Neurons exhibit varying electrical activity during repeated tasks, even with consistent outcomes. Recent research suggests that these fluctuations can be attributed to local electric fields affecting neurons, a process known as “ephaptic coupling.” Published in Cerebral Cortex, the study supports the idea that electric fields in the brain serve as significant control signals for brain functions.<\/p>\n
“The brain is awash with electrical influences,” stated Earl K. Miller, a co-author of the study and Picower Professor of Neuroscience at MIT. “Traditionally, brain function has been viewed through the lens of neuron connections, but now electric field effects are gaining recognition.” The study reveals how ephaptic effects contribute to neural variability by influencing neural activity.<\/p>\n
In 2022 and 2023, Miller and Dimitris Pinotsis, an associate professor at City St George\u2019s, University of London, published findings that local electric fields in the brain’s cortex not only mirror the information processed by neurons but also organize the neural spiking necessary for processing. Like a conductor leading an orchestra, these fields synchronize neuron activity. They propose that fields influence brain structure through cytoelectric coupling, aligning neurons to oscillate together.<\/p>\n
Miller and Pinotsis suggest that manipulating electric fields could provide new therapeutic avenues for enhancing brain function when it is impaired by disease. Adjusting individual neural connections is challenging, but intervening at the level of electric fields could achieve therapeutic goals. “Properly devised electric field manipulations could help patients rewire faulty circuits,” they wrote.<\/p>\n
Previous studies by the pair analyzed average signals over time, showing that even though local electric fields arise from individual neuron activity, they ultimately coordinate neuron function. Neurons act like citizens, while the fields serve as their governing body. Once established, the fields unify and direct neuron activity.<\/p>\n
The new study examined whether these mesoscale electric fields influence brain function trial by trial, a scale closer to real-time brain operations critical for health and disease. Researchers recorded data from animals playing a video game, where they memorized positions of dots to win rewards. During this, neural electrical spiking and local field potentials were recorded to determine the prevailing electric field at each moment.<\/p>\n
Statistical analysis revealed that neural activity varied significantly between trials. Using Granger Causality, they found the electric field exerted a dominant influence over neural activity. “We found that electric fields emerging from neural activity, captured with LFPs, turn around and influence this activity in a top-down fashion,” the researchers noted.<\/p>\n
The study’s models and calculations indicated that the strength of ephaptic coupling correlated with variations in LFP power, further demonstrating the fields’ impact on neural activity. “The larger the variability, the more evident the top-down organizing effects,” the researchers stated. “The emerging picture is that electric fields serve as control parameters.”<\/p>\n
The research received funding from the U.K. Medical Council, the U.S. Army Research Office, the U.S. Office of Naval Research, the Freedom Together Foundation, and the Picower Institute.<\/p>\n