Atypical modulation of medial prefrontal cortex to self-referential comments in generalized social phobia
Introduction
Generalized social phobia (GSP) involves a strong and persistent fear of social or performance situations that have the potential for negative evaluation. It is a relatively common disorder associated with a high risk for alcohol and drug abuse, depression, and suicide (Kaufman and Charney, 2000, Kessler, 2003, Beesdo et al., 2007).
Functional magnetic resonance imaging (fMRI) studies in GSP have focused on examining responses to social stimuli. In particular, extensive work has examined the response to facial expressions, including harsh (Phan et al., 2006), angry (Stein et al., 2002, Straube et al., 2004, Straube et al., 2005, Blair et al., submitted for publication), fearful (Stein et al., 2002, Blair et al., 2008b, Blair et al., submitted for publication), disgusted (Amir et al., 2005), happy (Straube et al., 2005) and neutral (Birbaumer et al., 1998, Stein et al., 2002) expressions. This work finds increased amygdala response in GSP (Stein et al., 2002, Straube et al., 2005, Phan et al., 2006), though the dorsal medial prefrontal cortex (MPFC) has also been implicated (Stein et al., 2002, Straube et al., 2004, Amir et al., 2005, Blair et al., 2008b).
However, the response to facial expressions in both healthy individuals (Pessoa et al., 2002, Pessoa et al., 2005, Mitchell et al., 2007) and patients (Pine et al., 2005, McClure et al., 2007) is under considerable attentional control; increased attention to other features in the environment reduces the representation of facial expressions and thus the emotional response to them (Pessoa and Ungerleider, 2004, Mitchell et al., 2007, Luo et al., 2010). Moreover, the intent and self-relevance of facial expressions can be difficult to ascertain (i.e., “Are you laughing at me or smiling with me? Angry with me or somebody else?”). Given that fears of other people's scrutiny and judgment lie at the core of GSP (First et al., 1995), aberrant processing of self-referential information may play a role in the disorder.
In the first study to directly examine self-referential processing in GSP using fMRI, patients were assessed when processing self- vs. other-referential criticism (e.g., “You're ugly” vs. “He's ugly”) and praise (e.g., “You're beautiful” vs. “He's beautiful”) (Blair et al., 2008a). This study revealed selectively increased BOLD responses within both the amygdala and the dorsal MPFC in patients with GSP to self-referential criticism. In short, these data indicated that the heightened sensitivity to self-referential criticism in patients with GSP reflects dysfunction in the dorsal MPFC as well as the amygdala (see also recent work by Goldin and colleagues that examines emotion regulation in social phobia to criticism [Goldin and Manber-Ball, 2009, Goldin and Gross, 2010]). The MPFC finding is of particular relevance given the extensive data implicating dorsal as well as ventral MPFC in self-referential processing (Johnson et al., 2002, Fossati et al., 2003, Phan et al., 2004, Seger et al., 2004, Mitchell et al., 2005, Moran et al., 2006; for review see Gillihan and Farah, 2005, Northoff et al., 2006, Schmitz and Johnson, 2007, Legrand and Ruby, 2009, van der Meer et al., 2010). Specifically, both regions show increased responses during self-related as opposed to non-self-related reasoning. Moreover, in addition to the MPFC, recent work has also highlighted the role of the amygdala in the response to praise and criticism in healthy individuals (Frewen et al., 2010). Taken together, these findings suggest that the MPFC might make independent contributions to GSP but may also interact as part of a circuit.
The goal of the current study was to extend our earlier work (Blair et al., 2008a) and to specifically examine whether patients with GSP show aberrant responding to self-referential comments depending on whether the origin of those comments is another individual (e.g., hearing “You're ugly”) or the self (e.g., thinking “I'm ugly”). Our aim is to go beyond describing the regions implicated in GSP and rather to probe the nature of information-processing perturbations that occur within these regions. Without this information, it will be difficult to optimize treatments for this disorder, particularly when they are targeted towards specific cognitive processes. As such, we used a novel verbal-comment paradigm to implement a 2(Viewpoint: 1st or 2nd Person) by 3(Valence: negative, neutral and positive) by 2(Group: GSP, healthy comparison) design.
On the basis of our earlier data, which found these stimuli to elicit GSP-related perturbations in dorsal and ventral MPFC (Blair et al., 2008a, Blair et al., 2010), we hypothesize that GSP involves hyper-responsiveness to social feedback from others. Thus, we expect patients with GSP to show (to 2nd person point-of-view comments) increased responses within MPFC (i.e., there will be a group-by-viewpoint interaction). This might be particularly marked for others' criticism (i.e., there will be a group-by-viewpoint-by-valence interaction). Alternatively, given that GSP is associated with an increased level of self-criticism (Cox et al., 2002, Cox et al., 2004), it could be hypothesized that it involves hyper-responsiveness to self-referential comments whether these are generated internally or externally (i.e., there will be a main effect of group within the MPFC).
Section snippets
Subjects
This study included 15 patients with GSP and 15 healthy comparison (HC) individuals, group-matched on age, gender, and IQ (see Table 1). Subjects were recruited from NIMH Institutional-Review-Board (IRB) approved advertisements. Subjects with GSP met criteria for GSP according to the DSM-IV (1994) criteria based on the Structural Clinical interview for DSM-IV Axis I disorders (SCID) (First et al., 1997) and a confirmatory clinical interview by a board-certified psychiatrist (DSP). No GSP
Behavioral data
Ratings data collected after scanning were analyzed by a 2(Group: GSP, HC) by 2(Viewpoint: 1st Person, 2nd Person) by 3(Valence: Negative, Neutral, Positive) ANOVA. There were significant main effects of viewpoint and valence. The 2nd person viewpoints were rated significantly more positively than the 1st person viewpoints (F(1,28) = 7.26; p < 0.05) and positive comments significantly more positively, and negative comments significantly more negatively, than neutral comments (F(1,29) = 390.29 and
Discussion
In this article, we examined the neural response to self-referential 1st and 2nd person viewpoints in GSP. We asked whether patients with GSP show increased BOLD responses to comments about themselves dependent upon whether they concern another person's point of view or the self view. Our results indicated a complex pathophysiology in patients with GSP with more ventral regions of the MPFC showing heightened responsiveness to others' viewpoint of the self relative to HCs. In contrast, more
Acknowledgements
This research was supported by the Intramural Research Program of the NIH, National Institute of Mental Health. The authors have no conflicts of interest or financial disclosures to report.
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