Methods of Studying the Brain Mrs. Joseph AP Psychology Solon High School

Clinical Observation Study effects of accidents/brain damage (oldest way of studying) Strokes Traumatic Injury Tumor Lesion

Clinical Observation Frontal lobotomy Phineas Gage

Electrical Stimulation Note effect of weak electrical currents on behavior Can be used on humans or animals

Electroencephalograph (EEG) Electrodes measure electrical waves sweeping across surface of the brain

EEG (Electroencephalography) Technique: Multiple electrodes are pasted to outside of head What it shows: A single line that charts the summated electrical fields resulting from the activity of billions of neurons

EEG (Electroencephalogram) Advantages – Detects very rapid changes in electrical activity, allowing analysis of stages of cognitive activity Disadvantages – Provides poor spatial resolution of source of electrical activity

Brain Scans CAT (or CT Scan) MRI PET fMRI

CAT (CT) Scan Computerized Axial Tomography Cross-section X-ray pictures of the brain Can reveal brain damage

MRI Magnetic Resonance Imaging Aligns atoms in brain, then disorients them, measures detectable signals as they move back into place Gives detailed picture of soft tissues

MRI (Magnetic Resonance Imaging) Technique: Exposes the brain to magnetic field and measures radio frequency waves What it shows: Traditional MRI provides high resolution image of brain anatomy, and newer functional images of changes in blood flow (which indicate specific changes in neuronal activity)

Advantages of MRI Requires no exposure to radioactivity Provides high spatial resolution of anatomical details (<1 mm) Provides high temporal resolution (<1/10 of a second)

PET Scan Positron Emission Tomography

PET (Positron Emission Tomography) SPECT (Single Photon Emission Computed Tomography) Technique: Positrons and photons are emissions from radioactive substances What it shows: An image of the amount and localization of any molecules that can be injected in radioactive form, such as neurotransmitters, drugs, tracers for blood flow or glucose use (which indicates specific changes in neuronal activity) PET Scan

PET (Positron Emission Tomography) SPECT (Single Photon Emission Computed Tomography) Advantages – Allows functional and biochemical studies – Provides visual image corresponding to anatomy – Can identify specific receptors or transporters associated with some neurotransmitters Disadvantages – Requires exposure to low levels of radioactivity – Provides spatial resolution better than that of EEG, but poorer than that of MRI – Cannot follow rapid changes (faster than 30 seconds)

fMRI Functional MRI

fMRI (functional Magnetic Resonance Imaging) Technique: uses paramagnetic properties of oxygenated and deoxygenated hemoglobin to see images of changing blood flow in the brain associated with neural activity What it shows: brain structures and processes associated with perception, thought and action

Advantages and Disadvantages of fMRI Advantages – Better resolution than PET scans – Extremely sensitive to changes in blood flow, so can detect even small changes in the brain (stroke) – No exposure to radioactivity (PET) Disadvantages Can identify specific receptors or transporters associated with some neurotransmitters