Thought is generated and regulated in the brain through the rhythmically and spatially coordinated activity of millions of neurons, according to scientists in a new article. To understand cognition and its disorders, it is necessary to study it at that level.The key is to comprehend the complete content of a video on the screen. Cognition is a similar emergent property in the brain, which can only be understood by observing the coordinated actions of millions of cells, according to a group of MIT neuroscientists. In a recent article, they present a framework for understanding how thought arises from the coordination of neural activity driven by oscillating electric fields, commonly referred to as brain “waves” or “rhythms.”
Brain rhythms, previously considered only as byproducts of neural activity, are actually crucial for organizing it, as stated by Picower Professor Earl Miller and research scientist.Authors Scott Brincat and Jefferson Roy wrote in Current Opinion in Behavioral Science that neuroscientists have gained valuable knowledge from studying individual brain cells and their connections, as well as how and when they emit impulses. However, they also emphasized the importance of acknowledging and applying new concepts at the brain rhythm scale, which can encompass individual or multiple brain regions.
Senior author Miller, a faculty member in The Picower Institute for Learning and Memory and the Department of Brain, stated, “Spiking and anatomy are important but there is more going on in the brain above and beyond that.”MIT’s Cognitive Sciences department emphasizes the importance of understanding higher-level cognitive function and its disruptions in diseases such as schizophrenia, epilepsy, and Parkinson’s. They believe that interpreting and interfacing with these disruptions will be crucial for developing effective treatments.
“The emergence of thoughts is closely linked to the scale of individual neurons and the coordination of many cells,” the researchers explain. They highlight the role of electric fields in connecting these two scales, through a process known as “ephaptic coupling.” This process involves the electrical field produced by a neuron’s activity affecting the voltage of nearby neurons, creating synchronization among them. As a result, electric fields not only mirror neural activity but also impact it. In a 2022 paper, Miller and his team demonstrated, through experiments and computer modeling, how information is represented in these electric fields.The information conveyed by ensembles of neurons’ electrical fields is more dependable than the data carried by the spikes of individual cells. In 2023, Miller’s lab presented proof that rhythmic electrical fields could synchronize memories between different brain regions. On a broader scale, these electric fields are responsible for transmitting information between brain regions. Miller’s lab has conducted several studies indicating that lower-frequency rhythms in the “beta” band originate in deeper layers of the brain’s cortex and seem to control the intensity of faster-frequency “gamma” rhythms in more superficial layers. This suggests that electric fields play a crucial role in coordinating brain activity.The lab has conducted research on the neural activity in the brains of animals playing working memory games. The results show that beta rhythms are responsible for sending “top down” signals to regulate the timing and location of gamma rhythms, which encode sensory information such as images that the animals need to remember in the game.
Recent findings from the lab indicate that beta rhythms control cognitive processes in specific areas of the cortex, essentially acting as templates for when and where gamma can encode sensory information into memory or retrieve it. This theory, known as “Spatial Computing” by Miller, suggests that beta rhythms can establish the spatial organization of cognitive processes.The study found that the general rules of a task remain the same, such as the steps needed to open a combination lock, even though the specific information may change, such as the numbers in the combination. This structure allows neurons to encode multiple types of information at the same time, a neural property known as “mixed selectivity.” For example, a neuron that encodes a number in the lock combination can also be assigned to a specific step in the unlocking process based on its location in the brain. In the new study conducted by Miller and Brin, Cat and Roy propose another benefit that aligns with the concept of cognitive control being dependent on a combination of large-scale coordinated rhythmic activity: “Subspace coding.” This theory suggests that brain rhythms organize the numerous potential outcomes that could occur when, for example, 1,000 neurons engage in independent spiking activity. Rather than numerous combinatorial possibilities, a much smaller number of “subspaces” of activity actually occur due to the coordination of neurons, as opposed to independence. This is comparable to the coordinated movements of a flock of birds, where the spiking of neurons resembles their synchronized movements. Various phases and frequencies of brain rhythms play a role in this.
Coordination is essential for the brain to function effectively. This can involve aligning neural activity to enhance its impact, or offsetting it to prevent interference. For example, when a piece of sensory information needs to be remembered, the neural activity representing it can be shielded from interference when new sensory information is perceived.
“Therefore, organizing neural responses into subspaces can both separate and integrate information,” the authors explain.
The ability of brain rhythms to coordinate and organize information processing in the brain is what allows functional cognition to occur at that level, according to the authors. Therefore, understanding cognition in the brain requires studying.The authors of the study emphasized the significance of analyzing individual neurons and synapses in understanding the brain, but also stressed the importance of studying these components together to fully comprehend the brain’s complexity. They highlighted the need to identify, study, and relate the emergent properties of these components.
