Rat Consciousness Manipulated by Scientists with New Method

First Posted: Dec 18, 2015 11:51 AM EST

Scientists have found a way to actually manipulate consciousness in rats. They've discovered a method to alter brain activity of rats and either wake them up or put them in an unconscious state by changing the firing rates of neurons in the central thalamus.

Located deep inside the brain, the thalamus acts as a relay station, sending neural signals from the body to the cortex. Damage to neurons in the central part of the thalamus may lead to problems with sleep, attention, and memory. Previous studies actually suggested that stimulation of thalamic neurons may awaken patients who have suffered a traumatic brain injury from minimally conscious states.

In this latest study, the researchers flashed laser pulses onto light sensitive central thalamic neurons of sleeping rats. This caused the cells to fire. High frequency stimulation of 40 or 100 pulses per second woke the rats. In contrast, low frequency stimulation of 10 pulses per second sent the rats into a state reminiscent of absence seizures that caused them to stiffen and stare before returning to sleep.

"This study takes a big step towards understanding the brain circuitry that controls sleep and arousal," said Yejun (Janet) He, one of the researchers, in a news release.

When the scientists used functional magnetic resonance imaging (fMRI) to scan brain activity, they saw that high and low frequency stimulation put the rats in completely different states of activity. Cortical brain areas where activity was elevated during high frequency stimulation became inhibited with low frequency stimulation. Electrical recordings confirmed the results.

"We showed how the circuits of the brain can regulate arousal states," said Jin Hyung Lee, one of the researchers. "We hope to use this knowledge to develop better treatments for brain injuries and other neurological disorders."

The findings are published in the journal eLife.

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