26.6 - Typical and Atypical Development

Question 1

Describe why the timing of a lesion is important for understanding development and developmental disorders.

[IMPORTANT]

Answer 1

• There are continued developmental changes in cortical regions from childhood into adulthood (Gogtay, 2004)
• Different systems develop at different times ->The rise and fall of synaptic density differs in timing for visual, auditory and prefrontal cortex systems (Huttenlocher, 2002)
• This means that lesions at different times will affect different aspects of functioning

Question 2

Compare lesions of language areas in children and adults.

[IMPORTANT]

Answer 2

• In infants, right hemisphere lesions lead to great risk for delays in word comprehension (Bates, 1997). In adults, it is left hemisphere lesions that cause language problems.
• In children, left POSTERIOR lesions lead to difficulties with language production. In adults, left ANTERIOR lesions lead to difficulties with language production (and left posterior lesions are associated with comprehension difficulties).

This suggests that there may be a change in language areas in infants through development (i.e. from right to left side).

Question 3

Can language area lesions recover if they occur in early life or adulthood?

[EXTRA]

Answer 3

If the lesion occurs in early life, the language skills usually resolve regardless of the side of lesion. Adults with left hemisphere lesions do not recover. (Bates, 2001)

Question 4

Compare lesions of visuo-spatial areas in children and adults.

[IMPORTANT]

Answer 4

• Right hemisphere lesions lead to problems with global aspects of visual stimuli in both children and adults.
• Left hemisphere lesions lead to problems with local aspects of visual stimuli in adults (remember left = local). In children, they lead to problems with both local and global aspects of visual stimuli.

Question 5

Can visuo-spatial processing area lesions recover if they occur in early life or adulthood?

[EXTRA]

Answer 5

In general, they cannot recover (unlike language, for example).

Question 6

Give two examples of functionally-defined developmental disorders. What is meant by functionally-defined?

Answer 6

• Attention Deficit Hyperactivity Disorder (ADHD)
• Autistic Spectrum Disorder (ASD)

They are functionally-defined because they show core neurocognitive deficits but they may be heterogeneous in aetiology, unlike acquired lesions.

Question 7

What the the DSM-IV criteria for diagnosis of ADHD?

Answer 7

• Criterion A: Child must exhibit six (or more) symptoms of either inattention or hyperactivity (see next flashcard) -> These must have persisted for over 6 months.
• Criterion B: Some inattentive or hyperactive-impulsive symptoms are present before age 7 years -> Changed to 12 years in DSM-V
• Criterion C: Symptoms are exhibited in two or more settings (e.g. at school or at home)
• Criterion D: Must be clear evidence of clinically significant impairment in social or scholastic functioning
• Criterion E: Symptoms do not occur exclusively during the course of, or can not be better accounted for by, another disorder -> Changed in DSM-V

Question 8

Describe the symptoms of ADHD.

Answer 8

Question 9

Do all patients with ADHD show symptoms of both inattention and hyperactivity?

Answer 9

No, and this gives rise to the different types of ADHD.

Question 10

What is the prevalence of ADHD?

Answer 10

3-5% of school children suffer from ADHD (Castellanos & Tannock, 2005)

Question 11

Describe the neurocognitive theories of ADHD.

[IMPORTANT]

Answer 11

• The classic view is that the symptoms of ADHD are caused by an inhibition deficit that leads to executive dysfunction (e.g. problems with working memory, etc.) (Barkley, 1997)
• This was suggested to be due to abnormalities in the fronto-striatal circuitry
• However, this fails to account for the inattention in ADHD (Huang-Pollock, 2006)
• Therefore newer theories suggest that ADHD may also be underlaid by:
  
  • Working memory difficulties (Lui & Tannock, 2007)
  • Sustained attention difficulties (Manly et al, 2001)
  • Motivational difficulties (Solanto et al, 2001) -> For example, executive functions may be present, but only when there is high motivation for a task (Liddle, 2011)
• This means that recently the view of a single deficit has been argued against and there is increasingly consideration of other areas of the brain

NOTE: The terms in bold are those mentioned in the spec.

Question 12

Describe the symptoms of autism spectrum disorder (ASD).

Answer 12

Question 13

Describe the neurocognitive theories of autism spectrum disorder (ASD).

[IMPORTANT]

Answer 13

• Classically, ASD is thought to be due to a core mentalising deficit (Mentalising is our ability to understand the mental state of oneself or others. This can be thought of as the ability to imagine the mental activity of others and understand their behaviour from it.)
• However, this is not always seen in all patients with ASD, so new theories suggest that ASD could also be caused by:
  
  • Executive difficulties (inhibiting true beliefs) (Russell, 1991) -> Executive functions predict later mentalising abilities in ASD
  • Weak central coherence (a human being’s ability to derive overall meaning from a mass of details) (Happe, 1994)
  • Multiple-hit hypothesis -> Multiple mutations contribute to ASD

NOTE: The highlighted terms are mentioned in the spec.

Question 14

What is meant by a core mentalising deficit in ASD? Give some experimental evidence for the core mentalising deficit theory of ASD.

Answer 14

• Mentalising is our ability to understand the mental state of oneself or others. This can be thought of as the ability to imagine the mental activity of others and understand their behaviour from it.
• (Baron-Cohen, 1985):
  
  • Used the Sally Anne test
  • This features a picture story where a girl’s ball is moved and then the subject is asked where she will look for the ball
  • By the age of 4, most children will answer correctly
  • 80% of children with autism fail the test and only gain the ability to answer correctly when they are older
• This theory can explain the deficit in understanding others’ emotions that patients with ASD present.

Question 15

What is meant by weak central coherence in ASD?

Answer 15

• Weak central coherence is a human being’s ability to derive overall meaning from a mass of details.
• For example, seeing a lot of trees and being able to recognise it as a forest.
• This may explain why children with ASD may be particularly good at finding details in situations, but not the bigger picture.

Question 16

Describe acquired developmental disorders of executive function in children and adults.

Answer 16

For executive functions, there are a significant range of different outcomes that can result from lesions and these are very hard to predict. [ADD DETAIL]