methods in cognitive neuroscience

Question 1

Dahaene et al (2004) - priming

Answer 1

Priming = faster if experienced before
lexical decision task = if shown word before for a short time - processed faster than if a different word
occipital junction activated less if word seen previously

Question 2

what to use when answering a ‘when’ question

Answer 2

temporal
human - MEG or ERP
animal - multi-unit and single cell recordings

Question 3

what to use when answering a ‘where’ question

Answer 3

spatial

fMRI

Question 4

single cell recording

Answer 4

• electrophysiological technique
• record from population of neurons
• small electrode inserted into axon (intracellular) or outside axon (extracellular)
• brain has no pain receptors in brain so can be done in awake animals
• can’t do in humans - too invasive
• records brain cell activity - electrical potential
• useful for mapping visual system

Question 5

EEG

Answer 5

• Electoencephalography
• measurement of electrical activity by placing recording electrodes on the scalp
• traces represent electrical signal from a large number of neurons
• electrodes labelled
• signals represent change in potential difference between 2 electrodes in time

Question 6

electrode labels

Answer 6

X = frontal
O = occipital
C = central
P = parietal

Question 7

ERP

Answer 7

• event related potential

- the EEG can be averaged together and time locked to a stimulus

Question 8

N170, N250, P300, P400-P600

Answer 8

N170 - specialised for faces (right posterior superior temporal sulcus)
N250 - know if you recognise
P300 - famous/familiar faces
P400-P600 - know whether can retrieve name

Question 9

biomarker of AD

Answer 9

low P300

Question 10

MEG

Answer 10

• magnetoenphalography
• used to measure magnetic fields produced by electrical activity in the brain
• done via extremely sensitive devices - SQUIDS
• very expensive
• not used regularly (no new paradigms)

Question 11

MRI

Answer 11

• (magnetic resonance imaging)

- used differential magnetic properties of types of tissue and blood to create image of the brain

Question 12

structural imaging

Answer 12

• different types of tissue have different physical properties
• used to create static maps
• e.g., CT and structural MRI

Question 13

functional imaging

Answer 13

• temporary changes in the brain physiology associated with cognitive processing
• e.g., PET and fMRI

Question 14

PET

Answer 14

• positron emission tomography
• measures local blood flow
• radioactive tracer injected into bloodstream
• takes up to 30s to decay and peak
• releases a positron which is picked up by detector

Question 15

DTI

Answer 15

• Diffusion Tensor imaging
• uses modified MRI scanner
• reveals bundles of axons in living brain
• measures white matter organisation based on limited diffusion of water molecules into axons
• can visualise connections in brain

Question 16

fNIRS

Answer 16

• functional near-infrared spectroscopy
• measures BOLD responses
• oxygenated and deoxygenated blood scatter light differently
• portable
• tolerant of head movement
• can’t image deep structures
• more naturalistic - can look at how 2 people cooperate

Question 17

iEEG or ECoG

Answer 17

• Intracranial electro-encephalography
• only method to give high spatial and temporal resolution
• record from inside human brain when patients undergo epilepsy surgery
• insert grid of electrodes into brain
• pinpoint location of epilepsy and avoid important areas

Question 18

iEEG and ECoG - Mirror neurons and facial recognition

Answer 18

Mirror neurons
- neurons in SMA and hippocampus respond to grasping and observing actions
face recognition
- if stimulate facial recognition - see faces in everything

Question 19

fMRI

Answer 19

• functional magnetic resonance imaging
• measures concentration of deoxyhemoglobin in blood
• oxygenated and deoxygenated blood have different magnetic qualities
• BOLD response
• can be used to produce activation maps showing which parts of the brain are involved in different processes
• measures activity in Voxels - volume pixels

Question 20

BOLD

Answer 20

blood oxygen level dependent contrast

Question 21

change in BOLD overtime

Answer 21

hemodynamic response-function

- peaks in 6-8s - limits temporal resolution of fMRI

Question 22

mirror neuron intention study

Answer 22

actions embedded in context and intention

• increase in posterior inferior frontal gyrus and ventral premotor cortex
• premotor mirror neurons - involved in understanding intensions of others

Question 23

cognitive subtraction

Answer 23

• experimental task - baseline/other task

- to infer functional visualisation/specialisation must compare relate differences