Thursday, October 13, 2005


Google Image Result for

" Laboratory of Brain Imaging

This laboratory uses high field MRI to investigate cortical plasticity, face representation in the cortex, and axonal connectivity. Members of the lab are also involved in the development of new MRI applications, and the verification of existing techniques using single unit recording and optical imaging. We are particularly interested in developing novel multimodal imaging techniques to simultaneously map the structure, function, and connectivity of various cortical functions in the mammalian brains. Few examples of our research enterprise are listed below:

Use of BOLD fMRI for mapping the detailed layout of the cortical functional architecture in vivo:

The BOLD technique is based on the use of deoxyhemoglobin as nature's own intravascular paramagnetic contrast agent. When placed in a magnetic field, deoxyhemoglobin alters the magnetic field in its vicinity, particularly when it is compartmentalized as it is within red blood cells and vasculature. The effect increases as the concentration of deoxyhemoglobin increases. At concentrations found in venous blood vessels, a detectable local distortion of the magnetic field surrounding the red blood cells and surrounding blood vessel is produced. This affects the magnetic resonance behavior of the water proton nuclei within and surrounding the vessels, which in turn result in decreases in the transverse relaxation times (T2 and T2*. During the activation of the brain, this process is reduced: increase in neuronal and metabolic activity results in a reduction of the relative deoxyhemoglobin concentration due to an increase of blood flow (and hence increased supply of fresh oxyhemoglobin) that follows. Consequently, in conventional BOLD fMRI, brain "activity" can be measured as an increase in T2 or T2* weighted MR signals. Since its introduction about 10 years ago, BOLD fMRI was successfully applied Ð among numerous other examples - to precisely localize the cognitive, motor, and perceptual function of the human cortex cerebri."

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