A ghost shrimp
My shoulders ache and I have blisters on the palms of both hands. There’s a cluster of bruises on my left upper thigh from attempting to balance a 9-foot pole by thrusting it into myself while furiously cranking its persnickety reel. Sand is lurking between my toes, between my teeth and under my fingernails. Everything smells fishy or salty but mostly fishy.
Yet somehow I feel mentally renewed. I have a new vocabulary which includes “ghost shrimp” and “bait thread”. I’ve learned that there is something called a “toadfish” (it’s ugly), that there is magic when fishing at sunrise or moonrise, and that one must always show respect to fellow anglers, especially when their lines become tangled or hung up on rocks. This indoor brain nerd has, momentarily, morphed into an outdoor sportswoman.
Learning anything new, be it Zumba steps or Mandarin Chinese, enhances the brain’s ability to adapt and form connections between neurons. From there, it sets a process into motion called memory consolidation and, after practice, the new information becomes a more stable, lasting memory that we can recall later. Even better, we can “update” these memories to accommodate fresh information.
A newly published study involving spatial learning in mice bears this out. Published in Nature and supported by the National Institutes of Health, the study examined the brains of mice that were trained to navigate a path through a maze, then had to renavigate to explore a different unexplored path. The control group mice navigated a space that they were already familiar with.
As expected, all the mice favored their original navigation strategy at first. But the mice that had explored a new space gradually overcame this bias and successfully learned the new navigation strategy about halfway through the training session. When the researchers tested a subset of the mice on the first task again, they found that the novelty-exposed mice were able to switch back to the original strategy, indicating that they updated and chose their strategy according to the demands of the task at hand.
The researchers looked at a key circuit involved in novel spatial learning – observing how the connections strengthened between the hippocampus (located in the middle of the brain) and the medial prefrontal cortex (the area right behind the forehead). Additionally, they observed that brain wave activity heightened during exploration of unknown territory and decreased when the task was mastered.
I like to think of new learning as a means to reset the brain, ramping up activity and connectivity of neurons when faced with conquering the skill, then tweaking to adjust as needed. To use the fishing metaphor, this means that as conditions change, the fisher’s mind must nimbly determine what kind of bait to use, how far to cast a line and what counts as a “keeper.”
Lab mice learn because they want the tangible reward (big hunks of cheese, presumably) at the end of the maze. Humans must motivate themselves to dive into new challenges for more intrinsic reasons, ultimately enjoying the pursuit for its own sake. Before the fish that was hooked and proudly photographed came all the fish that got away. But those make for good stories too.
The study mentioned in this blog:
Alan J. Park, Alexander Z. Harris, Kelly M. Martyniuk, Chia-Yuan Chang, Atheir I. Abbas, Daniel C. Lowes, Christoph Kellendonk, Joseph A. Gogos, Joshua A. Gordon. Reset of hippocampal–prefrontal circuitry facilitates learning. Nature, 2021; DOI: 10.1038/s41586-021-03272-1