Talks and Conference Presentations

Society for Neuroscience
32nd Annual Meeting
November 3-7, 2002
Orlando, Florida

• Dynamic and Strategic Aspects of Executive Processing: A Comparison of Blocked and Event-Related fMRI Measures
  Scott A. Huettel^1-3,5, Anita Jurkowski^3,5, Judyta Misiurek⁵, Gregory McCarthy^2-6
  Departments of ¹Psychiatry, ²Neurobiology, ³Psychology, and ⁴Radiology, ⁵Brain Imaging and Analysis Center, Duke University; ⁶VA Medical Center, Durham, NC

  Recent neuroimaging results have converged on common regions associated with executive processing, including lateral prefrontal and parietal cortices. Although dynamic aspects of executive processing, such as response selection and working memory, reliably evoke activity in these regions, the effects of strategic aspects of task attention are unknown. We investigated the relation between phasic, stimulus-related and tonic, task-related activation using a modified version of the common oddball paradigm, using 1.5T fMRI. Task and non-task blocks alternated every 24 seconds. During task blocks, the subjects pressed a button to infrequent targets (blue circles) embedded within a series of standard stimuli (blue squares) that did not require a button press. During non-task blocks, red triangles were presented and required no button press. We hypothesized that brain regions associated with dynamic response selection would show event-related activity to the target stimuli, while regions associated with task strategy would show blocked activity across the task/non-task conditions. Transient and sustained activity was observed in similar regions of dorsolateral prefrontal cortex (dlPFC), insular cortex/inferior frontal gyrus, anterior cingulate gyrus, and the basal ganglia. Similar transient dlPFC activity was observed to both target events and block changes. We conclude that similar brain systems mediate dynamic and strategic aspects of executive processing, and that lateral prefrontal cortex plays a primary role in dynamic response selection.

  View Presentation (HTML)

• Brain Activation Evoked by the Perception of Concurrent Speech and Mouth Movements
  T. M. Wright¹, K. A. Pelphrey^1,3, Martin J. McKeown¹, T. Allison², G. McCarthy^{1
  1}Duke-UNC Brain Imaging and Analysis Center, Duke University Medical Center; ²Department of Neurology, Yale University School of Medicine; ³Neurodevelopmental Disorders Research Center, UNC-Chapel Hill School of Medicine

  Many socially significant biological stimuli are polymodal (e.g., mouth movements accompanied by spoken words), a feature that may enhance information processing. The superior temporal sulcus (STS) region of the human brain is involved in processing such stimuli, particularly those derived from biological motion such as mouth movements and gaze shifts. Human neuroimaging studies have shown that lip-reading activates auditory regions of the lateral temporal lobe (Calvert et al., 1997). We hypothesized that STS regions previously shown to be activated by biological motion (Puce et al., 1998) – such as mouth movements may be influenced by concurrent sound. We evaluated whether speech sounds with concurrent mouth movements were more potent activators of STS than either speech sounds or mouth movements alone.

  In an event-related fMRI study, participants observed an animated character that produced audiovisual speech (i.e. mouth movements and synchronous auditory speech) and the auditory and visual components of speech alone. This design allowed us to compare the responses to audiovisual speech and its individual components. We predicted activation of the STS to all three conditions, with greatest levels of activity elicited by audiovisual speech. Additionally, we sought to identify polysensory areas of the STS region by identifying regions responsive to the individual components of speech that also demonstrated supra-additive and/or under-additive responses to audiovisual speech when compared to the sum of the audio and visual components.

  View Poster (PDF)