Neglect as a Violation of Species-Expectant Experience: Neurodevelopmental Consequences

Abstract

The human brain requires a wide variety of experiences and environmental inputs in order to develop normally. Children who are neglected by caregivers or raised in institutional environments are deprived of numerous types of species-expectant environmental experiences. In this review, we articulate a model of how the absence of cognitive stimulation and sensory, motor, linguistic, and social experiences common among children raised in deprived early environments constrains early forms of learning, producing long term deficits in complex cognitive function and associative learning. Building on evidence from animal models, we propose that deprivation accelerates the neurodevelopmental process of synaptic pruning and constrains myelination, resulting in age-specific reductions in cortical thickness and white matter integrity among children raised in deprived early environments. We review evidence linking early experiences of psychosocial deprivation to reductions in cognitive ability, associative and implicit learning, language skills, and executive functions as well as atypical patterns of cortical and white matter development—domains that should be profoundly influenced by deprivation through the learning and neural mechanisms we propose. These patterns of atypical development are difficult to explain with existing models that emphasize stress pathways and accelerated limbic system development. A learning account of how deprived early environments influence cognitive and neural development provides a complementary perspective to stress models and highlights novel pathways through which deprivation might confer risk for internalizing and externalizing psychopathology. We end by reviewing evidence for plasticity in cognitive and neural development among children raised in deprived environments following interventions that improve caregiving quality.

Subcortical structural variations associated with low socioeconomic status in adolescents

“…Future research is needed to identify the specific exposures that underlie these associations. The quality of early caregiving is a potential candidate (McLaughlin, Sheridan, & Nelson, 2017). With additional research on the developmental persistence and behavioral implications of these patterns, we will acquire a more thorough understanding of the mechanisms through which socioeconomic conditions affect children's life outcomes.…”

The relationship between cognitive enrichment and cognitive control: A systematic investigation of environmental influences on development through socioeconomic status

“…These may take the form of greater language complexity, education quality, travel experiences, specialized sports team membership, books and toys, music lessons, etc. (e.g., Conger & Donnellan, ; Hackman, Gallop, Evans & Farah, ; McLaughlin, Sheridan & Nelson, ). Taken together with the PFC model predictions (Rougier et al., ), these data lead us to predict that SES differences in the development of rule‐guided behavior specifically, and WM more broadly, may arise from more numerous and variable opportunities for building stable, abstract rule representations in higher SES homes.…”

“…However, our goal is to understand how SES across a wide income range impacts WM, not how the biological embedding of stress impacts WM. A critical distinction is that stress and enrichment act through different mechanisms to shape development (Amso & Lynn, ; Conger & Donnellan, ; Johnson et al., ; Lawson, Camins, et al., ; Lawson, Hook, et al., ; McLaughlin & Sheridan, ; McLaughlin et al., ; Sheridan, Peverill, Finn, & McLaughlin, ; Ursache & Noble, ) . When incorporating the adversities more common in poverty, there is little doubt that stresses acts to shape outcomes.…”

Sensitive periods for the effect of childhood interpersonal violence on psychiatric disorder onset among adolescents

“…Early interpersonal violence could be more damaging than later interpersonal violence because it occurs when foundational neural circuits are developing that provide the scaffolding for more complex abilities. 8,9 Further, early violence exposure could also compromise a child’s ability to master early developmental tasks, such as emotion regulation and the formation of secure attachments, creating a negative developmental cascade that influences future developmental tasks. 10,11 Alternatively, later interpersonal violence could be more harmful than earlier violence exposure because adolescents have developed the cognitive skills to conceptualise experiences of interpersonal violence and their meaning.…”