1: Introduction and Research Methods Flashcards
give 3 examples of cognitive processes
thinking, perceiving, remembering
how does cognitive neuroscience add to our understanding of cognition
provides a brain based account of cognitive processes
what are the limitations of cognitive neuroscience’s explanatory power?
Cognitive neuroscience tests psychological theories but local blood oxygen and RTs are just data, they do not tell us HOW things happen
what does EEG stand for?
Electroencephalography
what does MEG stand for?
Magnetoencephalography
what does PET stand for?
Positron Emission Tomography
what does fMRI stand for?
Functional Magnetic Resonance Imaging
what does DTI stand for?
Diffusion Tensor Imaging
what does fNIRS stand for?
Functional Near-Infrared Spectroscopy
what does iEEG stand for?
Intracranial electroencephalography
what does TMS stand for?
Transcranial magnetic stimulation
what does TES stand for?
Transcranial electrical stimulation
what does tACS stand for?
Transcranial alternating current stimulation
what does tDCS stand for?
Transcranial direct current stimulation
what are two invasive methods in cognitive neuroscience?
single-cell recording & PET
which 2 methods use the electrical properties of the brain?
EEG & single-cell recordings
which neuroscience measure uses the electromagnetic part of the brain?
TMS
which neuroscience measure uses the brain’s magnetic properties?
MEG
which 2 neuroscience methods rely on the brain’s hemodynamic properties?
PET & fMRI
which neuroscience measure looks at activity on the neuron level?
single-cell recording & multi-unit recording
how do electrophysiological techniques (eg single-cell recording) work?
Very small electrode implanted into axon (intracellular) or outside axon membrane (extracellular)
Records neural activity from population of neurons
Electrodes, consisting of thin wires, are implanted into specific areas of the brain. Recordings of brain cell activities are made by measuring the electrical potential of nearby neurons that are in close proximity to the electrode.
how does EEG work?
The measurement of the electrical activity of the brain by recording from electrodes placed on the scalp.
EEG signals represent the change in the potential difference between two electrodes placed on the scalp in time
The EEG obtained on several trials can be averaged together time locked to the stimulus to form an event-related potential (ERP) - individual reading have too much noise
ERPs are voltage fluctuations that are associated in time with particular event (visual, auditory, olfactory stimuli)
what would be the EEG code for a point on the brain on the occipital lobe?
O then a number
what role does a reference electrode play in EEG?
Reference electrode goes down the centre of the head and is used to compare the difference between areas and the centre
which ERP peak is associated with distinguishing a face from other stimuli?
N170
what does ERP stand for?
event-related potential
which ERP peak is associated with recognising familiar and famous faces?
P300
which ERP peak is associated with recognising what a face is?
N250
what range of ERP peak is associated with recognising exactly who someone is?
P400-600
how is the N170 ERP peak influenced?
perceptual change to image
how is the N250 ERP peak influenced?
familiarity
how is the P400-600 ERP peak influenced?
faces and names
what part of the brain would P3 coincide with (EEG)?
parietal 3
what EEG differences do patients with dementia show compared to contols?
reduced P300 is seen for the demented patients at each electrode site - used for recognition of familiar/famous faces
how is the resolution for MEGs?
Excellent temporal and spatial resolution
what do single cell recordings tell us about the brain?
Single cells studies tell us how neurons code information, by measuring their response to external stimuli
how are electrical fields produced by neurons converted into an EEG?
when the electric field can be detected at the scalp (EEG). When many waves are averaged and linked to the onset of the stimulus, then an ERP is obtained
what does varying stimuli for EEG tell us about cognition?
The timing and independence of cognitive processes
what is the difference between structural & functional MRI?
structural: a static image
functional: measures temporary changes
what does fMRI directly measure?
concentration of deoxyhemoglobin in the blood -BOLD response (Blood Oxygen Level Dependent contrast)
what is the BOLD response over time called?
hemodynamic response function
what limits the temporal resolution of fMRI
Hemodynamic Response Function peaks in 6–8 seconds
what are voxels in fMRI?
measure of brain activity - volume pixels the smallest distinguishable box-shaped part in 3D image
what does it mean to day a brain area is ‘active’ (fMRI)
it shows a greater response in one condition relative to another
what is a cognitive subtraction (fMRI)
activity in a control task in subtracted from the activity in the experimental task
what is the difficulty with cognitive subtractions?
you must find an appropriately difficult & relevant control task to make the subtraction/ effect size valid.
what was the disharmony in results for dementia patients in lesions vs fMRI studies?
Lesion studies in semantic dementia patients found lesions in the temporal lobe, where the earlier fMRI study did not.
what can limit fMRI signal that is not found in PET scans?
air-filled sinuses block fMRI signal
how do fMRI & PET scans differ in their results for semantic tasks?
PET found activation in the temporal lobes, and also the frontal lobes that the fMRI did not
how does PET work?
Measures local blood flow (rCBF)
Radioactive tracer injected into blood stream (invasive)
When the material undergoes radioactive decay, a positron is emitted, which can be picked up by the detector
Areas of high radioactivity are associated with brain activity, based on blood volume
what limits the temporal resolution of PET?
Tracer takes up to 30 seconds to peak
how does DTI work?
An imaging method that uses a modified MRI scanner to reveal bundles of axons in the living brain
Measures white matter organisation based on limited diffusion of water molecules in axons
what does DTI show us?
We can visualise connections in the brain
how does fNIRS work?
Measures the same BOLD response as fMRI but in a completely different way
‘Light’ in infrared range passes through skull and scalp but is scattered differently by oxy- v. deoxyhemoglobin
how does fNIRS compare to fMRI in practicality?
Portable and more tolerant of head movement but can’t image deep structures
what are the advantages of iEEG/ECoG
The only method that gives us the high resolution in both place and time is intracranial recording
when is iEEG used?
when we record directly from inside the human brain, when people are undergoing neurosurgery
why are iEEGs placed on the brain?
They are placed to locate the seizure and map function (for neurosurgery purposes)
where does iEEG/ECoG measure from?
straight from the cortical surface
what parts of the brain are activated by a hand grasping task?
neurons in supplementary motor area (SMA), and hippocampus
is single cell recording used on humans?
no
