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This 6 page Class Notes was uploaded by Anahit Ghaltaghchyan on Saturday July 16, 2016. The Class Notes belongs to PSY 3 at University of California Santa Barbara taught by Staff in Summer 2016. Since its upload, it has received 46 views. For similar materials see Psych 3-Biopsychology in Psychlogy at University of California Santa Barbara.
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Date Created: 07/16/16
▯ Methods of visualizing the human brain ▯ ▯ Contrast X rays: inject something that observes X rays less or more than surrounding tissues ▯ Brain mostly made of similar tissues, so the x rays are absorbed similarly ▯ Cerebral angiography o Inject radio opaque dye into a cerebral artery to visualize the cerebral circulatory system. ▯ X ray computed tomography Used to create one slice picture ▯ Magnetic resonance imaging MRI- constructed from measurement of waves emitted by hydrogen atoms that have been activated within a magnetic field Protons within hydrogen align with the magnetic field of the MRI machine The MRI machine then emits a burst of radio waves, which knock the protons out of alignment Once the radio waves are turned off, the protons realigh and emit a radio signal in the process. Different types of tissues take different amounts of time to realign, allowing for the MRI to distinguish between types of tissues Good spatial resolution Diffusion tensor imaging DTI A variant of MRI, DTI measures the direction of water diffusion in the brain o Nerve tracks are the main routes of water diffusion in the brain DTI measures the direction of water diffusion, revealing the location and direction of nerve tracks in the brain Good spatial resolution ▯ ▯ Methods of measuring Brain activity ▯ Positron emission tomography PET A radiolabeled substance is administered prior to the scan Scan is an image of levels of radioactivity in various parts of one horizontal level of the brain. Get something that the brain uses, attach radiolabeled substance, and see which brain region uses things up as you are completing tasks Provides local measurements of brain metabolism Can only be used on the same person a few times because it requires injecting a radioactive substance into the body Not very good temporal resolution ▯ Functional MRI fMRI Provides images of brain structure and activity Like the MRI, fMRI uses a strong magnetic field Brain activity is measured similarty to MRI but with impornt differences o Different types of tissue emit stronger/weaker signals in MRI o In fMRI more active brain regions require more oxygenated blood than less active regions Oxygenated blood produces a larger signal (more protons) ability to distinguish between more/ less active regions ▯ Magnetoencephalography MEG A measure of neural activity Measures changes in magnetic fields on the surface of the skull o Created by underlying patterns of neural activity Fast temporal resolution (responsive) Quick changes in neural activity is shown as very rapid changes, but cannot tell where exactly it is happening Poor spatial ▯ Scalp electroencephalography EEG Measures of electrical activity of the brain Uses electrodes attached to the scalp ▯ Types of EEG assessment Wave form assessment (eg, alpha waves) o Indication of state of consciousness, pathology) Event related potentials ERP o Measure activity accompanying psychological events ▯ Determining brain functions ▯ Invasive and non invasive ▯ ▯ TMS- a non invasive method for determining brain functions A transracial magnetic stimulation o Not a measure of neural activity o But provides an experimental probe to alter neural activity o TMPS applies a brief strong magnetic field that alters neural activity Can activate or deactivate brain structures Observes changes in behavior o Can only target regions within 2 inches of the skulls surface o ▯ Invasive research methods Stereotaxic surgery o Requires use of stereotaxic atlas and instrument Bregma Point on top of the skull where two major sutures (seams) connect Used as main reference point ▯ 1)Lesion methods- several different procedures to remove or damage a part o parts of the brain selectively Aspiration o Suction Radio frequency current o A heated electrode burns of the targeted tissue Knife cuts o Serving nerves or tracts with tiny blade Reversible lesions o Cooling or anesthetizing the targeted structure o ▯ 2) Electrical stimulation while lesioning can be used to remove damage or inactivate a structure o electrical stimulation may be used to activate a structure stimulation of a structure may have an effect opposite to that seen when the structure is in lesion. Similar to TMS which is non invasive but more direct and capable of being directed toward more brain structures ▯ 3) Invasive electrophysiological recording methods intracellular unit recording o membrane potential of a neuron extracellular unit recording o firing of a neuron multiple unit recording o firing many neurons invasive EEG recording ▯ ▯ Measuring brain activity outside the brain ▯ ▯ Measuring muscle tension (somatic) Electromyography is the technique of measuring the electrical activity of muscles Electromyography indicates tension of muscles under the skin Measure of somatic NS activity ▯ Eye movements Electrooculography is the techniques of recording eye movements Electrooculogram EOG indicates changes in electrical potential between the front and back of the eyeball Measures of somatic NS activity ▯ Skin conductance (autonomic) Measures of electrodermal activity Skin conductance level vs skin conductance response ▯ Cardiovascular activity Often used to link physiological changes with emotional state Measured include hear rate, blood pressure and blood volume (within a particular region) ▯ ▯ Chapter 6- the visual system ▯ ▯ Somatic- afferent (touch smell vision and hearing) ▯ Efferent- motor Properties of light in relation to visual properties Light can be though as Particles of energy (photons) Waves of electromagnetic radiation Waves have a characteristic frequency and wavelength ▯ Light is both of these things
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