TRADITIONAL POSTER - ismrm

Poster Sessions
1172. Resting-State Functional Connectivity Strength Depends on the Magnitude of Resting BOLD
Fluctuations and Not Differences in CBF
Anna Leigh Rack-Gomer 1,2 , Joy Liau 3 , Thomas T. Liu 1,2
1 Bioengineering, UC San Diego, La Jolla, CA, United States; 2 Center for Functional MRI, UC San Diego, La Jolla, CA, United States;
3 School of Medicine , UC San Diego, La Jolla, CA, United States
Interpretation of inter-subject differences in resting-state functional connectivity is complicated by the BOLD signal’s dependence on vascular factors. We
found functional connectivity strength to be correlated with resting-state fluctuation amplitude (RSFA) across healthy subjects, where RSFA has previously
been shown to correspond to vascular reactivity within subjects. However, we did not find RSFA to be related to either the task-related cerebral blood flow
(CBF) response or baseline CBF, suggesting that RSFA does not indicate vascular differences across subjects. Instead, RSFA may reflect true differences in
spontaneous neural activity, which contribute to the normal variability found in resting-state functional connectivity.
1173. Spontaneous Increase in Neuronal Activity in the Resting State Is Associated with Increase in Blood
Oxygenation
Shmuel Na'aman 1 , Sebastien Thomas 1 , Mirza Baig 1 , Peter O'Connor 1 , Amir Shmuel 1,2
1 MNI, Dept. of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada; 2 Center for MR Research, U. of Minnesota,
Minneapolis, MN, United States
Recent studies have demonstrated large amplitude spontaneous slow (< 0.1 Hz) fluctuations in functional-MRI (fMRI) signals in humans in the resting state.
Despite the large body of human imaging literature on spontaneous activity and functional-connectivity in the resting state, the link to underlying neural
activity remains tenuous. We show that spontaneous neurophysiological activity in rat S1FL includes events in which changes in local field potentials across
cortical layers resemble the corresponding changes in response to sensory stimulation. These spontaneous neurophysiological events are accompanied by
increases in blood oxygenation that peak approximately 5 s following the events.
1174. Resting-State FMRI After Experimental Hemispherectomy in Rats: Changes in Functional
Connectivity and Network Synchronization
Willem M. Otte 1,2 , Rick M. Dijkhuizen 2 , Peter C. van Rijen 1 , Peter H. Gosselaar 1 , Maurits P.A. van Meer 1,2 ,
Onno van Nieuwenhuizen 1 , Kees P.J. Braun 1
1 Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, Netherlands; 2 Image Sciences Institute,
University Medical Center Utrecht, Utrecht, Netherlands
Hemispherectomy is a last resort treatment for catastrophic hemispheric epilepsy. The remarkable motor recovery after hemispherectomy reflects the plastic
capacities of the brain. We studied the remaining brain in hemispherectomized rats, 7 and 49 days post surgery using resting-state fMRI, graph analysis and
interregional connectivity. The sensorimotor cortex and striatum in the healthy contralesional hemisphere exhibited significantly increased functional
connectivity after surgery. The graph analysis results assume a shift toward a more regular network organization. We have shown that rs-fMRI, connectivity
analyses and specific network measures can provide unique insights into functional reorganization in the remaining brain after experimental
hemispherectomy.
fMRI: Neuroscience
Hall B Tuesday 13:30-15:30
1175. The Non-Linear Dynamic Characteristics of Olfactory BOLD ResponseΞ
Christopher W. Weitekamp 1 , Jianli Wang 1 , Paul J. Eslinger 2,3 , Jeffrey Vesek 1 , Xiaoyu Sun 1 , James R.
Connor 4 , Qing X. Yang 1,4 , Jianzhong Yin 1 , Martin A. Lindquist 5
1 Radiology, Penn State University College of Medicine, Hershey, PA, United States; 2 Neurology, Penn State University College of
Medicine, Hershey, PA, United States; 3 Neural & Behavioral Sciences, Penn State University College of Medicine, Hershey, PA,
United States; 4 Neurosurgery, Penn State University College of Medicine, Hershey, PA, United States; 5 Statistics, Columbia
University, New York, NY, United States
This study examined the dynamic nonlinear BOLD response pattern in the primary olfactory cortex (POC) and associated brain structures during an
olfactory fMRI paradigm. An intricate relationship among perception threshold, sensitivity, and habituation of the human olfactory system challenges the
fundamental assumption of linearity in BOLD response. The goal of this study was to emphasize an unconventional nonlinear model of BOLD response
through the use of olfactory fMRI and to suggest that such dynamic characteristics may extend to other neuronal systems with a feedback mechanism,
profoundly impacting fMRI data acquisition/analysis and its clinical applications.
1176. The Dependency of Age-Related Change of Brain Activation on the Visual Stimuli - Demand-
Reservation Balance
Toshiharu Nakai 1 , Makoto Miyakoshi 1 , Epifanio Bagarinao 1 , Masaki Yoshida 2 , Chikako Nakai 3 , Kayako
Matsuo 4
1 Functional Brain Imaging Lab, National Center for Geriatrics and Gerontology, Ohbu, Aichi, Japan; 2 Ophthalmology, The Jikei
University, Tokyo, Japan; 3 School of Health Sciences, Toyoshashi Sozo University, Toyohashi, Aichi; 4 Psychology, National Taiwan
University, Taipei, Taiwan
We evaluated the effect task demand for visual processing on the age-related change of the brain activation in healthy subjects. In the elderly subjects, the %
HRF in V1 was reduced by the flickering checkerboard stimuli. By a visuo-motor translation task the % HRF in BA19/7/39 was increased in the elderly,
while no significant difference of % HRF was detected between the two age groups in V1. HRF analysis suggested that age-related change of % HRF may
depend on the existence of neuronal network to compensate the potential functional decline according to aging.