Sleeping Behavior and Neuro-Behavioral Development Measure
Neurobehavioral Development and Nutritive Sucking
Neurobehavioral development is a genetically determined process by
which the primitive central nervous system (CNS) achieves maturity in form and
function.
Neuro development also depends on the environment since CNS
development occurs through an “experience expectant” process in which normal
species typical experiences enable the CNS to make the structural and
functional changes necessary for the next stages of development (Greenough,
Black, & Wallace, 1987). ).
In order to balance the needs of the present developmental
stage and the anticipated needs of subsequent stages, this process is somewhat
plastic (Oppenheim, 1981). When an infant is placed in an atypical environment
such as a neonatal intensive care unit, ontogenetic adaptation is affected.
Although the infant may initially adapt successfully, changes in the trajectory
of the infant’s neurobehavioral development may be maladaptive at older ages.
The effects of this disturbance vary depending on the timing and severity of
environmental stresses, individual genetic background, the interaction of
genetic background and prenatal history, adaptations made to uterine stresses,
and specific neurological insults.
Infants probably develop normally when
neural plasticity the process by which the brain develops new connections after
neural damage-compensates for abnormalities due to any atypical ontogenetic
adaptation and neurological insults.
Infants exhibit abnormal neurobehavioral
development when neural plasticity is not able to compensate, or when compensatory
processes result in structural or functional changes that are maladaptive at
later ages.
Exploring the Concept & Framework
The Synactive Model of Neonatal Behavioral Organization provides a
framework for exploring the concept of neurobehavioral development. Als (1991)
has proposed a dynamic model for assessing infant behavioral organization.
She
proposed that the behavioral organization displayed by an infant is a
reflection of the infant’s central nervous system integrity, defined as the
potential for the brain to develop normally. The infant’s behaviors reflect
subsystems of functioning, which include the autonomic, motor, state,
attentional or interactive, and regulatory systems.
The autonomic system
controls physiologic functions that are basic for survival, such as respiration
and heart rate. The motor system involves muscle tone, infant movements, and
posture. State organization encompasses clarity of states and the pattern of
transition from one state to another.
The attentional or interactional system
can be observed only in the alert state and is indicative of an infant’s
ability to respond to visual and auditory stimulation. An infant’s regulatory
system reflects the presence and success of an infant’s efforts to achieve and
maintain a balance of these other subsystems.
Multidisciplinary Framework
Another framework used is the perspective of developmental science,
a multidisciplinary field that brings together researchers and theorists from
psychology, biology, nursing, and other disciplines (Cairns, Elder, &
Costello, 1996; Miles & Holditch Davis, 2003).
In this perspective, infants
are viewed as developing in a continuously ongoing, reciprocal process of
interaction with the environment. Infants and their environments form a complex
system, consisting of elements that are themselves systems, such as mother and
child, interacting together so that the total system shows less variability
than the individual elements.
Furthermore, plasticity is assumed to be inherent
in infants, their families, and the environment. Infants are active
participants in their families and the greater environment, constantly changing
them at the same time that they are influencing the infant. Interactions,
rather than causation, are the focus of this perspective.
No action of one
element can be said to cause the action of another since interactions between
elements are simultaneous and bidirectional. The interactions affecting
development of infants are too complex to ever be fully identified, and infants
can achieve the same developmental outcomes through different processes.
Neonatal Behavior
Newborn behavior, which includes sucking, sleeping, and waking, is
the infant’s primary expression of brain functioning and the critical route for
communication with adults. Investigation of these behaviors and their central
mechanisms is essential for nursing understanding of the needs of infants and
in planning interventions to improve their neurodevelopmental status.
The idea of evaluating the vitality and central nervous system
integrity of a neonate by assessing sucking is not new. Nutritive sucking is
initiated in utero and continues to develop in an organized pattern in the
early weeks after birth.
It involves the integration of multiple sensory and
central motor nervous system functions (Wolff, 1968). Sucking behaviors are
thought to be an excellent barometer of central nervous system organization.
They can be quantified in detailed analysis and are disturbed to various
degrees by neurological problems. Wolff describes the study of sucking rhythms
to investigate serial order in behavior and development, which has remained
among the most resistant to empirical investigation.
The work of Medoff-Cooper and colleagues (Medoff-Cooper, 1991;
Medoff-Cooper, McGrath, & Bilker, 2000; McGrath & Medoff-Cooper, 2001)
demonstrated that changes in the pattern of nutritive sucking behaviors can be
described as a function of gestational age in healthy preterm and full-term
infants.
They reported a systematic pattern of gestational related change in
sucking behavior that was reflected at each level of temporal analysis, with a strong
correlation between increasing maturation and more organized sucking patterns
(Medoff-Cooper, 2002).
When comparing sucking behaviors at term of 213
extremely early born infants (gestational age ≤ 29 weeks), more mature preterm
infants (30-32 weeks gestational age) and newly born full-term infants, feeding
behaviors were noted to be a function of gestational age at birth as well as
the interaction of maturation and experience.
Extremely early born preterm
infants were found to demonstrate less competent feeding behaviors than either
more mature preterm infants or newly born full term infants.
Lau, Smith, and Schandler (2003) also found that with increasing
post conceptual age (PCA), preterm infants demonstrated significant improvement
in feeding performance.
They reported a significant relationship between
average bolus size and sucking pressures and sucking frequency. Tolerating as
well as adapting to increasing bolus size serves as an indicator of maturation
in feeding behaviors.
