A groundbreaking study published in Nature Neuroscience provides the first evidence of flexible neuron modules in the brain, revealing how the same populations of neurons can adapt to perform diverse computations and store varied information, from sensory input to action plans, with remarkable efficiency.
Key Points
- A new study reveals the existence of flexible neuron modules in the brain, challenging previous assumptions about dedicated neuron groups.
- These neuron clusters, particularly in the prefrontal cortex, can store both sensory input and action plans in working memory.
- The research suggests that the brain uses reusable circuits, allowing the same populations of neurons to perform varied computations across different tasks.
- This adaptability enables the brain to efficiently process and store diverse information, contributing to a rich variety of behaviours.
- The findings, published in Nature Neuroscience, offer insights into how the brain manages an unlimited variability of information with a finite number of neurons.
A study provides first evidence for the existence of modules in the brain, or clusters of neurons, that perform the same computation across varied tasks, which may help explain how the brain takes on many functions with flexibility.
Researchers identified neurons in the prefrontal cortex that can be used to store either a sensory input or an action plan in working memory.
"We found that the brain doesn't dedicate a separate group of neurons for every type of information. Instead, it uses the same populations of neurons to perform the same computation on different kinds of information, which means the same subset of neurons can hold both an action and a sensory stimulus in working memory," lead author Yuma Osako, a postdoctoral researcher from the Massachusetts Institute of Technology (MIT), US, said.
Unveiling Reusable Brain Circuits
The discovery, published in the journal Nature Neuroscience, supports the theory that reusable circuits allow the brain to mix and match components to generate a rich variety of behaviour, the researchers said.
"Our everyday life requires us to temporarily hold many different kinds of information. One big question is how the brain can represent an unlimited variability of information using only a finite number of neurons," Osako said.
Mice were trained on a task and learned to determine whether two sensory stimuli (high or low pitched tones) were the same, and respond.
Electrical activity in the mice's brains were recorded, focusing on the prefrontal cortex, which is involved in executive functions such as planning and decision-making, and the parietal cortex, which processes sensory information and plans movement.
How Neurons Adapt to Store Memories
An analysis of the electrical activity allowed the researchers to identify groups of neurons that encode specific pieces of information.
The team looked at two time periods -- the time between the first and second tone, when the animals are holding a memory of the first tone, and the time between the second tone and the point where they have to decide on an action.
During the second time period, the animals are holding their decision and action plan in their working memory.
Neurons within the parietal cortex appeared to exclusively store a memory of the tone.
However, in the prefrontal cortex, a cluster of neurons were identified that could switch between the two types of memory. During the first duration, the neurons stored a memory of the first tone, but during the second, they were responsible for remembering the plan of action, the researchers found.
Re-using the clusters for varied purposes allows the animals to flexibly store different types of information, they said.
The study findings support the idea that the same neurons involved in computations are possibly used for varied purposes, the researchers said.
