Bayley 4 Clinical Use and Interpretation

Glen P. Aylward

• Publisher: Academic Press
• Year: 2020
• ISBN:
  9780128177556
• Topic: Psychology
• Subtopic: Psychotherapy
• Index: Psychology

Bayley 4 Clinical Use and Interpretation provides clinicians with a guide for use, administration, scoring and interpretation of the Bayley Scales of Infant and Toddler Development, Fourth Edition. The book begins with why and how the Bayley 4 was revised. Separate chapters discuss the clinical use and interpretation of the cognitive, language, motor, social-emotional and adaptive scales, each with illustrative clinical cases. Recommendations are provided to aid clinicians in the efficiency of test administration, as well as how to interpret and integrate results within a diagnostic assessment format and in planning intervention. The clinical validity of the Bayley 4 is demonstrated for eight clinical groups. There is an overview of Autism Spectrum Disorder (ASD) with the Bayley 4 ASD Checklist, accommodations, and red flags indicative of abnormality. Additional chapters discuss digital administration and how to present feedback to caregivers.

• Summarizes what is new and different in the Bayley 4
• Guides clinicians in use, administration, scoring, and interpretation
• Identifies the clinical validity of Bayley 4 for eight clinical groups
• Suggests how to integrate results into assessment and intervention
• Includes use for autism assessment and an ASD checklist
• Provides case studies on typical and atypical development

Chapter 1

Brain, environment, and development: A synthesis and a conceptual model

Abstract

This chapter introduces the underlying theoretic orientation that was influential in the development of the Bayley-4. Concepts such as neuronal plasticity, environmental influences (experiential, physical, and social transactions), epigenetics, brain disruption, and insult are important components of the Neuro-environmental Synthesis Model of development. This model emphasizes the assumption that internal brain developmental processes are affected by external influences. These internal changes, in turn, are manifest in developmental acquisitions assessed by the Bayley-4.

Keywords

Plasticity; Neuro-environmental model; Neural circuits; Epigenetics; Brain-behavior relationships

Contents

• Introduction
  • Changes from earlier theoretic orientations
  • Canalization
• Neuronal plasticity
  • Types of neural circuits
  • Critical and sensitive periods
  • Summary of plasticity
  • Application to developmental assessment
• Epigenetics
  • Components of epigenetics
• Environment
  • Components of the environment
• Extrapolation to other theories and developmental assessment
  • Cognitive theory
  • Attachment theory
  • Maturational theory
  • Serial assessment
• Disruption and insult
  • Developmental disruption
  • Insult
  • Translating to developmental assessment
• Summary of main points
  • Summary of plasticity
  • Summary of epigenetics
  • Disruption/insult summary
  • Role of the environment
  • Relationship to assessment

Introduction

This chapter contains an overview of several pertinent processes that affect brain development and developmental assessment. These include the concepts of neuronal plasticity, environmental influences, and epigenetics. An overarching theme is that environmental input will affect brain neuro- and synaptogenesis. These effects, in turn, will have an impact on the infant and toddler’s cognitive, language, motor, and social development, as well as our ability to assess these constructs. Application of this approach to other theories and discussion of the negative effects of brain alternations due to disruption and/or insult are also addressed.

Multiple, rapid changes in brain functions that underlie behavioral development occur in infancy and toddlerhood. These changes include development of higher-order capacities such as attention, working memory, and self-regulation—also known as executive functions (EFs; Guyer, Perez-Edgar, & Crone, 2018).

Changes from earlier theoretic orientations

The previous Bayley Scales (Bayley, 1969, 1993, 2006) were developed without subscribing to a specific theory of child development. However, the Bayley-4 is influenced by evolving concepts and new data regarding factors that affect brain function and related early developmental acquisitions. Essentially, this is an integrated neuro-environmental synthesis model of development. Basically, external biological and environmental influences work in combination to affect the course of internal brain development (Shonkoff & Gardner, 2012). In turn, brain changes are assumed to be manifest in behaviors that can be observed or assessed with instruments such as the Bayley-4. Stated differently, the child’s central nervous system (CNS) undergoes biological maturation, with changes in structure and function occurring in response to experience and/or injury. This, in turn, influences the dynamics of synaptic connections and formation of neural circuits, leading to developmental gains and increased complexity in behavior.

Biological components of development include brain growth and plasticity (e.g., synaptogenesis, myelination, and pruning), as well as epigenetic modifications (methylation, microRNAs, histone modification) that will be discussed subsequently. Brain growth involves additions such as creating new connections, as well as deletions (pruning).

