L1: Cognitive Neuroscience

Question 1

Dehaene et al 2004

Answer 1

• fMRI study carried out
• found that specific area of the brain activated
• if the brain exposed to the word for the first time its activation levels are greater then when exposed to same word again
• brain vs cognitive psychology findings

Question 2

Methods for looking at the brain

Answer 2

• Single unit recording
• Electroencephalography (EEG)
• Magnetoencephalography (MEG)
• Positron Emission Tomography (PET)
• Magnetic Resonance Imaging (MRI)
• Functional MRI – fMRI
• Diffusion Tensor Imaging – DTI

do we need to learn….
• Functional Near-Infrared Spectroscopy – fNIRS
• Intracranial electroencephalography (iEEG) - ECoG

Question 3

Electroencephalography (EEG):

Answer 3

measurements of electrical signals generated by the brain through electrodes placed on different points on the scalp.

(non-invasive)

• high temporal acuity

Question 3

Event-related potential (ERP)

Answer 3

the average amount of change in voltage at the scalp that is linked to the timing of particular cognitive events

Question 4

single-cell recordings

Answer 4

measure the responsiveness of a neuron to a given stimulus (in terms of action potentials per second)

(invasive method)

Question 5

how are single-cell recordings made:

Answer 5

intracellular recording: implanting a v small electrode into the neuron

extracellular recording: implanting a small electrode outside the membrane

Question 6

Magnetoenecephalography (MEG)

Answer 6

an imaging technique that measures magentic fields produced by electrical activity in the brain - using devices known as SQUIDs.

• good temporal AND spatial resolution and NON INVASIVE
• v expensive and lacks accessibility.

Question 7

rate coding:

Answer 7

the informational content of a neuron may be related to the number of APs per second

Question 8

temporal coding:

Answer 8

the synchrony of firing may be used by a population of neurons to code the same stimulus or event

Question 9

dipole

Answer 9

a pair of positive and negative electrical charges separated by a small distance.

Question 10

slowest to fasted EEG frequencies:

Answer 10

the EEG signal tends to oscillate at different rates

slowest to fastest:

1. delta
2. theta
3. alpha
4. beta

Question 10

slowest to fasted EEG frequencies:

Answer 10

the EEG signal tends to oscillate at different rates

slowest to fastest:

1. delta
2. theta
3. alpha
4. beta

Question 11

what do ERPs tell us:

Answer 11

variations in the ERPR waveform tell us about the TIMING and INDEPENDENCE of cognitive processes.

Question 12

structural versus functional imaging

Answer 12

structural: different types of tissue (skull, gray matter, CSF fluid) have different physical properties used to create STATIC maps (CT and structural MRI)

Functional: based on the assumption that temporary neural activity produces local physiological changes in that region of the brain. (PET and fMRI)

Question 13

Positon Emission Therapy (PET)

Answer 13

• measures local blood flow (rCBF)
• radioactive tracer injected into blood stream
• areas with high radioactivity - associated with high brain activity - based on blood volume
• more red in image = more blood flow.

Question 14

fMRI

Answer 14

• directly measures conc of deoxyhaemoglobin in the blood
• this is called blood oxygen level dependent contact (BOLD response)
• the change in BOLD response over time is called the haemodynamic response function
• the haemodynamic response function peaks in 6-8s - limiting the temporal resolution of fMRI.

Question 15

difference between fMRI and PET

Answer 15

• PET measures the change in blood flow to a region directly
• fMRI measures the richness of the blood in oxygen

both are haemodynamic methods though

Question 16

voxel-based morphometry (VBM)

Answer 16

• a technique for segregating and measuring differences in white matter and gray matter concentration

Question 17

diffusion tensor imaging (DTI)

Answer 17

• uses MRI to measure white matter connectivity between brain regions

Question 18

voxel

Answer 18

a volume-based unit in imaging research the brain is divided into many thousands of these.

Question 19

cognitive subtraction

Answer 19

• an activity in a control task is subtracted from the activity in an experimental task

Question 20

functional near-infrared spectroscopy (fNIRS)

Answer 20

• measures same BOLD response
• but in a different way - light in the infrared range passes through skull and scalp but is scattered differently by oxy- v. desoxyhaemoglobin
• cant image deep pictures but is portable and more tolerant to head movements

Question 21

intracranical EEG or ECoG