Neuroscience has made great progress on how the brain processes sight and sound, as well as in how it decodes motor activity—the use of muscles to perform functions. But one area that has eluded explanation in this line of work is ‘thought’—what comes between the sensing and the doing, which is ‘thought’ to be. foundational to higher-order cognitive processes.
New studies by researchers at the John Hopkins University in the United States aim to take knowledge of the thinking and learning process in the brain further ahead. In a groundbreaking new study, the scientists have revealed what happens in the brain when a mouse makes a mistake and the learning process involved in it.
By observing the activity of individual neurons, the team pinpointed the exact moment that mice learned a new skill. This confirmed earlier work that suggested animals are fast learners that purposely test the boundaries of new knowledge, and upended assumptions about the speed of learning and the role of the sensory cortex. The researchers believe their finding in the mice will hold true across animal species including humans
Through their new perspectives on how the brain learns, the researchers were able to make predictions about how the human brain might work. Although the ability to learn quickly would benefit any animal in the wild, animals studied in labs seem to learn slowly and methodically. It typically takes mice, for instance, thousands of tries to learn a task, several hundred at best.
Earlier studies had found that the performance of animals does not necessarily sync with their knowledge. In other words, animals might know a lot more than they demonstrate in tests. Those studies also showed that animals that seem to be slow learners might be testing their new knowledge. But by merely watching animals struggle at tasks, the researchers could not tell a slow learner from a strategic tester of boundaries.
The core question the scientists sought to answer was, what is the neural basis of this distinction between learning and performance. For this, they taught mice to lick when they heard a certain tone, but not to lick when they heard a different sound. From the moment training began, the team recorded the activity of neurons in the auditory cortex, an area of the brain associated with hearing and perception.
There were two major surprises from the experiments. First, the mice learned in 20 to 40 tries, which was considered ‘extraordinarily fast’, by the team. The second surprise was that this learning activity happened in the sensory cortex, something that has typically been associated with non-sensory brain areas.
The new study highlighted the importance of assessing how brain activity impacts behavior at different stages of the learning process and in different conditions. Additionally, the study revealed that besides processing sensory inputs, the sensory cortex also plays a vital role in forming associations between sensory cues and reinforced actions.
When the mice continued to make errors, licking at the wrong times long after their neural activity showed they had learned the task, their brain activity confirmed to the researchers that the mice knew the rules of the game, but that they were just experimenting.
The study enabled the team to decode the cognitive driver of an error, and recognize when the animal was making a mistake or was just seeking to give the other option a try. They found that once the mice had mastered the task and ceased their exploratory behavior, this higher-order activity started to diminish, and the sensory cortex was no longer involved in the task.
Condensing their study the researchers said, “Animals are smarter than we think, and there are distinct brain dynamics related to learning. You might know something, but there is a parallel process related to how you use it. The brain seems wired to do that well, to allow us to toggle between performance and learning as we get better and better at something.
