Long-range temporal organisation of limb movement kinematics in human neonates

Highlights

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  Movement occurrence is periodic in healthy newborns, with 1-hour cycle.

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  Peaks in movement occurrence associated with higher acceleration, and higher proportion of movements being bilateral.

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  Wearable sensors effectively characterise newborn movements, and have potential to be synchronised with EEG in future.

Abstract

Objective

Movement provides crucial sensorimotor information to the developing brain, evoking somatotopic cortical EEG activity. Indeed, temporal-spatial organisation of these movements, including a diverse repertoire of accelerations and limb combinations (e.g. unilateral progressing to bilateral), predicts positive sensorimotor outcomes. However, in current clinical practice, movements in human neonates are qualitatively characterised only during brief periods (a few minutes) of wakefulness, meaning that the vast majority of sensorimotor experience remains unsampled. Here our objective was to quantitatively characterise the long-range temporal organisation of the full repertoire of newborn movements, over multi-hour recordings.

Methods

We monitored motor activity across 2–4 h in 11 healthy newborn infants (median 1 day old), who wore limb sensors containing synchronised tri-axial accelerometers and gyroscopes. Movements were identified using acceleration and angular velocity, and their organisation across the recording was characterised using cluster analysis and spectral estimation.

Results

Movement occurrence was periodic, with a 1-hour cycle. Peaks in movement occurrence were associated with higher acceleration, and a higher proportion of movements being bilateral.

Conclusions

Neonatal movement occurrence is cyclical, with periods consistent with sleep-wake behavioural architecture. Movement kinematics are organised by these fluctuations in movement occurrence. Recordings that exceed 1-hour are necessary to capture the long-range temporal organisation of the full repertoire of newborn limb movements.

Significance

Future work should investigate the prognostic value of combining these movement recordings with synchronised EEG, in at-risk infants.