The bionic revolution: exploring how the brain decodes touch

The bionic revolution is transforming people’s lives through artificial body parts or prosthetics, such as a limb or implant.

One of the biggest challenges in bionics is replicating the sense of touch.

Neuroscientists at NeuRA and UNSW Sydney were featured on ABC TV’s Catalyst program as part of an episode exploring this work.

Dr Ingvars Birznieks and Dr Richard Vickery are exploring how the brain decodes touch to give people with prosthetic limbs the ability to feel.

“How we sense and interpret stimuli underpins some of the most crucial functions of the human hand,” says Dr Birznieks.

When physically stimulated, neurons in our hand generate signals to communicate with one another and with the nervous system, but the rules that explain this process are not fully known, explains Dr Birznieks.

By combining human psychophysical data with recordings from individual tactile impulses sent to the central nervous system, Dr Birznieks and his team can begin to decode the language sent from the hand to the brain.

“Our aim is to uncover some of the fundamental sensory mechanisms that control the perception of tactile stimuli.”

“This project has one branch focusing on the development of non-invasive stimulation techniques that can restore tactile perception – or touch – in patients.”

Non-invasive stimulation techniques could also be used in brain-machine interfaces and prostheses that feel, or remote sensing devices such as telesurgery.

In another project, Dr Birznieks and Dr Heba Khamis of UNSW Sydney are investigating the sensory mechanisms that let our hands manipulate objects and use tools.

“The unmatched human ability to control the hand so that brittle objects are gently held without slipping or being crushed by excessive force relies on sophisticated tactile sense in the fingertips,” says Dr Birznieks.

He explains that frictional information signalled by receptors in the skin, available within one tenth of a second when first touching an object, is vital for such control.

“We are just now beginning to decipher the mechanisms by which this information is sensed and sent to the central nervous system,” says Dr Birznieks.

This knowledge is one of the missing links in prosthetic and robotic manipulators to enable us to come closer to resembling the human ability to use hands. No such artificial sensors have been available before.

However, there is hope. Associate Professor Stephen Redmond and Dr Heba Khamis, engineers working on the project with Dr Birznieks and his lab, have built and demonstrated a biomimetic artificial sensor prototype showing such unique sensory capabilities.

“Our advances in understanding neural code and new stimulation techniques will enhance the development of next-generation sensory-controlled prosthetic and robotic manipulators.”

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