Title: fMRI in Glasgow
1fMRI in Glasgow
- Jennifer Chisholm
- Institute of Neurological Sciences
- Glasgow
2Outline
- Scanner stability in EPI scanning.
- Intra-subject variation in language laterality.
- Effect of learning Eccentric Viewing Techniques
on fMRI in ARMD subjects.
3Project 1
4Temporal Stability of 3T
Materials Methods
- 30 minute EPI, phantom acquisition
- 600 volumes, TR 3s, TE 30ms, matrix 64x64, 25
slices. - Analysis
- FSLs motion correction McFLIRT
- MIPAV ROI tools
5Temporal stability of 3T
Results
- Levitation of 2.5mm in y-dir.
- Significant heating.
- Non-significant signal drift.
- GE INTERVENTION - Bore Lining Installation.
6Temporal Stability of 3T
Results
- Eliminated levitation
- Introduced Signal error
- Vacuum switch
- Vacuum off
- Drift remained, no sawtooth.
- ? Vacuum pressure changes
- Vacuum off for several days
- Sawtooth drift resolved to within acceptable
limits - Small positional shift (0.35mm).
7Temporal Stability of 3T
Results
- Vacuum pump modification
- Electrical switch replaced by mechanical valve.
- Positional stability.
- Signal stability - 1.2 variation over 30 mins.
8Project 2
9Language Laterality Reproducibility
Introduction
- Epilepsy cannot always be treated with drugs
- In severe, intractable cases, surgical removal of
the seizure focus (often frontal lobe) is used as
treatment. - Area can be close to areas that provide language
and memory function - need to determine likelihood of post-surgical
deficit
10Language Laterality Reproducibility
Introduction
- WADA test.
- Injection of barbiturate (anaesthetic) into right
or left internal carotid artery. - Send half of brain to sleep.
- Perform memory language tasks.
- lt1 risk of inducing a stroke.
11(No Transcript)
12WADA Test
Delivery of amytal
Receptors (BZR/GABA)
intra-arterial injection of HMPAO with amytal
intra-venous injection of iomazenil
Effect on function
intra-venous injection of HMPAO
13WADA Test
Delivery of amytal
Receptors (BZR/GABA)
intra-arterial injection of HMPAO with amytal
intra-venous injection of iomazenil
Effect on function
intra-venous injection of HMPAO
14Language Laterality Reproducibility
Materials Methods
- fMRI language tasks
- Word generation
- Verb generation
- Block design
0
30
60
90
120
15Language Laterality Reproducibility
Materials Methods
- Laterality indices based on
- No. of activated voxels, NV
- Average value of Z-statistic in activated voxels,
ZAV - Repeated at a 2 week interval on each of 15
normal, healthy volunteers.
16Language Laterality Reproducibility
Results
- NV
- Different laterality outcome in 2/15 subjects
between two time points - Mixed at both time points using ZAV.
- ZAV
- Different laterality outcome in a different 1/15
subjects - Left at both time points using NV .
- In all 3 subjects, change from Left to Mixed or
vice versa
17Language Laterality Reproducibility
Conclusion
- Two language paradigm approach is reproducible
over 2 week period in healthy volunteers. - Calculation of both laterality indices is useful.
- Repetition of protocol with epileptic patients
and comparison with WADA test data under way.
18Project 3
19fMRI Learning
- Neuron. 2004 Oct 2844(3)411-22 Neural changes
following remediation in adult developmental
dyslexia. Eden GF et al - Cogn Affect Behav Neurosci. 2004 Mar4(1)67-88
- The neurobiology of adaptive learning in reading
a contrast of different training conditions. - Sandak R et al.
20fMRI in ARMD with Eccentric Viewing Learning
Age Related Macular Degeneration
21fMRI in ARMD with Eccentric Viewing Learning
Eccentric Viewing
- Peripheral retina employed for fixation tasks.
- Training
- 1 hours sessions 4 - 12 weeks.
22(No Transcript)
23fMRI in ARMD with Eccentric Viewing Learning
Hypothesis
- MD subjects have been shown to recruit visual
cortex usually receiving foveal input to receive
input from the new preferred retinal locus - Baker C et al
- Eccentric viewing may increase the significance
and/or extent of activation seen in previous
foveal cortical locations.
24fMRI in ARMD with Eccentric Viewing Learning
Study Protocol
- 8 ARMD subjects
- 8 age and gender matched controls
- Ophthalmic investigations
- Standard
- Electrophysiology mfERG
- Retinotopic mapping via fMRI
25fMRI in ARMD with Eccentric Viewing Learning
Multifocal Electroretinogram (mfERG)
26fMRI in ARMD with Eccentric Viewing Learning
Multifocal Electroretinogram (mfERG)
Normal
ARMD
27fMRI in ARMD with Eccentric Viewing Learning
fMRI
- Simulator
- Eyetracker
- Reversing checkerboard pattern
- Expanding annulus
- Dilating contracting
- (to remove and examine between-area phase
delays). - Rotating hemi-field
- Clockwise anti-clockwise
- E-prime
28(No Transcript)