Gewolb, Bosma, Reynolds, and Vice (2003) used to increase rhythmic
stability as the index of maturation of sucking or feeding behaviors.
In their
comparison of healthy preterm infants and preterm infants with broncho
pulmonary dysplasia (BPD), an increase in stability of rhythm and uniformity of
wave form morphology was correlated with feeding efficiency and increasing PCA
in healthy preterm infants. This relationship was not found to be true in the
BPD cohort.
They concluded that the poor feeding efficiency may be related to decreased
respiratory reserves or may be secondary to nonspecific neurologic impairment.
Nutritive Sucking and Impact on Developmental Stages
The potential link between nutritive sucking and future
developmental problems has been identified throughout the feeding literature.
One early study by Burns and colleagues (1987) showed that infants with
significant intraventricular hemorrhage were delayed in their ability to
achieve a nutritive suck reflex.
At week 40 only 75% of the 110 infants
demonstrated mature nutritive sucking patterns. Medoff-Cooper and Gennaro
(1996) reported that sucking organization or rhythmicity was a far better
predictor than neonatal morbidity of developmental outcome at 6 months of age.
At 12 months of age, organized feeding patterns at 40-week PCA were
significantly correlated with both Mental Developmental and Psychomotor
Developmental Index (Medoff-Cooper, 2002).
Sleeping and waking states are clusters of behaviors that tend to
occur together and represent the infant’s level of arousal, responsiveness to
external stimulation, and central nervous system activation.
Three states have
been identified in adults: wakefulness, non-REM (rapid eye movement) sleep, and
REM sleep. In infants, it is also possible to identify states within waking and
states that are transitional between waking and sleeping.
Because the
electrophysiological patterns associated with sleep in infants are different
than those in adults, infant sleep states are usually designated as active and
quiet sleep.
Clinical ECG Evidences
Because of infants’ neurological immaturity, EEG and behavioral scoring
of states in preterm and full-term infants provide quite similar results.
Sleeping and waking states in infants can be validly scored either by EEG or by
directly observing infant behaviors.
Four standardized systems for scoring
behavioral observations of sleep wake states are currently being used by nurse
researchers: the 6-state system developed by T. Berry Brazelton, the 10-state
system of Evelyn Thoman, the 12-state system from Heideliese Als’s Assessment
of Preterm Infant’s Behavior (APIB), and 12 state scoring system based on the
Anderson Behavioral State Scale (ABSS) developed by Gene Anderson (see
Holditch-Davis, Blackburn, & Vandenberg, 2003).
These systems define states
in very similar ways and are probably equally useful for clinical purposes.
However, the Brazelton system is the most limited for research as it can only
be used with infants between 36- and 44-week PCA, and Thomann’s is the most
flexible as it has been used with 27-week PCA preterm infants through 1-year olds.
Sleeping and waking states have widespread physiological effects. The
functioning of cardiovascular, respiratory, neurological, endocrine, and
gastrointestinal systems differs in different states. Sleeping and waking also
affect the infant’s ability to respond to stimulation.
Thus, infant responses
to nurses and parents depend on a great deal on the state the infant is in when
the stimulation is begun. Timing routine interventions to occur when the infant
is most responsive is an important aspect of current systems of individualized
nursing care.
Sleeping and Waling and Their Neurological Pattern
Studies have indicated that sleep and waking patterns are closely
related to neurological status (Thoman, 1982; Halpern, Maclean, &
Baumeister, 1995). State patterns of infants with neurological insults differ
markedly from those of healthy infants.
Abnormal neonatal EEG patterns are
associated with severe neurological abnormalities and major neurodevelopmental
sequelae during childhood . Also, preterm infants with severe medical illnesses
exhibit patterns of sleepwake states that differ from those of healthier
preterms, although most of these differences disappear when infants recover
(see Holditch-Davis et al., 2003b for references).
Sleep Direct Link to Development
Sleep and wakefulness may be directly related to brain development.
For example, because active sleep is less common in adults than non-REM sleep
but is much more common in infants, it has been hypothesized to be necessary
for brain development (Roffwarg, Mazio, & Dement, 1966).
Also, EEG changes
over age in sleep architecture, increasing spectral energies, and greater
spectral EEG coherence probably indicate maturational changes in the brain,
including synaptogenesis, evolution of neurotransmitter pools, and myelination.
Sleep and Walking as an Developmental Parameter
Sleep-wake patterns can also be used to predict developmental
outcome. Measures of sleep wake states during the preterm period (amount of
crying, quality of state organization, sleep cycle length, and amount of night
sleep) predict Bayley scores during the 1st year.
Developmental changes in the
amounts of specific sleep behaviors during the 1st year are related to
developmental and health outcomes in the 2nd year.
Furthermore, the stability
of behavioral sleep wake patterns in the late fetal period and in the 1st,
month predicts later development.
EEG sleep measures in preterm infants have
been related to developmental outcome at up to 8 years. Acoustic
characteristics of infant cries have been used to predict developmental outcome
in preterm infants and infants exposed to drugs prenatally (see Holditch-Davis
et al., 2003b for references).
Conclusion
In summary, nutritive sucking, a noninvasive and easily measured
behavior, appears to be an excellent index of neurodevelopment in preterm
infants.
Sleeping and waking patterns appear to provide an excellent index of
neurodevelopmental status in preterm and full-term infants that can be either
scored behaviorally or by EEG.