Biomedical subjects

Pia Rotshtein

Publications and source records attributed to Pia Rotshtein.

8 recordsLinked to original sources

PubMed2006

Differential stimuli and task effects in the amygdala and sensory areas.

Whether the amygdala responds in a stimulus- or a task-specific way, and how it corresponds to such effects in sensory cortices is dubious. Eighteen volunteers participated in a functional magnetic resonance imaging study in which they were asked to identify either emotion or gender in visually presented scenes, faces, and sentences. Amygdala and the lateral occipital complex showed similar stimulus effect with greater activation to scenes than to faces and sentences, whereas the superior temporal complex responded preferentially to sentences. No task effect was observed in the amygdala, whereas lateral occipital complex and superior temporal complex showed left lateralized selectivity to the emotional task. These results suggest that the amygdala is more sensitive to stimulus than explicit task parameters when processing emotion.

Adult↗

PubMed2006

On-line attentional selection from competing stimuli in opposite visual fields: effects on human visual cortex and control processes.

We used fMRI to investigate competition and on-line attentional selection between targets and distractors in opposite visual hemifields. Displays comprised a high-contrast square-wave grating, defined as target by its orientation, presented alone (unilateral) or with a similar distractor of orthogonal orientation in the opposite hemifield (bilateral displays). The target appeared unpredictably on the left or right, precluding anticipatory attention to one side. We found greater activation in target-contralateral superior occipital gyrus for unilateral than for bilateral displays, indicating suppression of the target's visual representation by distractor presence despite the competing distractor projecting to a different occipital hemisphere. Several frontal and parietal regions showed greater activation for bilateral than unilateral trials, suggesting involvement in on-line attentional selection. This was particularly pronounced for regions in bilateral intraparietal sulcus (IPS), which also showed greater functional coupling with occipital cortex specifically on bilateral trials that required selection plus some repetition-suppression effects when target side was repeated, but again only on bilateral trials requiring selection. Our results indicate that competition between visual stimuli in opposite hemifields can influence occipital cortex, and implicate IPS in resolution of this competition by selection.

Adult↗

PubMed2006

Pupillary contagion: central mechanisms engaged in sadness processing.

Empathic responses underlie our ability to share emotions and sensations with others. We investigated whether observed pupil size modulates our perception of other's emotional expressions and examined the central mechanisms modulated by incidental perception of pupil size in emotional facial expressions. We show that diminishing pupil size enhances ratings of emotional intensity and valence for sad, but not happy, angry or neutral facial expressions. This effect was associated with modulation of neural activity within cortical and subcortical regions implicated in social cognition. In an identical context, we show that the observed pupil size was mirrored by the observers' own pupil size. This empathetic contagion engaged the brainstem pupillary control nuclei (Edinger-Westphal) in proportion to individual subject's sensitivity to this effect. These findings provide evidence that perception-action mechanisms extend to non-volitional operations of the autonomic nervous system.

Adult↗

PubMed2004

Morphing Marilyn into Maggie dissociates physical and identity face representations in the brain.

How the brain represents different aspects of faces remains controversial. Here we presented subjects with stimuli drawn from morph continua between pairs of famous faces. In the paired presentations, a second face could be identical to the first, could share perceived identity but differ physically (30% along the morph continuum), or could differ physically by the same distance along the continuum (30%) but in the other direction. We show that, behaviorally, subjects are more likely to classify face pairs in the third paired presentation as different and that this effect is more pronounced for subjects who are more familiar with the faces. In functional magnetic resonance imaging (fMRI), inferior occipital gyrus (IOG) shows sensitivity to physical rather than to identity changes, whereas right fusiform gyrus (FFG) shows sensitivity to identity rather than to physical changes. Bilateral anterior temporal regions show sensitivity to identity change that varies with the subjects' pre-experimental familiarity with the faces. These findings provide neurobiological support for a hierarchical model of face perception.

Adult↗

PubMed2004

Activity in the human brain predicting differential heart rate responses to emotional facial expressions.

