[Abstract Title]. - Society for Neuroscience

Title: Connectivity of the human working memory system
Authors: *C. C. FARACO 1 , J. E. MACKEY 2 , N. YANASAK 3 , Q. ZHAO 1 , L. S. MILLER 1 ;
1 Psychol, Neurosci, Univ. Georgia, Athens, GA; 2 Univ. of Georgia, Athens, GA; 3 Radiology,
Med. Col. of Georgia, Augusta, GA
Abstract: Working memory (WM) is a critical cognitive component required for normal
performance in activities of daily living. Many of the cortical components of the WM system
have been mapped through lesion and neuroimaging studies. Neuroimaging studies have used
tasks such as the N-back to elicit activity in these areas, but many of these tasks have not been
shown to correlate with measures of everyday functioning. The operation span (O-SPAN) task,
on the other hand, is a robust measure of WM and has been shown to be highly correlated with
measures of daily living. The current study has a dual purpose, the first is to asses the OSPAN
task's ability to elicit proper activation of the WM system using functional magnetic resonance
imaging (fMRI). The second is to develop a structural connectivity (white matter) map of the
working memory system using diffusion tensor imaging (DTI). Participants performed a
modified version of the OSPAN task, as per Kondo, et al. 2004, while fMRI data were acquired.
Additionally, a DTI scan was acquired for each participant and fieldmaps were developed to
correct for the inherent distortion in fMRI and DTI scans. Areas of fMRI activation will be used
as seeding and tracking points for the DTI data in order to develop the white matter connectivity
map. Whole brain fMRI and DTI scans were acquired on a 3T GE scanner (fMRI: 64x64 matrix,
2.5mm slice thickness, 220mm FOV, 57 slices, TR=3s, TE=25ms, ASSET=2; DTI: 128x128
matrix, 2.5mm slice thickness, 220mm FOV, 57 slices, TR=15600ms, TE=76.2ms, ASSET=2,
25 directions, b-value=1000). Preliminary analysis of the fMRI data, using the FMRIB Software
Library (FSL), indicate robust activity in areas usually implicated in different aspects of working
memory. These include cingulate gyrus (BA32), granular frontal (dorsolateral prefrontal cortex;
BA9), superior parietal (BA7), supramarginal (BA40), and insular (BA13) areas. The robust
activity for each participant should provide sufficient highly activated voxels to be used as
reference points for seeding and tracking of each participant's DTI data (i.e., cortical voxels will
not be directly used as seeding or tracking points due to the significantly lower anisotropy values
in gray matter). Based on previous neuroanatomical findings, direct connections are expected
between frontal, parietal, and cingulate areas/netowrks; connections are also expected to pass
through different thalamic regions. A group averaged fractional anisotropy map will be used to
show the anatomical "strength" of these connections.
Disclosures: C.C. Faraco, None; L.S. Miller, None; Q. Zhao, None; N. Yanasak, None; J.E.
Mackey, None.
Poster
288. Working Memory: Disorders, Genes and Connectivity
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm