Neural network models that are able to make decisions or store memories have long captured scientists’ imaginations. In these models, a hallmark of the computation being performed by the network is the presence of stereotyped sequences of activity, akin to one-way paths. This idea was pioneered by John Hopfield, who was notably co-awarded the 2024 Nobel Prize in Physics. Whether one-way activity paths are used in the brain, however, has been unknown.
A collaborative team of researchers from Carnegie Mellon University and the University of Pittsburgh designed a clever experiment to perform a causal test of this question using a brain-computer interface (BCI). Their findings provide empirical support of one-way activity paths in the brain and the computational principles long hypothesized by neural network models.
Stereotyped sequences of neural population activity, also known as neural dynamics, is believed to underlie numerous brain functions, including motor control, sensory perception, decision making, timing, and memory, among others. The group focused on the brain’s motor system for their work, recently published in Nature Neuroscience, where neural population activity can be used to control a BCI.
