Talks and Conference Presentations
Cognitive Neuroscience Society
13th Annual Meeting
April 8-11, 2006
San Francisco, California
Role of the Ventrolateral Prefrontal Cortex in Coping with Distracting Emotions: Event-Related fMRI Evidence
Florin Dolcos1, Philip Kragel1, and Gregory McCarthy1,2
Lesion and functional neuroimaging evidence suggests a role of the ventrolateral prefrontal cortex (vlPFC) in general inhibitory processes. It is not clear, however, whether this brain region is also associated with inhibitory processes that are specifically engaged in the inhibition of distracting emotions. Investigation of the neural mechanisms of coping with emotional distraction has relevance for understanding clinical conditions associated with increased susceptibility to emotional distraction, such as depression and PTSD. The present study used event-related fMRI to investigate the neural mechanisms of coping with emotional distraction in healthy participants. Functional MRI data were recorded while participants performed a delayed-response WM task with task-irrelevant emotional and neutral distracters presented during the delay interval. Following scanning, subjects also provided ratings of distractibility and emotional intensity for each distracter, and average indexes of "distractibility" and "emotionality" were calculated for each subject. First, emotional distracters produced the most detrimental effect on WM performance. Second, emotional distracters enhanced activity in the vlPFC, which was greater for trials associated with correct responses than for trials associated with incorrect responses. Third, activity in this region was also highly correlated with the subjective scores for distractibility/emotionality for the emotional but not for the neutral distracters. Specifically, subjects who showed greater activity to emotional distracters in the vlPFC also tended to rate them as both less distracting and less emotional. These results provide evidence concerning the neural correlates of coping with emotional distraction, and identify a specific role of the vlPFC in the inhibition of distracting emotions.
Guided Saccades Modulate Object and Face-Specific Activity in the Right Fusiform Gyrus
James P. Morris1 and Gregory McCarthy1,2
We investigated the influence of guided saccadic eye movements on the magnitude of functional magnetic resonance imaging (fMRI) activation in brain regions known to participate in object and face perception. In separate runs, subjects viewed a static image of a uniform gray field, a face, or a flower. Every 500 ms, a small fixation cross made a discrete jump within the image and subjects were required to make a saccade and fixate the cross at its new location. Each run consisted of alternating blocks in which the subject was guided to make small and large saccades. A comparison of large versus small saccade blocks revealed robust activity in the occulomotor system, particularly within the frontal eye fields (FEF), intraparietal sulcus (IPS), and superior colliculi regardless of the background image over which the saccades were made. Activity within portions of the ventral occipitotemporal cortex (VOTC) was also modulated by saccades, but here saccade-related activity was strongly influenced by the background image. Activity within the VOTC was strongest when large saccadic eye movements were made over an image of a face or a flower compared to a uniform gray image. Of most interest was activity in the functionally predefined face-specific region of the fusiform gyrus, where large saccades made over a face image increased activity, but where similar saccades made over a flower or a uniform gray field did not increase activity. These results demonstrate the potentially confounding influence of uncontrolled eye movements for neuroimaging studies of face and object perception.
Altruism, Charity, and the Brain
Dharol Tankersley1,3, C. Jill Stowe4, and Scott A. Huettel1,2
Social stimuli can be highly rewarding. For example, people will gtive to charities even though there are minimal direct benefits to themselves. Despite the importance of social factors for processing rewards, most neuroeconomic studies use personal, non-social rewards (e.g., money, foods). To understand how the brain processes social and non-social rewards, we used functional magnetic resonance imaging (fMRI) to measure neural activity while subjects worked to obtain rewards for themselves or for selected charities. Subjects performed a modified version of the monetary incentive delay (MID) reaction-time task with four conditions: subjects working for themselves, subjects working for charitry, charity (i.e., computer program) earning money for the subject, and the charity earning money for the charity. At the outset of each trial, subjects were told who would be the palyer and the potential recipient for the trail, then a fixation cross was presented for a variable amount of time before presentation of the target cue. If the subject or computer responded rapidly enough, money was earned for the recipient on that trial. Activation of a fronto-striatal system was moudlated both by who was playing (i.e., subject or computer) on a given trial and by who was the recipient. In these regions, the largest amplitude hemodynamic responses were observed when the subject was performing the task for him or herself. We conclude that both the agent and target of reward-directed action matter for the activity of brain systems for reward processing and decision making.
Age-related Changes in Processing Emotional Distracters: An fMRI Study
Lihong Wang1, Kevin S. LaBar 2,David Steffens3, Gregory McCarthy1,4
Avoiding distraction by emotional events is an important skill for maintaining goal directed behavior. However, age-related neural changes associated with the control of emotional distraction have rarely been examined. To address this issue, we acquired functional magnetic resonance imaging in 20 young (36.5±10.5 yrs) and 20 old (73.1±5.3 yrs) healthy subjects during an emotional oddball distracter task. This task requires subjects to detect infrequent and irregularly presented circle targets within a series of rectangle standards. Task-irrelevant sad and neutral distracting pictures were intermittently presented within the rectangles. Attentional targets activated the dorsal attentional executive system including dorsolateral prefrontal cortex (dlPFC) and the anterior cingulate, while sad distracters activated the ventral emotional system including orbital frontal cortex and amygdala in both young and elderly. There were no differences in amygdala activation between groups. Reaction times (RT) to attentional targets were slower in the elderly, and this was accompanied by lower activation in the dlPFC, caudate, and thalamus. Stronger activation in the supplementary motor and motor cortex suggested a compensatory effort for the elderly. Sad distracters evoked less activity in the inferior frontal gyrus (IFG) for the elderly than the young. In the young, greater activity in the IFG evoked by sad distracters was correlated with faster RTs, suggesting that the IFG was instrumental in inhibiting distraction. This correlation was not found in the elderly, suggesting that the sad stimuli might be less distractive - an interpretation supported by the finding that the elderly rated sad distracters as less sad than the young.