Psychophysiological Methods Flashcards
1
Q
METHODS LIST
A
- structural/functional Magnetic Resonance (MRI/fMRI)
- Positron Emission Tomography (PET)
- Transcranial Magnetic Stimulation (TMS)
- Transcranial Direct Current Stimulation (TDCS)
- Electroencephalography (EEG) & Event-Related Potentials (ERPs)
- eye-tracking
- pupillometry
- microelectrode recordings
- Galvanic Skin Response measurements
- cardiac measurements (ie. heart-rate)
- Electromyography (EMG)
2
Q
MOST WIDELY USED METHODS
A
- structural/functional Magnetic Resonance (MRI/fMRI)
- Transcranial Magnetic Stimulation (TMS)
- Electroencephalography (EEG) & Event-Related Potentials (ERPs)
- eye-tracking
3
Q
MAGNETIC RESONANCE: BASICS
A
- magnetic resonance imagining (MRI) = based on measurement of magnetic resonance (MR) signal
- when magnetic field that changes over time w/rate of radio waves (radio frequency aka. RF) is applied to hydrogen atoms -> respond/resonate w/measurable magnetic signal
- aka. magnetic resonance (MR) signal
4
Q
STRUCTURAL MAGNETIC RESONANCE IMAGING
A
- MR images are obtained via measuring MR signal from hydrogen atoms in brain
- ie. images depend on hydrogen amount/density aka. ^ hydrogen = brighter brain areas
- used by psychologists for for comparing brain structure in individual groups (ie. healthy individuals VS people suffering from psychiatric disorders)/examining brain structure changes as function of experience/training/psychological interventions
5
Q
FUNCTIONAL MAGNETIC RESONANCE IMAGING (FMRI)
A
- MRI can also examine brain activity
- O2 = transported to cells via hemoglobin molecule (oxygehemoglobin aka. Oxy-Hb)
- transfer of O2 to cells transforms oxyhemoglobin -> deoxygenated hemoglobin (deoxyhemoglobin aka. deoxy-Hb)
- oxyhemoglobin doesn’t significantly alter MR signal; deoxyhemoglobin does aka. reduces signal
- ^ active brain areas receive ^ oxygenated blood than they use aka. contain less deoxygenated hemoglobin; deoxygenated hemoglobin reduces MRI signal in such areas less aka. there’s more MRI signal coming from such brain areas
- hence BOLD fMRI = ^ sensitive to blood flow-rated oxygen supply to this area > oxygen consumption in active area
- AKA. BOLD fMRI = sensitive to difs in blood flow into active area
6
Q
FMRI: REVERSE INFERENCE
A
- scientific interpretation most commonly used by psychologists on basis of fMRI data
- ie. effectiveness of acupuncture compared brain activity w/ VS w/o acupuncture in people w/chronic pain; found reduced brain activity (blood flow) in brain area set in acupuncture presence
- areas were previously found activated in studies modulating pain perception
- conclusion: reduced activation in said regions = objective evidence that pps felt less pain during acupuncture
7
Q
REVERSE INFERENCE LOGIC
A
- more general reverse inference: if changes in activation in given brain area = specifically associated w/psychological process then changes in activation point to involvement/modulation of hypothesised psychological process
- how credible/valid it is depends on if given brain activity patter is also associated w/other psychological processes (specificity)
- if brain area = activated by multiple psychological process types then activation cannot be taken as evidence of involvement in specific psychological process
- researchers who make reverse inferences need to provide detailed info on both sensitivity/specificity BUT oft don’t
8
Q
BOLD FMRI: LIMITS
A
- blood flow changes associated w/neuronal activity = slow aka. BOLD response to brief stimulus to which pp responds in 1s = 16s
- aka. fMRI temporal resolution = relatively low (cannot distinguish activations in response to stimuli at interval <3s)
- scanner = v noisy aka. harder to use auditory stimuli/record vocal responses; one needs to pause scanning while auditory stimulus is presented/while pp is making response aka. “sparse imaging”
- space in scanner = tight aka. not suitable for individuals w/claustrophobia
9
Q
ELECTROENCEPHALOPGRAPHY (EEG)
A
- change in voltage (electricity) recorded from sensors on scalp
- can extract state of brain (ie. sleep) via EEG frequencies
- EEG segments associated w/particular stimuli can be analysed separately aka. event-related potentials (EPRs)
10
Q
FREQUENCY
A
- oscillation number per unit of time (ie. x4 p/second = 4Hz)
- EEG has complex frequency patterns
11
Q
EEG: SLEEP
A
AWAKE & STAGES 1-4 SLEEP
- gradual slowing of EEG (lower frequencies) as sleep becomes deeper
REM SLEEP
- fast (awake-like) EEG seen in Rapid Eye Movement sleep during which most vividly recalled dreams are believed to occur
12
Q
EVENT-RELATED POTENTIALS (ERPs)
A
- segments of EEG
- time-locked to particular events stimuli
- dif types of stimuli are separately averaged then compared
13
Q
ERP: LEXICAL DECISION TASK
A
- pps presented w/words (ie. TALL/readable strings (not words)/non-words ie. TOLB)
- asked to respond w/1 keypress if stimulus = word & with another if it’s not
- words start to diverge from non-words at 250ms; clearly dif by 400ms
14
Q
EEG: EVALUATION
A
- EEG/ERP has very high temporal resolution aka. it can provide detailed temporal info about processing of stimulus
- relatively cheap/accessible compared to fMRI
- BUT has limited spatial resolution aka. it can’t localise activity in brain w/precision/confidence due to complexity of the inverse problem
15
Q
EEG: THE INVERSE PROBLEM
A
- inferring cortical generators from known scalp potentials
- solution = highly uncertain
- mathematically there is an infinity of cortical current distributions that could result in 1 scalp distribution
