Week 3: From normality to pathology: the pitfalls of neuropsychological assessment

Question 1

(Ritchie, Mcintosh and Della Sala, 2011) - Irlen overlays study. Background, findings and interpretations

Answer 1

Irlen overlays coloured sheets supposedly used to help children with reading difficulties
60% of students diagnosed as needing the sheets by evaluator
61 primary school children - one group assigned the sheets compared to control group
1 year follow up –> no difference in reading abilities between treatment and non-treatment group!

Question 2

Why are group studies difficult?

Answer 2

Heterogeneity between participants - often cannot control for everything so must assume homogeneity for many variables
Recruitment of sufficient sample
More time consuming
Studies less flexible as more participants involved

Question 3

Why are single cases often used?

Answer 3

• Don’t have to assume homogeneity for any variables
• Each person serves as their own control
• ## Can replicate results WITHIN rather than ACROSS experiments

Question 4

‘Gold standard’ of conducting research into treatment?

Answer 4

RCT is ‘gold standard’
Analysis by ANOVA to see if improvement is significant
In the event of a significant improvement in the experimental conditions group, can assign difference to the treatment
MUST control for sources of potential bias!!!

Question 5

Testing a deficit - required conditions?

Answer 5

1) Calculate normal range from the population
2) Test individual with lesion against MATCHED subjects (age gender etc)
3) Can then try and infer mental processes from measuring changes in task performance

Question 6

Problems with double dissociation

Answer 6

• Tests are poorly specified –> often can’t specify what is actually being measured by a task
• Doesn’t actually tell us anything ABOUT a mental function, only that there are 2 separate functions!
• Don’t account for individual differences in brain anatomy and functioning
• Difficult to replicate results
• Assumes that a lesion is impacting one of 2 modules and one of two tasks (assumption that system has only two components!)

Question 7

Brain, 1954 - what dbl dissociation was observed?

Answer 7

• The ability to visualise (objects and buildings)

- The ability to draw objects from memory

Question 8

(Zeeman, Della Sala et al., 2010) - CASE MX - details of patient case study?

Answer 8

• Surgery of arteries in brain
• Normal neurological assessment
• Double dissociation observed between visualisation of faces and visuo-spatial task performances (could not visualise) therefore perception
  perception //// imagery

Question 9

(Zeeman, Della Sala et al., 2010) - CASE MX - findings of case study in face perception task?

Answer 9

Participants were presented with the name of a famous person and asked to visualise their face.

• -> no significant differences were found between MX and other controls in the area of brain used for perception
• -> MX used different areas of the brain for visualisation task than the healthy participants
• -> MX activated other regions of the brain not normally used for imagery and there was a notable difference in the posterior regions of the posterior networks

Question 10

(Zeeman, Della Sala et al., 2010) - CASE MX - findings of case study with regards to areas of brain used?

Answer 10

1) there was a notable difference in the posterior networks used in the task
2) Also used DIFFERENT regions of the brain more (Inferior frontal gyrus, prenucleus, anterior cingulate nuclei)

Question 11

(Zeeman, Della Sala et al., 2010) - CASE MX - summary and interpretation of findings?

Answer 11

• MX uses frontal network for visualisation tasks as a compensatory mechanism for being unable to use the standard networks?
• The frontal network is associated with semantic retrieval
• This network attempts to visualise objects using a non-visual route –> makes use of a network which is highly regulated and strategic

Question 12

What condition was named as a result of (Zeeman, Della Sala et al., 2010) - CASE MX? What does this condition enatil?

Answer 12

CONGENITAL APHANTASIA

Lack of imagery - deficit of imagery of objects

Question 13

What can we infer due to Congenital Aphantasia?

Answer 13

Imagery and perception are ran by independent modules in the brain
The visual system is driven by incoming stimuli during perception and this involves BOTTOM UP processes, but areas of the brain must ALSO be activated by TOP DOWN regions
–> CA suggests that there is a disconnection between the anterior regions required to generate imagery, and posterior regions which support the content of perception and imagery

Question 14

Features of visuo-spatial neglect

Answer 14

Patients only attend to half of the space in their visual field
Contralateral to the position of the lesion
Typically RHS of brain (so impacts LHS of visual field)
They SEE IT but they don’t ATTEND TO IT

Question 15

Visuo-spatial neglect not the same as AMENIOPIA - how do we know this?

Answer 15

Not the same as ‘half vision’ - patients see it but don’t attend to it! We know that it is not a problem with vision because no crossing @ midline and neglect impacts the side contralateral to the lesion