Enhanced emotional reactivity after selective REM sleep deprivation in humans: an fMRI study

Converging evidence from animal and human studies suggest that rapid eye movement (REM) sleep modulates emotional processing. The aim of the present study was to explore the effects of selective REM sleep deprivation (REM-D) on emotional responses to threatening visual stimuli and their brain correlates using functional magnetic resonance imaging (fMRI). Twenty healthy subjects were randomly assigned to two groups: selective REM-D, by awakening them at each REM sleep onset, or non-rapid eye movement sleep interruptions (NREM-I) as control for potential non-specific effects of awakenings and lack of sleep. In a within-subject design, a visual emotional reactivity task was performed in the scanner before and 24 h after sleep manipulation. Behaviorally, emotional reactivity was enhanced relative to baseline (BL) in the REM deprived group only. In terms of fMRI signal, there was, as expected, an overall decrease in activity in the NREM-I group when subjects performed the task the second time, particularly in regions involved in emotional processing, such as occipital and temporal areas, as well as in the ventrolateral prefrontal cortex, involved in top-down emotion regulation. In contrast, activity in these areas remained the same level or even increased in the REM-D group, compared to their BL level. Taken together, these results suggest that lack of REM sleep in humans is associated with enhanced emotional reactivity, both at behavioral and neural levels, and thus highlight the specific role of REM sleep in regulating the neural substrates for emotional responsiveness

Antisocial and impulsive personality traits are linked to individual differences in somatosensory maps of emotion

Abstract Somatosensory experience is an important component of emotion, playing a prominent role in many traditional emotion theories. Nonetheless, and despite the extensive literature on the influence of individual differences in emotional processing, the relation between personality traits and emotion-related somatosensation has received little attention. Here, we addressed this question in a large sample of healthy individuals through the “bodily maps of emotion” behavioural paradigm, in which participants indicated the location and extent of their body sensations for the 6 basic and 4 additional social emotions (contempt, envy, pride, shame). We found that emotional somatosensation in specific body areas, including the heart, the stomach, and the head, was related to specific personality factors, particularly antisocial attitudes and impulsivity. Moreover, the similarity of individual participants’ maps to the group-average was likewise negatively correlated with antisocial tendencies. Overall, our results suggest that differences in individuals’ sensitivity to somatosensation from different body areas, as well as the typicality of their topographical patterns, may partly underlie variation in higher-order social and affective traits

Amygdala responses to nonlinguistic emotional vocalizations

Whereas there is ample evidence for a role of the amygdala in the processing of visual emotional stimuli, particularly those with negative value, discrepant results have been reported regarding amygdala responses to emotional auditory stimuli. The present study used event-related functional magnetic resonance imaging to investigate cerebral activity underlying processing of emotional nonlinguistic vocalizations, with a particular focus on neural changes in the amygdala. Fourteen healthy volunteers were scanned while performing a gender identification task. Stimuli, previously validated on emotional valence, consisted of positive (happiness and sexual pleasure) and negative (sadness and fear) vocalizations, as well as emotionally neutral sounds (e.g., coughs). Results revealed bilateral amygdala activation in response to all emotional vocalizations when compared to neutral stimuli. These findings suggest that the generally accepted involvement of the amygdala in the perception of emotional visual stimuli, such as facial expressions, also applies to stimuli within the auditory modality. Importantly, this amygdala response was observed for both positive and negative emotional vocalizations

Is voice processing species-specific in human auditory cortex? An fMRI study

Recent studies suggested a sensitivity of regions of the human superior temporal sulcus (STS) to the sound of the human voice. However, the question of the species specificity of this response is still open. Healthy adult volunteers were scanned in an event-related fMRI design to compare responses in the STS to human and animal vocalizations, as well as to control nonvocal sounds (e.g., musical instruments). Bilateral activation of anterior STS was observed for human vocalizations, when contrasted with both nonvocal sounds and animal vocalizations. Animal vocalizations, compared to nonvocal sounds, elicited a more restricted left STS activation, although this region responded even more strongly to human vocalizations. This study provides the first evidence suggesting a species specificity in STS responses to vocalizations in humans

Effects of attention and emotion on face processing in the human brain : an event-related fMRI study

We used event-related fMRI to assess whether brain responses to fearful versus neutral faces are modulated by spatial attention. Subjects performed a demanding matching task for pairs of stimuli at prespecified locations, in the presence of task-irrelevant stimuli at other locations. Faces or houses unpredictably appeared at the relevant or irrelevant locations, while the faces had either fearful or neutral expressions. Activation of fusiform gyri by faces was strongly affected by attentional condition, but the left amygdala response to fearful faces was not. Right fusiform activity was greater for fearful than neutral faces, independently of the attention effect on this region. These results reveal differential influences on face processing from attention and emotion, with the amygdala response to threat-related expressions unaffected by a manipulation of attention that strongly modulates the fusiform response to faces

Emotional processing and its impact on unilateral neglect and extinction

Unilateral spatial neglect is a neurological disorder characterized by impaired orienting of attention to stimuli located in the contralesional space, typically following right-hemisphere damage. Neuropsychological investigations in the past two decades have demonstrated that neglect is caused by deficits affecting a widespread cortico-subcortical fronto-parietal network controlling spatial attention, but usually sparing early sensory pathways. As a consequence, certain residual abilities in sensory processing remain intact and still take place for stimuli in the neglected space, such as the extraction and organization of coherent or meaningful object features. Moreover, these residual abilities can alleviate inattention symptoms when contralesional stimuli are perceptually or biologically salient. Here we review recent studies suggesting that the emotional content of stimuli may also be processed despite impaired attention towards contralesional space, and that such processing may act to enhance attention and partly reduce neglect for these stimuli, relative to similar but emotionally neutral stimuli. For example, faces with emotional expressions, voices with emotional prosody, as well as pictures of scenes or even spiders have been found to be less severely extinguished from awareness in conditions of bilateral stimulations, and/or lead to fewer omissions in search tasks with multiple distracters. Gaze cues and reward learning might also produce similar effects. Altogether, these findings suggest that emotionally significant information is not only extracted from stimuli at neglected locations through spared pathways, but can also induce emotional biases in attention that partly counteract the abnormal spatial biases caused by fronto-parietal damage. We discuss results from neuropsychology and neuroimaging research suggesting that specific mechanisms for emotional attention might exist, centered on the amygdala and other limbic regions, and that these mechanisms can operate partly independent from other circuits controlling spatial and object-based attention. Although we are only beginning to understand these interactive effects of emotion and attention and to identify their neuroanatomical substrates, we believe that a deeper knowledge of such mechanisms and their conditions of optimal operation will help develop or improve therapeutic strategies in neglect patients