Limb-specific emotional modulation of cervical spinal cord neurons.

Emotional stimuli receive prioritized attentional and motoric processing in the brain. Recent data have indicated that emotional stimuli enhance activity in the cervical spinal cord as well. In the present study, we used fMRI to investigate the specificity of this emotion-dependent spinal cord activity. We examined whether the limb depicted in a passively viewed image (upper vs. lower) differentially influenced activity in the cervical segments that innervate the upper limbs, and whether this effect was enhanced by emotion. Participants completed four fMRI runs: neutral-upper limb, neutral-lower limb, negative-upper limb, and negative-lower limb. The results indicated main effects of limb and emotion, with upper limbs and negative stimuli eliciting greater activity than lower limbs and neutral stimuli, respectively. For upper-limb runs, negative stimuli evoked more activity than did neutral stimuli. Additionally, negative stimuli depicting upper limbs produced stronger responses than did negative stimuli depicting lower limbs. These results suggest that emotional stimuli augment limb-specific responses in the spinal cord.

Functional MRI of the thoracic spinal cord during vibration sensation.

PURPOSE: To demonstrate that it is possible to acquire accurate functional magnetic resonance images from thoracic spinal cord neurons. MATERIALS AND METHODS: The lower thoracic spinal dermatomes (T7-T11) on the right side of the body were mechanically stimulated by vibration for 15 participants. Neuronal responses to vibration sensation were measured in the thoracic spinal cord using a HASTE sequence on a 3 Tesla MRI system. RESULTS: Signal increases were observed in the corresponding lower thoracic spinal cord segments ipsilateral to the side of stimulation in the dorsal aspect of the spinal cord. CONCLUSION: This is the first study to provide proof of principle that functional imaging of the entire thoracic spinal cord is possible, by detecting neuronal activity in the thoracic spinal cord during sensory stimulation using spinal fMRI.

Altered voxel-based and surface-based morphometry in inflammatory bowel disease.

Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is characterized by inflammation of the gastrointestinal tract and is a disorder of the brain-gut axis. Neuroimaging studies of brain function and structure have helped better understand the relationships between the brain, gut, and comorbidity in IBD. Studies of brain structure have primarily employed voxel-based morphometry to measure grey matter volume and surface-based morphometry to measure cortical thickness. Far fewer studies have employed other surface-based morphometry metrics such as gyrification, cortical complexity, and sulcal depth. In this study, brain structure differences between 72 adults with IBD and 90 healthy controls were assessed using all five metrics. Significant differences were found for cortical thickness with the IBD group showing extensive left-lateralized thinning, and for cortical complexity with the IBD group showing greater complexity in the left fusiform and right posterior cingulate. No significant differences were found in grey matter volume, gyrification, or sulcal depth. Within the IBD group, a post hoc analysis identified that disease duration is associated with cortical complexity of the right supramarginal gyrus, albeit with a more lenient threshold applied.

Empathy, defending, and functional connectivity while witnessing social exclusion.

Peers are present for most bullying episodes. Peers who witness bullying can play an important role in either stopping or perpetuating the behavior. Defending can greatly benefit victimized peers. Empathy is strongly associated with defending. Yet, less is known about defenders' neural response to witnessing social distress, and how this response may relate to the link between empathy and defending. Forty-six first-year undergraduate students (Mage = 17.7; 37 women), with varied history of peer defending, underwent fMRI scanning while witnessing a depiction of social exclusion. Functional connectivity analysis was performed across brain regions that are involved in cognitive empathy, empathetic distress, and compassion. History of defending was positively associated with functional connectivity (Exclusion > Inclusion) between the left orbitofrontal cortex (OFC) - medial prefrontal cortex (MPFC), and right OFC - left and right amygdalae. Defending was negatively associated with functional connectivity between the left OFC - anterior cingulate cortex. The relationship between history of defending and empathy (specifically, empathetic perspective taking) was moderated by functional connectivity of the right OFC - left amygdala. These findings suggest that coactivation of brain regions involved in compassionate emotion regulation and empathetic distress play a role in the relationship between empathy and peer defending.

Unique brain regions involved in positive versus negative emotional modulation of pain.

Background and aims Research has shown that negative emotions increase perceived pain whereas positive emotions reduce pain. Here we aim to investigate the neural mechanisms underlying this phenomenon. Methods While undergoing functional magnetic resonance imaging of the brain, 20 healthy adult females were presented with negative, neutral, and positive emotion-evoking visual stimuli in combination with the presentation of a noxious thermal stimulus to the hand. Participants rated the intensity and unpleasantness of the noxious thermal stimulus during each of the valence conditions. General linear model analyses were performed on the imaging data for each valence condition and specific contrasts were run. Results Significant differences were detected for the emotional modulation of pain (EMP) between the positive and negative conditions. Unique to the positive condition, there was increased activity in the inferior parietal, parahippocampal/perirhinal, precuneus/superior parietal, and the prefrontal cortices. Unique to the negative condition, there was increased activity in anterior and posterior cingulate and angular gyrus. Conclusions Positive and negative EMP appear to involve different brain regions. Implications Although there is some overlap in the brain regions involved in the positive and negative EMP, brain regions unique to each condition are identified and, moreover, the regions identified are involved in internal and external focus, respectively, pointing to a potential mechanism underlying this phenomenon.

