Techniques to Learn about the Brain and Neural Function

1. Techniques to Learn about the Brain and Neural Function Studying patients with brain damage linked loss of structure with loss of function Phineas Gage http://www.youtube.com/watch?v=9QXI_BxlY7M Paul Broca and Carl Wernicke Gunshot wounds, tumors, strokes, Alzheimer’s disease >Korsakoff’s Syndrome: caused by B1 deficiency related to malnutrition or alcoholism

2. Lesions: damaging the structure • Allows study loss of function • Ablation – removal of the structure • Vast majority of lesion studies are with lab animals, work is determined by Animal Care and Use Committees

3. Organization and Evaluation of Brain Function http://www.learner.org/resources/series142.html?pop=yes&pid=1569 http://www.learner.org/resources/series142.html?pop=yes&pid=1569

4. Direct electrical stimulation provides another way to test brain function • EEG (electroencephalogram) – amplified tracing of activity of a region of the brain produced when electrodes positioned in direct contact with the scalp transmit signals about the brain’s electrical activity to an EEG machine

7. EEG • Used to study epilepsy • Present stimulus repeatedly to a subject and have it filter out activity unrelated to the stimulus • conclusion: identification of electrical wave evoked by the stimulus • Ex: we can detect where information goes in a cat’s brain when its whiskers are stroked

8. Imaging Techniques Provide Images of Brain Anatomy(CAT/CT and MRI)

9. CAT Scan/CT Scan(computerized axial tomography) • CAT scan creates computerized image of X-rays passed through brain • Creates 2D “slices” • Arranged to show extent of a lesion

10. CAT Scans 2. Procedure may involve injection of contrast dye • Shorter scanning periods than MRI (no magnets used) • Used for patients with pacemakers and metallic implants

12. MRI(magnetic resonance imaging) • Giant circular magnet causes hydrogen nuclei in the water of cells to orient in a single direction • Pulses of radio waves cause atoms to spin at a frequency • Computer constructs images based on these signals • MRI images more detailed than CAT or PET scans • Can be produced for any plane of view

13. MRI: produces the most detailed picture of brain structure – 3D

14. Some imaging techniques have enabled neuroscientists to observe activity of the brain as it functions. • fMRI (functional magnetic resonance imaging) • PET scans (positron emission tomography)

15. fMRI • Capitalizes on MRI ability scanners to detect changes in oxygen during heightened neural activity • Heightened activity = more oxygen used by brain • fMRI preferred to PET b/c it doesn’t expose brain to radioactivity • Magnetic fields pose mild risk, if overused

17. PET Scans (positron emission tomography scan) • Ready for this? Here goes… • When neurons are active, automatic increase in blood flow to active regions of the brain bring oxygen and glucose necessary for respiration • Blood flow changes are used to create brain images when tracers (i.e. radioactively labeled glucose) injected into the blood of the subject emit particles called positrons • Positrons are then converted into signals detected by PET scanner • In other words, the positrons almost immediately are destroyed and produce pairs of gamma particles, and the gamma radiation is detected by the scanner • Glucose concentrates in the areas of greatest activity and the concentration of labeled substances taken up by the brain tissue • Revealed in colored computer graphics • This all depends on the amount of metabolic activity in the imaged brain region • This technique tracks complex series of interactions in different brain areas associated with specific mental processes 2. PET scans expose subject to radioactivity

19. Other advances allow neuroscientists to learn about relationship of neurological function to behavior • BEAM – brain electrical activity mapping • Feeds EEG information from numerous recording sites – more accurate diagnoses of tumors, epilepsy, and learning disorders B. MEG – magnetoencephalogram C. SQUID – superconducting quantum interference device • Sensitive devices to detect magnetic fields D. PRONG – parallel recording of neural groups E. TMS – transcranial magnetic stimulation F. Gene knock out technology (removal of specific genes from mice)

20. How well did you do?1999 AP Exam #79 Which of the following is a brain-imaging technique that produces the most detailed picture of brain structure? a. Electroencephalography (EEG) b. Magnetic resonance imaging (MRI) c. Positron emission tomography (PET) d. Computerized axial tomography (CAT) e. Electromyography (EMG)

21. I think my hyperactive 5 year old may have ADD. To make sure that he is in fact suffering from Attention Deficit Disorder and not epilepsy, doctors would most likely use which machine to conduct the necessary tests using strobe lights? a. MRI b. CT c. PET d. EEG e. fMRI

22. If while in an experiment where I am asked to select and defend some options, I am told that, “Hypothetically, if we were to deceive you, would you be deceived?” and I answer that I would know if I was being deceived – and then they deceived me anyway and I did NOT notice it all, I would be exhibiting a. Hindsight bias b. Confirmation bias c. Change blindness d. Choice blindness e. Choice-blindness blindness