Chapter 5 - Chapter 5 Experimental Ablation Phineas Gage(1823-1860-railroad worker-explosives-tamping iron through the head 1848-personality

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1Chapter 5 Experimental Ablation •Phineas Gage (1823-1860) -railroad worker -explosives -tamping iron through the head 1848 -personality changes -“not the same Gage” •experimental ablation: the removal or destruction of a portion of the brain of a laboratory animal; presumably, the functions that can no longer be performed are the ones the region previously controlled Evaluating the Behavioral Effects of Brain Damage •lesion study: a synonym for experimental ablation •goal: discover what functions are performed by different regions of the brain and then to understand how these functions are combined to accomplish particular behaviors -circuits within the brain perform functions, not behaviors -each region performs a function (or set of functions) that contributes to performance of the behavior -understand functions that are required for performing a particular behavior and to determine what circuits of neurons in the brain are responsible for each of these functions -does X cause Y?? Producing Brain Lesions •electrical current -brain lesions of subcortical regions (regions beneath cortex) -stainless steel wire coated with an insulating varnish except for tip -produces radio frequency -> heat that kills cells in region around -kills axons and neurons in region •excitotoxic lesion: a brain lesion produced by intracerebral injection of an excitatory amino acid, such as kainic acid -does not kill fibers of passage -but non-specific -helps researchers decide if it is neurons in area or axons that pass through area •6-hydroxydopamine (6-HD): a chemical that is selectively taken up by axons and terminal buttons of noradrenergic or dopaminergic neurons and acts as a poison, damaging or killing them -used to induce Parkinsonism in mice, rats, monkeys - to test medicines that might be used to treat Parkinson’s disease •sham lesion: a placebo procedure that duplicates all the steps of producing a brain lesion except for the one that actually causes the brain damage Stereotaxic Surgery •stereotaxic surgery: brain surgery using a stereotaxic apparatus to position an electrode or cannula in a specified position of the brain -not only for brain lesions The Stereotaxic Atlas •bregma: the junction of the sagittal and coronal sutures of the skull; often used as a reference
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point for stereotaxic brain surgery •stereotaxic atlas: a collection of drawings of sections of the brain of a particular animal with measurements that provide coordinates for stereotaxic surgery The Stereotaxic Apparatus •stereotaxic apparatus: a device that permits a surgeon to position an electrode or cannula into a
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This note was uploaded on 03/30/2008 for the course PSY 454 taught by Professor Auger during the Spring '08 term at Wisconsin.

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Chapter 5 - Chapter 5 Experimental Ablation Phineas Gage(1823-1860-railroad worker-explosives-tamping iron through the head 1848-personality

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