March 1, 2014
Differences In The Motor Cortex Possibly Linked To Insomnia
redOrbit Staff & Wire Reports - Your Universe Online
The movement-based part of an insomniac’s brain tends to be more active and demonstrate greater neuroplasticity than the same region in good sleepers, researchers from Johns Hopkins Medical Institution report in the March issue of the journal Sleep.Study leader Rachel E. Salas, an assistant professor of neurology at Johns Hopkins, and her colleagues found that the increased brain plasticity in the motor cortex of people with chronic insomnia was more adaptable to change than those who do not struggle to get a good night’s sleep.
In addition, the researchers found more “excitability” among neurons in this region in patients who frequently have difficulty sleeping, which suggests that insomniacs are constantly living in a state of elevated information processing which could help interfere with their attempts to get enough slumber.
“Insomnia is not a nighttime disorder,” Dr. Salas said in a statement Friday. “It's a 24-hour brain condition, like a light switch that is always on. Our research adds information about differences in the brain associated with it.”
They hope that their findings, which were obtained using a painless and noninvasive process known as transcranial magnetic stimulation (TMS), can lead to improved diagnosis and treatment of this common and often difficult to manage sleep disorder, which impacts an estimated 15 percent of all Americans.
TMS, which has been approved by the US Food and Drug Administration (FDA) to treat some individuals suffering from depression, delivers electromagnetic currents to precise locations in the brain. The process temporarily and safely disrupts the function of a targeted area (such as the mood control region of the brain).
The researchers recruited 28 adults, 18 of whom had suffered from insomnia for at least one year, and outfitted each of them with an electrode on their dominant thumbs and an accelerometer to measure the thumb’s speed and direction. Each was then given a series of 65 electrical pulses using TMS, which stimulated parts of the motor cortex as the study authors looked for involuntary thumb movements linked to the procedure.
“Subsequently, the researchers trained each participant for 30 minutes, teaching them to move their thumb in the opposite direction of the original involuntary movement. They then introduced the electrical pulses once again,” the institute said. The goal was to measure the extent to which each of the participants’ brains could be conditioned to move their thumbs involuntarily in the newly trained direction, indicating the plasticity of their motor cortexes.
Since a link between decreased daytime memory and concentration has been associated with a lack of sleep during the nighttime, Dr. Salas and her associated believe that the brains of good sleepers could be more easily retrained. However, their research indicates that the opposite is true: the brains of men and women suffering from chronic insomnia were found to have far more neuroplasticity than their counterparts.
According to the Johns Hopkins researchers, “the origins of increased plasticity in insomniacs are unclear, and it is not known whether the increase is the cause of insomnia. It is also unknown whether this increased plasticity is beneficial, the source of the problem or part of a compensatory mechanism to address the consequences of sleep deprivation associated with chronic insomnia.”
Dr. Salas said that the increased metabolism, elevated cortisol levels and heightened anxieties described in chronic insomnia could be associated with increased plasticity in some way. There is no objective test for insomnia, nor is there a single treatment plan that is effective for all patients, but the new study shows that TMS could help diagnose the condition and potentially prove to be a way to treat it by reducing excitability.