Unit 2 Scanning Techniques Methodology PET and MRI scanning Unit 2 Scanning Techniques

How can we study the brain? With a partner Identify 3 methods used to study the brain. What types of scanning techniques have you heard of? Why would brain scanning techniques be a useful research method for psychologists? Dissection – autopsy brain damage – Phineus Gage brain scanning

Lesson Outcome All Students will be able to describe both PET and MRI scanning techniques using appropriate terminology

(link) POSITRON EMISSION TOMOGRAPHY PET PET scanning involves producing computer-generated coloured pictures of the brain. A radioactive tracer is taken into the body. It is usually attached to glucose. As it breaks down it emits radioactivity that can be picked up by the scanner. The picture indicates the amount of tracer absorbed, which shows the area of the brain that is active. The PET scan can measure blood flow and oxygen use

Positron Emission Tomography The Science Bit The scanner detects radioactive material. Oxygen and glucose accumulate in brain areas that are metabolically active. As the glucose is used in the active parts of the brain, the radioactive material breaks down and gives off a neutron and a positron. When a positron hits an electron, both are destroyed and two gamma rays are released. Gamma ray detectors record the brain area where the gamma rays are emitted. This method provides a functional view of the brain.

MAGNETIC RESONANCE (link) IMAGING MRI MRI uses magnetic and radio waves. The person lies in a large cylinder magnet and radio waves are then sent through the body, affecting the body’s atoms. The scanner picks up signals as the atoms move back into position and the computer turns the signals into pictures

(Link) Magnetic Resonance Imaging (MRI) Put another way MRI uses detection of radio frequency signals produced by displaced radio waves in a magnetic field. It provides an anatomical view of the brain.

Magnetic Resonance Imaging (MRI) Advantages Disadvantages Expensive to use. Cannot be used in patients with metallic devices, like pacemakers. Cannot be used with uncooperative (or claustrophobic) patients because the patient must lie still. No X-rays or radioactive material is used. Provides detailed view of the brain in different dimensions. Safe, painless, non- invasive. No special preparation (except removal of all metal) is required from the patient.

Positron Emission Tomography (PET) Advantages Disadvantages Provides an active image of brain. Less invasive then surgery It is valid, can be used to check things like the language area of the brain It is reliable – consistent findings Expensive to use Not portable Radioactive material used Can be difficult to interpret

Electroencephalogram (EEG) Multiple electrodes are placed on the scalp. EEGs record electrical activity along the scalp produced by the firing of neurons within the brain It takes 20–40 minutes

EEG read out

Functional Magnetic Resonance Imaging (fMRI) Other Brain scans Angiography Functional Magnetic Resonance Imaging (fMRI) detects changes in blood flow to particular areas of the brain. It provides both an anatomical and a functional view of the brain. Angiography involves a series of X-rays after dye is injected into the blood. This method provides an image of the blood vessels of the brain.

Computed Tomography Scan (CT Scan) CT scans use a series of X-ray beams passed through the head, creating cross-sectional images of the brain showing the structure, but not the function.

MRI and PET scans You can find out more information about scanning using your text book. Brain p240-243

Complete gap fill page 6 & 7 of your pack Link Task Complete gap fill page 6 & 7 of your pack