Electrodes adhere to the surface of the scalp or to the brain in animals only

Electrodes adhere to the surface of the scalp or to

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Electrodes adhere to the surface of the scalp or to the brain (in animals only) There is a lot of cortical activity, and the electrodes are able to measure the activity of the neurons in the cortex EEG testing has contributed to the discovery of sleep stages and important epilepsy research Provides a picture of what is happening in the brain o CT/CAT: Only provides structural information Takes an x-ray of the brain by sending rays into the brain and detecting how much of those rays were absorbed by the head X-rays contain radiation You only get a horizontal image of the brain from a CT scan Medium resolution o MRI: Only Provides structural information Detects radio waves of H atoms Creates magnetic fields that cause H protons to line up into straight lines. Then, a wave knocks them out of place. As the protons try to line up again, the emit radio waves that are detected to create a sagittal view of the brain. An MRI creates higher resolution images than a CT scan o PET: Structural and Functional Done by injecting the brain with radioactive glucose More active portions of the brain will take up the glucose faster than less active portions. When neurons take up the radioactive glucose, the emit positron, which is detected by scanners which can then create a real time image of the brain and its activity levels Used to track changes in brain activity 13
o fMRI: Structural and Functional Measures changes in oxygen flow within the brain to see which areas are receiving more blood and are, therefore, more active Same as an MRI but with the added benefit of seeing brain function Important for the study of cognitive psychology o MEG: Structural and Functional When neurons fire, there is electrical activity and they create small magnetic fields MEG measures the small changes in magnetic fields within the cortex This indicates functional information Creates real time 3-Dimensional maps that can look at all planes Stereotexic Surgery o This is the first step in all invasive physiological and pharmacological research techniques o Step One: Use a Stereotexic Atlas to determine the location of the target area within the brain The stereotaxic atlas gives 3 coordinates based on the anterior/posterior, medial/lateral, and ventral/dorsal coordinate planes o Step Two: Put the rat in the stereotaxic apparatus Cut the scalp of the anesthetized rat open The stereotaxic apparatus has two arms to hold the head and a bite arm that keeps the rat from hurting itself in the even that it wakes up during the surgery. It also has adjusting knobs for each of the three coordinate planes o Step Three: After adjusting for the coordinates, drill a hole in the rat’s skull o Step Four: Use the arm to lower the electrode onto the location of interest o Step Five: Anchor the electrode with dental acrylic o Step Six: Euthanize the rat and look at the brain to see if you hit the mark that you were initially aiming to hit by staining the brain slice of interest.

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