Wk 3 - Methodology Flashcards
Eight methods for visualising/stimulating the brain
Contrast x-rays X-ray computed tomography (CaT) Positron Emission Tomography (PET) Magnetic Resonance Imaging fMRI Paired image subtraction method Transcranial magnetic stimulation Magnetoencephalography (MEG)
Five methods for recording psychophysiological activity
Electroencephalography (EEG) Electromyography (EMG) Electroculography (EOG) Skin conductance Cardiovascular activity (through electrocardiogram, blood pressure etc)
Seven invasive methods for studying brain activity
Stereotaxic surgery Lesioning Invasive electrophysiological methods Pharmacological methods Chemical lesions Measuring chemical activity Genetic studies/engineering
Three behavioural methods of biopsychology
Neuropsychological testing
Language lateralisation
Secondary tests of frontal lobe function
Contrast x-rays - function (x1) plus dis/advantages (x1)
Shows abnormalities of blood vessels, eg tumors, blockages
Good for medical diagnosis, but not brain function
X-ray computed tomography (CaT scan) - function (x1) plus dis/advantages (x2)
Computer creates 3D image from many slices
Higher spatial res than x-ray,
Doesn’t tell which regions are active
Positron Emission Tomography (PET) - involves (x1), which gives (x1) plus dis/advantages (x4)
Inject or inhale a radioactive isotope
Gives correlational evidence - brain activity associated with particular input
Very expensive = uncommon, creation of own isotopes, invasive, side-effects
Magnetic resonance imaging… (x1) - plus method (x2), plus dis/advantages (x1)
Detects waves emitted from hydrogen atoms in magnetic field, which lines up atoms in row
Magnet pulses on and off, atoms snap in and out of alignment
Imaging detects waves produced as they fall out of alignment
Can see brain during processes
fMRI relies on the fact that... (x1) - the ??? signal (x1) Plus advantages (x4) and disadvantages (x1)
Oxygenated blood has magnetic properties
BOLD signal: Blood Oxygen Level Dependent signal.
Advantages:
Gives anatomical info, which PET doesn’t
Very high spatial res – about 1mm cubes
Non-invasive
Structural/functional info in same image.
Disadvantages:
Temporal res – due to blood taking time to move around, even though brain activates more quickly. Maybe 1-1.5 second lag/uncertainty
Paired image subtraction method (x1), plus dis/advantages (x2)
Taking aggregate of bunch of people
Increase confidence in results
Still correlational, not causal…
Transcranial magnetic stimulation entails… (x2)
Plus dis/advantages (x1)
Single magnetic pulses applied locations on scalp at specific times during task; or repetitively prior to task (rTMS/“virtual lesioning”) disrupts activity
Cognitive/behavioural consequences then observed.
Permits causal inference about specific brain region for given task - adjunct to PET/fMRI.
Magnetoencephalography (MEG) (x1)
Plus dis/advantages (x2)
Detects tiny magnetic fields on surface of scalp, generated perpendicular to electrical current going down a wire
Recording through tissue trashes spatial res – very good temporal
But, combine fMRI scan while doing task to get location
Electroencephalography (EEG) functions to… (x1)
By… (x1)
Plus dis/advantages (x2)
Records all brain activity at particular time –
Taking aggregate info, average over many trials, identify wave patterns that emerge
Not very accurate - maybe used within fMRI scanner = structural data too
Electromyography (EMG) (x2)
Recording signal from specific muscles - the action potential spikes associated with muscle activity
Integrated EMG signal smoothes data, gives clearer view of timing of events
Electrooculography (EOG) (x2)
Monitors specific contractions of six eye muscles
Can tell where eye is moving, eg left and right by recording lateral and medial rectus muscle
Skin conductance is… (x2)
Plus 2 measurements
Primary method in fear conditioning, phobias etc
As often changes in response to emotional stimuli.
SCL: the skin conductance level (baseline)
SCR: the skin conductance response, the change in skin conductance in response to a stimulus.
Stereotaxic surgery involves… (x4)
Recording/stimulating device in target region of brain - precise manipulation of surgical devices
Need stereotaxic atlas - each page a thin coronal slice, labelled with coordinates, and
Stereotaxic device
Use bregma (last piece of skull to fuse) as landmark/starting point
Lesion methods are (x1)
Plus four types and dis/advantages
Removing/disabling portion of brain, observing resulting behaviour.
