Methods of Cognitive Neuroscience

Question 1

What are the differences between cognitive psychology and cognitive neuroscience?

Answer 1

Cognitive psychology explores mental processes and representations, while cognitive neuroscience delves into how and where these processes occur in the brain

Question 2

What is a mental representation?

Answer 2

Anything that ‘means’ something to the individual e.g. the concept of a ‘tree’

Question 3

How are mental processes and mental representation linked?

Answer 3

1. Your eyes process the incoming light (e.g. of a tree),
2. Your visual system processes the information (i.e. a basic mental process takes place)
3. You see the tree (one form of a mental representation).
4. Seeing the tree triggers a mental process (e.g. ‘avoid’ if you drive a car).

Question 4

What happened in Posner’s Letter Matching Task?

Answer 4

Posner’s letter matching task measures reaction times to letters displayed on a monitor, which can be the same or different. In this version of the task, the subject responds “same” when both letters are either vowels or consonants and “different” when they are from different categories.

Question 5

Posner’s letter matching task utilised Chronometry. What is Chronometry?

Answer 5

Chronometry is the process of using time measures (reaction times) to infer the workings of the brain.

Question 6

What did Posner say the different reaction times in his task indicate?

Answer 6

He said that the different reaction times indicate the degree of processing required for each task

Reaction times increase with task complexity and time delay

Question 7

In Posner’s task, what was the order of activity representations?

Answer 7

1. Stimulus identity representations activate first (AA)
2. Phonetic identity representations second (Aa)
3. Categorizations are activated last (AS).

Question 8

What is different in Version 2 of Posner’s task, and how is it defined?

Answer 8

Version 2 of the task is the same, but with an interval (stimulus onset asynchrony) separating the presentation of the two letters.

Question 9

How does reaction time change in Posner’s task as the stimulus onset asynchrony gets longer?

Answer 9

He found that the reaction time changes as the stimulus onset asynchrony gets longer.

Question 10

What happens to the difference in reaction time to physical identity and phonetic identity as time goes on in Posner’s task?

Answer 10

As time goes on, the difference in reaction time to physical identity and phonetic identity becomes smaller, suggesting a transformation of the representation of abstract code

Question 11

What happened in the mental comparison task?

Answer 11

Subjects memorize sets of letters and later determine if a probe letter was in the memory set

Question 12

What are the four hypothesised stages of the memory comparison task?

Answer 12

1. Encode
2. Compare
3. Decide
4. Respond

Question 13

What were the findings from the memory comparison task?

Answer 13

Reaction times increased with the size of the memory set.
Suggesting comparisons are done sequentially, not in parallel

Question 14

Experimental Techniques

What do single cell recordings do and how are they used?

Answer 14

• Record action potentials in the brain.
• Used mainly in animals but sometimes in humans during medical procedures (epilepsy of the medical temporal lobe (MTL))

Question 15

What do the results of single cell recordings tell us?

Answer 15

Help researchers understand how individual cells respond to specific stimuli

Question 16

Define: Receptive Field

Answer 16

The location in the visual space a cell represents.
Different cells have different receptive fields and together they tile the entire visual field.

Question 17

Define: Retinotopy

Answer 17

Spatial arrangement of cells on the retina. Cells with similar functions are often clustered together.

Question 18

Neurology

What does neurology primarily focus on?

Answer 18

Neurology primarily deals with degenerative and infectious disorders of the central nervous system (CNS)

Question 19

Name 5 disorders that can result in brain damage according to neurology

Answer 19

1. Traumatic Brain Injury (TBI):
   Physical injury to the head or brain caused by accidents, falls, or blunt force. Can result in various degrees of brain damage depending on the severity of the injury.
2. Stroke: Occurs when the blood supply to the brain is disrupted, either due to a blockage (ischemic stroke) or bleeding (hemorrhagic stroke). Lack of oxygen and nutrients can lead to damage in the affected brain tissue.
3. Alzheimer’s Disease: A progressive neurodegenerative disorder affecting memory, cognitive function, and behavior. Results in the gradual loss of brain cells, leading to widespread brain damage over time.
4. Brain Tumors: Abnormal growth of cells in the brain. Tumors can compress or invade surrounding brain tissue, causing damage.
5. Neurological Disorders: Various disorders like Parkinson’s disease, Huntington’s disease, and multiple sclerosis. These disorders can result in progressive damage to specific regions of the brain.

