Baby steps: investigating the development of perceptual-motor couplings in infancy

Abstract

There are cells in our motor cortex that fire both when we perform and when we observe similar actions. It has been suggested that these perceptual-motor couplings in the brain develop through associative learning during correlated sensorimotor experience. Although studies with adult participants have provided support for this hypothesis, there is no direct evidence that associative learning also underlies the initial formation of perceptual-motor couplings in the developing brain. With the present study we addressed this question by manipulating infants' opportunities to associate the visual and motor representation of a novel action, and by investigating how this influenced their sensorimotor cortex activation when they observed this action performed by others. Pre-walking 7-9-month-old infants performed stepping movements on an infant treadmill while they either observed their own real-time leg movements (Contingent group) or the previously recorded leg movements of another infant (Non-contingent control group). Infants in a second control group did not perform any steps and only received visual experience with the stepping actions. Before and after the training period we measured infants' sensorimotor alpha suppression, as an index of sensorimotor cortex activation, while they watched videos of other infants' stepping actions. While we did not find greater sensorimotor alpha suppression following training in the Contingent group as a whole, we nevertheless found that the strength of the visuomotor contingency experienced during training predicted the amount of sensorimotor alpha suppression at post-test in this group. We did not find any effects of motor experience alone. These results suggest that the development of perceptual-motor couplings in the infant brain is likely to be supported by associative learning during correlated visuomotor experience.

© 2014 The Authors Developmental Science Published by John Wiley & Sons Ltd.

Figures

Figure 1

Screensaver-like baseline videos and stepping actions presented during the pre- and post-test EEG sessions.

Figure 2

Experimental setup during the training phase of the experiment. Infants were placed in a baby bouncer while they were supported over the infant treadmill by the experimenter. Infants either saw their own leg movements online or another infant's previously recorded leg movements on a 51-inch plasma screen. Infants wore a skirt to prevent them from receiving correlated visuomotor experience by looking down at their own legs.

Figure 3

(a) Mean sensorimotor alpha suppression over the central leg areas at pre- and post-test. We found a significant increase in sensorimotor alpha suppression between pre- and post-test over the central leg areas *p

Figure 4

Scatter plot of the relationship between experienced visuomotor contingency during the training and sensorimotor alpha suppression at post-test in the Contingent condition. Stronger visuomotor contingency is associated with more sensorimotor alpha suppression (indicating more sensorimotor cortex activation) at post-test. One data point was replaced with a value .01 greater than the highest non-outlier scores to normalize the distribution. The replaced data point is represented by the transparent dot and the dotted line represents the regression line after the outlier correction.