Ways to Study Brain Structures and Functioning Can physically trace connections Is the most primitive Can be done with any structures Ablation Can remove a piece of the brain and see what happens If the behavior changes, you can assume that part had some effect. Occasionally done with epilepsy patients 1
Accidents, Tumors, Strokes After they occur can look at changes in behavior. Problem The whole system can be affected. Electrical and Chemical Stimulation. Fritsch and Hitzig, later Penfield Electrically stimulated the brain of humans in surgery and observed what happened. Hands moved, thoughts were recalled, etc. Commonly done today in neurosurgery - called brain mapping. Reaction depends on where the needle is placed. Can also use chemicals to stimulate the system. EEG (Electroencephalogram) Used to record the electrical activity of the brain Excellent for the diagnosis of epilepsy Best when the person is asleep 2
MEG (Magnetoencephalogram) Records the changes in magnetic fields produced by electrical activity in the brain. Angiogram Used to examine blood vessels in the brain Important to diagnose strokes and tumors Can add contrast mediums (dyes) X - Rays.Can use to view brain structures. Important for examining ventricles and other structures Not used as much today 3
CAT Scan or CT Scan (Computerized Axial Tomography or Computerized Tomography) Provides a cross section X-Ray of the brain Good to diagnose tumors and strokes PET Scans (Positron Emission Tomography) Provides a picture of Brain Functioning Monitors the amount of glucose (sugar) the brain is using. Make the glucose radioactive The more glucose you use, the more brain activity there is. MRI (Magnetic Resonance Imagery) Sets up a magnetic field Causes water molecules to vibrate, and changes ion structure. Allows you to get a good picture of brain structures Excellent for diagnosis of Multiple Sclerosis. 4
SPECT Single-Photon Emission Computerized Tomography Is similar to PET Uses radioactively-tagged tracer Resolution is lower Is lower cost. Makes it more practical for widespread use SQUID Superconducting Quantum Interference Device Very new Like MRI Senses changes in magnetic fields When nerves fire they create magnetic fields Fields indicate neural activity. Found The brain hears loud sounds in different places than quiet sounds Areas were laid out like a piano keyboard. Distance between areas that hear low c and middle c is the same as middle c and high c Place where the brain remembers faces is different from where it remembers objects. e.g. Faces were recalled in the right hemisphere that specializes in spatial configurations Objects (spatula) Recalled in the cortex that originally processed how the spatula felt and the hands moved it. (Parietal Lobe) 5
Psychological Tests of Brain Functioning Halstad-Reitan Contains a variety of sub-tests Most tasks are simple and can be easily done by normal people With eyes close, individual is asked, Which hand am I touching? Identify the number that has been traced on a finger. Also have a lot of more complicated tests Aphasia Screening test WAIS-III Luria-Nebraska Has 269 discrete items in several categories. Includes categories such as Tracing objects on wrist Motor coordination Strong reliability and validity >80% or better on identification of brain damaged subjects Other Tests Porteus Mazes Get out of mazes. Look at errors and time to get out. Bender Gestalt Give a picture and have the person draw it. Line Orientation tests Which line is oriented with the stimulus line. 6