Cognitive Neuropsychology

Question 1

Name two important historical cases in cognitive neuropsychology

Answer 1

• Paul Broca; lost the ability to speak after history of epilepsy
  *Autopsy revealed damage to Broca’s area (a region in the left hemisphere)
  *Finding: Broca’s area is for language/speaking and Wernicke’s area is for speech comprehension
• Phineas Gage; survived an explosion where a metal rod went through his skull
  *Autopsy revealed the rod went through his frontal lobe
  *Finding: The frontal lobe is crucial for personality, inhibition and decision-making

Question 2

Explain and differentiate between dissociations and double dissociations

Answer 2

• Dissociation: Patient A can do task x, but not task y
• Double dissociations: Patient A can do task x, but not y whilst Patient B can do task y but not x

Question 3

What is an engram?

Answer 3

The localised memory trace for an event
OR
A neural trace/representation (location) of a specific memory for a specific event

Question 4

What is Karl Lashley’s contribution to cognitive neuropsychology?

Answer 4

• Famous for unsuccessfully hunting for a memory ‘engram’
• Proposed the principle of “mass action”

Question 5

What is the principle of mass action?

Answer 5

• Learning is distributed across all parts of the brain rather than stored in a single region
• Thus, in the context of brain damage, the degree of memory impairment is proportional to the amount of brain that was damaged

Question 6

What are the contributions of Brenda Milner in cognitive neuropsychology?

Answer 6

Designed cognitive experiments to test memory deficits, starting with patient H. M.

Question 7

Describe Shallice and Warrington’s experiment

Answer 7

• Studied KF (a patient with damage to the left parieto-occipital region; digit span of about 2, normal long-term memory)
• Double dissociation with H. M.
• Implications for STS > LTS

Question 8

Illustrate the Atkinson & Shiffrin Model

Answer 8

• Contains 3 systems that differ in terms of storage capacity and persistence of information
• Systems: (in the order “Info” passes through)
  1. Sensory Stores
  *lost to Decay, or
  *if given Attention, it proceeds to…
  2. Short-term Store
  *lost to Displacement, or
  *if given Rehearsal, it proceeds to…
  3. Long-term Store
  *lost to Interference, or
  *remains in Long-term Store

Question 9

Explain Transcranial Magnetic Stimulation (TMS)

Answer 9

This technique of examining the brain sends an electrical impulse in a coil, to induce a sudden change in magnetic field in the area below it

Question 10

What are the strengths of TMS?

Answer 10

• Good temporal resolution
• Can have reasonable (<1cm) spatial resolution in conjunction with 3D MRI registration systems
• No known side effects in normal human subjects

Question 11

What is the function of double dissociations?

Answer 11

A way of linking brain structure to different functions, by examining behaviourally what happens in different parts of the brain

Question 12

Name the new technologies used by psychologists to examine brain structure and function

Answer 12

• Phrenology
• CT Scanning
• fMRI scanning
• EEG
• Electrophysiology

Question 13

Explain Magnetic Resonance Imaging (MRI)

Answer 13

• MRI manipulates the behaviour of hydrogen ions (protons) to yield radio signal, by applying radio-frequency pulses
• Subject is placed in a magnetic field
• Credits to Dr Paige Scalf

Question 14

Explain Functional MRI (fMRI)

Answer 14

The resonant frequency can be turned to detect blood oxygen level, wherein a change in signal indicates a metabolically active brain region

Question 15

What are the strengths of fMRI?

Answer 15

• As magnet field strengths increase, fMRI’s spatial and temporal resolutions become better and better
• Can visualise individual columns (<1mm)

Question 16

What are the limitations of fMRI?

Answer 16

• Enormous magnetic fields make behavioural testing difficult
• No computers, displays, keyboards, loudspeakers or electrical response boxes in the machine room
• The confined tube limits what the subject can see and can make them claustrophobic

Question 17

Describe Donders’ subtraction logic

Answer 17

• Used reaction times to infer cognitive processes
  Task 1 = Time A;
  Task 1 + Task 2 = Time B;
  Time B - Time A = time for Task 2

Question 18

What are the limitations of subtraction logic?

Answer 18

assumption of pure insertion

Question 19

What is the strength of Multi-Electrode EEG?

Answer 19

The temporal resolution of EEG is very good (ms)

Question 20

What are the limitations of Multi-Electrode EEG?

Answer 20

• EEG signals are very weak and need to be averaged over many trials to stand out from noise
• Spatial resolution is poor and not all neurons can contribute to an EEG signal
• Methods aimed at revealing deep sources for scalp activity are complex and controversial