In the first months of life, infants continually produce and modify motor behaviors and
acquire new ones. They kick their legs in patterns that show temporal and spatial
organization, they flap their arms in a march to midline, and gain strength against
gravity with their head and trunk. Most of this happens spontaneously without specific
toys or environmental modifications. Over the same time period, infant also continually
use and modify their voice and acquire new vocal behaviors. Three broad categories of
sound occurring in vocal communication are described in infants: cries, laughs, and
protophones which are seen as the precursors to speech. Motor function and voice
production are not isolated developmental processes --they are present and developing in
the same baby, and, they have common ontological origins in the motor cortex. It can be
argued that the earliest precursors to language, spontaneous cries and protophones, are
the result of a "movement" originating in signals from the CNS that can be studied to
detect health and disease in combination with physical movements. Grounded in the
developmental cascades framework and developmental neuroscience this project is informed
by clinical and scientific advancements in: 1) Methodology for reliably scoring of
spontaneous behaviors in the first months of life that are sensitive to normal and
disordered movements and predictive of neurodevelopmental disabilities including Cerebral
Palsy (CP) - particularly the General Movements Assessment (GMA) and associated Motor
Optimality score (MOS); 2) The ability to detect abnormal voice production in populations
with neurodevelopmental disabilities using acoustic analysis. Motor function and speech
production are complex processes that require precise coordination of 100s of muscles. In
disease states, with damage to the CNS, poor coordination can be observed through motor
and voice behaviors and specific diseases identified. Importantly, motor and voice are
some of the first indicators of health after birth that occur spontaneously (e.g. crying,
kicking, muscle tone). Even more importantly, motor function and voice production can be
measured, non-invasively, in early infancy including the newborn period.
The overall goal is to discover features of normal and disordered motor-voice profiles
that are biobehavioral markers of physical disability in infants. Disabilities are
difficult to identify in this ultra-early infancy period because infants cannot speak or
produce voluntary movements necessary for formal testing. Furthermore, medical testing
such as MRI is expensive, not accessible everywhere, and has limited predictive value for
neurodevelopmental outcomes. Laboratories have demonstrated the promise of using video
and audio recordings from spontaneous and elicited behaviors to identify disordered motor
or voice production from normal. Arm and leg movements, midline behaviors, writhing and
fidgety movements are all implicated in neurodevelopmental outcomes and some are uniquely
implicated in the identification of cerebral palsy (CP). Vocalizations (grunts, squeals,
raspberries, trills, clicks), crying, protophones -- core behavioral features of voice
production, are also implicated in neurodevelopmental outcomes; and some are uniquely
implicated in autism, but none have been consistently evaluated in infants.
Multidimensional assessment of motor function and voice production will be used at two
time periods that are relevant to the earliest possible screening and detection of
neurodevelopmental disorders and important for general movement assessment:
term-equivalent age (writhing period), 3.5 months of corrected age (fidgety period), and
9 month of corrected age in N=46 infants with newborn-detectable risk. To fully capture
the complexity of motor function and voice production in infancy, a battery of tests with
emerging sensitivity will be used to measure disability during development and the
sensitivity to detect both major impairments and small delays; some of these measures can
be reliably tested simultaneously. Tests include: (1) General Movement Analysis (GMA);
(2) the GMA-associated Motor Optimality Score (MOS); (3) Voice acoustic analysis
(fundamental frequency, ratio of voiced sound, shimmer, jitter, Harmonic-to-noise ratio,
frequencies of the first four formants), and number of vocalizations; (4) Bayley Scales
of Infant Development (Bayley-4) for motor, cognitive, and language function; (5) Test of
Infant Motor Performance (TIMP); and (6) Ages and Stages Questionnaire (ASQ).
