Neuroscience Research Methods (3b) Flashcards
electroencephalography (EEG)
- measures gross electrical brain activity
- good temporal resolution
- weak spatial resolution
- various waveform frequencies are associated with different levels of arousal/ sleep
- event related potential (ERP) or frequency analysis methods are often sued to ink EEG activity to cognitive function
advantages of ERP techniques
non-invasive
direction reflection of neuronal activity
good temporal resolution
disadvantages of ERP techniques
- poor spatial resolution due to recording made at the scalp
- ERPs are small - need many trials per condition to differentiate signal from noise
- eyes need to remain still during ERP recording
how do structural MRI scans work
- a strong magnetic field (1.5-7 Tesla) causes hydrogen atoms to align in the same orientation
- when a radio frequency pulse is passed through the head, atomic nuclei emit electromagnetic energy
- the scanner is turned to detect radiation emitted from the hydrogen molecules
- computer reconstructs image using FFT modelling techniques allowing the construction of brain images in multiple planes
- different types of tissue produce different RF signals
DTI
diffusion tensor imaging
diffusion tensor imaging (DTI)
- reveals fibre tracts
- measures movement of water molecules (diffusion)
- molecules movement is constrained to travel along white matter pathways
- molecule movement is more random elsewhere in the brain
advantages of fMRI
good spatial resolution
non invasive
combines functional/ structural information
disadvantages of fMRI
limited temporal resolution
correlational method
noisy and claustrophobic
no metal in scanner
TMS
transcranial magnetic stimulation
how does TMS work?
- electrical induction
- faraday principle (an electric current passed through one coil induces a current in a nearby coil)
how do you measure the strength of the TMS pulse intensity?
relative to maximum output
relative to the (cortico) motor threshold
application of TMS
parkinson’s disease
depression
schizophrenia
stroke recovery
advantages of TMS
- non-invasive
- allows causal inferencing
- allows the creation of ‘virtual lesions’ or the ‘excitation’ of brain areas
what does spatial accuracy depend on in TMS
experimental procedure
what are neuroscience techniques sorted by
spatial resolution
temporal resolution
correlational method
causal method
what is typically used for ERP research
IAPs
valence effects
are there ERP differences between positive (pleasant) and negative (unpleasant) pictures?
early posterior negativity
frontocentral negative
temporo-occipital positive ERP
more negative waveform from 200 ms until stimulus offset for more arousing stimuli
function of early posterior negativity
automatic attention processes (maybe subconscious)
late positive potential
- ERP arousal effect is consistent but amplitude can vary depending on task relevance
- ERP arousal effects can be inhibited by emotional reappraisal and task instruction
function of late positive potential
motivation and selective attention for memory encoding and storage
what is the rule of thumb of valence effects
processed very early (100-300ms) and there is a negativity bias
when are arousal effects processed?
later than valence effects but they stay fro longer (200-300 ms onwards)
what are late potentials modulated by
emotional regulation
what do verbal and pictorial stimuli induce and reveal? (Schlochtermeier et al., 2013)
induce emotions
reveal the involvement of a network of brain areas including limbic and para-limbic regions
pictorial superiority effect
pictorial stimuli induce stronger emotional responses than words
why is there a pictorial superiority effect?
- have a faster an more direct access to meaning (words requires additional translational activity)
what was Schlochtermeier et al. (2013) study?
160 positive and neutral concrete objects were presented as stimuli - half as words and pictograms / half as phrases and photos
behavioural results from Schlochtermeier et al., (2013) study
- no RT differences between valence judgements for pictorial and word materials
- no RT differences between positive and neutral materials
- valence ratings: positive > neutral
imaging results from Schlochtermeier et al., (2013) study
- both modalities activated the same emotion network - no picture superiority effect
- network activation for pictures less strong and widespread than for words
- complexity effect only found for pictures
