When it hurts even more: The neural dynamics of pain and interpersonal emotions.

OBJECTIVE: Chronic pain is highly prevalent among patients with mood, anxiety, personality, and somatic symptom disorders; and patients with chronic pain often suffer from persistent interpersonal distress. However, the neural mechanisms underlying this phenomenon and its possible role in the etiology of chronic pain are not yet understood. Based on our Developmental Theory of Centralized/Somatoform Pain, and prior research suggesting the existence of a shared neural system subserving interpersonal emotions and pain, we aimed to identify the neural basis for modulation of pain by feelings of interpersonal rejection and the role of the early interpersonal environment in development of this shared neural system. METHODS: During fMRI scanning, 22 healthy participants received moderately painful thermal stimuli in 3 interpersonal contexts: Acceptance, Rejection, and Reacceptance (modified Cyberball paradigm). Early interpersonal environment was assessed using the Parental Bonding Instrument. RESULTS: Interpersonal context modulated activity in pain neural systems during rejection and during accepting interactions with previously rejecting others. Moreover, the subjective perception of rejection, even when rejection was not occurring, correlated positively with reported pain severity and neural activity in the insula. The magnitude of neural modulation in pain circuits by feelings of rejection was associated with the quality of early interpersonal experience with caregivers. CONCLUSIONS: Results suggest that interpersonal emotions play an important role in the development and functioning of the pain system, supporting our Developmental Theory of predisposition to chronic centralized pain. These findings have direct implications for clinical practice, including the importance of treating interpersonal distress to alleviate pain.

Multimodal magnetic resonance imaging: The coordinated use of multiple, mutually informative probes to understand brain structure and function.

Differing imaging modalities provide unique channels of information to probe differing aspects of the brain's structural or functional organization. In combination, differing modalities provide complementary and mutually informative data about tissue organization that is more than their sum. We acquired and spatially coregistered data in four MRI modalities--anatomical MRI, functional MRI, diffusion tensor imaging (DTI), and magnetic resonance spectroscopy (MRS)--from 20 healthy adults to understand how interindividual variability in measures from one modality account for variability in measures from other modalities at each voxel of the brain. We detected significant correlations of local volumes with the magnitude of functional activation, suggesting that underlying variation in local volumes contributes to individual variability in functional activation. We also detected significant inverse correlations of NAA (a putative measure of neuronal density and viability) with volumes of white matter in the frontal cortex, with DTI-based measures of tissue organization within the superior longitudinal fasciculus, and with the magnitude of functional activation and default-mode activity during simple visual and motor tasks, indicating that substantial variance in local volumes, white matter organization, and functional activation derives from an underlying variability in the number or density of neurons in those regions. Many of these imaging measures correlated with measures of intellectual ability within differing brain tissues and differing neural systems, demonstrating that the neural determinants of intellectual capacity involve numerous and disparate features of brain tissue organization, a conclusion that could be made with confidence only when imaging the same individuals with multiple MRI modalities.

Neural systems subserving valence and arousal during the experience of induced emotions.

The circumplex model of affect construes all emotions as linear combinations of 2 independent neurophysiological dimensions, valence and arousal. We used functional magnetic resonance imaging to identify the neural networks subserving valence and arousal, and we assessed, in 10 participants, the associations of the BOLD (blood oxygen level-dependent) response, an indirect index of neural activity, with ratings of valence and arousal during the emotional experiences induced by the presentation of evocative sentences. Unpleasant emotional experience was associated with increased BOLD signal intensities in the supplementary motor, anterior midcingulate, right dorsolateral prefrontal, occipito-temporal, inferior parietal, and cerebellar cortices. Highly arousing emotions were associated with increased BOLD signal intensities in the left thalamus, globus pallidus, caudate, parahippocampal gyrus, amygdala, premotor cortex, and cerebellar vermis. Separate analyses using a finite impulse response model confirmed these results and revealed that pleasant emotions engaged an additional network that included the midbrain, ventral striatum, and caudate nucleus, all portions of a reward circuit. These findings suggest the existence of distinct networks subserving the valence and arousal dimensions of emotions, with midline and medial temporal lobe structures mediating arousal and dorsal cortical areas and mesolimbic pathways mediating valence.