Neonatal control of nutritive sucking pressure: evidence for an intrinsic τ-guide

Abstract

 Human newborns appear to regulate sucking pressure when bottle feeding by employing, with similar precision, the same principle of control evidenced by adults in skilled behavior, such as reaching (Lee et al., 1998a). In particular, the present study of 12 full-term newborn infants indicated that the intraoral sucking pressures followed an internal dynamic prototype – an intrinsic τ-guide. The intrinsic τ-guide, a recent hypothesis of general tau theory is a time-varying quantity, τ_g, assumed to be generated within the nervous system. It corresponds to some quantity (e.g., electrical charge), changing with a constant second-order temporal derivative from a rest level to a goal level, in the sense that τ_g equals τ of the gap between the quantity and its goal level at each time t. (τ of a gap is the time-to-closure of the gap at the current closure-rate.) According to the hypothesis, the infant senses τ_p, the τ of the gap between the current intraoral pressure and its goal level, and regulates intraoral pressure so that τ_p and τ_g remain coupled in a constant ratio, k; i.e., τ_p=kτ_g. With k in the range 0–1, the τ-coupling would result in a bell-shaped rate of change pressure profile, as was, in fact, found. More specifically, the high mean r ² values obtained when regressing τ_p on τ_g, for both the increasing and decreasing suction periods of the infants’ suck, supported a strong τ-coupling between τ_p and τ_g. The mean k values were significantly higher in the increasing suction period, indicating that the ending of the movement was more forceful, a finding which makes sense given the different functions of the two periods of the suck.