Environment can exert negative effects via physical exposures (e.g., tobacco, Bisphenol A, lead, alcohol, and other toxicants), experiences (e.g., NICU experiences that overwhelm the infant’s immature nervous system with nociceptive, visual, auditory, and proprioceptive sensory input), and social transactions (early life adversity, abuse/neglect, low SES, lack of stimulation, poor quality caregiver-child interaction, and allostatic load). Environmental components affecting brain development are classified as: (a) events of omission, where factors that are necessary for normal brain development are absent (e.g., the preterm infant does not receive intrauterine nutrients critical for third trimester brain development); and (b) events of commission where adverse effects to the brain are caused by exposure to substances that should not be present (e.g., fetal alcohol, Bisphenol A) (Georgieff, Tran, & Carlson, 2018). The omissions and commissions can also work in combination as in the case of fetal alcohol exposure (commission) that leads to iron deficiency (omission). (Georgieff et al., 2018).

Recent data indicate that children living 1.5 times below federal poverty level have smaller brain volumes in brain regions critical for cognitive and academic performance, namely gray matter, frontal and temporal lobes, and the hippocampus (Noble et al., 2015). This again underscores an environmental influence on brain development. Nutrition, inflammatory processes, and intrauterine exposures also must be considered. There is growing awareness that negative experiences or exposures do not have to be extreme to have an impact (i.e., not necessarily total deprivation or excessive stimulation), and seemingly innocuous exposures can still have significant effects on brain development (Kolb, Harker, & Gibb, 2017).

In the case of synaptogenesis and pruning (which provide the basis for central nervous system plasticity and functional capabilities), the brain responds or “listens” to the environment. In epigenetics, however, genes respond to the environment.

Canalization

Canalization, conceptualized as prewired, species-specific neural circuits that facilitate simple behaviors, also plays a significant role in early development (McCall, 1983). Canalized behaviors are primarily sensorimotor and tend to be resistant to negative influences such as perinatal trauma, prematurity, or hypoxic ischemic encephalopathy, provided these negative influences are not severe. Canalized behaviors are relatively simple (e.g., smiling, reaching, babbling), self-righting, and are in contrast to increasingly complex higher-order functions that are more susceptible to disruption. The canalized behaviors are buffered so that minor perturbations can be compensated for without causing a major developmental problem (Johnson, Jones, & Gliga, 2015). Early infant tests typically are heavily weighted with tasks involving canalized behaviors; this may partially explain why predicting later outcome is so difficult, because later higher-order functions require more complex and vulnerable circuits that are not functional early on.

During development, brain alterations range from the cellular level (e.g., dendritic organization) to synaptic structuring, to changes in functional organization. These brain changes, particularly growth of new synapses and neural networks, are inferred to be the source of behavioral changes that are assessed in developmental evaluation. Although a direct linkage between brain changes and observable behavior is assumed, in actuality we are faced with associations that are not clearly causative or necessarily fixed over time (Kolb & Gibb, 2013).

Neuronal plasticity

Types of neural circuits

Neuronal plasticity in typical development refers to structural and functional changes in neuronal circuits that are in response to experience (Fu & Zuo, 2011). Plasticity is associated with increased capacity for learning. There are three types of neural circuits that are involved in plasticity: (1) experience-independent; (2) experience-expectant; and (3) experience-dependent (Greenough, Black, & Wallace, 1987). Experience-independent synapses (largely a prenatal process) are groupings of cells that are connected and fire together in response to internal stimulation. This repeated synchrony in firing in the absence of external sensory input further strengthens connections of the cells within the group and refines brain connectivity. Cell assemblies that fire out of synch gradually weaken and become nonfunctional (e.g., Campbell & Shatz, 1992).

Experience-expectant synapses are innate and prewired, but to become functional, they need to receive input (essentially being activity-dependent). Input occurs mostly during early postnatal development (Kolb et al., 2017). For example, prior to 6 months of age, infants are “wired” to discriminate phonemes in all languages. At approximately 6–10 months, this ability diminishes, while the infant’s ability to discriminate phonemes in the native language to which he or she is exposed increases (Kuhl, Williams, Lacerda, Stevens, & Lindblom, 1992). Babbling provides another experience-expectant example: Initially, infants babble all sounds of a language, but this becomes restricted to the sou...