Washington, March 31 : Scientists at University College London (UCL) claim that they have for the first time observed how the left and right-sided nerve cells in a part of the brain, called the habenula, are wired.
This work attains significance because differences in the left and right sides of the brain are thought to influence cognitive performance and social behaviour.
Lead researcher Stephen Wilson says that causing habenular neurons to produce a bright green fluorescent protein showed that they form remarkable "spiral-shaped" axons, the long nerve fibres that act as the nervous system's transmission lines.
"It's clear that the left and right halves of the brain process different types of information but almost nothing is known about the differences in the brain's circuitry which achieve this" Wilson says.
"One possibility is that totally different types of neuron might be found on the left and right. Alternatively, both sides could contain the same building blocks but put them together in different ways," he adds.
The study revealed two types of habenular neuron, which can be found on both left and right sides. However, whilst most left-sided cells have spiral axons shaped into a domed crown, such neurons are not very common on the right.
Instead, most right-sided cells form flat, shallow spirals, which are formed only occasionally on the left.
"In the same way that an engineer can make different electronic circuits from the same set of electronic components, so the left and right halves of the brain use the same types of neuron but in different combinations" says Isaac Bianco, the student who did this work as part of his PhD studies.
The left and right habenular circuits both connect to the same part of the brain, and the researchers found that this target can either combine signals from the left and right or handle them independently.
"Even though language is processed largely on the left side of the human brain, people don't speak with only one half of their mouth. The brain must contain circuits which take information from the left or right and then send it on to targets on both sides of the body" says Wilson.
A paper describing the study has been published in the open access journal Neural Development.