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During the procedure the person can communicate with

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). During the procedure, the person can communicate with the experimenter througha microphone and can respond to visual stimuli presented on a screen inside the scanning device.With either PET or fMRI, a computer is used to generate a three-dimensional image of the brainthat depicts variations in amount of blood flow as variations in color (seeFigure5.14).How do researchers damage, stimulate, and record from neurons in specific areas of animalbrains to learn about the functions of those brain areas?Areas of damage (referred to as lesions) can be produced in the brains of rats or other laboratoryanimals by either electrical or chemical means. To produce a lesion electrically, a thin wireelectrode, insulated everywhere except at its tip, is surgically inserted into the brain with the helpof astereotaxic instrument(seeFigure5.15), and enough current is sent through the electrode todestroy the neurons adjacent to its tip. To produce a lesion chemically, a tiny tube called acannulais inserted into the brain, again using a stereotaxic instrument, and a small amount of achemical is injected through the cannula, destroying neurons whose cell bodies are located nearthe cannula’s tip. The lesions produced by such means can be as small as one-fourth of amillimeter in diameter. By varying the precise location of the damage in different groups ofanimals, and then comparing the groups in behavioral tests, researchers can identify precise areasof the brain that are crucial for specific types of behaviors.SECTION REVIEWStructure and Function7Neurons in a given nucleus and tract have the same or similar functions, and groups ofneighboring nuclei generally have closely related functions.8To study a brain area’s function, we can observe behavioral effects of inactivating or artificiallystimulating that area, or we can measure its neural activity during behavioral tasks.Human StudiesStudying the effects of existing localized brain damage can aid identification of the functionsassociated with the damaged area.TMS temporarily disrupts or briefly triggers activity in specific cortical areas by means of amagnetic field.An EEG records gross electrical activity in areas of the brain just beneath the skull fromelectrodes placed on the scalp.PET and fMRI produce images that depict changes in neural activity in each area of the brain by
measuring changes in blood flow.Animal StudiesPrecisely placed lesions in the brain can be created electrically or chemically to see how damageaffects behavior.Electrical or chemical stimulation of a specific brain area can help to reveal its functions.Microelectrodes permit the recording of electrical activity in single neurons.5.3How do the autonomic and skeletal motor systems differ from one another in function?

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Term
Fall
Professor
Ennis

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