CH 5: Research Methods of Biopsychology Flashcards
Describe 2 x-ray based techniques for visualizing the living human brain.
(1) Contrast X-Ray Techniques:
- injecting into 1 compartment of the body a sub that absorbs X-rays less/more than surrounding tissues
(2) Computed Tomography (CT):
- computer-assisted x-ray procedures
- used to visualize brain & other internal organs
Describe the PET technique.
- PET = position emission tomography
- Visualizes brain activity via measuring the accumulation of radioactive flurodeoxyglucose (FDG) in active areas of brain
- Each pet scan = image of levels of radioactivity (indicated by colour coding) in various parts of horizontal level of brain.
–> Used to show correlation b/w brain activity & cognitive activity, but can’t prove that brain activity CAUSED the cognitive activity
List 3 magnetic-field-based techniques for imaging the living human brain.
- MRI = magnetic resonance imaging
- fMRI = functional MRI
- Diffusion Tensor Imaging
Describe how an MRI is used to image the living human brain.
- MRI = structural brain-imaging procedure
- High-res images constructed from measurement of radio-frequency waves that H-atoms emit as they align w/ powerful magnetic field
- Provides clearer images of brain than CT
- Prod 3D images
Describe how an fMRI is used to image the living human brain
- Prod images rep the ^O2 flow in blood to active areas of brain
- Active areas of brain take up ^O2 blood
- -> thus oxygenated blood accumulates in activate areas of brain
- Oxygenated blood has magnetic properties that influence the radio-frequency waves emitted by H-atoms in MRI
–> Used to show correlation b/w brain activity & cognitive activity, but can’t prove that brain activity CAUSED the cognitive activity
Describe how DIFFUSION TENSOR IMAGING is used to image the living human brain
- Identifies pathways along which H2O molecules rapidly diffuse
- Helps understand connections among brain structures
List 2 trans-cranial stimulation techniques.
- Transcranial Magnetic Stimulation (TMS)
2. Transcranial Direct Current Stimulation (tDCS)
Describe TMS
- MAGNETIC stim temp turns off part of brain while effects of disruption on cognition & behaviour are assess
- Turns off an area of human cortex by creating a magnetic field under a coil positioned next to skull
- Can also ‘turn on’ areas of cortex
Describe tDCS
- ELECTRICAL stim temp ^activity in part of brain while effects of stimulation on cognition & behaviour are assessed
- Stimulates (‘turns on’) area of cortex by applying an electrical current through 2 electrodes placed directly on scalp
What are trans-cranial stimulation techniques used to establish?
- The causal effects of human cortical activity on cognition behaviour
List 2 psychophysiological measures of brain activity.
- Electroencephalography (EEG)
2. Magnetoencephalography (MEG)
Describe EEG.
- Measure of gross electrical activity of the brain
- Recorded via large electrodes placed on scalp
- Scalp EEG signal reflects sum of electrical events throughout head – incl. action potentials & postsynaptic potentials etc.
- Its value relies on fact that some EEG wave forms are ass w/ particular states of consciousness (ie. aroused, relaxed, asleep, etc)
Describe MEG.
- Also monitors brain activity from scalp
- Measures changes in magnetic fields on the surface of scalp that are produced by changes in underlying patterns of neural activity
List 2 psychophysiological measures of SOMATIC NS activity.
- Muscle tension
2. Eye movement
How is muscle tension psychophysiologically measured?
- via Electromyography (EMG)
- EMG activity recorded b/w 2 electrodes taped to surface of skin over muscle of interest
How is eye movement psychophysiologically measured?
- via Electrooculography (EOG)
- based on fact that steady potential diff exists b/w the front (positive) & back (negative) of eyeball
- When eye moves, a change in electrical potential b/w electrodes placed around eyes are recorded.
List 2 psychophysiological measures of AUTONOMIC NS activity.
- Skin conductance
2. Cardiovascular activity
How is skin conductance psychophysiologically measured?
Define SCL & SCR.
- Emotional thoughts & experiences ass. w/ ^ability of skin to conduct electricity
- Skin Conductance Level (SCL) = measure of background live of skin conductance ass. w/ particular situation
- Skin Conductance Response (SCR) = measure of transient changes in skin conductance that are ass. w/ discrete experiences
- -> ie) sweat glands become active in emotional situations
- -> rel sweat
- -> ^electrical conductivity of skin
How is cardiovascular activity psychophysiologically measured?
HEART RATE
- Electrical signals ass. w/ each heartbeat recorded via electrodes placed on chest
- Recording = ECG = electrocardiogram
BLOOD PRESSURE
BLOOD VOLUME
- Changes in blood V in p articular parts of body ass w/ psychological events
- ie) boner in men during sexual arousal
Define STEREOTAXIC SURGERY & list the 2 things it requires.
