As hypothesized, social proximity to a caregiver during a potentially stressful situation attenuated activity in the hypothalamus, VMPFC, and VLPFC (left) in clinically anxious youths. These results are consistent with earlier research 
, suggesting that hypothalamus and ventral prefrontal activity during a stressful situation are decreased in the presence of a loved one. Also, Coan et al. 
found that hypothalamic attenuation was dependent upon the quality of the relationship with the hand holder. A similar process could be occurring here, and could explain the results of the sensitivity analysis in the hypothalamus.
As activity decreased for all three structures it is unlikely that these results reflected regulatory influences of the hypothalamus by the ventral prefrontal cortex but rather, as suggested by Beckes and Coan's Social Baseline Theory 
, these data could suggest a “return” to a baseline state of low reactivity. To the extent that this baseline represents a positive motivational state, as opposed to an anxious threatened state, these data are consistent with a positivity offset 
or the general expectation of positive outcomes for unknown events, in the absence of a specifically stressful stimulus.
A baseline state would include proximity to trusted members of one's social network, and failing this proximity, negative affect should arise in proportion to perceived situational demands. Social proximity would provide the individual with a sense of the environment to which he or she is already adapted, and therefore allow the individual to be less vigilant to potential threats as perceived contextual demands decrease. Less vigilance would translate into less emotional regulation as well as less self-regulatory inhibition. In a sense, social regulation effects do not down-regulate affect so much as dyadically remove the need for the generation of negative affect.
Here, the presentation of threat stimuli can be seen as a threatening situation. Youths with an anxiety disorder would, in theory, be using all their regulatory mechanisms to cope with their anxiety and maintain their baseline state. When these individuals are subjected to a stress inducing event, such as viewing threatening stimuli, their resources may already be partially depleted from regulating their anxiety, and further maintenance of their baseline state will become difficult. Social proximity, however, functions as a cue, informing these individuals that more resources are available and fewer problems need to be solved. Therefore, there would be a decrease in the perceived context demand, a decrease in the use of regulatory mechanisms and a return to the baseline state. So, instead of viewing the significant differences seen in the brain activity of the youths with an anxiety disorder that requested a caregiver in the scanner room as decreases in neural activity, it could be interpreted as a return to a baseline state. Whereas, the youths with an anxiety disorder that did not request a caregiver in the scanner room have increased activity from baseline due to their lack of social proximity. fMRI scans can be considered stressful in and of themselves due to the lack of social interaction when confronting a novel, noisy and potentially threatening environment. That said, such effects are tonic and thus not likely to entirely account for the alterations in stimulus related reactivity observed in this experiment.
These data suggest changes in emotional processing in the presence of a caregiver; caregivers may act as emotion regulators. Thus, considering their role in facilitating emotion regulation could be useful in structuring treatments for anxious youths that aim to increase emotion regulatory function, e.g., by initially involving and gradually removing parental support. Barrett et al. 
found that children with an anxiety disorder responded significantly better to cognitive-behavioral therapy plus family anxiety management training than cognitive-behavioral therapy alone based on seven clinical evaluation scales completed at posttreatment and at 6- and 12-month follow-ups.
It is important to note that the current findings may not generalize to adult populations. Further, no controls (youths without anxiety) naturalistically requested to be accompanied by a caregiver in the scanner room; it would be interesting to determine if attenuation of similar neural systems would be seen in controls with proximity to a caregiver. Another limitation is our small sample sizes, which is due to the fact that these data are from a larger study examining anxiety among youths.
Additionally, there was a non-random assignment of participants to groups (with versus without caregivers). It could be fundamental differences between the anxious youths that requested a caregiver in the scanner room and the anxious youths that did not request a caregiver in the scanner room rather than state-related potentiation. We did not identify such a variable; there were no significant differences in the severity of anxiety symptoms between these groups.
These limitations notwithstanding, our results bring to light the potential importance of social proximity in distress alleviation. Specifically, the lowest-level neural features of threat reactivity associated with anxiety in youths may be contextual, manifesting primarily in situations in which anxious youths are alone and unsupported. Helping anxious youths to feel more supported and less alone could be important to normalizing brain function in this population.