Parkinson’s disease (PD) patients suffer from increasing uncontrollable movements of their bodies that impair their abilities to function in society. Michael J. Fox, a well-known celebrity actor and PD patient, has brought a lot of attention and fundraising to the illness, but there is still no cure, and treatments are only temporarily effective. A study was performed among12 PD patients, four with REM sleep behavior disorder (RBD), to determine whether REM sleep movements were processed by an alternative neural network than movements during wakefulness or non-REM sleep. Although the study was only performed in Parkinson’s patients, the results indicate that there is an alternative motor network that controls movement during REM sleep, which could have huge implications for both PD patients and people in general (Hackius, Werth, Surucu, Baumann & Imbach, 2016).
This study began because it was noted that PD patients with RBD had normal motor function during REM sleep. The mechanism for motor function was previously assumed to be similar, but differences in motor function during states of wakefulness versus REM sleep called that into question (Hackius et al., 2016).
In order to understand this study, one must understand that PD motor dysfunction is caused by an impaired basal ganglia network. The subthalamic nucleus (STN) is the neural structure responsible for control. Therefore, deep brain stimulation of the STN through medication has aided PD patients in regaining some motor control. Other methods of regaining control include strong emotions such as fear and REM sleep when patients have a concurrent diagnosis of RBD (Hackius et al., 2016).
To perform the experiment, β oscillatory activity was measured in the STN using local field potentials. The important aspects of this test, without using too much neurological lexicon, is that the activity should be similar in all states if motor control is gained from the same motor networks. There was no significant difference in activity between wakefulness and REM states. Next, β synchronization should be similar in all states. There was a difference here. Movement was desynchronous in the STN when subjects were awake. It was synchronous during REM sleep. If REM sleep movements were controlled in the basal ganglia network, there would be desynchronization seen there as well as during wakefulness (Hackius et al., 2016). These results support the idea that REM sleep movement is processed elsewhere.
Limitations to this study include the fact that only four of the 13 PD patients had RBD. Therefore, only 113 REM sleep movements, 30 wakeful movements, and 99 non-REM movements were measured. Additionally, these findings have implications for all populations with sleep- or movement- related disorders, yet only subjects with PD and RBD were studied (Hackius et al., 2016). At this time, the study size and narrowness is very limiting.
The implications in this study are relatively large in a PD population where humans suffer due to a lack of bradykinesia (slow movement). Their jerks and twitches plague their existence, and the identification of an alternative motor network to be held responsible for movement introduces countless research and treatment alterations that could lead to successful treatment of the disease. In the broader population, an alternative motor network could lead to the treatment of many ailments from restless leg syndrome (RLS) to paralysis. Even with its limitations, this study’s significant results open doors to neural communication that was previously unavailable and leads credence to the movement of traditional PD treatment in the STN to the consideration of treatment in other yet undiscovered parts on the brain. Further studies based off of this one will likely make huge headway in the treatment of PD and other movement disorders. In the past, there has been one pathway to movement and one road that the brain uses to get movement to the body. Splitting that road into two opens an impressive realm of possibilities.
- Hackius, M., Werth, E., Surucu, O., Baumann, C. & Imbach, L. (2016). Electrophysiological evidence for alternative motor networks in REM sleep behavior disorder. The Journal of Neuroscience 36(46). Retrieved from file:///C:/Users/Robert%20Rahim/Downloads/neuroscience%20(1).pdf
