burst of ankle flexor muscle 2
- Extensor muscles can show load responses at midstance, indicating variable interlimb coordination and incomplete sensory modulation 2
Developmental Aspects of Neonatal Limb Movements
- The complexity of limb movements evolves from disorganized to more selectively coordinated during the first year of life, as infants learn to navigate and interact with their environment 5
- The developmental changes in limb movement complexity can be captured using Multidimensional Recurrence Quantification Analysis (MdRQA), which shows task-dependent changes in MdRQA parameters at 9 and 12 months of age 5
- The primary motor cortex begins to develop functional connectivity with limb muscles during the neonatal stage, with corticomuscular coherence and Granger causality indicating a positive correlation with postnatal age 4