David Anderson frames emotions as a neurobiological class of internal state, like arousal or motivation, which changes the brain's input-output transformation.
Anderson distinguishes emotional states from simple reflexes by two key properties: persistence and generalization. Fear can outlast a threat, and a bad day at work can generalize to make someone more irritable at home.
Anderson clarifies that aggression describes a behavior, not a single internal state. It can reflect anger, fear, or predatory hunger, each with different neural circuits.
Walter Hess's Nobel-winning work showed electrical stimulation of the cat hypothalamus could evoke two distinct aggression types: defensive rage and predatory aggression.
Offensive aggression stimulated in male mouse ventromedial hypothalamus is rewarding. Male mice will work to get the chance to fight a subordinate, indicating positive valence.
The ventromedial hypothalamus integrates sensory data into a low-dimensional 'pressure to attack' signal. It projects to 30 brain regions for cost-benefit analysis before risky behavior.
Aggression neurons in male mice require the estrogen receptor. Testosterone's aggression-promoting effects are mediated by its conversion to estrogen via the aromatase enzyme.
Female mice fight only when nursing pups, transitioning from sexual receptivity to hyper-aggression. Their VMH contains separate, sex-specific neuron subsets for fighting and mating.
The medial preoptic area contains 'make-love-not-war' neurons. Stimulating them stops a fighting male mouse, making it sing and attempt to mount its opponent.
Anderson posits that dense connections between aggression and mating circuits could underpin sexual violence if states become improperly linked or reinforcing.
Subjective emotion maps reflect the somatic marker hypothesis, where brain states trigger bodily changes via the autonomic nervous system, sensed by vagal afferents feeding back to the brain.
Joe Rogan argues sleep deprivation severely impairs his memory and cognitive function, causing him to misremember details like the timeline of current events.