Joseph M. Moran

Neuroanatomical Evidence for Distinct Cognitive and Affective Components of Self

This study examines whether the cognitive and affective components of self-reflection can be dissociated using functional magnetic resonance imaging. Using a simple paradigm in which subjects judged the personal relevance of personality characteristics that were either favorable (e.g., honest) or unfavorable (e.g., lazy, we found that distinct neural circuits in adjacent regions of the prefrontal cortex subserve cognitive and emotional aspects of self-reflection. The medial prefrontal cortex responded only to material that was self-descriptive, and this did not differ as a function of the valence of the trait. When material was judged to be self-relevant, the valence of the material was resolved in an adjacent region of ventral anterior cingulate. The nature of self is one of the most enduring questions in science, and researchers are now beginning to be able to decompose the neural operations that give rise to a unitary sense of self.

Associations and dissociations between default and self-reference networks in the human brain.

Neuroimaging has revealed consistent activations in medial prefrontal cortex (MPFC) and posterior cingulate cortex (PCC) extending to precuneus both during explicit self-reference tasks and during rest, a period during which some form of self-reference is assumed to occur in the default mode of brain function. The similarity between these two patterns of midline cortical activation may reflect a common neural system for explicit and default-mode self-reference, but there is little direct evidence about the similarities and differences between the neural systems that mediate explicit self-reference versus default-mode self-reference during rest. In two experiments, we compared directly the brain regions activated by explicit self-reference during judgments about trait adjectives and by rest conditions relative to a semantic task without self-reference. Explicit self-reference preferentially engaged dorsal MPFC, rest preferentially engaged precuneus, and both self-reference and rest commonly engaged ventral MPFC and PCC. These findings indicate that there are both associations (shared components) and dissociations between the neural systems underlying explicit self-reference and the default mode of brain function.

Overlapping and non-overlapping brain regions for theory of mind and self reflection in individual subjects

When subjects are required to reason about someones false belief, a consistent pattern of brain regions are recruited including the medial prefrontal cortex, medial precuneus and bilateral temporo-parietal junction. Previous group analyses suggest that the two medial regions, but not the lateral regions, are also recruited when subjects engage in self-reflection. The current study directly compared the results of the false belief and self tasks in individual subjects. Consistent with previous reports, the medial prefrontal and medial precuneus regions recruited by the two tasks significantly overlap in individual subjects, although there was also evidence for non-overlapping voxels in medial regions. The temporo-parietal regions are only recruited for the theory of mind task. Six possible models of the relationship between theory of mind, self-reflection and autobiographical memory, all consistent with both neurobiological and developmental evidence to date, are discussed.

Neural correlates of humor detection and appreciation

Humor is a uniquely human quality whose neural substrates remain enigmatic. The present report combined dynamic, real-life content and event-related functional magnetic resonance imaging (fMRI) to dissociate humor detection (getting the joke) from humor appreciation (the affective experience of mirth). During scanning, subjects viewed full-length episodes of the television sitcoms Seinfeld or The Simpsons. Brain activity time-locked to humor detection moments revealed increases in left inferior frontal and posterior temporal cortices, whereas brain activity time-locked to moments of humor appreciation revealed increases in bilateral regions of insular cortex and the amygdala. These findings provide evidence that humor depends critically upon extant neural systems important for resolving incongruities (humor detection) and for the expression of affect (humor appreciation).

Local and long-range functional connectivity is reduced in concert in autism spectrum disorders

Long-range cortical functional connectivity is often reduced in autism spectrum disorders (ASD), but the nature of local cortical functional connectivity in ASD has remained elusive. We used magnetoencephalography to measure task-related local functional connectivity, as manifested by coupling between the phase of alpha oscillations and the amplitude of gamma oscillations, in the fusiform face area (FFA) of individuals diagnosed with ASD and typically developing individuals while they viewed neutral faces, emotional faces, and houses. We also measured task-related long-range functional connectivity between the FFA and the rest of the cortex during the same paradigm. In agreement with earlier studies, long-range functional connectivity between the FFA and three distant cortical regions was reduced in the ASD group. However, contrary to the prevailing hypothesis in the field, we found that local functional connectivity within the FFA was also reduced in individuals with ASD when viewing faces. Furthermore, the strength of long-range functional connectivity was directly correlated to the strength of local functional connectivity in both groups; thus, long-range and local connectivity were reduced proportionally in the ASD group. Finally, the magnitude of local functional connectivity correlated with ASD severity, and statistical classification using local and long-range functional connectivity data identified ASD diagnosis with 90% accuracy. These results suggest that failure to entrain neuronal assemblies fully both within and across cortical regions may be characteristic of ASD.

Modulation of cortical midline structures by implicit and explicit self-relevance evaluation

Abstract Recent neuroimaging work has observed activity in cortical midline structures (CMS) such as medial prefrontal and posterior cingulate cortices during self-referential processing. Moreover, items rated as self-relevant produce increased activity in these regions relative to items that are deemed not self-relevant. A common thread among previous reports has been reliance on experimental tasks that encourage or require online self-referential processing. In this paper, we report findings from two experiments that manipulated requirements for self-reflection. In Experiment 1, subjects rated trait adjectives for social desirability and for self-relevance. Results revealed increasing activity in CMS with increasing self-relevance, but only during explicit ratings of self-relevance. In Experiment 2, we examined CMS activity during passive viewing of personal semantic facts (such as subjects’ own first names). Taken together, these results suggest that highly self-relevant information captures attention through neural mechanisms that are comparable to those engaged during explicit self-reflection, namely via recruitment of CMS structures.