Functional connectivity across social inclusion and exclusion is related to peer victimization and depressive symptoms in young adults.

BACKGROUND: Peer victimization is associated with increased risk for depression, as well as increased neural response to social exclusion in the anterior cingulate cortex (ACC) and the amygdala. Altered functional connectivity (FxC) of fronto-limbic circuitry is associated with risk for various affective disorders. The present study examined the relationship between fronto-limbic FxC during social exclusion, prior peer victimization experience and depressive symptoms. METHODS: Three mutually exclusive groups were formed: peer victimized (with a history of peer victimization), defenders (history of defending peers), and controls (no prior peer victimization experience) (n = 15/group; Mage = 17.7 years). Functional Magnetic Resonance Imaging data were collected while participants completed the Cyberball paradigm (simulating the experience of social exclusion). FxC between the Medial Prefrontal Cortex (MPFC), ACC, right insula and left amygdala, was compared between groups and examined in relation to depressive symptoms. RESULTS: Prior peer victimization experience was associated with differences in fronto-limbic FxC across social inclusion and exclusion. Defenders displayed distinct shifts in FxC across the transition from being included to excluded. Peer victimized individuals exhibited a unique pattern of amygdala-specific FxC during inclusive interaction with peers, and in the continuous FxC across inclusion and exclusion. FxC of the MPFC-amygdala across inclusion and exclusion moderated the relationship between peer victimization and depressive symptoms. LIMITATIONS: Small sample size and cross-sectional design limit interpretation of the findings. CONCLUSIONS: Peer victimized individuals who exhibit continuous positive FxC of the MPFC-left amygdala across inclusion and exclusion may be at greater risk for depressive symptoms.

Generating facial expressions of disgust activates neurons in the thoracic spinal cord: a spinal fMRI study.

Facial expressions of disgust, which involve movement of the levator labii muscles on the nose, allow an organism to restrict the intake of potentially aversive stimuli by constricting the air cavities in the nostrils and reducing the speed of air intake. In the current research, we used fMRI of the thoracic spinal cord to measure neural activity related to (1) the contraction of the intercostal muscles that modulate the velocity of air intake and (2) the sensory feedback associated with this contraction. Thirteen participants completed two spinal fMRI runs in which the thoracic segments of the spinal cord were measured. Each five-minute 40-second run consisted of three 60-second blocks in which participants repeatedly generated a disgusted facial expression or a non-emotional expression consisting of repeated stretching of the lips (which did not involve the nasal cavity). Forty-second rest blocks were interleaved between each expression block. The results demonstrated that generating emotional expressions of disgust produces significantly more activity than producing non-emotional facial expressions. This activity occurred in both ventral (motoric) and dorsal (sensory) regions of the upper segments of the thoracic spinal cord and demonstrates a link between the generation of facial expressions and embodied emotional responses.

A neural correlate of visceral emotional responses: evidence from fMRI of the thoracic spinal cord.

Functional magnetic resonance imaging (fMRI) of thoracic spinal cord neurons was used to examine the neural correlates of visceral emotional responses. Participants completed four spinal fMRI runs involving passive viewing (i.e. no movement) and motoric responses to negative or neutral images. Negative images, particularly in the movement condition, elicited robust activity in motoric nuclei, indicating 'action preparedness'. These images also enhanced activity in autonomic and sensory nuclei, thus providing a clear neural representation of visceral responses to emotional stimuli.

Default mode network functional connectivity altered in failed back surgery syndrome.

UNLABELLED: The purpose of this study was to identify alterations in the default mode network of failed back surgery syndrome patients as compared to healthy subjects. Resting state functional magnetic resonance imaging was conducted at 3 Tesla and data were analyzed with an independent component analysis. Results indicate an overall reduced functional connectivity of the default mode network and recruitment of additional pain modulation brain regions, including dorsolateral prefrontal cortex, insula, and additional sensory motor integration brain regions, including precentral and postcentral gyri, for failed back surgery syndrome patients. PERSPECTIVE: This article presents alterations in the default mode network of chronic low back pain patients with failed back surgery syndrome as compared to healthy participants.

The effects of valence and arousal on the emotional modulation of time perception: evidence for multiple stages of processing.

Previous research has demonstrated that both emotional valence and arousal can influence the subjective experience of time. The current research extends this work by (1) identifying how quickly this emotional modulation of time perception can occur and (2) examining whether valence and arousal have different effects at different stages of perception. These questions were addressed using a temporal bisection task. In each block of this task, participants are trained to distinguish between two different exposure durations. Participants are then shown stimuli presented at a number of durations that fall between the two learned times, and are asked to indicate whether the test stimulus was closer in duration to the shorter or longer learned item. In the current study, participants completed blocks of trials in which the durations were "Short" (100-300 ms) or "Long" (400-1600 ms). Stimuli consisted of neutral photographs as well as four categories of emotional images: high-arousal negative, high-arousal positive, low-arousal negative, and low-arousal positive. In Short blocks, arousing and nonarousing negative images were judged to have been shown for shorter durations than they actually were (i.e., the duration was underestimated); this effect occurred at durations as brief as 133 ms. In Long blocks, the display time for highly arousing negative items was overestimated, whereas durations were underestimated for highly arousing positive items and less arousing negative items. These data suggest that arousal and valence have different effects at different stages of perception, possibly due to the different neural structures involved at each stage of the emotional modulation of time perception.