Cognition, an emergent property in the brain, relies on the flexible organization of neural activity. According to a trio of MIT neuroscientists, cognition can be better understood by observing how millions of cells act in coordination.
In a new study, scientists provide a framework for comprehending how brain “waves” or “rhythms,” which are fluctuating electric fields that coordinate neuronal activity and give rise to thought.
Although formerly disregarded as mere consequences of cerebral activity, brain rhythms play a crucial role in structuring it. Furthermore, although research on the connections between individual brain cells and the timing and manner in which they release “spikes” to transfer impulses through particular circuits has provided neuroscientists with a wealth of information, understanding, and application of new ideas at the brain rhythm scale—which can span one or more brain regions—is also necessary.
Senior author Miller, a faculty member of The Picower Institute for Learning and Memory and the Department of Brain and Cognitive Sciences at MIT said, “Spiking and anatomy are important, but there is more going on in the brain above and beyond that. There’sA lot of functionality is taking place at a higher level, especially cognition.”
Electric fields link the scale of individual neurons and several cells’ larger-scale coordination. The electrical field produced by a neuron’s activity can affect the voltage of nearby neurons through a process known as “ephaptic coupling,” which aligns them. In this sense, electric fields both cause and reflect brain activity.
In 2022, scientists demonstrated through computational modeling and tests that information stored in the electric fields produced by neuronal ensembles can be read out with greater accuracy than information stored in the spikes of individual cells. In 2023, scientists offered evidence that rhythmic electrical fields could coordinate memory across regions.
In essence, beta rhythms function as stencils that indicate where and when gamma can encode or recover sensory information from memory. They do this by applying this control over cognitive processes to specific cortex regions. This idea, which Miller refers to as “Spatial Computing,” states that beta can determine the overall guidelines for a work.
Generally, this structure enables neurons to flexibly encode more than one kind of information at a time- a widely observed neural property called “mixed selectivity. For example, a neuron encoding a lock combination number can also be assigned, depending on the beta-stenciled patch it is in and the specific unlocking phase for which the number is relevant.
In this new study, scientists suggest another advantage consistent with cognitive control based on an interplay of large-scale coordinated rhythmic activity: “subspace coding.”
According to this theory, brain rhythms structure the enormous array of conceivable outcomes that could arise from 1,000 neurons firing independently. Because neurons are coordinated rather than independent, substantially fewer “subspaces” of activity exist instead of the many combinatorial possibilities.
A group of birds coordinating their movements is analogous to neurons spiking. Several brain rhythm phases and frequencies provide this coordination, offset to avoid interference or aligned to amplify one another. For example, brain activity associated with sensory information that needs to be retained can be shielded from interference when viewed alongside fresh details.
Scientists noted, “Thus, the organization of neural responses into subspaces can segregate and integrate information.”
“The power of brain rhythms to coordinate and organize information processing in the brain enables functional cognition to emerge at that scale. Understanding cognition in the brain, therefore, requires studying rhythms.”
“Studying individual neural components in isolation — individual neurons and synapses — has made enormous contributions to our understanding of the brain and remains important. However, it’s becoming increasingly clear that, to capture the brain’brain’sexity fully, those components must be analyzed in concert to identify, study, and relate their emergent properties.”
Journal Reference:
- Earl K Miller, Scott Brincat, Jefferson Roy, et al. Cognition is an emergent property. Current Opinion in Behavioral Sciences. DOI: 10.1016/j.cobeha.2024.101388