Beta rhythms, which range from 14 to 30 Hz, are vital for cognitive control and influence the brain's information processing. They could also assist in diagnosing and treating cognitive disorders. Source: SciTechDaily.com
Short periods of brain rhythms at “beta” frequencies play a role in determining how and when cortex neurons process sensory input and plan reactions. Investigating these bursts could enhance knowledge of cognition and clinical disorders, according to researchers.
The brain operates at various levels when processing information. While individual cells transmit signals in circuits, at a larger scale necessary for cognition, millions of cells work together, guided by rhythmic signals at different frequencies. A team of neuroscientists suggests that studying beta rhythms, which range from approximately 14 to 30 Hz, is critical for understanding how the brain manages cognitive processes and how it may lose control in certain disorders, in a new review article.
Beta Rhythms and Cognitive Control
Referring to experimental data, mathematical modeling, and theory, the scientists argue that beta rhythm bursts control brain cognition by regulating when and where higher gamma frequency waves can synchronize neurons to integrate new sensory information or devise action plans. They propose that beta bursts establish adaptable but controlled patterns of neural activity for deliberate thinking.
“Cognition relies on organizing goal-oriented ideas. Therefore, to comprehend cognition, we must understand this organization,” stated co-author Earl K. Miller, Picower Professor at The Picower Institute for Learning and Memory and the Department of Brain and Cognitive Sciences at MIT. “Beta is the frequency range that can guide neurons at the right spatial scale to produce organized thought.”
A 2018 study by the authors demonstrates brain wave bursts at gamma (higher) and beta (lower) frequencies during a working memory task. When beta bursts occur, gamma bursts are absent. However, when stimuli (S1) and (S2) are presented, the lack of beta allows gamma bursts to encode the information. Source: Miller Lab/MIT Picower Institute
By studying bursts of beta rhythms to understand their emergence and significance, Miller and colleagues Mikael Lundqvist, Jonatan Nordmark, and Johan Liljefors at the Karolinska Institutet and Pawel Herman at the KTH Royal Institute of Technology in Sweden believe it could help in understanding cognition, as well as diagnosing and treating cognitive disorders.
“Due to the importance of beta oscillations in cognition, we predict a significant shift in biomarker identification practices, particularly considering the prominence of beta bursting in inhibitory control processes, as well as their relevance in ADHD, schizophrenia, and Alzheimer’s disease,” they write in the journal Trends in Cognitive Sciences.
Beta Data
Various experimental studies, including humans, different brain regions, and multiple cognitive tasks, have revealed crucial features of beta waves in the cortex, as stated by the authors: Beta rhythms occur in rapid but strong bursts; they suppress the activity of higher frequency gamma rhythms; and while they originate in deeper brain regions, they travel within specific areas of the cortex. Based on these properties, the authors suggest that they all support precise and adaptable regulation, in both space and time, of gamma rhythm activity, which experiments have shown to carry signals related to sensory information and motor plans.
The authors say that beta bursts provide new opportunities to study how sensory inputs are processed, changed by inhibitory cognitive operations, and lead to motor actions.
For instance, Miller and colleagues discovered in animals that beta bursts in the prefrontal cortex help control when gamma activity can store new sensory information, retrieve the information when needed, and then discard it when no longer needed. Another example is when beta rises in human volunteers asked to suppress a previously learned association between word pairs or forget a cue not used in a task anymore.
In a paper last year, Lundqvist, Herman, Miller and others highlighted experimental evidence suggesting that beta bursts carry out cognitive control. In the brain's space, they essentially limit sections of the cortex to represent the general rules of a task while individual neurons within those sections represent specific information. For example, in a working memory task to remember a padlock combination, beta rhythms help designate sections of the cortex for general steps like “turn left,” “turn right,” “turn left again,” allowing gamma to enable neurons within each section to store and later remember the specific numbers of the combination.
Another important aspect of beta bursts, according to the authors, is that they travel across long distances in the brain involving multiple regions. Investigating their spatial direction and timing could provide further insight into how cognitive control works.
New Ideas Bring About New Questions
The authors note that beta rhythm bursts can vary not only in frequency, but also in duration, amplitude, origin, and other characteristics. This diversity shows their flexibility, but it also requires neuroscientists to study and understand these various forms of the phenomenon and what they represent to gain more information from these neural signals.
Lundqvist stated, “It quickly becomes very complicated, but I think the most important aspect of beta bursts is the very simple and basic premise that they shed light on the transient nature of oscillations and neural processes associated with cognition. This changes our models of cognition and will impact everything we do. For a long time, we implicitly or explicitly assumed oscillations are ongoing, which has colored experiments and analyses. Now we see a first wave of studies based on this new thinking, with new hypotheses and ways to analyze data, and it should only pick up in years to come.”
The authors acknowledge another major issue that must be resolved by further research—How do beta bursts emerge in the first place to perform their apparent role in cognitive control?
The authors state that they do not know how beta bursts occur as a messenger of a leading direction which spreads to other parts of the brain.
The authors acknowledge that they do not have all the answers. Instead, they suggest that because beta rhythms seem to play a crucial role in controlling thinking, it's important to ask the unanswered questions.
The authors propose that beta bursts offer both experimental and computational studies an opportunity to investigate how cognitive functions are organized and carried out in real time. They also emphasize the need to address the remaining questions with new experimental methods, analytical techniques, and modeling approaches.
Reference: “Beta: bursts of cognition” by Mikael Lundqvist, Earl K. Miller, Jonatan Nordmark, Johan Liljefors and Pawel Herman, 23 April 2024, Trends in Cognitive Sciences.
DOI: 10.1016/j.tics.2024.03.010