= Experimental devices precisely positioned in depths of brain
Requires:
- atlas to provide directions to target site
- instrument for getting there
List 4 types of lesion methods.
- Aspiration lesions
- Radio-frequency lesions
- Knife cuts
- Reversible lesions
Describe Aspiration Lesions
- Aspiration = tissue drawn off by suction through fine tip of glass pipette
- Used when lesion is made in area of cortical tissue that’s accessible to the eyes & instruments of surgeon
- -> Leaves underlying white matter & major bv’s undamaged
Describe Radio-Frequency Lesions
- Pass radio-frequency current through target tissue to destroy tissue
- Intensity & duration of current depends on size of tissue
Describe Knife Cuts
- Sectioning (cutting)
- -> Eliminates conduction in a nerve or tract
Describe Reversible Lesions
- Temp eliminate the activity in particular part of brain while tests are conducted
- Advantage = same subjects can be repeatedly tested in both lesion & control conditions
Explain why it’s important to be cautious when interpreting the effects of lesions (2).
- Brain structures are small & tightly packed
- -> Can’t completely destroy a structure w/o prod sig damage to adjacent structures - Behavioural effects of unilateral lesions (lesions on 1/2 of brain) are much milder than symmetrical bilateral lesions
Describe the technique of ELECTRICAL BRAIN STIMULATION.
- Electrically stimulating neural structure –> give clues about its function
- Important bc often has behavioural effects
- is INVASIVE procedure, often tested on nonhumans
List 4 invasive electrophysiological recording methods.
- Intracellular unit recording
- Extracellular unit recording
- Multiple-unit recording
- Invasive EEG recording
Describe Intracellular Unit Recording
- Provides moment-by-moment record of graded fluctuations in one’s neuron’s membrane potential
Describe Extracellular Unit Recording
- Record action potentials of neuron through micro electrode tip placed in extracellular fluid next to it
- Provides record of firing of a neuron but NO info about the neuron’s membrane potential
Describe Multiple-Unit Recording
- ^Larger electrode tip - picks up signal from many neurons
- Slight shift in movement of subject have minimal effect on overall signal (unlike above)
Describe Invasive EEG Recording
- EEG signals recorded through large implanted electrodes rather than scalp electrodes
Describe the 3 methods of drug administration.
- Fed to subject
- Injected through tube into stomach
- Injected hypodermically into:
- peritoneal cavity of abdomen
- large muscle
- fatty tissue beneath skin
- large surface vein
- -> problem w/ peripheral routes of admin = drugs don’t readily pass through blood-brain barrier
- -> admin drugs in small amounts through fine tube stereotaxically implanted in brain
Define NEUROTOXINS
- Neural poisoning = affinity for certain components of NS
Describe the method of selective neurotoxic lesions.
- Neurotoxins injected to make more selective lesions
- Bc effects of surgical, radio-frequency & reversible lesions are hard to interpret bc they affect all neurons in area.
List 2 techniques for measuring chemical activity in the brain.
- 2-Deoxyglucose Technique
2. Cerebral Dialysis
Describe how 2-Deoxyglucose Technique is used for measuring chemical activity in the brain.
- Place animal that’s been injected w/ radiative 2-DG in test situation where it engages in activity of interest
- 2-DG is similar to glucose (brain’s main source of E)
- -> neurons active during test absorb 2-DG but don’t metabolize it
- Kill subject, remove & slip brain, analyze parts of brain that absorbed high levels of radioactive 2-DG
Describe how Cerebral Dialysis is used for measuring chemical activity in the brain
- Measures extracellular [ ] of specific neuro-chemicals in behaving animals
- Implantation in brain of fine tube w/ short semipermeable section
- -> Positioned in brain structure of interest so that extracellular chem of structure diffused into tube
- Collect contents of tube to freeze, store & later analyze
List 2 techniques for locating particular NTs or receptors in brain.
- Immunocytochemistry
2. In Situ Hybridization
Describe how Immunocytochemistry is used for locating particular NTs or receptors in the brain.
- Locates particular neuro-proteins in brain by labelling their antibodies w/ dye or radioactive element
- -> Then expose slices of brain tissue to the labelled antibodies
- Regions of dye radioactivity accumulation in brain slices mark the locations of target neuroprotein
- Expose brain slices to labelled antibodies that bind to enzymes located in only those neurons that contain the NT of interest
Describe how In Situ Hybridization is used for locating particular NTs or receptors in the brain.
