Biological Psychology: Research Methods Dr. Katherine Mickley Steinmetz Outline Neuroscience Methods Histology Electrophysiological Recordings Lesion Neuroimaging
Neuroanatomy Histology: Brain structure Brain organization Connections Neurotracers Autoradiography inject radioactive substance allow uptake by neurons and transport throughout the dendrites and axons (24-72 hrs) Slice brain and develop radioactive substance
Neuroanatomy Immunocytochemistry uses the immune antibody system to label any cellular component Can label neurotransmitters, enzymes, receptors, types of cells (particular neurons, glial cells, etc.) Can even measure neural activity - c-fos - a protein produced in neuron s soma following excitation Outline Neuroscience Methods Histology Electrophysiological Recordings Lesion Neuroimaging
Electrophysiological Recordings Nerve Recordings - whole nerve, single fiber Whole nerve are integrated to show overall activity level in response to stimuli Single unit can analysis individual action potential response to stimuli NaCl HCl QHCl Sucrose Outline Neuroscience Methods Histology Electrophysiological Recordings Lesion Neuroimaging
What is a lesion? What can it tell us? Neuropsychological Approach Logic: If a region of the brain is essential for some aspect, Then damage to that region should affect performance on that aspect ** So neuropsychological approaches can tell us about the NECESSITY of a region for a particular function
What are the pros and cons to naturally occurring lesions in humans? Techniques for Studying Brain Function Ablation/Lesion Stereotaxic apparatus - accurate access to brain areas Stereotaxic atlas - map used to locate structures
Transcranial Magnetic Stimulation clip TMS Video http://www.youtube.com/watch?v=xjtnpqcj-ia
Introduction to Biological Psychology Neuroscience Methods Histology Electrophysiological Recordings Lesion Neuroimaging Neuroimaging Approaches SPECT: single photon emission computed tomography CT (CAT): computed (axial) tomography PET: positron emission topography fmri: functional magnetic resonance imaging ERP: event-related potentials
PET! (Positron Emission Tomography)" Small dose of a chemical (radionuclide) used to label glucose is injected into patient. " The radionuclide emits positrons. " A PET scanner will rotate around a patient's head to detect the positron emissions given off by the radionuclide. " PET! (Positron Emission Tomography)!! Can be used to examine brain function" brain regions will uptake more of the labeled glucose when active during a cognitive task" The computer then uses the measurements of glucose utilization to produce a picture which is color coded."
PET! (Positron Emission Tomography)! " resting in scanner (no task) PET! (Positron Emission Tomography)! " reading words
PET! (Positron Emission Tomography)! " trying to remember words for a later memory test PET! (Positron Emission Tomography)! " must perform tasks in blocks of at least 30 sec rest read rest remember rest read rest cannot sort by performance (e.g., words that are later remembered vs. words that are later forgotten)
(f)mri: (functional) magnetic resonance imaging MRI (Magnetic Resonance Imaging) Radio waves 10,000-30,000 times stronger than the magnetic field of the earth are sent through the body. This affects the body's atoms, forcing the nuclei to align to the magnetic field. As they move back into random position, they send out radio waves of their own, measured by the scanner. fmri measures the signals emitted by oxygenated and deoxygenated blood
functional MRI! (Magnetic Resonance Imaging)! Subtractive Logic Most of the brain is active during most events We want to isolate regions that are specific to a task So, construct 2 conditions that you believe have just some crucial interesting difference Treat one as baseline and subtract it from the other, to get rid of all the activity the 2 conditions have in common
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fmri vs PET Measures magnetic properties of blood Measures glucose uptake (deoxyhemoglobin) no radiation temporal resolution = 2-3 seconds spatial resolution = 2-3mm radiation temporal resolution = 30 seconds spatial resolution = 5-6mm trials can be blocked/ trials can only be blocked randomized True of both: poor temporal (time) resolution (seconds) results dependent on task and baseline (subtractive logic + pure-insertion problem) Indirect measures of neural activity Non-invasive Functional Neural Activity Measurements Low spatial resolution, high temporal resolution Event Related Potentials: average of many EEG stimulus presentations reduces variability
ERP: event-related potentials advantages: excellent temporal resolution you can know when something happened down to the msec! event-related neural responses Direct measure of neural activity disadvantages: poor spatial resolution You might not know exactly what part of the brain the activity is coming from Group Activity Hypothesis: Orbitofrontal cortex is not critical for learning face-name pairs. What technique would be best to test this hypothesis? (behavioral study? Neuroimaging? Lesion studies? Other methods?) What result would support this hypothesis? Reject it? What factors would you need to control for?