enhancing medications and repetitive exposure-based interventions, either alone or in combination, may offer a paradigm shift in anxiety disorders. Instead of treating the symptoms of anxiety pharmacologically, this strategy attempts to improve the extinction learning that occurs during cognitive-behavioral therapy (Myers and Davis, 2007; Quirk and Mueller, 2008).

Attachment

Early bonding to a primary caregiver is an innate predisposition for children. It is an important feature of infant development that contributes to social and emotional learning, as well as to resilience and risk for psychopathology (Bakermans-Kranenburg and van Ijzendoorn, 2007; Corbin, 2007; Swain, Lorberbaum, et al., 2007). The classic model for early attachment is visual imprinting in newly hatched chicks. During a specific sensitive period, they develop an enduring selectivity for following either their mother or a replacement object. This imprinting consists of three independent behavioral processes: approaching the mother, learning and remembering her identity, and avoiding others while maintaining an affiliation with her. Specific cortical brain regions and synaptic changes are involved in the memory of and response to the imprinted object in chicks (Insel and Young, 2001).

Mammalian animal models of the attachment of an infant to a caregiver, as well as the behavioral and neuroendocrine responses to separation from that caregiver, have revealed physiological mediators of attachment and separation responses that have specific and long-term regulatory effects on the hormonal, physiological, and behavioral reactivity of the infant (Hofer, 1994). The interactions of the parent and child that are involved in attachment and separation responses include tactile sensation, motor activity, the warmth and temperature of the mother’s body, and nutritional factors (Hofer, 1994, 1996). The cry of the infant upon separation, for example, is released by loss of the warmth, specific odors, and passive tactile cues of the mother (Shair, Brunelli, et al., 2003). Nutritional and tactile factors also regulate hormone release and thereby cause abnormal levels of stress-response hormones during separation. Loss of the maternal nutrient supply affects hormone production by the adrenal gland, whereas loss of the tactile interaction between mother and infant affects hormone release by the pituitary gland (Hofer, 1996). These physiological regulators constitute the building blocks from which attachment develops.

Infants attach regardless of the quality of care provided by the object of attachment. During the imprinting-sensitive period, for example, chicks will follow their mother even while being shocked. Similarly, rat pups attach strongly even to a handler providing a shock or rough treatment, and infant



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