- Locates peptides & other proteins in brain
- Identify nucleotide base sequences that direct stn of many neuroproteins
- -> artificially create the complementary base sequences
- see pg 117 for details
Describe Gene Knockout Techniques
- Creating organisms that lack a particular gene
- Conducted to clarify the neural mech of behaviour
- Behaviour is controlled by many genes interacting w/ another + experience via epigenetic mech
Describe Gene Replacement Techniques
- Creating organisms where a particular gene is replaced w/ another
Define TRANSGENIC
- ie) transgenic mice = contains genetic material of another sp
Explain how green fluorescent protein has been used as a research tool in neurosciences.
- GFP = Green Fluorescent Protein = pro that exhibit bright green fluorescence when exposed to blue light
- Strategy: Insert GFP in target cell
- -> Activate GFP gene in only the particular cells under investigation
- -> ^visualization
Define OPSINS
- Light-sensitive ion channels found in cell membranes of certain bacteria & algae
Explain how opsin have been used as a research tool in the neurosciences
- Opens & allows ions to enter cell when illuminated w/ light
- Light can either hyper polarize or depolarize the cell membrane
- Insert opsin gene into particular types of neurons
- Activate opsin channels
- -> ^ or suppress activity of neuron
List 3 approaches to neuropsychological testing
- Single-Test Approach
- Standardized-Test-Battery Approach
- Customized-Test-Battery Approach
Describe the Single-Test Approach. Is is successful or unsuccessful?
- Goal = discriminate b/w patients w/ psych problems resulting from structural brain damage, vs. those w/ psych problems resulting from functional (rather than structural) changes to brain
- UNSUCCESSFUL approach bc no single test can be sensitive to the varied & complex psych symptoms occurring in brain-danged patient
Describe the Standardized-Test-Battery Approach.
Pros & cons?
- Identify brain-damaged patients using standardized batteries (sets) of tests rather than a single test
- Add together test scores to form single aggregate score
- -> If below designated cutoff, then brain damage diagnosis
- Good at discriminating b/w neurological patients & healthy ppl
- NOT good at discriminating b/w neurological patients & psychiatric patients
Describe the Customized-Test-Battery Approach
- Objective = characterize nature of psych deficits of each brain-damaged patient
- Starts w/ common battery tests to provide indication of general nature of neuropsychological symptoms
- Dependent on test results, select series of tests customized to each patient to characterize more detail of the symptoms revealed by common batter
- see pg 121-122 for more details
Describe the 4 types of tests that are often administered as part of an initial common neuropsychological test battery.
- INTELLIGENCE
- Knowing a patient’s IQ can help a neuropsychologist interpret the results of subsequent tests - MEMORY
- Limitation = 2 forms of memory are least likely to be disrupted by brain damage - LANGUAGE
- LANGUAGE LATERALIZATION
- Knowing which hemisphere is dominant for language is useful in interpreting results of other tests
- see pg 123 for more details
Describe the WISCONSIN CARD SORTING TEST
- **Evaluates patient’s ability to remember that previously learned rules of behaviour are no longer effect & to learn to respond to new rules
- Sort cards based on diff rules each time (ie. by colour, shape, etc.)
- Patients w/ damage to frontal lobes cont. to sort on basis of 1 sorting principle
- Difficulty learning & remembering that previously appropriate guidelines for effective behaviour are no longer appropriate
Describe the PAIRED-IMAGE SUBTRACTION TECHNIQUE
- Use of PET of fMRI to locate constituent cognitive processes in brain by prod an image of the diff in brain activity ass w/ 2 cognitive tests that differ WRT a single constituent cognitive process
- Involves obtaining functional brain images during several diff cognitive tasks
- Brain activity ass w/ that process estimated by subtracting the activity in the image ass w/ one of the 2 tasks from the activity in the image ass w/ the other
- see pg 125 for more details
Define DEFAULT MODE
- Pattern of brain activity present when person sits quietly & lets their mind wander
Define DEFAULT MODE NETWORK & the structures that are a part of it (4)
- Network of brain structures active when brain in default mode
- Comprised of many structures incl. 4 cortical areas:
1. Medial parental cortex
2. Lateral parental cortex
3. Medial prefrontal cortex
4. Lateral temporal cortex
Explain what a MEAN DIFFERENCE IMAGE is.
- Mean = averaged
- DIFFERENCE IMAGE = In context of functional neuro-imaging, the average of the difference images (obtained via paired-image subtraction) obtained from multiple participants
- Averaging can lead to a problem:
- -> If 2 ppl had specific but diff patterns of cortical activity, the average image derived would reveal little about either
