Individual differences and the cortex Flashcards
The brain and evolution
- cranium has increased throughout evolution implying that so has brainsize.
- as cranium size increased so did levels of sopjistication of tool use
- brainsize also associated with various other features of society and culture
e. e community activities, development of clothes, language, religion, agriculture
Cultural brain hypothesis
Explains how evolutionary, brains have been selected based on their ability to store knowledge and manage social learning through time. Explains link between increased brain/cranium size through evolution.
as we evolve, jouvinile period is elongated, allowing for an increased opportunity for cortical development.
Encephalisation quotient
As body size increases, brain size increases by about 2/3ds of the body weight.
brain size provides a measure of behavioral complexity.
Humans have the highest brain size to body weight ration, with dolphins being very close.
Brain size vs neuron density
Elephant: 12lbs brain =5.6 billion neurons
Humans: 3-4lbs = 16 b
shows brain size and complexity correlates with societal complexity
Brain size is everything
although brain size has been shown through much research to be associated with social complexity and intelligence, that doesn’t mean that a bigger brain always indicates intelligence of species, for example elephants have much bigger brains but the amount of neurons within it is much smaller
additionally, although brain size corrilates with intellectual sophistication across species, not an indicator within species.
E.e einstein IQ 166 - brain on average slightly smaller.
Anatomy of Einsteins brain
(controversial as wasnt preserved properly)
- Parietal cortex 15% wider (viso-spatial cognition - could see space in time / visualisation)
- no parietal division
- 80% more glia (support main neurons, clear debris, feed neurons neurients)
= may be anatomical differences in einsteins brain that explain his high IQ
= may be glia allow for 3effective communication between neurons
Low IQ
compared low and high IQ brains
found high IQ had low neurite** density and much more structured organization
*** projection from a neuron
Not size of the cortex, but the organization and communication of cells.
Frontal grey matter volume
found do be weakly correlated with spearmans G in comparison to other brain structures
Down syndrome
extra copy of chromosome 21 - intellectual deficit and greater risk of dementia
Surface area of the cortex is reduced - however thickness of the cortex enlarged.
In normal development, the number of neurons decreases and pruning happens in order for specific connections to be made more efficiently.
This pruning is not happening in down syndrome
Individual differences in intelligence due to organizational communication of neurons.
Genetic contribution to cortical morphology
Monozygotic twins have a stronger correlation between cortical volume in key areas in comparison to unrelated or eternal twins.
Seems there is a genetic element to cortical development and its relationship with certain intellectual abilities.
Modern tools
FMRI : detect changes in oxygen levels
Individual differences in creativity (shi et al)
Artistic creativity: size of supplementary motor area, anterior cingulate
Scientific creativity: greater activation of left middle frontal gyrus, left middle occipital girus
Brain connectivity and individual differences
Connectome- FMRI identifies network activity
Schacter compared highly creative people with low creatives and found that they were more likely to set up connections in the periatal and frontal cortex when completing a task. The low creatives when completing the same task were more likely to have connections activate in the parietal and temporal lobe
Not just anatomical differences- but networks support different functions and individual differences.
Switching between networks
A persons ability to switch between networks has also been highlighted as a reason for individual differences in abilities.
- high creative individuals were found to have higher frequency of transitions between networks when compared to low creatives by schacter
The big 5
It has been found that there are specific networks within the brain associated with individual differences in openness, extraversion, agreeableness, conscientiousness and neurroticism (adlestein et al)
