Methods in Cognitive Neuroscience

Question 1

Cognitive Neuroscience

Answer 1

provides a brain based account of cognitive processes e.g. thinking, perceiving, remembering etc.

Question 2

how was cognitive neuroscience made possible

Answer 2

by technological advances in studying the brain that are safer than Penfield’s method

Question 3

what did cognitive psychology provide

Answer 3

experimental paradigms and theoretical framework

Question 4

Dehaene et al. 2001

Answer 4

compared reaction times with fMRIs
- reaction time faster to second word when it follows the same word (that is previously shown so quick it is not consciously perceived)
- left fusiform cortex has less activation if same word
- processing for word has already happened earlier hence faster and less activation

Question 5

Methods of Behavioral Neuroscience

Answer 5

Question 6

advantages and disadvantages of methods in Cognitive Neuroscience - Spatial and Temporal resolution

Answer 6

temporal - the accuracy of measuring when an event is occurring

spatial - the accuracy of measuring where an event is occurring

Question 7

Single-cell recording

Answer 7

• electrophysiological technique
• spatial resolution at neuron level as measuring directly from neuron
• records electrical activity

Question 8

how are single cell recordings done

Answer 8

• electrode implanted into axon: intracellular
  AND/OR
• electrode implanted outside axon membrane: extracellular
• records neural activity from a population of neurons
• normally in animals e.g. monkey

Question 9

EEG

Answer 9

• measures electrical activity of brain through recording electrodes attached to the scalp
• electrical signal from large number of neurons
• often in humans

Question 10

what do EEG signals represent

Answer 10

the change in the potential difference between two electrodes placed on the scalp in time

Question 11

what are ERPs

Answer 11

• event related potentials
• average of EEGs over trials
• voltage fluctuations that are associated in time with particular event e.g. visual stimuli
• tell us about timing

Question 12

using ERP to study face recognition

Answer 12

• different ERP peaks associated with different aspects of face processing
• N170
• N250
• P400-600

Question 13

N170

Answer 13

perceptual encoding of the face / recognizing it is a face
- recording from right posterior superior temporal sulcus

Question 14

P300

Answer 14

famous and familiar faces

Question 15

N250

Answer 15

identity processing
- affected by familiarity

Question 16

P400-600

Answer 16

person recognition (faces and names)
- affected by faces and names

Question 17

ERPs in Alzheimer’s disease

Answer 17

• reduced P300 for dementia patients
• shows how ERPs can be used as biomarkers for diseases

Question 18

MEG

Answer 18

• magnetoencephalography
• measures magnetic fields produced by electrical activity in the brain via extremely sensitive devices know as SQUIDs
• high temporal and spatial resolution

Question 19

what does neuronal activity generate

Answer 19

electrical and magnetic field that can be measured invasively (single cell) and non-noninvasively (EEG, MEG)

Question 20

what do single cell studies tell us

Answer 20

how neurons code information by measuring their response to external stimuli

Question 21

what can electric field produced by neurons be measured by

Answer 21

EEG

Question 22

MRI

Answer 22

• magnetic resonance imaging
• uses magnetic properties of tissue and blood to produce images of the brain

Question 23

Structural imaging

Answer 23

different tissues have different physical properties so can be used to create STATIC maps
- CT and MRI

Question 24

functional imaging

Answer 24

temporary changes in brain physiology associated with cognitive processing
- PET and fMRI

Question 25

PET

Answer 25

positron emission tomography - measures local blood flow (rCBF) - radioactive tracer injected into blood stream - tracer peaks after 30s - when material undergoes radioactive decay, positron emitted is picked up by detector - high radioactivity = high brain activity based on BLOOD VOLUME - neurochemical changes

Question 26

fMRI

Answer 26

- directly measures concentration of deoxyhemoglobin in the blood - BOLD response (Blood Oxygen Level Dependent contrast) - hemodynamic response function - behavioural aspects - limited temporal

Question 27

what is the change in BOLD response over time called

Answer 27

hemodynamic response function - peaks in 6-8s

Question 28

what do we normally study with fMRI

Answer 28

correlation between brain activity and stimulus timings - produce activation maps showing which parts are involved in mental processes

Question 29

how is activity measured in fMRI

Answer 29

- in voxels or volume pixels (smallest box shaped part in 3D image)

Question 30

when we say a brain region is active we mean...

Answer 30

it shows a greater response in one condition relative to the other - normally have a baseline

Question 31

cognitive subtraction

Answer 31

activity in a control task is subtracted from the activity in an experimental task (only problem is baseline task may result in different areas of activation)

Question 32

Disagreements between imaging and lesion studies

Answer 32

- lesion suggests it is more central to the task/ critical - imaging implies it is used in a given task or not used - evidence from semantic processing and semantic dementia patient (lose meaning of words and objects etc) who have degeneration of temporal lobes - imaging: left inferior frontal gyrus - lesions: left anterior temporal gyrus - inconsitent data...

Question 33

Devlin et al.

Answer 33

- compared imaging methods in semantic task - PET scans, found activation in temporal area - fMRI may not pick up activation in temporal lobe - important to keep discovering methods

Question 34

DTI

Answer 34

diffusion tensor imaging - modified MRI scanner to show bundles of axons in the living brain

Question 35

what does DTI measure

Answer 35

- measures white matter organization based on limited diffusion of water molecules in axons - allows us to visualise connections in the brain

Question 36

fNIRS | what does it measure

Answer 36

- functional neaer-infrared spectroscopy - measures the same BOLD responses as fMRI but in a different way - portable and more tolerant of head movement - can't image deep structures

Question 37

fNIRS | how does it measure

Answer 37

'light' in infrared range passes through skull and scalp but is scattered differently by oxy- v. deoxyhemoglobin

Question 38

iEEG or ECoG

Answer 38

- intracranial electroencephalography - high resolution in place and time - record directly from insde the brain in neurosurgery - used to locate a seizure and map function

Question 39

where does an iEEG record from

Answer 39

the cortical surface

Question 40

Why does an EEG signal need to be averaged over many trials to generate an ERP ?

Answer 40

EEG has low signal-to-noide ratio

Question 41

what does the term P300 refer to ?

Answer 41

a positive peak around 300 msec

Question 42

what does BOLD stand for ?

Answer 42

Blood Oxygen Level Dependent Contrast