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Regina SULLIVAN" The impact of attachement quality on cognitive and emotional developement "

Abstract :

To support attachment to the caregiver, altricial infants such as humans and rats, must identify, learn, and remember their caregiver.
As suggested by Bowlby in the 1950’s, this rapid attachment learning must rely on a biological attachment system in the brain. While the attachment circuit has not yet been identified in the human, research in the rat is beginning to document the early attachment neurobehavioral process in the rat, which is exquisitely suited to promote the infant-caregiver relationship. Foremost, pups have the enhanced ability to acquire learned preferences/approach, and this behavior is supported by the hyperfunctioning noradrenergic locus coeruleus and experience-induced changes in the olfactory bulb and anterior piriform cortex. However, of equal importance, infants also have a decreased ability to acquire learned aversions/fear, and this behavior is facilitated through attenuated amygdala plasticity. The neural mechanisms for pups’ decreased ability to learn fear or avoidance depends upon pups low levels of corticosterone, which prevents amygdala plasticity. Thus, odors paired with reward (including pain) become preferred and actually take on characteristics of the natural maternal odor. Presumably, this attachment learning circuitry constrains the infant to form only preferences for the caretaker regardless of the quality of the care received.

With maturation, the developing underlying circuitry transition to a more “adult-like’ learning system to accommodate life outside the nest (around postnatal day 10). During a brief developmental period, pups rapidly transition between infant attachment learning when with the mother to “adult-like” learning when not with the mother. That is, odor-pain pairings continue to produce odor approach learning when experienced with the mother but produce odor avoidance learning and amygdala activation when the mother is not present. The mother’s ability to block pups’ release of the stress hormone corticosterone returns these older pups to the neural equivalent of the younger pup when level of corticosterone are too low to support amygdala plasticity. This transitional period, when pups switch between attachment or fear learning form odor-shock conditioning ends around postnatal day 16, when amygdala plasticity no longer requires corticosterone.

Selected publications

Raineki C, Moriceau S, Sullivan RM. Developing a Neurobehavioral Animal Model of Infant Attachment to an Abusive Caregiver. Biol Psychiatry. 2010 Feb 15.
Moriceau S, Shionoya K, Jakubs K, Sullivan RM. Early-life stress disrupts attachment learning: the role of amygdala corticosterone, locus ceruleus
corticotropin releasing hormone, and olfactory bulb norepinephrine. J Neurosci. 2009 Dec 16;29(50):15745-55.
Sullivan RM, Holman PJ. Transitions in sensitive period attachment learning in infancy: the role of corticosterone. Neurosci Biobehav Rev. 2010
Barr GA, Moriceau S, Shionoya K, Muzny K, Gao P, Wang S, Sullivan RM. Transitions in infant learning are modulated by dopamine in the amygdala. Nat
Neurosci. 2009 Nov;12(11):1367-9.

Muriel Koehl