Lorenza S. Colzato, Nelleke C. van Wouwe and Bernhard Hommel
Neuropsychologia, in press
The primate cortex represents the external world in a distributed fashion, which calls for a mechanism that integrates and binds the features of a perceived or processed event. Animal and patients studies provide evidence that feature binding in the visual cortex is driven by the muscarinic–cholinergic system, whereas visuo-motor integration may be under dopaminergic control. Consistent with this scenario, we present indication that the binding of visual and action features is modulated by emotions through the probable stimulation of the dopaminergic system. Interestingly, the impact of emotions on binding was restricted to tasks in which shape was task-relevant, suggesting that extracting affective information is not automatic but requires attention to shape.
Friday, August 25, 2006
Friday, August 18, 2006
ARTICLE UPDATE - Separating subjective emotion from the perception of emotion-inducing stimuli: An fMRI study.
Garrett AS, Maddock RJ.
NeuroImage, in press
fMRI was used to dissociate neural responses temporally associated with the subjective experience of emotion from those associated with the perception of emotion-inducing stimuli in order to better define the emotion-related functions of the amygdala, lateral orbital frontal cortex (OFC), and hippocampus. Subjects viewed aversive pictures followed by an extended post-stimulus period of sustained subjective emotion. Brain regions showing activation paralleling the period of sustained subjective emotion were distinguished from those showing activation limited to the period of aversive picture presentation. Behavioral results showed that subjective ratings of emotion remained elevated for 20 s after offset of the aversive pictures. fMRI results showed that viewing aversive pictures activated the amygdala, lateral OFC, and hippocampus. Subjective emotion (present both during and after aversive pictures) was temporally associated with activation in the right lateral OFC and left hippocampus but not the amygdala. Ratings of subjective emotion were correlated with activation in the right lateral OFC and left hippocampus. The results support direct amygdala involvement in emotion perception but suggest that amygdala activation is not temporally associated with subjective emotion that occurs after the offset of emotion-related stimuli. The results are consistent with a general role for the lateral OFC in monitoring or reflecting on internal experience and show that hippocampal activation is sustained during a period of subjective emotion, possibly related to enhanced memory encoding for the aversive pictures.
NeuroImage, in press
fMRI was used to dissociate neural responses temporally associated with the subjective experience of emotion from those associated with the perception of emotion-inducing stimuli in order to better define the emotion-related functions of the amygdala, lateral orbital frontal cortex (OFC), and hippocampus. Subjects viewed aversive pictures followed by an extended post-stimulus period of sustained subjective emotion. Brain regions showing activation paralleling the period of sustained subjective emotion were distinguished from those showing activation limited to the period of aversive picture presentation. Behavioral results showed that subjective ratings of emotion remained elevated for 20 s after offset of the aversive pictures. fMRI results showed that viewing aversive pictures activated the amygdala, lateral OFC, and hippocampus. Subjective emotion (present both during and after aversive pictures) was temporally associated with activation in the right lateral OFC and left hippocampus but not the amygdala. Ratings of subjective emotion were correlated with activation in the right lateral OFC and left hippocampus. The results support direct amygdala involvement in emotion perception but suggest that amygdala activation is not temporally associated with subjective emotion that occurs after the offset of emotion-related stimuli. The results are consistent with a general role for the lateral OFC in monitoring or reflecting on internal experience and show that hippocampal activation is sustained during a period of subjective emotion, possibly related to enhanced memory encoding for the aversive pictures.
ARTICLE UPDATE - How do emotion and gaze direction interfere with overt orienting of visual attention?
Bonifacci P, Ricciardelli P, Lugli L, Chitti F, Nicoletti R.
Cognitive Proceedings, 7 (supp 5), 155
BACKGROUND: Several studies using spatial cueing paradigms have demonstrated that observing gaze direction may trigger a reflexive visual orienting in the direction of the other person's gaze. Recently, it has been reported that facial expression may enhance the reflexive orienting of attention to gaze stimuli. However, some researchers have also suggested that, rather than facilitating attentional orienting away from the face, emotional expressions may, in fact, delay or prevent orienting. In the present study we investigated the effects of facial expression and gaze direction on a visual orienting oculomotor task to test whether an angry face may or may not interfere with visual orienting. METHOD: Participants performed an oculomotor task in which they had to make a saccade towards one of two lateral targets, depending upon the colour of the fixation dot which appeared at the centre of the computer screen. The instruction dot remained visible for 50 ms and then disappeared. At different time intervals (stimulus onset asynchronies, SOAs: 50, 100, 150 ms) following the onset of the instruction cue, a real face (gazing either to the right or to the left) was presented at the centre of the monitor. Gaze direction could be congruent or incongruent with respect to the instruction and target location. Facial expression was also manipulated. In half of the trials the diverted gaze (i.e., congruent or incongruent) appeared with an angry expression, whereas in the other half the face had a neutral expression. Participants were instructed to saccade either to the target on the left or to the target on the right (the targets were visible throughout the trial), as indicated by the instruction dot, while completely disregarding the face because it was irrelevant for the task. RESULTS: Eye movement recordings on correct trials showed that saccades congruent with the direction of the distracting gaze had shorter latencies than incongruent ones. However, the time-course of this effect varied depending on the facial expression. With a neutral expression, the congruency effect was found only at the shortest SOA (50 ms). On the contrary, for the angry face the congruency effect occurred at the longer SOAs. These findings suggest that gaze direction (even when task-irrelevant) is capable of interfering with the orienting of visual attention, and that faces with an angry expression may hold attention and affect its orienting longer than a neutral expression.
