Neuroscience of intelligence and personality

Question 1

What is brain structure like as a baby grows?

Answer 1

• 3 weeks: midbrain, forebrain and spinal cord formed
• 7 weeks: cranial nerves formed and hindbrain
• 11 weeks: forebrain, midbrain and hindbrain
• At birth: forebrain, hindbrain (hidden), cerebellum and medulla

Question 2

How do you measure a brain?

Answer 2

• MRI scanner – structural MRI
• Take snapshots of the brain – anatomy
• Look at the function of the brain, the brain at work

Question 3

How do brains differ between controls and those with alzheimers?

Answer 3

• Alzheimer’s disease (AD) – thinned cortex
• Can look at cortical thickness between participants
• Healthy brain: white matter and grey matter. In white matter there are thousands of white matter connections

Question 4

What did Pietschnig et al (2015) find in regard to brain size?

Answer 4

• Studied the size effect of 148 healthy and clinical participants (88 studies)
• Significant positive association of brain volume and IQ (.24 correlation – modest)

Question 5

Why might be bigger brain be better?

Answer 5

• Bigger brain = more neurons? – Perhaps, but not much clear evidence yet of this. Larger neurons?
• In short, it’s a somewhat mysterious, albeit, robust, association

Question 6

What is the parieto-frontal integration theory of intelligence ?

Answer 6

• Jung & Haier
• Different brain regions associated with intelligence
• More grey matter – higher intelligence
• Cross communication between brain regions which influence intelligence

Question 7

What is P-FIT?

Answer 7

• Robust evidence for the involvement of frontal and parietal regions in intelligence – Lesions; fMRI; PET; neuroanatomy
• But why? – “We are inclined to propose that intelligence may be defined as the degree to which the frontalparietal network integrates and controls the flow of information throughout the brain”

Question 8

What did -Penke et al (2012) find about white matter and intelligence?

Answer 8

• Measured white matter tract integrity with 600 people, measured their intelligence too
• Whether thickness of white matter was related to intelligence

Question 9

White matter, processing speed, and g (general intelligence)?

Answer 9

• Why do brain measures predict g?
• g is argued to reflect processing speed
• White matter integrity is a plausible neural marker of brain processing capacity – Information transfer is greater with high integrity
• Prediction: white matter will predict g via processing speed

Question 10

What was found between white matter and speed of processing?

Answer 10

• Measured g (general intelligence)
• GFA (measure of white matter tract integrity)
• GT1 (global brain size/volume)
• Measures predict general intelligence
• gspeed (speed of processing)
• More white matter, less time it took to perform the task
• Test whether white matter integrity predict general intelligence via processing speed

Question 11

What did Eysenck believe about reticular formation?

Answer 11

• The reticular formation was important for extraversion and introversion
• Pathway controls how much information and stimulation reaches the brain

Question 12

What did Eysenck believe about introverts and extroverts/

Answer 12

• Ascending reticular activating system – Manages the amount of arousal or stimulation that the brain receives
• Eysenck argued that: – Extraverts were chronically under-aroused (not very much information reaching the brain) – Introverts were chronically over-aroused (hyper-stimulated)
• Seems counter-intuitive? – The idea is that over-arousal will cause an individual to seek out less stimulation, and vice versa

Question 13

What did -Geen (1984) find about personality and noise levels?

Answer 13

– Lab study: Ps chose noise levels for performing a task
– Extraverts chose more intense noise levels than introverts
– Extraverts and introverts were equal in psychophysiological arousal when stimulated with noise of an intensity chosen by themselves
– Learning was best among introverts and extraverts who were stimulated at a level of intensity chosen by themselves

Question 14

What did -DeYoung et al (2010) find about gray matter and personality?

Answer 14

• Used 116 adults how gray matter volume in the brain relates to personality traits
• Extraversion correlated with volume
• Extraverts are not under aroused, they’re reward sensitive

Question 15

What did Lewis et al (2018) find about cortical thickness and the big 5 traits?

Answer 15

• The field is a complete mess
• Find any paper you want to support any claim you want
• Used almost 600 participants
• For all of the big 5 traits, there was no link to cortical thickness except for conscientiousness

Question 16

What is the current thinking?

Answer 16

• Gray matter links to personality still unclear
• Somewhat crude measure – What does more gray matter (e.g. cortical thickness) actually mean?
• More neurons, more synapses, etc?
• But samples have been somewhat small to date – Larger samples needed for more definitive answers

Question 17

What is believed about white matter?

Answer 17

-Less well studied to date – more sophisticated
-Requires a more recent technique and analytical tools
-Diffusion tensor imaging
-Some promising findings to date…

-Some previous work had also noted that N was associated with left uncinate fasciculus
-McIntosh et al (2013)
-N,C, & A underpin meta-trait stability
-So is this brain region actually related to stability?

Question 18

What did Lewis et al find about brain areas and personality?

Answer 18

• Trait conscientiousness and the personality meta-trait stability are associated with regional white matter microstructure
• White matter integrity linked to neuroticism
• -Left uncinate fasciculus related to agreeableness and conscientiousness
• Some previous work had also noted that N was associated with left uncinate fasciculus – McIntosh et al (2013)
• N,C, & A underpin meta-trait stability
• So is this brain region actually related to stability?

Question 19

Combing genes and brains

Answer 19

• Imaging genetics – Thompson et al (2001)
• Can combine genetic studies and brain studies
• Identical and non-identical twins
• Identical twins – have the same amount of cortical thickness
• Non-identical – brain images look different

Question 20

Lewis et al (2014) - Results - structure of the amygdala

Answer 20

• Measured the amygdala
• Positive emotionality (extraversion)
• Positive phenotypic association (β=.16)
• Positive genetic association (rg=.23)

Question 21

What did Gosling & John (1999) find about animals and personality?

Answer 21

• Examined 19 studies (12 species) with factor analyses of animal personality
• Attempted to classify identified factors into FFM
• Found neuroticism in different animal species
• Agreeableness in chimps
• Gorillas are extroverted

Question 22

Is there sex differences in personality?

Answer 22

• Neuroticism low in males than female

- Opposite in hyenas – females are larger and more dominant, determine a lot of what goes on in the pack