The Neural Substrates of Attachment in Adults

A general short summary of my attachment research in adults can be found in two of my blogs – the neural signature of attachment insecurity and the insecurely attached brain. Moreover, in 2012, Patrik Vuilleumier and I have published a first review paper in Frontiers in Human Neuroscience including a functional neuro-anatomical framework of adult attachment (see here), which I have recently updated in a book chapter on “The Social Neuroscience of Attachment“. Below is a Figure depicting our version of a possible attachment system in humans:

Fig_1

Functional neuro-anatomical framework of human attachment (Vrticka , 2017)

Functional Neuro-Anatomical Framework of Human Attachment
In the above functional neuro-anatomical framework, Patrik Vuilleumier and I differentiate between an affective evaluation and a cognitive control module. While the affective evaluation module is thought to process incoming information rather quickly and automatically, the cognitive control module represents more voluntary regulatory processes that can modulate affective evaluation mechanisms.

The so far available data in adults suggests that attachment avoidance and anxiety differentially influence affective evaluation and cognitive control mechanisms. While both insecure attachment orientations appear to (at least partially) interfere with emotion regulation mechanisms as part of the cognitive control module (see also here), attachment avoidance and anxiety seem to have opposite effects on affective evaluation processes. Attachment avoidance may be mainly associated with a general blunting of affective evaluation processes, particularly in the case of positive social information. In turn, attachment anxiety may be mainly linked to a general intensification of affective evaluation processes, especially in the case of negative social information.

Attachment as a Meaningful Adaptation to the Environment
Please note that inter-individual differences in attachment represent specific adaptations to the environment attachment was originally formed in. Although it is generally understood that a secure attachment is most beneficial for social and emotional development, caution is advised in labeling attachment insecurities – and their associated modulations of behavioral, biological, and brain responses – as inferior or detrimental per se. If so, why would so many of us (up to 50%) be insecurely attached? According to the Social Defense Theory, attachment insecurities may even represent specific advantages on the group level that couuld compensate possible disadvantages of single individuals by providing the overall group with crucial information on an emerging threat and on how to escape from the latter (for example, see here).

Cultural Differences in Attachment
It is also important to keep in mind that attachment theory was developed in a western, educated, industrialized, rich, democratic – in short WEIRD – cultural context, and that most research is still performed on WEIRD culture participants. More cross-cultural research therefore is still crucially needed to further extend and specify attachment theory and the emerging applied attachment research – including the above functional neuro-anatomical framework -, on many levels. As nicely put by Rothbaum et al. (2000), “an awareness of different conceptions of attachment would clarify that relationships in other cultures are not inferior but instead are adaptations to different circumstances“ (p. 1101).

Different Neurobiological Models of Human Attachment
Finally, it should be mentioned here that there are (at least) two other neurobiological models of human attachment available in the literature.

A first prominent model by Helen Fisher (for example, see here) suggests that three principal human social behaviors can be dissociated by their underlying neurotrans-mitter / -peptide systems: (1) the sex drive / lust mediated by androgens, (2) attraction / mate choice / romantic love mediated by catecholamines, and (3) attachment (understood as a long-term non-sexual bond between individuals; child-parent, but also romantic partners, etc.) mediated by oxytocin.

A second prominent model by Ruth Feldman (for a recent review, see here) suggests a differentiation of human attachment behaviors by means of four principal mammalian bonds, namely: (1) parent-infant bonds, (2) pair-bonds, (3) peer bonds, and (4) bonds between conspecifics. Furthermore, Ruth Feldman proposes that the strenght of these bonds can be categorically distinguished by their degree of bio-behavioral synchrony expressed within the bond – with parent-infant bonds having the strongest degree of bio-behavioral synchrony.

In the above-described functional neuro-anatomical framework of adult attachment we propose, the models by Fisher and Feldman are also considered. These models, however, are extended by the notion put forward by attachment theory that the very same mammalian bond / attachment  – mediated by the very same neurotransmitter / -peptide systems – is subjected to strong inter-individual differences depending on the quality of the bond / attachment. For example, parent-infant bonds may be generally characterized by high bio-behavioral synchrony and prominently mediated by oxytocin, but strong inter-individual differences in the bio-behavioral signature are to be expected depending on the quality of the bond – the latter being reflected in secure versus insecure, anxious and/or avoidant attachment orientations (not only on the individual but also the dyadic and family level). What therefore is key in our model are inter-individual differences and their influence on the psychological, behavioral, biological, physiological, and neural basis of human attachment.