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)