An Anterior-to-Posterior Shift in Midline Cortical Activity in Schizophrenia During Self-Reflection

BACKGROUNDnDeficits in social cognition, including impairments in self-awareness, contribute to the overall functional disability associated with schizophrenia. Studies in healthy subjects have shown that social cognitive functions, including self-reflection, rely on the medial prefrontal cortex (mPFC) and posterior cingulate gyrus, and these regions exhibit highly correlated activity during resting states. In this study, we tested the hypothesis that patients with schizophrenia show dysfunction of this network during self-reflection and that this abnormal activity is associated with changes in the strength of resting-state correlations between these regions.nnnMETHODSnActivation during self-reflection and control tasks was measured with functional magnetic resonance imaging in 19 patients with schizophrenia and 20 demographically matched control subjects. In addition, the resting-state functional connectivity of midline cortical areas showing abnormal self-reflection-related activation in schizophrenia was measured.nnnRESULTSnCompared with control subjects, the schizophrenia patients demonstrated lower activation of the right ventral mPFC and greater activation of the mid/posterior cingulate gyri bilaterally during self-reflection, relative to a control task. A similar pattern was seen during overall social reflection. In addition, functional connectivity between the portion of the left mid/posterior cingulate gyrus showing abnormally elevated activity during self-reflection in schizophrenia, and the dorsal anterior cingulate gyrus was lower in the schizophrenia patients compared with control subjects.nnnCONCLUSIONSnSchizophrenia is associated with an anterior-to-posterior shift in introspection-related activation, as well as changes in functional connectivity, of the midline cortex. These findings provide support for the hypothesis that aberrant midline cortical function contributes to social cognitive impairment in schizophrenia.

Dissociable neural systems supporting knowledge about human character and appearance in ourselves and others

Functional neuroimaging has identified a neural system comprising posterior cingulate (pCC) and medial prefrontal (mPFC) cortices that appears to mediate self-referential thought. It is unclear whether the two components of this system mediate similar or different psychological processes, and how specific this system is for self relative to others. In an fMRI study, we compared brain responses for evaluation of character (e.g., honest) versus appearance (e.g., svelte) for oneself, ones mother (a close other), and President Bush (a distant other). There was a double dissociation between dorsal mPFC, which was more engaged for character than appearance judgments, and pCC, which was more engaged for appearance than character judgments. A ventral region of mPFC was engaged for judgments involving ones own character and appearance, and ones mothers character, but not her appearance. A follow-up behavioral study indicated that participants rate their own character and appearance, and their mothers character, but not her appearance, as important in their self-concept. This suggests that ventral mPFC activation reflects its role in processing information relevant to the self, but not limited to the self. Thus, specific neural systems mediate specific aspects of thinking about character and appearance in oneself and in others.

Voting behavior is reflected in amygdala response across cultures

Voting to determine ones leaders is among the most important decisions we make, yet little is known about the brains role in how we come to these decisions. Behavioral studies have indicated that snap judgments of political candidates faces can predict election outcomes but that the traits that lead to these judgments differ across cultures. Here we sought to investigate the neural basis for these judgments. American and Japanese natives performed simulated voting judgments of actual American and Japanese political candidates while neural activity was measured using functional magnetic resonance imaging (fMRI). Candidates for whom participants chose to vote elicited stronger responses in the bilateral amygdala than candidates for whom participants chose not to vote. This was true regardless of either the participants culture or the targets culture, suggesting that these voting decisions provoked the same neural response cross-culturally. In addition, we observed a participant culture by target culture interaction in the bilateral amygdala. American and Japanese participants both showed a stronger response to cultural outgroup faces than they did to cultural in group faces, however this was unrelated to their voting decisions. These data provide insight to the mechanisms that underlie our snap judgments of others when making voting decisions and provide a neural correlate to cross-cultural consensus in social inferences.

Face value: amygdala response reflects the validity of first impressions.

The human amygdala responds to first impressions of people as judged from their faces, such as normative judgments about the trustworthiness of strangers. It is unknown, however, whether amygdala responses to first impressions can be validated by objective criteria. Here, we examined amygdala responses to faces of Chief Executive Officers (CEOs) where real-world outcomes could be measured objectively by the amounts of profits made by each CEOs company. During fMRI scanning, participants made incidental judgments about the symmetry of each CEOs face. After scanning, participants rated each CEOs face on leadership ability. Parametric analyses showed that greater left amygdala response to the CEOs faces was associated with higher post-scan ratings of the CEOs leadership ability. In addition, greater left amygdala response was also associated with greater profits made by the CEOs companies and this relationship was statistically mediated by external raters perceptions of arousal. Thus, amygdala response reflected both subjective judgments and objective measures of leadership ability based on first impressions.