In Ted Chiang’s “Understand”, the protagonist, Leon takes a new hormone therapy (hormone K therapy) to regenerate neurons after an accident rendered him in a vegetative state. Leon regains consciousness and subsequently gains extreme intelligence and extraordinary motor skills. With his new superhuman abilities, Leon evades the pursuit of the US government and becomes enraptured with finding new Gestalt patterns in the universe. Conflict arises when Leon is sent a message by another superhuman that was given hormone K. The two eventually come into contact and a battle of superhuman ability ensues.

Although, I enjoyed Chiang’s short story/novelette, I disagreed with the science of how hormone K endowed great intelligence onto Leon. Chiang explains how hormone K increases the number of synapses and, thus, the critical mass of the brain. Individuals are then able to use their new synapses and neural connections to their “fullest extent”, so they are able to increase their intelligence. However, the concept of Hebbian plasticity makes me doubt individuals would be able to use their new synapses to their “fullest extent”.

Image of a neural synapse or “cleft” between two neurons. The neuron before the synapse is called the pre-synaptic neuron while the neuron after the synapses is called the post-synaptic neuron.

In my neurobiology course, we learned how babies are born with an excess number of synaptic connections which are then pruned down with usage. The pruning down of neural synapses is the basis of Hebbian plasticity. Hebbian plasticity notes that when pre- and post- synaptic neurons are activated at the same time, they trigger a process that causes the synapse to grow. However, when the two neurons are not activated at the same time, there is no synaptic growth. Over time, pre- and post- synaptic neurons that repeatedly do not activate together will have their synapse removed or pruned. This pruning process is the basis of learning and memory as neural connections are strengthened and weakened. There’s an old neuroscience saying that says neurons that fire together wire together; the more a neural circuit is activated by use (such as repeating a phone number to memorize or practicing a piano song), the more the pre- and post-synaptic neurons in that neural circuit are activated at the same time. Thus, that neural circuit becomes stronger as the synapses in that circuit grow. Children’s brain are the most plastic– have the greatest ability to change–  because they have a higher number of neural synapses that can be strengthened or pruned. This is why that children are better at learning languages and are able to grow and comprehend complex things at a faster rate than adults. This extensive period of learning is widely known as the critical learning period.

I believe gaining more synapses will not necessary confer intelligence right away, such as the story suggests because having more synapses does not mean you can use all the synapses. Increasing the number of synapses may reintroduce the critical learning period seen in children but in an adult, so the adult has the opportunity to efficiently learn new things like a new language. I speculate Leon has the opportunity to  become more “intelligent” by learning new and complex topics at a faster rate than he would be able to as a normal adult with a less plastic brain. However, this process would take time and practice as he strengthens and prunes his neural synapses. I wouldn’t expect Leon to gain so much intelligence as quickly as he did in the story nor would I believe he would be able to gain a superhuman level of intelligence.

Leon definitely shouldn’t be able to do some of his motor abilities described in the story, such as raising and lowering his heart rate and blood pressure. Increasing synapses shouldn’t allow him to control processes such as heart rate and blood pressure regulation because those are automatically monitored by the hindbrain that is responsible for basic survival processes. On the other hand, the forebrain is responsible for learning and intelligence. Voluntary muscles we can control are connected to the neurons that link to the forebrain while involuntary muscles that allows our heart to beat and our lungs to breathe are connected to neurons that link to the hindbrain. Thus, conscious processes, such as learning, belong to a different network of neurons than the network that controls automatic processes, such as heartbeat.

However, I do concede that the hormone K may be out of our comprehension with our current knowledge we have about neurons and neural circuits. Perhaps, hormone K could initiate the described processes, but we just can’t understand its effects with the information we have today. Perhaps, this is why Chiang does not go into too much detail with the mechanism of the hormone; the vagueness of how hormone K leads to superhuman intelligence allows the us, the readers, to imagine the possibility of a treatment that can turn people into superhumans. Or, perhaps, it leaves an empty space for future scientific discoveries to explain.