Robert Sapolsky on the Limbic System (por StanfordUniversity)
- olfactory bulb takes up 40% of a rodent brain’s projections
- rhine encephalon — originally viewed as to do with olfaction in all species
- gathers whatever sense-data pertains to emotions
- Paul McLean’s triune brain (phylogenetic conservation): hypothalamus⊕pituitary⊕brainstem⊕midbrain⊕thyroid⊕pancreas⊕heart (robotic, boring—until it goes wrong) + the limbic system (mostly a mammalian invention: birds, reptiles, fish have less complex limbic systems) ⊕ emotional complexity + cortex (gleaming analytical machine of cognitive expertise — greatly expanded in vertebrates, in mammals, in primates, in us — cortex tied to limbic system, not independent)
- decisions made under duress
- think about your own mortality (kicking out “CRH”)
- so limbic influences cortex and vice versa
- we are “a fancy species”
- Odene’s curse — lose the capacity for automatic breathing (you die of sleep deprivation)
- Antonio DiMasio, Descartes’ Error
- James Pabes
- the limbic regions compete to control the hypothalamus (they can shush each other up)
- edge/network/synaptic distance to the hypothalamus
- every sense has to go through ge;3 synapses to tell the limbic system anything—except olfaction can hop 1.
- olfaction takes up only 5% of our brain
- grey matter (nuclei) vs white matter (axon cables wrapped in myelin)
- amygdala, hippocampus, septum, mammilary bodies, hypothalamus, thalamus, prefrontal cortex
- frontal cortex: where am I being touched? which note are you playing? how do I do long division? which limb do I want to move? plus long-term planning, gratification postponement, emotional regulation, impulse control
- frontal cortex is most recently evolved, relatively largest in humans, not fully mylenated until age 25;size of prefrontal cortex in primates grows as size of typical social group
- amygdala tells you to be afraid and pings the hippocampus: “Hey, remember to be afraid of this in future”
