Unravelling the brain’s wiring

20 Jun 2014

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 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 plays a role in the development of social skills, language, somatosensation, 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 such as 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 was conducted in developing mice and 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.

“It also showed that malformations of the corpus callosum can occur in subtle ways, as connections were disrupted only in their final stages of being established.”

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.

The study was funded by the National Health and Medical Research Council and findings are published in the journal Neuron.

Media: Mikaeli Costello, +61 401 580 685, mikaeli.costello@uq.edu.au; Professor Linda Richards, +61 7 3346 6355, +61 431 853 857, richards@uq.edu.au.