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University of Toronto Scarborough
Janelle Leboutillier

CHAPTER 1INTRODUCING BIOLOGICAL PSYCHOLOGY Biological Psychology as an Interdisciplinary FieldBiological psychology the branch of psychology in which the biological foundations of behaviour emotions and mental processes are studiedResearchers in this field try to identify the relationships between the activity of the nervous system and observable behaviour Historical Highlights in Biological PsychologyAs long as 70 000 years ago people tried to cure others by drilling holes in the skullThis process is known as trephining or trepanationBased on Egyptian text the Edwin Smith Surgical Papyrus represents the oldest known medical writing in historyHippocrates suggested that the brain was the source of intelligenceGalen made accurate observations from dissection but he believed fluids transmitted messagesDescartes is notable for his support of hydraulic transmission and mindbody dualism a philosophical perspective put forward by Rene Descartes in which the body is mechanistic whereas the mind is separate and nonphysicalModern neurosciences are based on monism a philosophical perspective characteristic of the neurosciences in which the mind is viewed as the product of activity in the brain and nervous systemGalvani and du BoisReymond established electricity as the mode of communication used by the nervous systemCajals concept that the nervous system was composed of an array of independent cells came to be known as the Neuron DoctrinePhrenology the pseudoscientific notion that skill contours indicate personality and character traitsCharles Sherrington coined the term synapse Research Methods in Biological Psychology HistologyHistology the study of cells and tissues on the microscopic levelHistological methods provide means for observing the structure organization and connections of individual cellsFirst investigation of nerve tissue under microscope was done by Anton van LeeuwenhoekHistological process includes fixing a tissue as in freezing it with formalino This allows you to cut thin slices and preserves the tissue from breakdown of enzymesAfter being fixed the tissue is sliced by a microtome a device sued to make very thin slices of tissue for histologyOne micrometer is one onemillionth of a meter or one onethousandth of a millimeterGolgi silver stain a stain developed by Golgi used to observe single neuronsNissl stain a stain used to view populations of cell bodiesMyelin stain a stain used to trace neural pathwaysHorseradish peroxidase a stain used to trace axon pathways from their terminals to points of origin from end fiber to cell bodyTissues are looked at under a light or electron microscope electron microscopes use highly concentrated electron beams that produce magnification of up to 1 million times AutopsyAutopsy means to view for oneselfAutopsy the examination of body tissues following deathLeVay believed the size of the INAH3 in the brain might be used to differentiate between homosexual and heterosexual males he studied the brains of deceased individuals ImagingComputerized Tomography CT o Rontgen discovered xrays o CT invented by Hounsfield and Cormack o CT an imaging technology in which computers are sued to enhance xrays images o The word tomography comes from the Greek words tomos to slice and graphia to writedescribe o CT scans provide no information regarding activity levels in the brain doesnt distinguish between a dead and a living brainPositron Emission Tomography PET o PET an imaging technique that provides information regarding the localization of brain activity o PET made possible by the invention of gamma camera that detects radiationMagnetic Resonance Imaging MRI o Damadian Minkoff Goldsmith produced the first MRI o MRI an imaging technique that provides very high resolution structural images o Powerful magnets align hydrogen atoms within a magnetic field o Radio frequency pulses are directed at part of the bod to be imaged producing resonance of the hydrogen atoms o When the RF pulses cease the hydrogen atoms return to original alignment o As atoms relax each emits a characteristic pulse that is detected by the scanner o To construct the image each small area of tissue is assigned a voxel short for volume pixelA voxel is the smallest distinguishable boxshaped part of a 3dimensional image o fMRI a technology using a series of MRI images taken 14 seconds apart in order to assess the activity of the brainfMRI takes advantage of the fact that active neurons require more oxygen than less active neurons and that variations in blood flow with reflect this need o How does fMRI track cerebral blood flow HEMOGLOBIN o Hemoglobin has different magnetic properties when combined with oxygen or not so signal from a voxel will change depending on the oxygenation of the blood in that area o This is known BOLD effectBlood Oxygenation Level Dependent effect RecordingElectroencephalogram EEG o EEG a technology for studying the activity of the brain through recordings from electrodes placed on the scalp o EEG most highly influenced by the activity of cortical cells closest to the electrodes o EEG recordings vary during wakefulness sleep anaesthesia epilepsyEvoked Potentials o Evoked potential an alteration in the EEG recording produced in response to the application of a particular stimulus o Allows researchers to correlate the activity of cortical sensory neurons recorded through scalp electrodes with stimuli presented to the participantMagnetoencephalography MMG o MMG a technology for recording the magnetic output of the brain o Skill bones and tissues allow magnetism to pass through without any reduction o MMG is also silent and is faster than fMRI and EEG scans o MEG provides researchers with important technique for studying brain responses to sound o MEG uses SQUIDs superconducting quantum interference devices that convert magnetic energy into electrical impulses that can be recordedSingleCell Recordings o Extracellular and intracellular events from a single neuron can be assessed using tiny microelectrodes surgically implanted in the area of interest o This allows free range of movement during stimulation Brain StimulationMost neurosurgery is conducted under local anaesthesia not globalThis way the neurosurgeon can stimulate the area in question and can identify whether the area participates in a particular type of behaviourPenfield investigated brains of more than 1000 patients undergoing surgery for epilepsyDelgado and his bullshe implanted electrodes in the bulls brain and when it charged towards him he would activate the electrodes via transmitter and the bull stopped in its tracksRepeated transcranial magnetic stimulation rTMS a technique for stimulating the cortex at regular intervals by applying a magnetic pulse through a wire coil encased in plastic and placed on the scalprTMS can inhibit some functions like hearing voices in schizos and disinhibit behaviours LesionLesion pathological or traumatic damage to tissueHe primary purpose of lesion analysis is to assess the probable function of an areaFlorens started the technique of deliberately lesioning brains of research animalsAblation the surgical removal of tissueLesions can be made by using electrodes and heating the cellsCells can also be killed by using neurotoxinsA reversible type of lesion can be done by cooling the area using a probe Biochemical MethodsMany chemicals are blocked from exiting the blood supply into neural tissue o ie most agents used for cancer chemotherapy simply circulate thru the brain without leaving the bloody supplyAdministering drugs includes eating inhaling injecting chewingChemicals can be directly administered to the brain thru the surgical implantation of micropipettesallows researchers to observe the effects of chemicals in an awake freely moving animalMicrodialysis a technique for assessing the chemical composition of a very small area of the brain Genetic MethodsTwin Studies o Comparing variable of interest by using identical and fraternal twins o Environment experienced by twins is more similar than nontwin siblings
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