lecture 7- introduction to neuropsychology

Question 1

neuropsychology

Answer 1

• studying the link between brain and behaviour
• fundamentally about studying impairments in individuals who have suffered brain damage, using this to understand how brains normally function

Question 2

causes of brain damage

Answer 2

• Traumatic injury (car accidents, falls, projectile)
• Stroke (leading cause on non-traumatic injury)
• Lack of oxygen (hypoxia)
• Tumors
• Brain infections or inflammation (e.g., encephalitis, hydrocephalus)
• Nutritional deficiencies
• Chronic alcohol abuse (e.g., Korsakoff’s syndrome)
• Surgery (e.g., intractable epilepsy)

Question 3

what are the two kinds of neuropsychology?

Answer 3

• clinical neuropsychology (clinical neuropsychologists are interested in understanding the impairment)
• cognitive neuropsychology (cognitive neuropsychologists are interested in learning about normal functions from studying impairment

both concern impairments in normal functions in the brain

Question 4

clinical neuropsychology

Answer 4

• focuses on understanding the condition
• trying diagnose and access and understand the cause of the disorder
  -focus on assessment (diagnosis and prognosis), management and rehabilitation for patients
• define pathological conditions/characterise deficits considering cognitive, behavioural, emotional and social aspects

Question 5

cognitive neuropsychology

Answer 5

• understand how the brain normally works, rather than trying to characterise the disorder itself just by understanding the disorder and what its like for the patient
• understand normal functions in the brain by studying patterns of impairment after brain damage
• map functions to brain regions

Question 6

what are the two types of cognitive neuropsychology?

Answer 6

• strong: use patient data to infer/ construct theory (starting out with no theory, study a bunch of patients and from that study of the patients you build a new theory, fundamentally construct
• weak: use patient data to constrain/ refine theory

Question 7

assumptions in cognitive neuropsychology

Answer 7

• universality
• modularity
• fractionation
• transparency

Question 8

universality

Answer 8

• idea here fundamentally the way our brains are organised are roughly the same
• cognitive processes are the same in all individuals
• still some scope for individual differences but the average of a group of individuals should be a good reflection of any individual in the wider population

Question 9

modularity

Answer 9

• idea here is if you look at any cognitive process in the brain, you can break it down into a series of steps
• complex cognitive processes can be broken down into simpler processing units

Question 10

fractionation

Answer 10

• brain damage can result in the selective impairment of a particular cognitive process
• whole level destruction or destruction to a particular component

Question 11

transparency (aka subtractivity)

Answer 11

• idea here is when you have selective impairment that it shouldn’t impair any other functions in the brain
• the cognitive system of a brain-damaged patient is fundamentally the same as that of a normal subject except for a ‘local’ modification of the system = all other processes are intact

Question 12

are these assumptions justified?

Answer 12

• fractionation
• modularity

Question 13

assumptions of universality

Answer 13

• structure wise all the lines of folds in the brain are similar to each other
• active locations are in different parts of the brain for different ppl

Question 14

assumptions of transparency

Answer 14

• everything else is functioning normally and we’ve just got a selective impairment
• behaviourally compensated for the damage in his brain in order to then be able to do the task a different way.
• neural re-organisation

Question 15

assumptions of transparency cont

Answer 15

• sometimes the damage that occurs in the brain as a result of surgery
• pre-surgery brain function
• other surgical damage

Question 16

methods in cognitive neuropsychology

Answer 16

• Studies of individuals (and groups of individuals) with localised brain damage
• Studies of individuals who have been surgically operated on
• Behavioural studies of healthy individuals
• Imaging studies of both healthy and brain-damaged individuals
• Inducing temporary ‘lesions’ in healthy brains

Question 17

how are the two ways we can study brain damaged individuals?

Answer 17

• patient-group studies
• single-patient studies

Question 18

group study approach

Answer 18

test a bunch of people and look for the common deficits or the common abilities that these individuals have, and then from that whole group data, you try to make inferences about the overall processes that are going on

• Data aggregated across subjects (i.e. averaging)
• Inferences drawn from between-group comparisons: patient group vs. control group
• Looking for ‘syndromes’: collection of symptoms which often co-occur in individuals
• Thus looking for associations of common deficits
• Can also look for common sites of damage

Question 19

group study problems

Answer 19

• Averaging across patients - the assumption of universality
• Similar behavioural symptoms may arise from very different underlying patterns of damage
• Prosopagnosia from damage to right (Marotta, Genovese & Behrmann, 2001) and left (Mattson, Levin & Grafman, 2000) hemispheres
• Similar sites of damage may be associated with very different symptoms
• Damage to right fusiform gyrus found in patients with prosopagnosia (Marotta, Genovese & Behrmann, 2001) and alexia (Leśniak, Soluch, Stępień, Czepiel & Seniów, 2014)
• Specific behavioural impairments within a syndrome may vary considerably
• e.g., different types of prosopagnosia
• Time consuming to find patients
• Risk of over-interpreting associations: the deficits may depend on functionally distinct processes that are anatomically related
• e.g., lesions to the ventral occipital lobe can produce severe deficits in colour vision (achromatopsia) and face recognition (prosopagnosia)

Question 20

case study approach

Answer 20

• look for specific single deficits in a patient
• mainly concerns dissociations between behaviours patients can and cant do
• single and double dissociations

Question 21

single dissociation

Answer 21

• we have an individual who has a particular problem, they cant do one task, but they can do something else

Question 22

double dissociation

Answer 22

• one patient can do A but not B, another patient can do B but not A

Question 23

are double dissociations really the ‘gold standard’

Answer 23

• the need for pure cases
• hard to find patients with damage purely to one cognitive process (and depending on the cause of the damage, damage may be to several brain regions)
• the impossibility of precise replication

Question 24

linking (impaired) functions to structures in the brain

Answer 24

• what can we conclude about localisation of function in the brain from studying a brain damaged patient?
• post mortem
• confirm / associate deficits with anatomy after death
• imaging techniques
• ways of imaging the brain

Question 25

structural imaging

Answer 25

• computed tomography (x-rays)
  =damage shows up as lighter, as brain tissue has died
• # magnetic resonance imaging (MRI) (radio waves/ magnetic field)

Question 26

linking (impaired) functions to structures in the brain cont

Answer 26

• can functional imaging resolve these issues?
• can compare function in brain damaged and healthy brains

Question 27

is there a way to get around it by looking at functions in the brain?

Answer 27

• yes, fMRI
• method that is commonly used to try understand activity in the brain

some problems
- doesn’t actually measure activity in the brain, it measures changes in the oxygenation level in the blood supply to the brain
- the reason that this is assumed to be connected is that essentially active tissue, muscles or neural tissue requires oxygen to be active to generate that energy. so when you are doing something active with your brain, you increase the blood flow in that area and lots of the oxygen is leaving the blood, the blood at the location and being used to drive the activity

Question 28

other types of functional imaging

Answer 28

• PET
• MEG
• EEG

Question 29

take a healthy brain and temporality disrupts activity in a localised region

Answer 29

• TMS (transcranial magnetic stimulation)
• magnetic pulse over region of cortex
• ‘transient lesion’
• rTMS