Aspiration – suck up a small piece of neural tissue. Adv - remove cell bodies, leave axons intact
Radio frequency – insert device that delivers microwave pulse. Destroys nearby tissue
Knife cuts – complement aspiration, cutting connections between cells, cut axons
Cryogenic blockade - reversible, very fine probe with refrigerant. Slows down neural activity. Similar to TMS
Cautions needed in interpreting effects of lesion methods (x4)
Lesions seldom administered 100% accurately
Effects on neighbouring tissue
Attributing functions of neighbouring tissue to target structure
Discounting the role of any remaining portions of the target tissue
Invasive electrophysiological recording methods (x2)
Electrodes placed next to each other in neuron, between them
Measure number of action potentials, or from population of neurons
Pharmacological methods for studying the brain aim to (x1), and involve… (x2)
Goal to increase/decrease the effects of particular neurotransmitters.
Drugs injected/fed to subject, often do not pass through blood brain barrier.
Use of stereotaxic device - guide cannula to deliver drug to target tissue.
Chemical lesions, general and 2 specific methods
Instead of removing target tissue, neurotoxic chemicals injected.
Kainic acid destroys cell bodies, leaves axons unaffected – similar to aspiration lesion
6 - hydroxydopamine taken up only by neurones that release norepinephrine or dopamine.
2-Deoxyglucose Technique is a method for… (x1)
Plus method (x2)
And dis/advantages (x2)
Measuring chemical activity in the brain
2-DG taken up by active neurons.
Sacrifice and brain sliced after engaging in target behaviour.
Regions with concentrations of 2-DG identified as responsible.
Only on animals, as have to kill them
Very fine res of regions involved in behaviour
Genetic method of measuring psych phenomena is.. (x1) Plus method (x3)
Twin studies
Monozygotic twins share 100% of their genotype, dizygotic 50%
Look at records for various disorders:
If monozygotic sample has higher concordance rate than dizygotic sample = heritability.
Genetic engineering method of measuring psych phenomena use… (x2)
Plus dis/advantages (x3)
Gene knockout techniques
Similar to lesion studies - knock out a specific gene and observe the consequence; infer a link.
Problems:
Behaviour often result of actions/interactions of several genes
Elimination of one gene often influences expression of others
Don’t forget about environmental determinants
Neuropsychological testing measures… (x1)
And involves which two initial stages?
Plus two egs of general tests
Psychological behaviours
Generally two stages:
Battery of general tests
Follow up of more specific tests guided by first.
General tests include:
IQ tests (with memory and language subtests)
Token test - a quick test of language ability.
Measuring language lateralisation is important for… (x1)
And involves… (x1)
Planning surgery, Eg surgery for epilepsy – removing structures but preserving vital functions
Sodium Amytal Test – an anaesthetic that shuts down the brain
Secondary tests of frontal lobe function are used to... (x1) Plus method (x4)
Follow up suspicion of frontal lobe damage
Card sorting task - Patient given a set of cards to sort.
Not told the rule, required to guess.
After sorting according to one rule, the examiner changes it.
Frontal lobe damaged patients exhibit perseparation – inability to adapt to new method of sorting
Psychophysical methods in ascending order of spatial resolution (x7)
Psychophysics ERP fMRI, PET, lesions Optical dyes Single unit
Psychophysical methods in ascending order of temporal resolution (x7)
Psychophysics on full spectrum (ms to days) Single unit (ms+) ERP, Optical dyes fMRI PET Lesions
Precision is.. (x3)
The consistency of response
How close together the darts are on the board
The SD
Accuracy is… (x3)
How close to objective target you are
How near the bulls-eye you get, on average
The mean
The standard stimulus is… (x1)
That to which you judge or adjust the comparison stimulus to
The comparison stimulus is… (x1)
The set judged relative to the standard stimulus
The point of objective equality (POE) is… (x1)
The point at which the comparison stimulus physically equals the standard
The point of subjective equality (PSE) is… (x1)
The point at which the comparison stimulus is judged to be equal to the standard (by the Ps)
The interval of uncertainty is… (x2)
The range of values within which the comparison stimulus cannot be reliably judged as different from the standard
JND x 2
The just noticeable difference is… (x1)
The smallest difference between stimuli that can be discriminated 50% of the time
Constant error is… (x1)
A systematic error of judging the POE and PSE significantly smaller/larger than each other
Variable error is… (x3)
Unsystematic errors in judgement
Relates to JND
Large = low precision, small = high
Weber’s Law states that… (x2)
The magnitude of the JND is a constant proportion of the stimulus intensity
JND = K (Weber fraction) x S (size of standard stimulus) + C (constant)
