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Key points
- The brain is split between archaic structures (amygdala) and more subtle areas devoted to memory (hippocampus).
- This divide can be harmful to our daily lives today.
- The amygdala and related fight-or-flight structures were helpful to face threats in our ancient past but are less relevant to modern society.
Earlier posts on "Shut Up and Listen" have touched on aspects of the human brain, and in researching them, I have never ceased to be awestruck by the wonder of this organ: three pounds of intricate, pulsing wet organic circuitry that perform tasks of which all the world's artificial intelligence software—all the giant, massively-paralleled supercomputers ever invented—are quite incapable.
Tasks as varied as solving mathematical conundrums, writing fine poetry, skating after a hockey puck, or wielding a steak knife are performed by our brain with an elegance and precision that took a million years of non-stop mutations, of evolutionary trial-and-error, to achieve.
But for all its efficiency and elegance, the brain is also an ad-hoc compilation that incorporates archaic structures, the nature of which direct, and often degrade, our lives.
It's important to point out here that the great and imperfectly understood complexity of the brain means that no single part of its structure is solely responsible for one pattern of behavior; the organ works more like a pint-sized Rembrandt (or Jackson Pollock, perhaps), dipping into myriad colors and textures of the synaptic palette to craft the image of one thought or action.
Nevertheless, researchers using functional MRI technology have managed to establish a rough relationship between certain general aspects of behavior and cerebral centers that are far more implicated in these aspects than other centers. And nowhere is this reality more evident than in the interaction between two key brain areas involved in human behavior: the amygdala and the hippocampus.
The hippocampal structure is clearly involved in storing memory, performing spatial navigation, and creative curiosity. In what is likely the direct result of those million years of hunting, gathering, and migrating, the hippocampal area—in close coordination with the prefrontal cortex—seems to fix memories of events based on the outside locations in which they occurred. Then, in a sweetly circular reprise of that navigational faculty, it maps those areas in the brain in which the memories are stored so that they can be retrieved and correlated with other memories and events.
It is tempting to speculate that because the processes of navigation and memory, both internal and external, were so crucial in facilitating the explorations of our proto-human and human ancestors, they eventually turned into a parallel synaptic architecture, enabling our curiosity and imagination. It is certainly the case that activities involving curiosity and exploration seem directly linked to heightened activity in the hippocampal structure.
And then there is the amygdala. Located quite close to the hippocampus, and like that area equally divided between the brain's two hemispheres, the amygdaloid body regulates multiple aspects of our emotions and indeed communicates with both our sensory areas and the hippocampus in modulating those emotions; but it seems most directly involved in short-term fear and aggression responses, such as the fight-or-flight reflex, and in triggering the release of hormones needed to implement such reflexes.
These reflexes, of course, were most useful for fast-breaking, real-world situations that our ancestors encountered in the wild, risk-filled environment in which they hunted, gathered, and migrated. The amygdala—pumping in large amounts of stress hormones, such as adrenaline, epinephrine, and cortisol, which widened the pupils and caused the body to reflexively freeze, sprint away, or attack—certainly saved our predecessors' butts from crouching saber-toothed cats, stampeding buffaloes, and the ambush of hostile tribes.
But times, of course, have changed. The Brooklyn street where I write these lines, while it includes one alley cat and a fair number of yappy dogs, is devoid of saber-tooths. With a few tragic exceptions, humans in most parts of the planet needn't worry much about short-term physical dangers or attacks in their daily lives. While fear and stress responses remain crucial for dealing with, say, a threatening stranger in the subway or a car speeding around a curve while you're walking a country road, they are pretty much useless for everyday life in modern society.
Unless, of course, you're running for office or working for one of the large social media corporations that increasingly direct how a democracy functions.
