Showing papers by "Israel Liberzon published in 2006"

Neuroimaging Studies of Emotional Responses in PTSD

Abstract: Neuroimaging research offers a powerful and noninvasive means to understand healthy as well as dysregulated emotional processing in healthy subjects and PTSD patients. Functional neuroimaging findings suggest specific roles for subregions of the medial prefrontal (mPFC), orbito frontal (OFC), anterior cingulate (ACC), and insular cortices as well as the sublenticular extended amygdala (SLEA) and hippocampus in various components of emotional processing. Some of the same regions appear to be associated with emotional response to trauma, and with symptom formation in PTSD. Neuroimaging findings of emotional processing in healthy subjects and PTSD patients are discussed, addressing the specific roles of cortical regions like mPFC, ACC, and insula, and their potential contribution to PTSD pathophysiology. Processes of cognitive-emotional interactions and social emotions are discussed in an attempt to synthesize the prefrontal findings in healthy subjects and PTSD patients. Further links between functional neuroanatomy of emotional responses and neuroendocrine stress regulation are proposed.

Medial Frontal Cortex Activity and Loss-Related Responses to Errors

Abstract: Making an error elicits activity from brain regions that monitor performance, especially the medial frontal cortex (MFC). However, uncertainty exists about whether the posterior or anterior/rostral MFC processes errors and to what degree affective responses to errors are mediated in the MFC, specifically the rostral anterior cingulate cortex (rACC). To test the hypothesis that rACC mediates a type of affective response, we conceptualized affect in response to an error as a reaction to loss and amplified this response with a monetary penalty. While subjects performed a cognitive interference task during functional magnetic resonance imaging, hemodynamic activity in the rACC was significantly greater when subjects lost money as a result of an error compared with errors that did not lead to monetary loss. A significant interaction between the incentive conditions and error events demonstrated that the effect was not merely attributable to working harder to win (or not lose) money, although an effect of motivation was noted in the mid-MFC. Activation foci also occurred in similar regions of the posterior MFC for error and interference processing, which were not modulated by the incentive conditions. However, at the level of the individual subject, substantial functional variability occurred along the MFC during error processing, including foci in the rostral/anterior extent of the MFC not appearing in the group analysis. The findings support the hypothesis that the rostral extent of the MFC (rACC) processes loss-related responses to errors, and individual differences may account for some of the reported variation of error-related foci in the MFC.

Corticolimbic Blood Flow During Nontraumatic Emotional Processing in Posttraumatic Stress Disorder

Abstract: Context Recent brain imaging studies implicate dysfunction of limbic and paralimbic circuitry, including the amygdala and medial prefrontal cortex (MPFC), in the pathogenesis of posttraumatic stress disorder (PTSD) during traumatic recollection and imagery. However, the relationship between activity in these regions and general emotional processing unrelated to traumatic experience has not been fully examined. Objective To investigate activity in the limbic and paralimbic brain regions in PTSD in response to a challenge with emotionally salient generic visual images. Design Cross-sectional, case-control study. Setting Academic medical center. Participants Sixteen Vietnam veterans with combat-related PTSD (PTSD group), 15 combat-exposed Vietnam veterans without PTSD (combat control group), and 15 age- and sex-matched healthy controls (normal control group). Main Outcome Measures We used positron emission tomography to study regional cerebral blood flow while participants viewed complex visual pictures with negatively valenced/aversive, nonaversive (“neutral”), and blank pictures. Psychophysiologic and emotional self-report data were also recorded. Results All 3 groups activated the dorsal MPFC to general salient content. Controls without PTSD activated the left amygdala in response to aversive stimuli. Normal controls activated the ventral MPFC and combat-exposed non-PTSD and PTSD participants exhibited either no response or deactivation in these regions, respectively, during negative emotional experience. Conclusions Consistent with current functional neuroanatomic models, patients with PTSD exhibited altered neural responses in the amygdala and ventral MPFC during the processing of emotionally salient but trauma-unrelated stimuli, potentially reflecting disorder-specific changes. Activation of the amygdala and lack of ventral MPFC deactivation to negatively valenced images in combat controls may reflect compensatory changes after trauma exposure that are not associated with PTSD.

BRIEF REPORTS Differential Subjective and Psychophysiological Responses to Socially and Nonsocially Generated Emotional Stimuli

Abstract: Sociality may determine the subjective experience and physiological response to emotional stimuli. Film segments induced socially and nonsocially generated emotions. Comedy (social positive), bereavement (social negative), pizza scenes (nonsocial positive), and wounded bodies (nonsocial negative) elicited four distinct emotional patterns. Per subjective report, joy, sadness, appetite, and disgust were elicited by the targeted stimulus condition. The social/nonsocial dimension influenced which emotional valence(s) elicited a skin conductance response, a finding that could not be explained by differences in subjective arousal. Heart rate deceleration was more responsive to nonsocially generated emotions. Taken together, these findings suggest that sociality affects the physiological profile of responses to emotional valence.

Differential subjective and psychophysiological responses to socially and nonsocially generated emotional stimuli.

Abstract: Sociality may determine the subjective experience and physiological response to emotional stimuli. Film segments induced socially and nonsocially generated emotions. Comedy (social positive), bereavement (social negative), pizza scenes (nonsocial positive), and wounded bodies (nonsocial negative) elicited four distinct emotional patterns. Per subjective report, joy, sadness, appetite, and disgust were elicited by the targeted stimulus condition. The social/nonsocial dimension influenced which emotional valence(s) elicited a skin conductance response, a finding that could not be explained by differences in subjective arousal. Heart rate deceleration was more responsive to nonsocially generated emotions. Taken together, these findings suggest that sociality affects the physiological profile of responses to emotional valence.

Functional Neuroimaging Research in Posttraumatic Stress Disorder

Abstract: Neuroimaging research in posttraumatic stress disorder (PTSD) is only two decades old, but is rapidly expanding and evolving in methodological sophistication (Pitman et al. 2001; Hull 2002; Liberzon and Phan 2003). Earlier structural and symptom-provocation studies are giving way to hypothesis-driven cognitive activation studies, longitudinal and treatment studies, and translationally driven integrative studies. The focused review of functional neuroimaging research in PTSD that follows discusses findings to better understand the functional neuroanatomy underlying PTSD symptoms and pathophysiology. We begin with a selective review of the research on functional neuroanatomy of emotions that is specifically relevant to PTSD. The ensuing discussion links the two bodies of literature in order to provide a better understanding of the processing of threat-related emotions and how this informs our understanding of the brain mechanisms that subserve PTSD. PTSD is characterized by exposure to life-threatening event/s associated with intense emotional reactions. Symptom clusters consist of reexperiencing the trauma (such as nightmares and intrusive memories), avoidance and numbing (avoiding trauma-related cues, feeling emotionally distant from loved ones), and hyperarousal (hypervigilance, sleep disturbances) (American Psychiatric Association 2000). Because these criteria are descriptive, atheoretical, and not confined to a specific diagnosis, it is possible that patients with different neurobiological subtypes will share the same diagnosis or that patients with similar neurobiological abnormalities may cross descriptive categorical boundaries. Neurobiological evidence does offer the potential to identify findings specific to trauma exposure and/or to PTSD's symptoms and pathophysiology, thereby helping to differentiate, define, and treat these disorders in a more meaningful way. One powerful, noninvasive means of investigating brain function in PTSD is the use of relatively new neuroimaging methods such as magnetic resonance imaging (MRI) and positron emission tomography (PET). MRI methodology relies on spin properties of protons in human brain tissue to outline brain structures and estimate