Elsevier

Neuroscience & Biobehavioral Reviews

Volume 47, November 2014, Pages 578-591
Neuroscience & Biobehavioral Reviews

Review
Childhood adversity and neural development: Deprivation and threat as distinct dimensions of early experience

https://doi.org/10.1016/j.neubiorev.2014.10.012Get rights and content

Highlights

  • Novel framework differentiating adverse early experiences of deprivation and threat.

  • Deprivation, or the absence of expected inputs, impacts proliferation and pruning.

  • Threat, or the presence of threats to one's physical integrity, impacts fear learning.

  • Predictions based on animal literature are supported by evidence from human studies.

Abstract

A growing body of research has examined the impact of childhood adversity on neural structure and function. Advances in our understanding of the neurodevelopmental consequences of adverse early environments require the identification of dimensions of environmental experience that influence neural development differently and mechanisms other than the frequently-invoked stress pathways. We propose a novel conceptual framework that differentiates between deprivation (absence of expected environmental inputs and complexity) and threat (presence of experiences that represent a threat to one's physical integrity) and make predictions grounded in basic neuroscience principles about their distinct effects on neural development. We review animal research on fear learning and sensory deprivation as well as human research on childhood adversity and neural development to support these predictions. We argue that these previously undifferentiated dimensions of experience exert strong and distinct influences on neural development that cannot be fully explained by prevailing models focusing only on stress pathways. Our aim is not to exhaustively review existing evidence on childhood adversity and neural development, but to provide a novel framework to guide future research.

Section snippets

Distinguishing between deprivation and threat

The framework we propose here distinguishes between core dimensions of environmental experience that underlie different forms of childhood adversity and describes their distinct impacts on neural development. The central distinction we make is between experiences of deprivation and experiences of threat. We suggest that these dimensions of experience can be assessed across different forms of childhood adversity (e.g., physical and sexual abuse, domestic violence, institutionalization, neglect)

Predictions based on animal literature

One of the areas where the impact of experience on neural development has been most clearly documented is in the pruning of synaptic connections during development in the central nervous system. These principals were first examined in studies employing sensory deprivation (Wiesel and Hubel, 1965b). Studies of deprived or anomalous sensory input during development illustrated that one of the primary mechanisms through which early experience shapes neural structure and function is by pruning

Predictions based on animal literature

Evidence from animal and human studies demonstrates consistently that early exposure to threat is associated with long-term changes in neural circuits that underlie emotional learning. Based on this evidence, we argue that early threat exposure impacts the structure, function, and coupling of the hippocampus, amygdala, and ventromedial prefrontal cortex (vmPFC). First, we predict that early threat exposure leads to changes in hippocampal morphology and function, including reduced dendritic

Recommendations for future research

The exposures that give rise to experiences of deprivation and threat co-occur at high rates in children and adolescents (Green et al., 2010, McLaughlin et al., 2012). This co-occurrence has generated many of the methodological and conceptual challenges in identifying dimensions of experience that influence specific aspects of neural development. We do not advocate that future research attempt to identify children who experience only one specific form of adversity, as that would surely result

Conclusion

We propose a novel conceptual framework for understanding the impact of childhood adversity on neural development and argue that the field must move beyond the prevailing approach of examining the impact of complex and co-occurring exposures on brain development to distilling those complex experiences into their core underlying dimensions. Two important dimensions that appear to have distinct effects on neural development are deprivation and threat. Existing evidence from human studies provides

Acknowledgements

This research was funded by the National Institutes of Mental Health (K01-MH092625 to McLaughlin and K01-MH092555 to Sheridan). The authors have no financial disclosures or conflicts of interest to report.

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    This research was supported by grants from the National Institutes of Health (K01-MH092526 and R01-MH103291 to McLaughlin and K01-MH092555 to Sheridan).

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    Please note that these authors contributed equally to this work.

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