Question 20

Define: Traumatic Brain Injury

Answer 20

A form of brain injury resulting from and accident such as a driving accident, bullet wound or blast injury.
The damage in TBI is usually diffuse, with both grey and white matter tracts affected.

Question 21

What are some examples of methods commonly used in neurology?

Answer 21

Common methods used in neurology include the electroencephalogram (EEG) and electrophysiological recordings.

Question 22

Electroencephalogram (EEG)

Answer 22

A technique to measure the electrical activity of the brain. In EEG, surface recordings are made from electrodes placed on the scalp. The EEG signals includes endogenous changes in electrical activity (e.g. due to changes in arousal), as well as changes triggered by specific events (e.g. stimuli or movements).

Question 23

Event related potential (ERP)

Answer 23

• A change in electrical activity that is time-locked to specific events, such as the presentation of a stimulus or the onset of a response, embedded within an EEG recording.
• When the events are repeated many times, averaging the EEG signals reveals the relatively small changes in neural activity triggered by these events.
• In this manner, the background fluctuations are removed, revealing the event-related signal with great temporal resolution

Question 24

Define: Functional Neurosurgery and provide some modern day examples

Answer 24

Altering brain activity using methods like ablation (removal), electrical stimulation, or pharmacological interventions to improve patient function.

Examples:
Movement disorders (e.g. Parkinsons, deep brain stimulation)
Psychiatric Disorders (depression, obsessive compulsive)
Chronic Pain
Epilepsy - uncontrolled seizures
Brain Tumours

Question 25

Single Dissociation

Answer 25

The patient group shows impairment on one task but not on the other

Question 26

Double Dissociation

Answer 26

One patient group shows impairment on one task and a second patient group shows impairment on the other task.
Double dissociations provide much stronger evidence for selective impairment

Question 27

Define: Optogenetics and give an example

Answer 27

A procedure (used in animals) in which genes are manipulated to express a photosensitive protein, which when exposed to light will activate the neuron. The genetic manipulation can be modified such that the protein expression is limited to particular neural regions.

Study - controlling fear in mice

Question 28

Transcranial Magnetic Stimulation (TMS)

Answer 28

A non-invasive method used to stimulate neurons in the human brain. A strong electrical current is rapidly generated in a coil placed over a targeted region. This current generates a magnetic field that causes the neurons in the underlying region to discharge.
TMS is used in clinical settings to evaluate motor function by direct stimulation of the motor cortex.
Experimentally it is used to transiently disrupt neural processing, creating brief, reversible legions.

Question 29

Functional Magnetic Resonance Imaging (fMRI)

Answer 29

A neuroimaging method that utilises MRI to track blood flow changes (oxygenated vs deoxygenated blood) in the brain that are thought to be correlated with local changes in neural activity.
Blood oxygen level-dependent (BOLD)

Question 30

How does an MRI work?

Answer 30

1. In their normal state, the orientation of spinning protons (hydrogen atom neuclei) are randomly oriented.
2. Exposure to the magnetic field of the MRI scanner aligns the orientation of the protons.
3. When a radio frequency pulse is applied, the axes of the protons are shifted in a predictable manner and put the protons in an elevated energy state.
4. When the pulse is turned off, the protons release their energy as they spin back to the orientation of the magnetic field - this is picked up by the MRI machine

As the density of hydrogen atoms is different in white and grey matter, it is easy to visualise these regions