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PSYB64H3 (201)
Chapter 1

Discovering Biological Psychology Textbook Chapter 1 and Chapter 2

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Janelle Leboutillier

Discovering Biological Psychology Chapter 1: Introducing Biological Psychology -the human brain contains 5% of the bodys mass but consumes 20% of its glucose and oxygen Biological Psychology as an Interdisciplinary Field -biological psychology = branch of psychology that studies the biological foundations of behaviour emotions and mental processes Historical Highlights in Biological Psychology -brain and nervous system = sources of intellect, reason, sensation and movement -7000 years ago, people tried to cure other by drilling holes in the skull (trephining/trepanation) healing following drilling indicated that person lived through trepanation -thought to release demons/feelings of pressure -5000 years ago: Egyptians did not view the brain as an important structure -Edwin Smith Surgical Papyrus (5000 y.o.) had observations like membrane covering the brain th (meninges), paralysis resulted from damaged nervous system -4 century: Greek scholars believed brain was organ of sensation Hippocrates: brain was soruce of intelligence; also identified that epilepsy as originating in brain -Aristotle: heart was source of intellect -Heorphilus (father of anatomy): ventricles (fluid filled- cavities) played important role -Galen: ventricles played important role in transmitting messages to and from brain (this is false but the belief that the NS was a network of fluid-filled tubes persisted until early modern times) -Descartes supported Galens ideas ws impressed by the hydraulic statues and used these as a model to explain how reflexes worked -when nerves sense heat/pain, they opened pores in the brain pores released animal spirits that circulate through hollow tubes in the body spirits fill reservoirs in muscles the cause foot to be pulled from fire for example -Descartes: mind-body dualism = body of animal and humans work mechanically but humans had mind that is separate and nonphysical -modern neuroscience holds monism view = mind is viewed as the product of activity in the brain and nervous system -people also struggle with the idea that factors such as personality, memory and logic is also due to activities of the neurons in the brain -between 1500-1800: progress in describing nervous system with invention of microscope by Anton van Leeuwenhoek -Luigi Galvani and Emil du Bois-Reymond established electricity as the mode of communication used by the nervous system -Galvani connected wires to legs of frogs which twitched in unison -now understood that it was understood that electrical signals transmitted information to andfromthe brain -Golgi: nervous system was composed of a vast, interconnected network of continuous fibres -Cajal: nervous system was composed of array of separate independent cells = Neuron Doctrine -Cajals view is the correct view -localization of function: Franz Josef Gall and Johann Casper Spusheim -also proposed that skull contours indicate personality and character traits = phrenology (invented by Gall) -more modern view of brain as organ of mind, composed of interconnected, cooperative and independent functional units -mid-1800s: Paul Broca correlated damge he observed in pateints with their behaviour and concluded that language functions were localized in brain -Fritsch and Hitzig: electrically stimulating cortex produce movement on opposite side of the body -Jackson (credited with founding of modern neuroscience): nervous system organized as hierarchy with simpler process in lower levels and more sophisticated process in higher levels i.e. cerebral cortex -Sherrington: coined synapse (point of communication between two neurons) -Loewi: demonstrated chemical signalling at synapse -Eccles, Huxley, Hodgkins advanced understanding of way neurons communicate ->38000 members of Society for Neuroscience Research Methods in Biological Psychology Histology -study of microscopic structures and tissues methods used to observe structure, organization and connections of individual cells -tissue must be made thin enough to allow light to pass through it -first step in histological process is the fix the tissue, either by freezing it or by treating it formalin, a liquid containing the gas formaldehyde -brain tissue is fragile and somewhat watery -formalin hardens the tissue and makes it possible to produce thing slices and pereserve the tissues from breakdown by enzyme or bacteria -same effect obtained by freezing -tissue is sliced thinly by a micrtotome -for light microscope, thickness must be 10-80 um thick -electron microscope need slices less than 1 um Slcies are mounted on slides for viewing -stains used to makeslices visible -Golgi silver strain = to see detailed structural analysis of small number of single cells -Nissl stain = identifies clusters of cell bodies, the bulk of nerve cells -myelin stain = follow pathways carrying information from one part of brain to another by staining the insulating material that covers many nerve fibres -horseradish peroxidase = to discover the point of origin of pathway if you know where pathway ends -travels backwards toward cell body -antibodies = can highlight particular proteins in cells -electron micrscopes developed in 1930s and uses concentrated short electron beam to form images -Palay and Palade provided clear images of a synapse Autopsy to view for oneself -examination of body following death -Simon LeVay used autopsy to examine INAH-3 in which the size of this region is thought to differentiate between homosexual and heterosexual males Imaging o Computerized Tomography (CT) -Rontgen discovered that X-rays can be used to produce negative photographic images -but X-rays dont do a good job of imaging soft tissue -CT was invented by Hounsfield and Cormack -modern CT technology allows for construction of highly detailed 3-D images -CT scan provides no information regarding activity levels in the brain limits usefulness in answering questions about behaviours o Positron Emission Tomography (PET) -allowed researchers to observe brain activity made possible by gamma camera which is used to detect radiation released by radioactive atoms that were decaying or breaking up -combines radioactive tracers with a wide variety of molecules including oxygen, water and drugs gamma ray record detectors -new PET can take images of adjacent slices at same time giving 3-D reconstruction o Magnetic Resonance Imaging -first MRI image produced by Dmadian, Minkoff and Goldsmith in 1977 -uses powerful magnets to align H atoms and radio frequency pulses is directed to body to be imaged, producing resonance/spinning of H atoms -after RF pulse cease, H atoms return to normal alignment and when they relax, they emit a characteristic pulse that is detected and each small area is assigned a voxel (volume pixel) which is a 3-D version of a pixel -darkness/coloration represents level of pulse activity o Functional MRI -used to assess brain activity takes advantage of the fact that active neurons need more oxygen and variations in blood flow to a particular area will reflect this need -Mosso: able to measure and correlate blood flow with patients mental activity -James reflected on Moosos work and Roy and Sherrington confirmed Mossos observation mechanism by which the blood supply to part of cerebral tissue is varied in accordance with activity of cerebral changes -blood glow is tracked using hemoglobin which carries oxygen within the blood has different magnetic properties when combined with oxygen or not -voxel signal change depending on the oxygenation of blood in area (Blood Oxygenation Level Dependent [BOLD] effect) -red and yellow are most active -more advantageous than CT and PET because it can provide images taken at any angle without any movement of individual -fMRI is considered superior in both spatial and temporal resolution to PET scans -fusiform face area part of brain visible when we view a face and parahippocampal palce area is visible when we see a building Recording -nerve cells are capable of generating small electrical charges across their membranes o The Electroencephalogram -created by Berger = technology for studying activity of the brain through recordings from electrodes placed on the scalp -results varied from wakefulness, sleep, anesthesia and epilepsy -EEG measure activity of large numbers of cells known as field potential many factors produce distortion between actual activity of brain and recorded field potential -EEG most highly influenced by the activity of cortical cells closest to electrodes deeper structures have little influence on EEG -bones and tissue separating the brain from electrodes substantially reduce the signal reaching the electrodes -espeically useful for study of sleep and epilepsy but with more powerful tools, can be used to diagnose disorders i.e. schizophrenia dementia, etc.
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