Scientists Manipulate Consciousness in Rats

Scientists showed that they could 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, a region known to regulate arousal. The study, published in eLIFE, was partially funded by NIH.

“Our results suggest the central thalamus works like a radio dial that tunes the brain to different states of activity and arousal,” said Dr. Jin Hyung Lee, assistant professor of neurology, neurosurgery and bioengineering at Stanford University and a senior author of the study.

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 suggested that stimulation of thalamic neurons may awaken patients who have suffered a traumatic brain injury from minimally conscious states.

Lee’s team flashed laser pulses onto light sensitive central thalamic neurons of sleeping rats, which 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.