Brains Flashcards
Body size scaling
Explains most of variation in primate brain size
EQ
Encephalisation quotient
=> how much larger is brain/bodysize ratio compared to average
not just compare brain/body ratio btw diff species, but compare to average brain size for given body size
Observed brain size/predicted brain size
Humans
Don’t have largest absolute brain size, but most encephalised
Neocortex ratio
Neocortex: “cauliflower part” => higher cognitive function
Rest of brain: “lollipop stick” => thalamus, brain stem, cerebellum => lower, autonomic functions = digestion, homeostasis
In primates: high
In humans: highest
Brain connectivity
How much white matter (connections, axons => long distance) compared to grey matter (neuronal cell bodies, dendrites => local)
Nothing special about himans in terms of white matter => as much white matter as predicted for our brain size => neocortical white matter hyperscales across all mammals
=> white matter grows universally faster than grey matter
Obstetrical dilemma
Big brains => big head compared to body => bipedalism?
But actually obstetric dilemma already in gibbons and other lesser apes, problem gone in grat apes, arose again with high encephalisation in humans
Brain convolution/gyrification
General increase in folding with increasing brain size
=> independent of encephalisation
Gyrification index
Humans don’t have highest GI
Frontal lobes
Believed to be uniquely large in humans, but absolutely no diff in frontal lobe proportion within apes
Brain-computer analogy
Not as straightforward => brain mapping function
Macrostructure of the brain
Lobes:
Frontal => lower: olfaction
Temporal => hearing
Parietal
Occipital => vision
Visual cortex
Visual areas (Vs) have diff functions
A lot of processing
Damage to
V1 => blindness
V4 =>colour information
V5 => motion perception
