Patrick Schooler

Biology 1610

3-16-2017

Brain Circuit that Drives Sleep-Wake States, Sleep Preparation Behavior is Identified

50 to 70 million adults in the US suffer from some type of sleep disorder and over 30 percent of the population suffers from insomnia specifically. Furthermore, people today sleep 20 percent less than they did 100 years ago. These issues have created a huge market for "sleep medicine" and insomnia treatment, which is a multi-billion dollar market for pharmaceutical companies. These companies offer benzodiazepine type drugs that non-specifically shut down the entire brain to help people sleep. Many people know that using these type of drugs are not the best way to get the sleep they need, but often feel it is the only way they can get any sleep. What if new therapies could induce a higher quality of sleep by targeting a specific "sleep preparation" brain circuit? That is exactly what could be coming our way in the near future.      

Scientists and students at Stanford University School of Medicine have discovered a brain circuit that is indispensable to the sleep-wake cycle (biologynews.net, 2016, para. 1). This brain circuit is a connected component of the reward system which promotes behavior necessary for animals (including humans), to survive. Sceientists have intuitively sensed that the brain’s reward system and our sleep -wake cycles could coordinate with each other, however, before this study was done at Stanford University School of Medicine, no anatomical location within the brain for this relationship between the reward and arousal system had been specified (biologynews.net, 2016, para. 3).

Dopamine plays a large role in the firing of the reward circuitry system. Neuroscientists know that the ventral tegmental area, aka "VTA", is the origin of numerous dopamine secreting nerve fibers. These nerve fibers run tracts to many different areas of the brain. These fibers run to the nucleus accumbens which is a structure in the frontal area of the brain that generates feelings of pleasure in anticipation of, or in response of obtaining a goal or objective (biologynews.net, 2016, para. 8).

Reward circuit activating drugs like amphetamines work by stimulating dopamine secretion keeping the user awake and alert. Because of this it was natural for post doctoral scholar Ada Eban-Rothschild, PhD of Stanford University School of Medicine to ask, "does dopamine play a key role in sleep-wake cycle as well as in reward" (para 10). To study this, Rothschild and Luis de Lecea, PhD, professor of psychiatry and behavioral sciences along with other researchers used bioengineered laboratory mice and various technologies to remotely excite, suppress and monitor activity in dopamine-secreting nerve cells from the mice's VTA. They were able to measure overall brain activity and muscle tone to determine stages of sleep or arousal.(biologynews.net, 2016, para. 10).

Throughout the research it was found that dopamine-secreting nerve cells from VTA went up and stayed elevated when mice were awake and drastically went down when mice went to sleep and remained low as the mice slept. Activation of the same circuitry was enough to wake up the mice and keep them awake for prolonged periods of time. Suppressing this same nerve cell population during regular active periods of the mice's 24 hour cycle resulted in the mice quickly falling asleep and staying asleep even during extreme arousal triggers such as fear inducing fox urine. These observations were made and compared to the control mice who would demonstrate regular sleep-wake cycles during a 24 hour period.(biologynews.net, 2016, para. 10-12)

I found this article interesting because researchers knew that stimulating the brain’s dopamine circuitry would increases the mice's goal directed behavior. However, what makes this study so interesting is that it shows that by inhibiting this specific area of the brain’s circuitry results in induced behavior. This is the first finding in of sleep-preparation starter in the brain. This anticipatory phase is usually one of the main issues of people’s sleep disorders. If it is found that we humans have one of these sleep-preparation starter sites within our brains, advanced technologies could help create a new therapy or drug for better sleep, by aiding users in easing into sleep resulting in better overall quality of sleep.

     

References:

http://www.biologynews.net/archives/2016/09/05/brain_circuit_that_drives_sleepwake_states_sleeppreparation_behavior_is_identified.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+biologynews%2Fheadlines+%28Biology+News+Net%29