The James-Lange theory of emotion proposes that automatically generated bodily reactions not only color subjective emotional experience of stimuli, but also necessitate a mechanism by which these bodily reactions are differentially generated to reflect stimulus quality. To examine this putative mechanism, we simultaneously measured brain activity and heart rate to identify regions where neural activity predicted the magnitude of heart rate responses to emotional facial expressions. Using a forewarned reaction time task, we showed that orienting heart rate acceleration to emotional face stimuli was modulated as a function of the emotion depicted. The magnitude of evoked heart rate increase, both across the stimulus set and within each emotion category, was predicted by level of activity within a matrix of interconnected brain regions, including amygdala, insula, anterior cingulate, and brainstem. We suggest that these regions provide a substrate for translating visual perception of emotional facial expression into differential cardiac responses and thereby represent an interface for selective generation of visceral reactions that contribute to the embodied component of emotional reaction.

Adult↗

PubMed2004

Neural systems supporting interoceptive awareness.

Influential theories of human emotion argue that subjective feeling states involve representation of bodily responses elicited by emotional events. Within this framework, individual differences in intensity of emotional experience reflect variation in sensitivity to internal bodily responses. We measured regional brain activity by functional magnetic resonance imaging (fMRI) during an interoceptive task wherein subjects judged the timing of their own heartbeats. We observed enhanced activity in insula, somatomotor and cingulate cortices. In right anterior insular/opercular cortex, neural activity predicted subjects' accuracy in the heartbeat detection task. Furthermore, local gray matter volume in the same region correlated with both interoceptive accuracy and subjective ratings of visceral awareness. Indices of negative emotional experience correlated with interoceptive accuracy across subjects. These findings indicate that right anterior insula supports a representation of visceral responses accessible to awareness, providing a substrate for subjective feeling states.

Acoustic Stimulation↗

PubMed2003

Sensing the invisible: differential sensitivity of visual cortex and amygdala to traumatic context.

To what extent does emotional traumatic context affect sensory processing in the brain? A striking example of emotional impact on sensation is manifested in posttraumatic stress disorder (PTSD), in which a severe emotional trauma produces recurrent and vivid unpleasant sensory recollections. Here we report on an fMRI study exploring the sensory processing of trauma-related pictures in the visual cortex and amygdala in respect to PTSD. The impact of traumatic experience on brain responses was tested in relation to stimuli content and its level of recognition in a parametric factorial design. Twenty combat veterans, 10 with and 10 without PTSD, viewed backward-masked images of combat and noncombat content, presented at below, near, and above recognition thresholds. The response to combat content evoked more activation in the visual cortex in PTSD subjects than in non-PTSD subjects, only when images were presented at below recognition threshold. By contrast, the amygdala demonstrated increased activation in PTSD subjects irrespective of content and recognition threshold of the images. These intriguing findings are compatible with the notion that in PTSD, emotional traumatic experience could modify visual processing already at the preattentive level. On the other hand, lack of content specificity in the amygdala point to a possible predisposed mechanism for pathological processing of traumatic experience. The differential sensitivity of the amygdala and visual cortex to traumatic context implies distinct roles of limbic and sensory regions in the registration and recollection of emotional experience in the brain.

Adult↗

PubMed2002

The role of the amygdala in signaling prospective outcome of choice.

Can brain activity reveal a covert choice? Making a choice often evokes distinct emotions that accompany decision processes. Amygdala has been implicated in choice behavior that is guided by a prospective negative outcome. However, its specific involvement in emotional versus cognitive processing of choice behavior has been a subject of controversy. In this study, the human amygdala was monitored by functional magnetic resonance imaging (fMRI) while subjects were playing in a naturalistic choice paradigm against the experimenter. In order to win, players had to occasionally choose to bluff their opponent, risk "getting caught," and suffer a loss. A critical period, when choice has been made but outcome was still unknown, activated the amygdala preferentially following the choice that entailed risk of loss. Thus, the response of the amygdala differentiated between subject's covert choice of either playing fair or foul. These results support a role of the amygdala in choice behavior, both in the appraisal of inherent value of choice and the signaling of prospective negative outcomes.

Adolescent↗