Rat brains analysed
The thalamus in rats was analysed to see how laser pulses could change their wakefulnessaudrey_sel/Flickr

Scientists have been altering the brain activity of rats in an attempt to help pave the way for new treatments for Parkinson's disease. They changed the amount of neurons reaching the rat's thalamus – a central part of the brain – to make them fall into an unconscious state, or to wake them up.

The thalamus is located deep inside the brain, and is known to stimulate arousal. Scientists used this information to control the arousal of rats, in an attempt to better understand how brain circulation affects sleep disorders and other neurological diseases.

"Our results suggest the central thalamus works like a radio dial that tunes the brain to different states of activity and arousal," said Jin Hyung Lee from Stanford University, and senior author of the study. "We hope to use this knowledge to develop better treatments for brain injuries and other neurological disorders."

The thalamus acts as the middle-man between the body and brain. It receives signals from all over the body, and relays that information to the cortex – the outermost part of the brain responsible for our five senses.

The study, published in eLife, used laser pulses to stimulate the thalamus. Seeing as it is sensitive to light, the thalamus began to "fire" neurons, meaning that the brain began to work more quickly.

It was discovered that different amounts of laser pulses caused different states of arousal in sleeping rats. Lots of pulses – or a high frequency – woke the rat up, but less of these pulses – or a low frequency – put them into an unconscious state.

This type of brain stimulation is already being used as a treatment in humans, for traumatic brain injuries, including the damage caused by Parkinson's disease. However, patients that are not fully conscious at the time of treatment show slower progress than those that are fully aware of their surroundings.

The researchers hope that this investigation will help to develop better treatments for this type of neurological disorder.