lecture 6 - the Cortex and individual differences Flashcards
(21 cards)
brain evolution and survival
increase in brain size - during human evolution
brain size and tool use
as their brain size increase the homo species developed increasingly sophisticated tools
brain size and culture
3 mill yrs ago - wood? stone, choppers, unifacial flaked tools
2 - 1.5 mill yrs ago - fire, shelters, systematic hunting, clothing, hand axes, flake tools, migrations
modern humans - language, burials, religion? integrated tools, agriculture, pottery, sedantism - societal factors related to an inc size of our brains
brain size
influenced by Group size, innovation, social learning, mating structure, length of juvenile period
Brain size
The organ responsible for intelligence is the brain, so surely the those with larger brains are more intelligent?
brain size down
humans
gorilla
dog
cat
mouse
However, larger animals have larger brains (as the brain also important for basic processes like breathing and movement)!
Brain size, Adaptability, Intelligence & Plasticity
for Homo sapiens - the modern human brain has the largest size relative to body weight
at around 50 kg body weight - deviation from the trend line indicates either larger (above) or smaller (below) brain size, than average, relative to body weight
Brain size or neuron density?
And our brains are lighter (3-4lbs) than an elephant’s (11-13lbs)…
But if you look at the number of neurons in the cortex (right), humans have many more neurons (16.3 billion) despite a smaller brain than an elephant (5.6 billion) as our brains are more sophisticated and complex
Individual differences
Brain size seems to be correlated with intelligence to a certain extent over time and between species, however, not particularly helpful when thinking about individual differences…
Let’s take a really intelligent individual, and compare his brain to other people’s.
Einstein’s IQ was about 160 (very extreme end!)
Individual differences: Einstein
Einstein’s brain was slightly smaller than the average brain BUT parietal lobe was 15% wider
What do we know parietal lobe is related to? - related to spatial cognition
Einstein’s brain also had about 80% more neuroglia
Neuroglia (aka glia) support neuron function in the brain, provides nutrients, facilitates communication
This suggests that the ability for the neurons to communicate may be the foundation of his intellect…
Neuron density and intelligence
diffusion markers of dendritic density and abroization in gray matter predict differences in intelligence
high IQ individuals have low neurone density, low neurone orientation dispersion - structured in a more organised way than low IQ individuals who have high neurite density and high neurite orientation dispersion
not about the size of the cortex its about the structure and organisation
Frontal cortex volume
Correlation between frontal cortex volume grey matter and Spearman’s g (IQ)
- results in notes
weak correlation between size of frontal lobe and intelligence
Intellect and genetic abnormalities
Down syndrome
3 x 21 chromosomes
its the most common cause of intellectual disability
have visual spatial abilities and implicit learning and memory
associated with language deficits and problems with memory
mild - IQ - 50-69
moderate - IQ - 35- 50
Cortical differences in DS
surface area decreases in down syndrome- particularly frontal lobe and temporal lobes
thickness increases in Down syndrome - diadem - should thin as you age but doesnt for them
Thickness caused by lack of pruning of synaptic connections between neurons
Decreased cortical surface area but increased thickness of cortex in DS
diagram in notes
no of synapses increases until 12 months of age they are pruned
Genetic contribution to cortical morphology
DZ twins: show 30% of the typical variation in grey matter density – in language centers and spatial association cortex
the more related the more similar the brain structure
creativity
different brain structures associated with artistic and scientific creativity - a voxel-based morphometry study
artistic - Supplementary motor area
Anterior cingulate
scientific - Left middle frontal gyrus
Left middle occipital gyrus
Differences in grey matter volume
(Brain cell density)
Brain Connectivity/Networks
and Individual Differences
Brain regions do not work in isolation but operate often as part of connected networks that display coordinated activity and synchronization across time and tasks
Connectome – fMRI methods to characterise network activity
During divergent (Alternate Uses Task) thinking task
Connectome based predictive modeling uses whole-brain connectivity patterns to predict individual traits and cognitive abilities
diagrams in notes - high-creative network, low-creative network
High creative individuals have a high frequency of transitions between dynamic functional connectivity patterns - the transition frequency was positively correlated with creativity.
Also: High creative individuals have a high frequency of transitions between dynamic functional connectivity patterns — the transition frequency was positively correlated with creativity.
Resting state functional connectivity and personality
personality is reflected in the brains intrinsic functional architecture
correlational between activity in certain areas in the brain and personality factors
Psychopaths: Reduced cortical density in prefrontal cortex
Antisocial personality – Psychopathy
Antisocial personality + Psychopathy
areas associated with understanding other peoples emotions - graph in notes
Psychopaths: Altered functional activity
Areas associated with:
Action control
Pain
Social cognition
activity in frontal lobes and amygdala is altered in those who have psychopathy
amygdala is smaller - less emotionally response
Conclusion
Intelligence:
Cortical evolution linked to emergence of intelligent behaviour
Brain size not everything when related intelligence
Neural organisation related to intelligence
Individual differences in personality and creativity can be linked with differences in anatomy AND functional networks.
Abnormal aspects of personality linked to modification of frontal cortex networks.
Learning outcomes
Intelligence:
Explain whether brain size is fundamental to intelligence.
Describe how other differences (e.g. in neurons and genetics) may explain individual variation in intelligence.
Creativity and personality:
Explore whether there is individual variation in the brain that correlates with a person’s creative ability and personality.