Cognitive Proceedings, 7 (supp 5), 155
BACKGROUND: Several studies using spatial cueing paradigms have demonstrated that observing gaze direction may trigger a reflexive visual orienting in the direction of the other person's gaze. Recently, it has been reported that facial expression may enhance the reflexive orienting of attention to gaze stimuli. However, some researchers have also suggested that, rather than facilitating attentional orienting away from the face, emotional expressions may, in fact, delay or prevent orienting. In the present study we investigated the effects of facial expression and gaze direction on a visual orienting oculomotor task to test whether an angry face may or may not interfere with visual orienting. METHOD: Participants performed an oculomotor task in which they had to make a saccade towards one of two lateral targets, depending upon the colour of the fixation dot which appeared at the centre of the computer screen. The instruction dot remained visible for 50 ms and then disappeared. At different time intervals (stimulus onset asynchronies, SOAs: 50, 100, 150 ms) following the onset of the instruction cue, a real face (gazing either to the right or to the left) was presented at the centre of the monitor. Gaze direction could be congruent or incongruent with respect to the instruction and target location. Facial expression was also manipulated. In half of the trials the diverted gaze (i.e., congruent or incongruent) appeared with an angry expression, whereas in the other half the face had a neutral expression. Participants were instructed to saccade either to the target on the left or to the target on the right (the targets were visible throughout the trial), as indicated by the instruction dot, while completely disregarding the face because it was irrelevant for the task. RESULTS: Eye movement recordings on correct trials showed that saccades congruent with the direction of the distracting gaze had shorter latencies than incongruent ones. However, the time-course of this effect varied depending on the facial expression. With a neutral expression, the congruency effect was found only at the shortest SOA (50 ms). On the contrary, for the angry face the congruency effect occurred at the longer SOAs. These findings suggest that gaze direction (even when task-irrelevant) is capable of interfering with the orienting of visual attention, and that faces with an angry expression may hold attention and affect its orienting longer than a neutral expression.
Wednesday, August 16, 2006
ARTICLE UPDATE - Attentional capture by task-irrelevant fearful faces is revealed by the N2pc component
Martin Eimer and Monika Kissa
Biological Psychology, in press
We measured the N2pc component as an electrophysiological indicator of attentional selection to investigate whether fearful faces can attract attention even when they are entirely task-irrelevant and attention is focused on another demanding visual monitoring task. Participants had to detect infrequent luminance changes of the fixation cross, while ignoring stimulus arrays containing a face singleton (a fearful face among neutral faces, or neutral face among fearful faces) to the left or right of fixation. On trials without a target luminance change, an N2pc was elicited by fearful faces presented next to fixation, irrespective of whether they were singletons or not, demonstrating that irrelevant fearful faces can bias the spatial distribution of attention. The N2pc to fearful faces was attenuated when face arrays were presented simultaneously with a target luminance change, suggesting that concurrent target processing reduces attentional capture by emotional salient events.
Biological Psychology, in press
We measured the N2pc component as an electrophysiological indicator of attentional selection to investigate whether fearful faces can attract attention even when they are entirely task-irrelevant and attention is focused on another demanding visual monitoring task. Participants had to detect infrequent luminance changes of the fixation cross, while ignoring stimulus arrays containing a face singleton (a fearful face among neutral faces, or neutral face among fearful faces) to the left or right of fixation. On trials without a target luminance change, an N2pc was elicited by fearful faces presented next to fixation, irrespective of whether they were singletons or not, demonstrating that irrelevant fearful faces can bias the spatial distribution of attention. The N2pc to fearful faces was attenuated when face arrays were presented simultaneously with a target luminance change, suggesting that concurrent target processing reduces attentional capture by emotional salient events.
Friday, August 11, 2006
ARTICLE UPDATE - Neuroimaging Studies of Emotional Responses in PTSD.
Liberzon I, Martis B.
Annuals of the New York Academy of Sciences, 1071, 87-109
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.
Annuals of the New York Academy of Sciences, 1071, 87-109
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.
ARTICLE UPDATE - Right hemispheric dominance in processing of unconscious negative emotion.
Sato W, Aoki S.
Brain and Cognition, in press
Right hemispheric dominance in unconscious emotional processing has been suggested, but remains controversial. This issue was investigated using the subliminal affective priming paradigm combined with unilateral visual presentation in 40 normal subjects. In either left or right visual fields, angry facial expressions, happy facial expressions, or plain gray images were briefly presented as negative, positive, and control primes, followed by a mosaic mask. Then nonsense target ideographs were presented, and the subjects evaluated their partiality toward the targets. When the stimuli were presented in the left, but not the right, visual fields, the negative primes reduced the subjects' liking for the targets, relative to the case of the positive or control primes. These results provided behavioral evidence supporting the hypothesis that the right hemisphere is dominant for unconscious negative emotional processing.
Brain and Cognition, in press
Right hemispheric dominance in unconscious emotional processing has been suggested, but remains controversial. This issue was investigated using the subliminal affective priming paradigm combined with unilateral visual presentation in 40 normal subjects. In either left or right visual fields, angry facial expressions, happy facial expressions, or plain gray images were briefly presented as negative, positive, and control primes, followed by a mosaic mask. Then nonsense target ideographs were presented, and the subjects evaluated their partiality toward the targets. When the stimuli were presented in the left, but not the right, visual fields, the negative primes reduced the subjects' liking for the targets, relative to the case of the positive or control primes. These results provided behavioral evidence supporting the hypothesis that the right hemisphere is dominant for unconscious negative emotional processing.
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