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Neuroimaging Methods: Visualising the brain & its injuries Structural (brain structure) –X-rays –CT (Computer Tomography) –MRI (Magnetic Resonance Imaging)

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Presentation on theme: "Neuroimaging Methods: Visualising the brain & its injuries Structural (brain structure) –X-rays –CT (Computer Tomography) –MRI (Magnetic Resonance Imaging)"— Presentation transcript:

1 Neuroimaging Methods: Visualising the brain & its injuries Structural (brain structure) –X-rays –CT (Computer Tomography) –MRI (Magnetic Resonance Imaging) Functional (brain function) –Blood flow (PET/SPECT/fMRI). –Neuron’s electrical responses (EEG/ERP) – Special thanks to Chris Rorden, U. South Carolina

2 X-ray tube projects through head Detector plate measures transmission of X-rays –Bone relatively opaque to X-rays –Soft tissue relatively transparent Use: –broken bones –Angiography Not good for much else Structural: X-rays

3 Structural: CT scans Uses: –Stroke –Brain tumors (larger than 2-4 mm) –Enhanced with contrast material –Subdural Hematoma –Evaluation of traumatic Head Injury

4 CT scan

5 MRI Magnetic resonance imaging Does not expose individual to X-rays

6 MRI scans Healthy enlarged ventricles MCA infarct & wide sulci

7 Types of MRI scan T1 (anatomical): –fast to acquire, –good detail (e.g. white and gray matter). T2 (pathological): –slower to acquire, thus worse resolution. –Excellent for finding lesions.

8 PET (Positron Emission Tomography SPECT (Single Photon Emission Computerized Tomography) Radioactive oxygen isotope injected into blood Brain regions that use oxygen emit more positrons Functional imaging: Measures brain activity

9 functional: fMRI fMRI: Functional Magnetic Resonance Imaging -Increase activity in certain brain area -Blood vessels dilate -The % of Oxygen in the blood in that area is changed -The MR machine registers that

10 Functional: Electroencephalogram (EEG) Measures electrical activity When neurons fire, they create electical dipoles. Neurons aligned perpendicular to cortical surface. + -

11 Event related potentials (ERPs) ERPs are a type of EEG –Continuously collect EEGs –Present many trials of stimuli (words: neutral vs. offensive) –Compute average brain response to stimuli Good temporal resolution (when activity starts happening). Poor Spatial resolution Time (ms) 0 100 200 300 + _ Signal  V neutral ‘rape’ http://brainserver.psych.indiana.edu/

12 In sum, Structural (brain structure) –X-rays –CT (Computer Tomography) –MRI (Magnetic Resonance Imaging) Functional (brain function) –Blood flow (PET/SPECT/fMRI). –Neuron’s electrical responses (EEG/EEG) –Neuron’s magnetic responses (MEG)


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