relationships, often involving either abuse and neglect or an inconsistency in parental nurturance (Fruzzetti, Shenk, and Hoffman, 2005; Johnson, Cohen, et al., 2006; Lieb, Zanarini, et al., 2004).

Perhaps the human condition that most obviously represents a disturbance in the formation of interpersonal attachments is reactive attachment disorder, which typically is manifested as an excessively inhibited or hypervigilant response to social interaction or, at the other extreme, as an excessively diffuse and indiscriminate sociability. Although its neurobiological underpinnings are not well understood, it is thought to be caused by a persistent disregard of the child’s basic emotional or physical needs or by repeated changes in the primary caregiver, which prevent formation of stable attachments during early development (Corbin, 2007).

Social Relatedness

Social relatedness is a complex construct that includes, among other components, the processing of sensory aspects of social stimuli, imitation and perspective taking, emotions induced by social interactions, and awareness of self and others. Distinct neural systems are likely to subserve each of these components.

Extensive evidence from human imaging studies suggests that the neural systems responsible for processing social stimuli are based primarily in the superior temporal cortex (Zilbovicius, Meresse, et al., 2006; Zahn, Moll, et al., 2007). A large body of recent work suggests that a “mirror neuron” system subserves knowledge of imitation, thought to be a precursor skill for the acquisition of knowledge of the intentional states that underlie the actions of others, although this evidence is not conclusive (Agnew, Bhakoo, and Puri, 2007; Iacoboni and Dapretto, 2006; Iriki, 2006; Lyons, Santos, and Keil, 2006; Rizzolatti and Craighero, 2004). Processing the sensory and conceptual aspects of social stimuli in the superior temporal cortex and understanding the actions of others through activity in the mirror neuron system are likely to work in concert with the medial prefrontal cortex to gain an understanding of one’s own and others’ intentional states. This understanding is referred to as having a “theory of mind” or the ability to “mentalize”—the knowledge that others have perspectives, beliefs, desires, and motivations that are different from one’s own.

Social relationships are an essential component of human mental health. Almost all forms of psychopathology involve difficulties in developing and maintaining healthy relationships. A primary example is autism, which is defined by the presence of qualitative deficits in social interaction and affiliation. Each of the systems that subserve the various aspects of social relatedness has been implicated in the pathogenesis of the socialization deficits in autistic children. For example, reductions in gray matter volume,



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