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  • HomefMRI and Cognitive Neuroscience

The technological potential of fMRI (functional Magnetic Resonance Imaging) was first recognized by Dr. Seiji Ogawa, in 1992. Since then fMRI instantly became the most highly sought technique in the brain functional mapping because it offers not only significantly low invasiveness but also provides high spatial resolution. fMRI is now the most important tool in neuroscience for the visualization of the brain functions in humans in vivo.

(Activation areas in the brain as a result of various stimuli - building or face)

1. Functional Imaging - Scanning the Brain

The most widely used scanning technique for fMRI is the assessment of change in the local cerebral blood flow in relation to neural activation. MRI signals, in accordance with the change of cerebral blood flow, can be classified into two types. The first is perfusion fMRI, which is proportional to cerebral blood flow; the other is BOLD (Blood Oxygenation Level Dependent) fMRI, which refers to blood oxygen saturation secondary to the changes in cerebral blood flow. Of these two types of fMRI, BOLD fMRI is the most widely used technique in the study of functional brain imaging.

2. Data Analysis

The most commonly used tools used to analyze fMRI image data are SPM and BrainVoyager. These programs discriminate the activated regions of the brain as shown in Fig. 1. Another commonly used display technique is shown in Fig. 2 for the activation of the FFA and PPA areas as a result of stimulation of the facial scene and building.

Fig. 1. Retinotopy imaging results using visual stimuli.

Fig. 2. Inflation imaging analysis for facial region/building recognition.

3. New methods applied to ultra-high field 7.0T MRI

We have performed an fMRI experiment using 7.0T MRI and compared the results with those obtained using conventional 1.5T and 3.0T MRI scanners. We defined the function of the brain according to three different stimuli: Object, Face, and Scene. We focused our analysis on two specific brain areas, the FFA (Fusiform Face Area) and the PPA (Parahippocampal Place Area). We displayed three kinds of pictures (Object, Face, and Scene) four times and then analyzed the activation of the FFA and PPA. We observed higher signal intensity with 7.0T MRI than with 1.5T and 3.0T MRI using BOLD (Blood Oxygen Level Dependent) fMRI. Fig. 3 shows the response of the FFA to a Facial stimulus. Fig. 4 shows the response of the PPA to a Scene stimulus. Fig. 5 and 6 show the comparison of the BOLD signal intensity between 3.0T and 7.0T MRI. As shown, the intensity of 7.0T MRI is larger than that of 3.0T MRI. Indirectly, it demonstrates that higher strength magnetic fields can induce a larger signal intensity.

Fig. 3. FFA response to a Facial stimulus Fig. 4. PPA response to a Scene stimulus
Fig. 5. BOLD signal change in the FFA area, comparison of Fig. 6. BOLD signal change in the PPA area, comparison of
7.0T and 3.0T MRI 7.0T and 3.0T MRI

• References

- Ogawa S, Tank DW, Menon R, Ellermann JM, Kim SG, Merkle H, Ugurbil K. Intrinsic signal changes accompanying sensory stimulation: functional brain mapping with magnetic resonance imaging. Proc Natl Acad Sci USA 1992;89:5951-5.
- Yoon, H.W., Chung, J.Y., Oh, J-H., Min, H-K., Kim, D-J., Cheon, Y., Joe, K.H., Kim, Y.B., Cho, Z.H. (2009) Differential activation of face memory encoding tasks in alcohol- dependent patients compared to healthy persons: an fMRI study, Neuroscience Letters, 450; 311 – 316
- Chung, J.Y., Yoon, H.W., Kim, Y.B., Park, H.W., Cho, Z.H. (2009) Susceptibility Compensated fMRI Study Using a Tailored RF Echo Planar Imaging Sequence, Journal of Magnetic Resonance Imaging, ;29(1):221-228.

• Research Interests

Investigating high order visual system and antisocial behavior
Study of Music & Brain function
Study of motor cortex & Brain function
Study of brain functions related to language