Hypothalamus

The hypothalamus is one of the evolutionarily most ancient areas in the brain, with primary responsibility for all of the major survival-relevant behaviors, sitting on top of the HPA axis (hypothalamic, pituitary, adrenal). It has sensory areas that detect the level of nutrients and water in the blood (interoception), driving motivation for feeding and drinking, and maintaining blood pressure. It secretes hormones to regulate processes throughout the body, while also sending ascending projections into areas like the amygdala reflecting the current status and events such as the increase in blood sugar etc.

Thus, the hypothalamus is the core area of the emotion system that drives survival-relevant behavior. It also receives top-down projections from other brain areas, consistent with the subsumption architecture, to control and override its built-in reflex-like responses.

The five Fs (one more than the 4 proposed by Pribram (1960), see the wikipedia page) represent the most basic survival-relevant behavioral patterns controlled by the hypothalamus in response to its basic sensory inputs (Cisek, 2021).

• Feeding: consuming nutrients (and water in land animals), which at its most basic level is triggered by the presence of nutrients in the immediate vicinity and the sensation of internal nutrient levels being low.

• Foraging: exploring the environment to find new nutrients, which is triggered by low internal nutrient levels and the absence of any in the immediate vicinity.

• Fleeing: rapidly leaving the immediate environment to avoid predation, triggered by sensory inputs indicating large, looming entities. This overrides other behaviors.

• Fighting: engaging in defensive or offensive behavior in response to threats judged sufficiently manageable to win.

• Fornication: engaging in mating behaviors in response to the presence of a potential mate and conditional on other contextual factors (seasonal, etc).