Aug. 29, 2023

Human Brain Project reveals the neural choirs that emerge in multi-area networks

In order for us to turn sensory information into memories, networks of interconnected neurons in our brains need to work together in concert. Human Brain Project (HBP) researchers set out to better understand the dynamics of such networks. To this end, they had a close look at the relationships between single neurons and neuron populations across multiple brain regions in rats, specifically, the cortical areas and the hippocampus.

To examine the network dynamics, the team recorded the activity of the hippocampal CA1 region and somatosensory, visual and perirhinal cortices while the animals performed a behavioural task on a maze. They were able to quantify the coupling of single neurons to population firing patterns, and characterise the spiking relationships within and between these areas.The researchers, from the University of Amsterdam and other institutions, made a series of analysis on the coupling of neurons within each area and between distinct sets of areas. With this, they investigated how single-neuron spike patterns correlate with population firing activity within and between these cortical and hippocampal areas.

While the animals performed a task on a maze, recordings of four brain areas were made. Image: Dorman et al. 2023.

Among their main findings, they observed that the coupling of single neurons to their local population was prominent across all four areas investigated, and this was stronger on the hippocampal CA1 area. 

At the same time, coupling between areas showed more variable profiles than within-area coupling and hub-like cells were found in all areas. “Hub” or “broadcasting” cells are neurons that are significantly coupled to more than one area. In other words, they not only engage locally, but are also involved in information processing with distant populations.

Lastly, the levels of coupling have been analysed in different contexts, such as cells function in spatial representations and different behavioural states, showing how population coupling might be a promising measure of network dynamics across the brain.

“From the cacophony of neural activation, it is amazing to see choirs of neurons emerge across the entire brain. What they are singing we have just begun to unravel,” says Reinder Dorman, researcher at the Cognitive & Systems Neuroscience Group at the University of Amsterdam and first author of the paper.

The results were published in Cerebral Cortex.

Text by Helen Mendes

Spike-based coupling between single neurons and populations across rat sensory cortices, perirhinal cortex, and hippocampus

Reinder Dorman, Jeroen J. Bos, Martin A. Vinck, Pietro Marchesi, Julien Fiorilli, Jeanette A.M. Lorteije, Ingrid Reiten, Jan G. Bjaalie, Michael Okun, Cyriel M.A. Pennartz.