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Chapter 1

Chapter 1 - B64

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University of Toronto Scarborough
Janelle Leboutillier

PSYB64 Chapter 1 Introducing Biological Psychology Biological Psychology as an Interdisciplinary Field  Biological Psychology: the branch of psychology that studies the biological foundations of behavior, emotions, and mental processes  Study the relationship between activity of the nervous system and observable behavior  Biology influences behavior and vice versa Historical Highlights in Biological Psychology  Ca. 3000 B.C. o Egyptians discard brain during mummification process, however, published case studies indicate accurate observations of neural disorders  Ca. 400 B.C. – 200 A.D. o Hippocrates declares that the brain is the source of intellect o Galen makes accurate observations from dissection; however, believed that fluids transmitted messages  1600 – 1800 o Rene Descartes suggests mind – body dualism; hydraulic transmission o Anton van Leeuwenhoek invents the light microscope o Galvani and du Bots – Reymond discover that electricity transmits messages in the nervous system  1800 – 1900 o Bell and Magendie determine that neurons communicate in one direction and that sensation and movement are controlled by separate pathways o Gall and Spurzheim demonstrate the phrenology is inaccurate, but the notion of localization of function in he nervous system is accurate o Paul Broca discovers localization of speech production o Fritsch and Hitzig identify localization of motor function in the cerebral cortex  1900 – Present o Ramon y Cajal declares that the nervous system is composed of separate cells o John Hughlings Jackson explains brain functions as a hierarchy, with more complicated functions carried out by higher levels of the brain o Otto Loewi demonstrates chemical signaling at the synapse o Charles Sherrington coins the term ‘synapse’, wins Nobel Prize in 1932 o Sir John Eccles, Andrew Huxley, and Alan Hodgkin share the 1963 Nobel Prize for their work in advancing our understanding of the way neurons communicate o Bernard Katz receives the 1970 Nobel Prize for his work on chemical transmission at the synapse o Society for Neuroscience counts more than 38 000 members in 2007 Research Methods in Biological Psychology Histology  Refers to the study of microscopic structure and tissues  Provide means for observing the structure, organization and connections of individual cells  Tissue to be studied under the microscope must be prepared in a series of steps o Tissue must be thin enough to allow light to pass through o For fragile tissues such as brain tissues (too fragile and watery to make thin enough)  Tissue is treated with formalin (liquid containing gas of formaldehyde) or is frozen  Formalin hardens the tissue to make it possible to cut into thin slices  Preserves tissue from breakdown by enzymes or bacteria o Tissue is sliced using a microtome into slices of 10 to 80 micrometers thick o Fragile slices are mounted on slides for viewing o For very transparent specimens (nerve tissues) a stain is used to see the specimen better PSYB64  Golgi silver stain: used to make detailed structural analysis of a small number of single cells  Nissal stain: used to identify a cluster of cell bodies (bulk of nerve cells)  Myelin stain: follow pathways carrying information from one part of the brain to another by staining insulating material that covers nerve fibers  Horseradish peroxidase: to discover the point of origin of a pathway ending  When enzyme is injected, it travels back to origin (cell body) from the ending o Antibodies can be combined with a variety of dyes to highlight particular proteins found in cells  Antibodies are also used to identify activity of the c – fos gene in the brain o Once tissue is prepared, it can be viewed using electron or light microscope  Electron – use short, highly concentrated electron beams  Modern electron microscopes produce magnifications up to 1M times Autopsy  Examination of the body following death  Means ‘view for oneself’  Simon LeVay used autopsy to exam unknown area of brain (INAH – 3)  Found differences in brain structure and it’s correlation to sexual orientation Imaging  New imaging techniques offer more advantages compared over autopsy Computerized Tomography (CT)  Normal X-rays cannot image soft tissues very well  CT was invented in 1972 by Godfrey Hounsfield and Allan Cormack  Can create high – resolution look at a living brain  Modern CT scans can show 3–D  CT scans cannot distinguish between living or dead brains o Does not show activity levels in the brain o Limits information about behavior Positron Emission Tomography (PET)  Allows researchers to observe brain activity  Done through a gamma camera which detects radiation released by radioactive atoms that were decaying or breaking up  PET brain studies combine radioactive tracers with a wide variety of molecules (oxygen, water, drugs)  Red and yellow – high activity  Green, blue, black – low levels  Newer technology allows for 3 – D imaging Magnetic Resonance Imaging (MRI)  Standard medical diagnostic tool and valuable research asset  Uses powerful magnets to align hydrogen atoms within a magnetic field  Then, radio frequency (RF) pulses are directed at the part of the body to be imaged producing ‘resonance” (spinning of hydrogen atoms)  When RF pulse cease, the hydrogen atoms return to their natural alignment within magnetic field and each atom becomes a mini radio transmitter o The pulse is detected by scanner  Image is conducted, a voxel (3 – D version of a pixel) is assigned o The darkness or coloration of each voxel represents level of pulse activity in an area  Functional MRI (fMRI): used to assess brain activity o First conducted by Belliveau et al PSYB64 o Takes advantage of the fact that active neurons require more oxygen than less active neurons o fMRI track cerebral blood flow because of the property of hemoglobin to carry oxygen within the blood  Signal of voxel change depending on oxygenation of the blood in that area o fMRI is considered superior in both spatial and temporal resolution to PET scams Recording The Electrocephalogram (EEG)  Hans Berger 1924 – first EEG  Recording vary during wakefulness, sleep, anesthesia, and epilepsy  EEG recordings measure activity of large numbers of cells (field potentials)  Several factors produce some distortion of the relationship between the actual activity of the brain and recorded field potentials  EEG is most highly influenced by the activity of cortical cells closest to the electrodes; recording electrodes are located on surface of scalp o Bones and tissues separating brain reduce the signal reaching electrodes  Computerized EEG brain tomography can be used to generate maps of activity – able to pinpoint sources of abnormal activity o Can be used also to help patients with withdrawal from psychoactive drugs or during a coma  Can be used to diagnose schizophrenia, dementias, epilepsy and attention deficit hyperactivity disorder Evoked Potentials  Allows researchers to correlate the activity of cortical sensory neurons recorded through scalp electrodes with stimuli presented to the participant  Brain’s electrical activity in response to stimulus is small compared to activity normally recorded in an EEG o Responses are averaged  Analysis is helpful in cases in which a person’s behavior does not provide clear indication of whether a particular stimulus has been perceived Magnetoencephalography  Allows researcher’s to record the brain’s magnetic activity  Easier to detect magnetic field than electrical field because of bones and tissue interference  Recordings of magnetic fields produced by the brain can be taken much faster than either fMRI or PET scans – provides moment by moment picture of brain activity  MEG uses sensors known as superconducting quantum interference devices or SQUIDS o Convert magnetic energy into electrical impulses that can be recorded and analyzed  MEG does not provide any anatomical data  MEG can locate cognitive functions (language)  Provides precise localization of the source of abnormal electrical activity (seizures) Single – Cell Recordings  Extracellular and intracellular events from a single neuron can be assessed by tiny microelectrodes surgically implanted in area of interest  Microelectrodes are made of fine wires or fluid – filled micropipettes or glass tubes  Electrodes can identify occurrence of electrical signals within a single neuron without contamination of activity from adjacent cells  Electrodes can be permanently implanted allowing free movem
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