Neuroscience of intelligence and personality Flashcards
What is brain structure like as a baby grows?
- 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
How do you measure a brain?
- MRI scanner – structural MRI
- Take snapshots of the brain – anatomy
- Look at the function of the brain, the brain at work
How do brains differ between controls and those with alzheimers?
- 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
What did Pietschnig et al (2015) find in regard to brain size?
- Studied the size effect of 148 healthy and clinical participants (88 studies)
- Significant positive association of brain volume and IQ (.24 correlation – modest)
Why might be bigger brain be better?
- 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
What is the parieto-frontal integration theory of intelligence ?
- Jung & Haier
- Different brain regions associated with intelligence
- More grey matter – higher intelligence
- Cross communication between brain regions which influence intelligence
What is P-FIT?
- 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”
What did -Penke et al (2012) find about white matter and intelligence?
- Measured white matter tract integrity with 600 people, measured their intelligence too
- Whether thickness of white matter was related to intelligence
White matter, processing speed, and g (general intelligence)?
- 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
What was found between white matter and speed of processing?
- 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
What did Eysenck believe about reticular formation?
- The reticular formation was important for extraversion and introversion
- Pathway controls how much information and stimulation reaches the brain
What did Eysenck believe about introverts and extroverts/
- 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
What did -Geen (1984) find about personality and noise levels?
– 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
What did -DeYoung et al (2010) find about gray matter and personality?
- 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
What did Lewis et al (2018) find about cortical thickness and the big 5 traits?
- 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
What is the current thinking?
- 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
What is believed about white matter?
-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?
What did Lewis et al find about brain areas and personality?
- 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?
Combing genes and brains
- 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
Lewis et al (2014) - Results - structure of the amygdala
- Measured the amygdala
- Positive emotionality (extraversion)
- Positive phenotypic association (β=.16)
- Positive genetic association (rg=.23)
What did Gosling & John (1999) find about animals and personality?
- 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
Is there sex differences in personality?
- 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
