Memory of early maltreatment: neonatal behavioral and neural correlates of maternal maltreatment within the context of classical conditioning.

Department of Zoology, University of Oklahoma, Norman, Oklahoma 73019, USA.
Biological Psychiatry (Impact Factor: 9.47). 05/2005; 57(8):823-31. DOI: 10.1016/j.biopsych.2005.01.032
Source: PubMed

ABSTRACT While children form an attachment to their abusive caregiver, they are susceptible to mental illness and brain abnormalities. To understand this important clinical issue, we have developed a rat animal model of abusive attachment where odor paired with shock paradoxically produces an odor preference. Here, we extend this model to a seminaturalistic paradigm using a stressed, "abusive" mother during an odor presentation and assess the underlying learning neural circuit.
We used a classical conditioning paradigm pairing a novel odor with a stressed mother that predominantly abused pups to assess olfactory learning in a seminaturalistic environment. Additionally, we used Fos protein immunohistochemistry to assess brain areas involved in learning this pain-induced odor preference within a more controlled maltreatment environment (odor-shock conditioning).
Odor-maternal maltreatment pairings within a seminatural setting and odor-shock pairings both resulted in paradoxical odor preferences. Learning-induced gene expression was altered in the olfactory bulb and anterior piriform cortex (part of olfactory cortex) but not the amygdala.
Infants appear to use a unique brain circuit that optimizes learned odor preferences necessary for attachment. A fuller understanding of infant brain function may provide insight into why early maltreatment affects psychiatric well-being.

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