Ch 5: Methods pt 1

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Understanding What Biopsychologists Do Chapter 5 The Research Methods of Biopsychology

Methods of Visualizing the Living Human Brain: Structure : 

Methods of Visualizing the Living Human Brain: Structure Contrast X-rays – inject something that absorbs X-rays less or more than surrounding tissue Cerebral angiography

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X-ray computed tomography (CT): 2-D images combined to create a 3-D image

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Magnetic resonance imaging (MRI): Produces 2-D and 3-D images with high spatial resolution 2-D image 3-D image

Methods of Visualizing the Living Human Brain: Function : 

Methods of Visualizing the Living Human Brain: Function Positron emission tomography (PET) Magnetoencephalo-graphy (MEG) Brain image archives Transcranial magnetic stimulation Positron emission tomography (PET)

Functional MRI (fMRI): BOLD : 

Functional MRI (fMRI): BOLD fMRIs during visual word identifi-cation

Advantages of fMRI over PET : 

Advantages of fMRI over PET Nothing injected Provides both structural and functional information in one image Better spatial resolution Can create 3-D images of activity over the entire brain

Other Methods of Brain Visualization : 

Other Methods of Brain Visualization Magnetoencephalography (MEG): Provides higher temporal resolution of brain activity changes than fMRI Brain image archives: allows researchers to share their raw data Transcranial Magnetic Stimulation (TMS): disrupts brain activity to observe effects on consciousness–allows causal inference

Recording Human Psychophysiological Activity : 

Recording Human Psychophysiological Activity Recording from the body surface Electroencephalography Muscle tension Eye movement Skin conductance Cardiovascular activity

EEG – Measuring “Brain Waves” : 

EEG – Measuring “Brain Waves” A measure of the average electrical activity of the brain Some EEG wave forms associated with: Specific states of consciousness Cerebral pathology (such as epilepsy) Event-related potentials (ERPs) accompany psychological events Example: sensory evoked potentials are triggered by sensory stimulation

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Some typical electro- encephalo-grams and their psychological correlates

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The averaging of an auditory evoked potential

Measures of Somatic Nervous System Activity : 

Measures of Somatic Nervous System Activity Electromyogram(EMG) measures muscle tension Can be used as a measure of psychological arousal

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Measures of Somatic Nervous System Activity (continued) Electrooculo- gram (EOG) records eyemovements

Measures of Autonomic Nervous System Activity: Electrodermal : 

Measures of Autonomic Nervous System Activity: Electrodermal Appears to reflect activity of sweat glands Skin conductance level (SCL) – measures background level Skin conductance response (SCR) – measures transient changes

Measures of Autonomic Nervous System Activity: Cardiovascular : 

Measures of Autonomic Nervous System Activity: Cardiovascular Heart rate Electrocardiogram (ECG, EKG) records electrical signals associated with heartbeats Blood pressure Measured with a sphygmomanometer Blood volume Plethysmography refers to techniques for measuring changes in blood volume in a particular body part

Invasive Physiological Research Methods : 

Invasive Physiological Research Methods Mainly limited to animal research Lesioning Electrical stimulation Invasive recording methods Manipulating or measuring within the brain

Stereotaxic Surgery : 

Stereotaxic Surgery Used to position experimental devices within the brain Stereotaxic atlas – provides coordinates for locating structures within the brain Bregma – a point on the top of the skull often used as a reference point Sterotaxic instrument – used to hold head steady and guide the device to be inserted

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Implanting an electrode in the rat amygdala Stereotaxic Surgery (continued)

Lesion Methods : 

Lesion Methods Remove, damage, or destroy a part of the brain to observe impact on behavior Aspiration lesions – suction cortical tissue Radio-frequency lesions – heat destroys tissue Knife cuts – may damage surrounding area Cryogenic blockade – “reversible lesion” Lesion studies must be interpreted carefully because it is difficult to make small, precise lesions in the brain

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Two methods of deactivating a brain structure: a subcortical knife cut lesion and a “reversible lesion” by cooling to just above freezing using a cryoprobe Lesion Methods (continued)

Electrical Stimulation : 

Electrical Stimulation Lesioning can be used to remove, damage, or inactivate a structure 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 lesioned

Invasive Electrophysiological Recording Methods : 

Invasive Electrophysiological Recording Methods Intracellular unit recording Membrane potential of a neuron Extracellular unit recording Firing of a neuron Multiple-unit recording Firing of many neurons Invasive EEG recording

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Invasive Electrophysiological Recording Methods (continued)

Pharmacological Research Methods : 

Pharmacological Research Methods Routes of drug administration Selective chemical lesions Measuring chemical activity in the brain Locating neurotransmitters and receptors

Measuring Chemical Activity of the Brain : 

Measuring Chemical Activity of the Brain 2-deoxyglucose (2-DG) technique Inject animal with radioactive 2-DG and allow it to engage in behavior of interest Use autoradiography to see where radioactivity accumulates in brain slices Cerebral dialysis – measures extracellular concentration of specific chemicals in live animals

Locating Neurotransmitters and Receptors : 

Locating Neurotransmitters and Receptors Dye or radioactive labels used to visualize the protein of interest Immunocytochemistry – based on the binding of labeled protein-specific antibodies Immune response - antibodies created that bind and remove/destroy antigens (foreign proteins) In situ hybridization – uses labeled RNA to locate neurons with complementary mRNA

Genetic Engineering : 

Genetic Engineering Gene knockout techniques Subjects missing a given gene can provide insight into what the gene controls Difficult to interpret results – most behavior is controlled by many genes and removing one gene may alter the expression of others, including compensation for missing gene Antisense drugs block expression of a gene Gene replacement techniques Insert pathological human genes in mice