Just as an archaeologist is born to dig, so too are those who study the brain adept at sifting the treasures of the past from those that arose more recently. To study the brain is to travel back in time. The oldest of our neural structures emerge from the ancestral brainstem, and over the millennia, evolution has layered newer and newer capabilities on top of the originals.
The most recent and superficial structure, the neocortex, gives us the particularly unique mental horsepower that distinguishes what it means to be “human.” Through advances in functional magnetic resonance imaging (fMRI) we can now look deeply into the living and thinking brain without, thankfully, any need for digging. The pictures that emerge provide remarkable color into our behaviors.
Humans are here today because our predecessors and we have gotten particularly good at adaptation and survival. The core algorithms focused on food, shelter, and reproduction, none of which are particularly unique to humans, are all driven by “old” neural structures and specific chemical communication signals. The struggles that we and other animals are willing to endure to survive and reproduce are just amazing.
Take the emperor penguin. Flightless marine birds, emperor penguins each year leave the sea en masse at the end of the Antarctic summer to congregate in their breeding ground, where monogamous breeding pairs court, bond, mate and eventually share in the rearing of a single chick. To survive and support their offspring’s survival, both parents endure multiple land traverses up to 60 miles each way at temperatures approaching -80F to reach the open ocean and return with food for their chick. Failure by either parent to return spells certain death to their chick, yet against all odds emperor penguins do return to their mates and ensure the survival of the species.
As we map more and more of the living brain the triggers and rewards that drive our behaviors are being catalogued. A particularly key region – the nucleus accumbens located just above the brain stem in the middle of brain and just behind our eyes – contains the epicenter of reward. It is here that dopamine release and receptor engagement drive our cravings and establish our rewards.
This region is critical to the processes of addiction and self-control. No one chooses to be addicted. As covered here earlier, only a very small fraction of our daily activities in fact rely on conscious choice mechanisms. For most of what we do, we run on autopilot using the older and subconscious part of our brains to guide us and the reward system lays out the ground work. If you speak to those who suffer from alcoholism, drug addiction or obesity it is clear that “thinking and choosing” as we normally consider it are completely secondary to their habit driven behavior.
A large fraction of addiction behaviors exist entirely beyond the realm of thinking, moving into patterned behaviors that are driven by these same reward-centered habit loops. Dissecting the problem with fMRI we are able to see that in fact the brains of those suffering from addictions began to trigger the power of the reward circuit just by seeing, smelling, or hearing about the substance of their addiction. Before they have even experienced it the brain is pulling them subconsciously toward their weakness, often before the thought has consciously entered their mind. Perhaps even more telling is when addicts report losing all the pleasure over time that was originally associated with their behavior, resulting in an all pain but no gain vicious cycle.
Thankfully, our brain is not a one trick pony when it comes to chemistry driven biology. The same brain that gives us addiction can also spare us pain. For that we’ve got endorphins, our natural opiates. While another neurotransmitter, called serotonin, helps to provide the reward for accomplishing those longer-term objectives that take time and/or others to achieve.
And perhaps most timely is oxytocin, the chemical workhorse of love and trust. Triggered by touch, familiarity of smell, sight and sound, oxy is what bonds us but it is also key to enhanced social memory and the securing of group behaviors. A small gene with an over 500 million year history, that makes long term co-existence possible and can make special days remarkable.
As you wish someone special a Happy Valentine’s Day you can give a little credit to natural selection. But maybe you should keep that thought to yourself. While it is fascinating to learn more about how the brain functions, some things may be better when they stay at least a bit mysterious.