Perception/action coupling of limb, head and rattle movements of infants exposed to cocaine

Perception/action coupling among head and limb movements and environmental events was evaluated in infants exposed to cocaine and control infants in three conditions: spontaneous, rattle, and face-to-face interaction. Time and frequency domain measures were used to quantify durations, median and peak frequency and coherence of body movements. Infants in both groups had significantly higher median movement frequencies in the rattle condition in comparison to the other two conditions. Infants exposed to cocaine moved less and with lower peak frequencies in the rattle condition in comparison to the control group. In addition, the cocaine-exposed group moved less and with lower peak frequencies in the rattle condition in comparison to the other two conditions. The magnitude of interlimb and head/limb coherence values increased for the cocaine infants in the rattle condition. Thus, the rattle condition elicited different movement organization from infants in comparison to the other conditions. Cocaine-exposed infants in particular appear differentially sensitive to the external rhythm introduced by the rattle.