Techniques to study the brain A brain lesion experimentally destroys brain tissue to study animal behaviors after such destruction (disease)
Brain Damage Lesion studies in animals show us what happens when certain parts of the brain stop working Neuropsychologists determine location of brain dysfunction by observing behavior on psychological tests
Microelectrode Techniques Very small electrodes inserted into individual neurons Used to study activity of a single neuron
Macroelectrode Techniques Used to get a picture of overall activity in the brain EEG (Electroencephalogram) uses electrodes placed on a person’s scalp to measure an amplified recording of the electrical waves sweeping across the brain’s surface. Non-invasive Measures electrical activity on surface of skull More about function than structure
Neuroimaging CT: 3D picture of structure using x-rays MRI: response to magnetic fields shows structure PET: measures uptake in glucose to determine changes in activity level (function)
Structural Imaging Computerized Axial Tomography (CAT-scan) Uses X-rays to create a 3-dimensional image of the brain CT scans can often show the size and locations of brain abnormalities caused by tumors, blood vessel defects, blood clots, strokes and other problems.
Structural Imaging cont’d Magnetic Resonance Imaging (MRI) Uses a magnetic field and radio waves to produce computer-generated images They distinguish among different types of brain tissue. Image shows ventricular enlargement in a schizophrenic patient.
CT Scan vs. MRI CT may be less expensive than MRI. In addition, it is less sensitive to patient movement. CT can be performed if you have an implanted medical device of any kind, unlike MRI. MRI contrast materials used for image enhancement have very low incidence of side effects
Functional Imaging Shows the brain functioning in real time (movies or series of images) Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT) Use radioactive glucose to determine location of greatest brain activity PET Scan of Alzheimer's Disease Brain PET Scan of Normal Brain
Neuroimaging fMRI: measures change in blood oxygenation levels to look at brain activity ( Shows function and structure by measuring movement of blood molecules within the brain WIRED SCIENCE | Lie Detectors | PBS WIRED SCIENCE | Lie Detectors | PBS MEG: (Magnetoencephalography) measures electrical activity in brain by measuring tiny magnetic fields with small time intervals
Neuroimaging CT & MRI give good static (still) images MRI is better for soft tissues PET, fMRI & MEG are functional (moving) image techniques PET scans are invasive fMRI is “best” for depicting moving images MEG good for very short time intervals
TMS (Transcranial Magnetic Stimulation)Transcranial Magnetic Stimulation Applies strong and quickly changing magnetic fields to enhance or interrupt brain function Can infer causation Depression Auditory hallucinations Auditory hallucinations
How much of our brain do we use? 10 percent 20 percent 50 percent 100 percent We use some parts more routinely than others, but everything gets used. We use some parts more routinely than others, but everything gets used.