The Physics in Psychology Jonathan Flynn
Wilhelm Wundt August 16, 1832 - August 31, 1920
Freud & Jung 6 May 1856 23 September 26 July 1875 6 June
Behaviorism September 14, 1849 February 27, 1936 August 31, 1874 August 9, 1949
Gestalt
Cognitive Psychology
Cognitive Neuroscience
How Do We Study the Brain?
Neuron
Brain
Methods Microscopy CAT Scan PET Scan MRI MEG EEG
Microscopy
Microscopy Golgi and the neuron doctrine Pros Cons Detailed analysis of the structure of single or small groups of neurons Subject must be dead Dynamic activity can only be inferred from sample
Electron Microscope
Computed Axial Tomography
CAT Scan Theory existed since early 1900s, but not applied until widespread adoption of computers Body tissue is differentially permeable to X-Rays Tomography is done by moving the X-Ray source and film in opposite directions, creating a visible focal plane A large series of these X-ray images are taken along an axis and stitched together with computers
CAT Scan Pros Cons High spatial resolution Relatively cheap 3 dimensional images Moderate radiation dose Poor contrast resolution - relies on contrast agents
Positron Emission Tomography Detects pairs of gamma rays emitted by decay of a tracer attached to biologically active molecule Tracer is a short lived isotope that undergoes beta decay Positron is emitted, and collides with local electron Gamma rays hit scintillators, detected by photomultiplier tubes
PET
PET Pros Cons Tracers can be used track metabolic pathways Easily used with CAT scans and MRIs Needs a local cyclotron to make radionucleides, and special labs for radiopharmaceuticals Lower spatial resolution
MRI http://upload.wikimedia.org/wikipedia/commons/d/db/ Structural.gif
MRI Nuclei with non-zero spin can be aligned Once aligned, they knocked out of alignment by an EMF burst. When the EMF burst is ended, an oscillating magnetic field is produced from nuclei This produces a small current in a receiver array A computer applies a 2D or 3D Fourier transform
MRI
MRI http://www.magnet.fsu.edu/education/tutorials/ma gnetacademy/mri/page3.html
MRI Pros Cons Detailed dynamic 3D image Good with soft tissue No radiation Can record dynamic activity Expensive Strong magnets are difficult to work with Only moderate temporal resolution Blood flow is does not have a one to one
Low Power MRI Only requires 46 microteslas, with one second 30 millisecond pre-polarization burst Primed with burst, uses super conducting quantum interference devices (SQUIDS) to detect the weak signal. Low spatial resolution, but research is improving it. Can be coupled with MEGs
Low Power MRI
Electro/Magneto Encephalography Ions in the brain produce magnetic and electric fields Potentiometers and SQUIDs are used to detect these fields Source localization runs into inverse problem
Inverse Problem Infinite number of solutions Techniques to overcome Estimation and successive refinement Correlations Beam forming Dipole model localization
Magnetoencephalography Pros Cons High temporal and spatial (with qualifications) resolution Can be paired with MRI Measures electrical activity Needs a magnetically shielded room Can only measure at the cortical level Expensive Inverse problem
Electroencephalography Measures potential on the scalp First used in ESP studies Pros Cons Cheap! High temporal resolution Inverse problem Mid to Low spatial resolution Skull and scalp alter electric fields
Sources Rugg, M.; Coles, M. (1995). Electrophysiology of mind: Event-related brain potentials and cognition. New York, NY, US: Oxford University Press, xii, 220 pp. Radiological Society of America (2008). Positron Emission Tomography Computed Tomography. http://www.radiologyinfo.org/en/info.cfm?pg=pet Morton, H. (1994). The Story of Psychology. Anchor Publishing Coyne, K. (2008). MRI: A Guided Tour.http://www.magnet.fsu.edu/education/tutorials/magnetacademy/mri/fullarticle.html Thanks to the wikimedia foundation for their collection of media under the creative commons copyright law.
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