Developmental emergence of self-referential and inhibition mechanisms of body movements underling felicitous behaviors.

Abstract

In young infants, activation or inhibition of body movements on perception of environmental events is important to enable them to act on the world or understand the world. To reveal the development of this ability, we observed movement patterns in all four limbs under the two experimental conditions. Infants assigned to the interaction condition were provided a connection between their arm and a toy, which allowed movements of the critical arm to produce movements in the overhead mobile. Infants assigned to the stimulation condition were presented with similar movements of the toy emulated by the experimenter. In 3-month-old infants, the arm movements increased under the interaction condition, whereas they decreased under the stimulation condition. Such condition-dependent behavior dissociation was not observed in 2-month-old infants. These results suggest that the distinct behavior of an "observer" of environmental events was differentiated from that of a "player" interacting with the surroundings between 2 and 3 months of age. The emergence of differentiation of behaviors points toward the development of self-referential and inhibition mechanisms in the perceptual-motor and attention/evaluation system in the cortico-subcortical network.

Precursors of Dancing and Singing to Music in Three- to Four-Months-Old Infants

“…As a group, the amount of movements decreased overall across the limbs in the music condition compared to the silent condition. This result is consistent with the previous study that showed reduced amount of movement in all of the four limbs in three-months-old infants when they attended to an auditory-visual stimulus such as a mobile toy that made sounds [25]. These findings suggest that the external inputs tap into perceptual-attentional system to inhibit all of the four-limb activities in most of the infants [25].…”

“…Although little is known on the neural mechanisms underlying movement generation in human infants, the spontaneous limb movements are thought to be mainly produced by the subcortical system composed of the brainstem and the spinal cord, including the CPGs, which activities interact with the higher-order cortical system [25], [26], [35], [48]. The leg movements are considered to be primarily generated by the subcortical system itself while the control of arm movements involves more contribution from the cortical system [25], [26], [35], [48].…”

“…The leg movements are considered to be primarily generated by the subcortical system itself while the control of arm movements involves more contribution from the cortical system [25], [26], [35], [48]. If so, the remarkable increases in the amount of limb movements in ID1 and ID25 could be interpreted as an enhancement of the CPG activities in the subcortical system elicited by the music, but the degree of interference from the cortical system might be different between ID1 and ID25.…”

“…Although Zentner and Eerola [11] pointed out the immature motor-control ability, infants younger than five-months already express rich and spontaneous limb movements, coined general movements [23], [24], [25], [26]. A previous study showed that general movements of the infants at three months of age were modified by audio-visual inputs possibly through the basal ganglia and cerebral cortex [25], which are the brain areas considered to be playing a central role in processing of the musical beat [27], [28], [29], [30], [31]. Thus, if human musicality arises spontaneously through entrainment mechanisms between our bodies and the environment [32], [33], synchronized limb movements to music may be observed even in infants younger than five-months-old.…”

Increasing selectivity of interlimb coordination during spontaneous movements in 2- to 4-month-old infants

“…Although limited information is available on the neural mechanisms underlying movement generation in human infants, it is speculated that early spontaneous movements, which begin during the fetal period, are primarily generated by the low-level central nervous system (e.g., spinal cord and brain stem), including the central pattern generators (CPGs) (Hadders-Algra 2007;Prechtl 1997;Watanabe et al 2011). According to an animal study, the motor patterns are primarily generated by the CPGs in the spinal cord, and the initiation, termination, and frequency of the movements are controlled by the brain stem (Grillner 1985).…”