Your brain makes sense of what you see by processing signals that are sent from the retina. The first stop on that journey is a relay centre called the lateral geniculate nucleus (LGN): a pea-sized collection of one million nerve cells, tucked deep inside the brain.

The LGN is made up of layers of different cell types: magnocellular cells (M-cells), parvocellular cells (P-cells) and koniocellular cells (K-cells). M-cells help us perceive movement and depth, while P-cells are involved in sharp vision. Less is known about K-cells. Although they have been implicated in colour vision and blindsight – the ability of blind individuals to respond to visual stimuli without realising they can see – their functions in the LGN weren’t clear.

Brain Function CoE researcher Calvin Eiber, a postdoctoral fellow in chief investigator Paul Martin’s lab, wanted to investigate K-cells in more detail. He and his colleagues showed marmoset monkeys different visual stimuli – moving or stationary, coloured or black and white – and then studied how single K-cells in the LGN responded.

The researchers found that one subset of K-cells responds very rapidly to any flashing or moving stimulus. The simple visual system of animals such as rats and mice is packed with this kind of K-cell to help them escape quickly from predators like cats. The team’s discovery of the same kind of K-cell in the marmoset LGN suggests that these cells are involved in guiding similar rapid responses in humans and other primates.

Based on these observations, the researchers believe that K-cells may help you process visual information quickly and thus respond more rapidly to nearby threats – perhaps even saving your life.

Next steps:
The team’s next goal is to discover the connections between different subgroups of K-cells and areas of the brain that regulate attention.

Reference:
Eiber, C. D., Rahman, A. S., Pietersen, A. N. J., Zeater, N., Dreher, B., Solomon, S. G., & Martin, P. R. (2018). Receptive field properties of koniocellular on/off neurons in the lateral geniculate nucleus of marmoset monkeys. Journal of Neuroscience. doi: 10.1523/JNEUROSCI.1679-18.2018