ELECTRONIC POSTER - ismrm

14:00 3465. Effect of EEG Electrodes Density (32 and 64 EEG Channels) on the FMRI Signal
Abdelmalek Benattayallah 1 , Nino Bregadze 2 , Aureliu Lavric 3
1 Physics, Peninsular MR Research Centre, Exeter University, Exeter, Devon, United Kingdom; 2 School of
Psychology, Exeter University, Exeter, Devon, United Kingdom; 3 School of Psychology , Exeter University,
Exeter, Devon, United Kingdom
We examined the effect of the number of EEG electrodes on the fMRI image quality, by employing a simple validation procedure.
Each participant performed the same cognitive task in two runs during the same scanning sessions, wearing in one run a 32-electrode
EEG cap and in the other run a 64-electrode EEG cap. fMRI activations in response to the experimental conditions in the task were
contrasted within each run and across runs. Statistical analysis of the fMRI data revealed that overall there was adequate
correspondence between the activations in the 32-electrode run and the 64-electrode run. Of the 13 regions that contained clusters of
statistically significant differences in activation (‘nogo’ > ‘go’ or ‘go’ > ’nogo’), 10 contained such clusters in both runs, 6 in the
‘nogo’ > ‘go’ contrast and 4 in the ‘go’ > ’nogo’ contrast.
14:30 3466. Withdrawn by Author
15:00 3467. Concurrent fMRI and Optical Imaging Spectroscopy at High Field (7T):
Investigation of the Haemodynamic Response Underlying the BOLD Signal
Aneurin James Kennerley 1 , David Keith Johnston 1 , Michael Port 1 , Luke William
Boorman 1 , Ying Zheng 1 , John Edward Mayhew 1 , Jason Berwick 1
1 Psychology, University of Sheffield, Sheffield, South Yorks, United Kingdom
We have developed a methodology for concurrent high field (7T) functional magnetic resonance imaging and 2D optical imaging
spectroscopy for the investigation of the haemodynamics underlying BOLD signal changes to neuronal activation. The technique has
been used to investigate the negative BOLD phenomenon and haemodynamic interactions between two adjacent cortical regions. Data
were used to test and refine biophysical models of the BOLD signal important in interpreting measurements of the BOLD signal as
reflecting changes in metabolic activity.
Thursday 13:30-15:30 Computer 22
13:30 3468. Visualization of Stripe of Gennari-Like Structure in the Primary Visual Cortex by
High-Resolution MRI: Correlation of Structure Vs. Function
Tae Kim 1 , Seong-Gi Kim 1
1 Radiology, University of Pittsburgh, Pittsburgh, PA, United States
Stripes of T1-dependent contrast were detected in the cat primary visual cortex by high-resolution imaging at 9.4 T. These stripes were
well-matched with the regions of highest stimulus-induced CBV fMRI percentage changes. The persistent presence of in stripes
paraformaldehyde fixed brains shows that they arise from structural features.
14:00 3469. High-Resolution FMRI of Visual Stimulation and Attention in Human Superior
Colliculus
David Ress 1,2 , Sucharit Katyal 2 , Clint Greene 1
1 Imaging Research Center, University of Texas at Austin, Austin, TX, United States; 2 Neurobiology, University
of Texas at Austin, Austin, TX, United States
We measured the retinotopic organization of superior colliculus to direct visual stimulation using a 90°-wedge of moving dots that
rotated around fixation. The retinotopy of covert attention was measured using a full-field array of moving dots. Subjects were cued to
perform a task within a 90° portion of the stimulus, and only the cue rotated around fixation. FMRI (1.2 mm voxels) data shows
retinotopic maps of both visual stimulation and covert attention that are in registration with each other. Visual attention and
stimulation produced activity primarily in the superficial and intermediate laminae, but attention activity was more superficial than
stimulation.
14:30 3470. The Ability of FMRI at 7T to Detect Functional Differences Between Areas 1 and 3b
of Primary Somatosensory Cortex
Elizabeth Ann Stringer 1 , Li Min Chen 1 , Robert M. Friedman 2 , J Christopher Gatenby 1 ,
John C. Gore 1
1 Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States; 2 Psychology, Vanderbilt
University, Nashville, TN, United States
Previously we have demonstrated the ability of ultra-high field fMRI to detect topographical organization of digits within areas 1 and
3b of human primary somatosensory cortex. Here we test the feasibility of 7T fMRI to detect functional differences between these
neighboring areas. Functional images were acquired using a 7T Philips Achieva scanner while air puffs were delivered to individual
distal fingerpads. Magnitude and temporal differences in the BOLD signal were detected between areas 1 and 3b. The data support
previous finding that using fMRI at high fields allows the detection of more stimulus selective responses.