Australian researchers reveal how we process visual cues

Wednesday, June 14, 2017

University of Queensland (UQ) scientists have used advanced electrical recording techniques to uncover new information about the way our eyes compute the direction of moving light.

The research, conducted at UQ’s Queensland Brain Institute, discovered that nerve cells within the retina were integral to the process. Specifically, according to study co-author Professor Stephen Williams, dendrites – the branching processes of a neuron that conduct electrical signals toward the cell body – play a critical role in decoding images.

“The retina is not a simple camera, but actively processes visual information in a neuronal network, to compute abstractions that are relayed to the higher brain. Previously, dendrites of neurons were thought to be passive input areas… [but] our research has found that dendrites also have powerful processing capabilities,” he said.

Williams further explained that the ability of dendrites in the retina to process visual information depended on the release of two neurotransmitters – chemical messengers – from a single class of cell.

“These signals are integrated by the output neurons of the retina. Determining how the neural circuits in the retina process information can help us understand computational principles operational throughout the brain,” he said.

Fellow co-author Dr Simon Kalita-de Croft said dendritic processing enabled the retina to convert and refine visual cues into electrical signals.

“We now know that movement of light – say, a flying bird, or a passing car – gets converted into an electrical signal by dendritic processing in the retina,” Kalita-de Croft said.

“The discovery bridges the gap between our understanding of the anatomy and physiology of neuronal circuits in the retina.”

It is hoped the new discovery will provide a new template for how neuronal computations may be implemented in brain circuits.

IMAGES: 1. Professor Stephen Williams, study co-author. 2. Dr Simon Kalita-de Croft, study co-author