Tag: long-term potentiation

Illustration made by Laura Elizabeth Hand, CC’19

Why are we all so unsatisfied? It’s both an existential and practical question, facing down administrators at colleges across the country. As diagnoses of mental disorders have skyrocketed and the palpable aura of discontent has began to seep into millennial spaces, especially the college campus, most experts are left wringing their hands without explanation. While hundreds of think pieces have been written about the existential dread of the modern world, very few have wondered if our brains themselves may be incompatible with the society we’ve made.

To understand where the disconnect between brains and our society comes from, it’s worth focusing on biology. Humans have evolved our complex brains over millennia to do one thing better than other species — to reduce uncertainty. We do this by predicting the future based on our past experiences, and then adjusting those models when they’re wrong. We call this process learning.

The neurons in our cortex and hippocampus, two areas essential for learning and prediction, are especially wired for these tasks. These neurons have two kinds of channels at their synapses that bind to glutamate, the primary excitatory neurotransmitter in the brain. The simpler channel opens up whenever glutamate is around, causing quick but fleeting pulses of activity. The more complex one needs a lot of glutamate to open, but when it does, it triggers a host of structural changes in the neuron to make it more responsive in the future.

This process is called long-term potentiation, and it is the molecular basis of learning from sea slugs all the way up the food chain to Homo Sapiens. But one innovation made by mammals is the addition of dopamine to the picture. For us, whenever something unexpectedly good happens that doesn’t meet our predictions, our brains send those neurons a pulse of dopamine. This cements those molecular changes of LTP on a scale of weeks to months, and makes sure that the association is learned.

This process was ideal for the hundreds of thousands of years humans spent as hunter-gatherers. We lived in an much more uncertain world, where many of our predictions were wrong and small unexpected pleasures (such as finding berries where there were none previously) abounded. Our brains would frequently receive small pulses of episodic happiness through dopamine. Learning based on rewarding prediction errors to motivate similar behavior in the future works only when those prediction errors are common.

While the world may seem uncertain existentially, in the most basic of ways it is far more predictable. That lack of constant, small pulses of dopaminergic inputs may be the root cause of many modern issues. When most of our material comforts are taken care of by technology, we turn elsewhere to find those hits of dopamine our brains are wired to crave. Whether that be through an alert notification on our phones, a pint of ice cream, or forcing a dopamine rush through  alcohol, opioids, cannabinoids, or other substances, we increasingly engineer artificial means of dopamine release — sometimes to addictive and destructive ends.

So what can be done to alleviate the issue? Instead of turning to massive and artificial methods of dopamine generation, re-introducing small and, more importantly, surprising pleasures into your life can provide a brain evolved to learn through unpredictability those necessary reward prediction errors. Eat a new food, explore a new place downtown without an agenda, have a conversation with someone unexpected. Our intelligence is how we’ve made it this far — maybe we can think our way out of this one.


Full credit for this conceptualization goes to Peter Sterling. For a more detailed elaboration on this idea I wholeheartedly recommend reading his essay “On Human Design” or his book Principles of Neural Design, specifically Chapter 14

Uniquely Human is written by Heather Macomber and runs every other Monday. To submit a comment/question or a piece of your own, email submissions@columbialion.com.