New ways in which our experiences can influence how the two sides of the brain are wired together during brain development have been discovered by QBI researchers.

The study, published in the journal Neuron, found that balanced sensory input from both sides of the body is required for correct wiring to occur.

This communication occurs across a large nerve fibre tract called the corpus callosum which acts as a bridge between the two halves of the brain, and in humans plays a role in the development of social skills, language, vision, hearing and motor control.

Professor Linda Richards said these connections form during brain development and are shaped by both genes and experience.

“This work showed that the developing brain connections that make up the corpus callosum require balanced sensory input from both sides of the body in order to form the right connections between the two brain hemispheres,” Professor Richards said.

“These results help us to understand how brain wiring occurs, which is fundamental for brain function.”

Malformations of the corpus callosum have an incidence of at least 1 in 4,000 people and result in a wide range of symptoms that include poor coordination, delayed childhood development milestones such as walking and even lower perception of pain.

Corpus callosum malformations are also sometimes associated with psychiatric illnesses such as schizophrenia and autism.

The study conducted in developing mice found that when corpus callosum neurons were deprived of sensory or endogenous activity in one brain hemisphere they wired themselves incorrectly in the opposite brain hemisphere.

This process could be rescued by depriving activation in both hemispheres in a symmetric manner, demonstrating that not just overall activation, but balanced levels of neuronal activity between brain hemispheres are critical for precise wiring.

“The study demonstrates that it’s not just environmental stimulation that’s important, but that the stimulation is balanced between the hemispheres,” Professor Richards said.

The researchers now want to know how the balanced activity influences the corpus callosum neurons to change their growth and they are looking for genes that might be involved.