Developmental Neuropsychology A.E.M. van Wordragen (u789251)
1: Child Neuropsychology: Theory and Practice
Knowledge of typical development is especially important in child neuropsychology, as it
provides a template for measuring deviations relating to early damage and subsequent
interruption to normal growth processes across a range of functional domains.
Historical perspectives
Plasticity, vulnerability and critical periods
Kennard and Teuber are well known for their seminal works. The Kennard Principle, interpreted
by Teuber: ‘if you’re going to have brain damage, have it early’.
Theory of function suggests the young child’s brain is seen to be less differentiated than that of
the mature adult and more capable of transferring functions from damaged cerebral tissue to
healthy tissue.
Mogford and Bishop define a critical period as ‘the time window during which external
influences have a significant effect’. Thus, if a cerebral region is damaged or dysfunctional at a
critical stage of cognitive development, it may be that the cognitive skill subsumed by that region
is irreversibly impaired.
No theoretical framework has succeeded in integrating biological, psychological and
environmental dimensions in a clinically meaningful way. However, two seminal models from
the late 1980s have both had a major influence in the field: ‘non-verbal learning disability’
(Byron Rourke) and ‘multidimension age at insult’ (Maureen Dennis).
Non-verbal learning disability (NVLD)
Rourke described a consistent pattern of neurobehavioral deficits observed in children with a
history of early, generalised, cerebral dysfunction resulting from brain insult occurring during
the perinatal period or in infancy.
The hallmark characteristics of NVLD include:
o Bilateral tactile-perceptual deficits (more marked on the left side of the body).
o Impaired visual recognition and discrimination and visuospatial organisational
deficiencies.
o Bilateral psychomotor coordination problems (more marked on the left side of the
body).
o Difficulties managing novel information.
Children with NVLD may also demonstrate a range of intact skills, primarily within the
auditory/verbal domain:
o Simple motor skills
o Auditory perception
o Rote learning
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,Developmental Neuropsychology A.E.M. van Wordragen (u789251)
o Selective and sustained attention for auditory-verbal information
o Basic expressive and receptive language
o Word reading and spelling
NVLD theory explains the spectrum of children’s neurobehavioral abilities and disabilities, as
well as the development trajectories of the three principle axes of relevance in the brain
behavior relationship: left-right, up-down, and anterior-posterior.
One of the greatest contributions of the NVLD model is linking cognitive characteristics to an
underlying neurologic explanation: the ‘white matter hypothesis’. Rourke’s model is based on
the assumption that normal development of white matter is essential for intact child
development. NVLD occurs when there is disruption to white matter development during critical
stage of early childhood. Some of these disruptions are:
o Traumatic brain injury
o Hydrocephalus
o Prematurity
o Cranial irradiation
However, early brain insult does not always lead to symptoms consistent with NVLD. Such as
cerebral infection with has symptoms of language problems or executive dysfunction, but intact
non-verbal skills or global cognitive impairments.
Developmental stage at insult and cognitive outcome
Maureen Dennis’ ‘heuristic’ does not propose a specific neurological mechanism for her theory.
Rather, it focuses primarily on age/developmental stage at time of insult and progression in
cognitive skills with time since insult. She divides skill development into several levels:
o Emerging > where an ability is in the early stage of acquisition, but not yet functional.
o Developing > where a capacity is partially acquired but not fully functional.
o Established > where abilities are fully matured.
Dennis integrates these developmental skill levels with three crucial age-related variables:
o Age at time of lesion > determines the nature of the cognitive dysfunction. Early lesions
disrupt the onset and rate of language development, while later lesions are associated
with a specific symptom pattern such as high-level language dysfunction.
o Age at testing > even healthy children vary in their ability to perform cognitive tasks at
different developmental stages.
o Time since insult > differing performance patterns identified at different stage of
recovery, with increase in some cognitive skills, but failure to develop others.
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,Developmental Neuropsychology A.E.M. van Wordragen (u789251)
Current theoretical approaches
The cognitive reserve model
A model framed around the concept of individual differences in a child’s reserve capacity, both
‘brain reserve capacity’ (BRC) and ‘cognitive reserve capacity’ (CRC).
BRC is measured directly by quantifying variables such as insult severity, brain volume or
structural connectivity, as well as neurological sequelae such as epilepsy. When BRC is depleted
below threshold levels, functional deficits emerge.
There are different factors which influence the outcome of recovery. These factors can be seen
on a continuum level:
o Injury > severity, nature, complications
o Cognitive skill > simple, complex
o Development > age at injury, age at assessment
o Environment > distal, proximal factors
A biopsychosocial model
Brain: the ‘bio’ dimension
Interruption to brain development during the prenatal period have been shown to result
primarily in structural abnormalities (dysplasia, neural tube defects, agenesis of the corpus
callosum). During the postnatal period developments primarily include dendritisation,
synaptogenesis, and myelination.
Early disruption to central nervous system (CNS) development may have irreversible
consequences. In contrast to the more localised cerebral pathologies of adulthood (stroke,
tumour, ec.), childhood brain disorders are more commonly diffuse, impacting on the brain as a
whole (traumatic brain injury, cerebral infection, metabolic disorder.
Recent research indicates that prenatal brain injury may not result in functional transfer, but
that skills may be maintained ineffectually in damaged tissue, leading to developmental delays.
Such finding suggest that recovery following early brain insult is not static, but is likely to reflect
ongoing disruption to maturation of functional neural networks and to have a major negative
impact on long-term outcome.
Environment: the ‘social’ dimension
An enriching early environment is critically important for optimal child development. The
development of a child’s cognitive and socio-emotional skills is dependent, to a large extent, on
the quality of the home environment and the role models provided by parents.
Studies have demonstrated reduced brain volume, impacting both grey and white matter, as well
as deficits in structural connectivity and atypical brain activation in survivors of early trauma.
Specific brain regions most susceptible to the impact of neglect and abuse influence fronto-
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limbic networks, impacting the medical prefrontal cortex, orbital prefrontal cortex,
hippocampus, amygdala, and corpus callosum.
Child cognitive and socio-emotional function: the ‘psych’ dimension
There are a number of stages of development, each characterised by increasing symbolic
thought and the ability to deal with increasingly complex and abstract information:
o Simple motor and sensory activities with little evidence of any abstract thought, with a
gradual emergence of object permanence that has been argues to provide the earliest
indicator of working memory.
o Early attention skills, such as joint attention are critical for socio-emotional
development, particularly attachment.
o The capacity to integrate information across multiple dimension and to perform mental
transformation. This stage heralds the emergence of executive skills, including ‘cold’
(reasoning, problem-solving, organisation and mental flexibility and ‘hot’ (social
cognition) abilities.
There is a multidimensional relationship between memory, processing speed, and executive
functions that is likely to be responsible for age-related progress.
Children with an early brain insult may have problems acquiring social and emotional skills and
knowledge and comprehending social rules due to intellectual impairments, reduced self-
regulation, functional disability, social stigma, and limited interaction with the environment.
Depending on the nature and localisation of cerebral pathology, children may present as
impulsive, hyperactive, aggressive, lacking in insight, depressed and anxious, and may
demonstrate reduced empathy, theory of mind, and moral reasoning skills.
The ‘social brain network’ describes the primary brain regions and neural network involved in
socio-emotional processing:
o Superior temporal sulcus (STS)
o Fusiform gyrus (FG)
o Temporal lobe (TP)
o Medical prefrontal cortex (mPFC)
o Frontal pole (FP)
o Orbitofrontal cortex (OFC)
o Amygdala
o Insula
o Temporoparietal junction (TPG)
o Cingulate
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