Chin EMG can be tricky to get right. For example if participant has a beard it makes it next to impossible to attach chin emg electrodes. In any case, chin EMG electrodes can come off easily even without a beard. I was wondering if there any other muscle location (such as arm or leg) that i can use to look for signs of REM's muscle atonia?
if you are considering other than the standard chin EMG for polysomnography recording, then you need to consider how you will be intepreting the data; other than the R&K manual. Theoretically, most striated muscles will display the typical changes & phasic activity during REM sleep; so you could choose any one of the other accessible striated muscles. However as there is no widely acceptable 'standard' that i know of that you will be able to site in 'scoring' the data, you will then need to create/site a standard.
Thank you for your reply Dr. Lue! I just need another heads up (other than EEG and EOG) for when my participant has entered rem sleep for my experiment so that i can initiate neurostimulation. EMG recording shows less complex activity that i can set neurofeedback parameters to alert me for when participant has entered REM sleep. It is very tiring having full attention so late at night looking for REM sleep....
I will test on the leg muscle tonight and see whats up. Why is chin emg the standard emg recording for polysomnography? It is so easy to come off and makes the patient/participant uncomfortable.
I have seen chin EMG leads placed on cheeks, directly above the beard-line, which seemed to serve it purpose. I don't think leg EMG would be sensitive enough to detect a drop in muscle tone due to REM. Impedance is typically very large on the tibialis anterior leads, really only capable of picking up large movements. I don't know the origin of chin EMG for low muscle tone during REM, but it makes sense when considering that upper airway tone may be contributing to REM-related obstructions. Also remember that this is AASM criteria, you would have to defend using EMG at any other site when identifying REM.
I've tested on the leg and you are right, leg EMG is not that sensitive in picking up REM related EMG changes. I am not looking into REM-related obstructions, i'm only looking at EMG to alert me for when participant has entered REM. Cheek EMG seems to be a good alternative in lieu of chin EMG thank you for the suggestion! I will be testing it soon.
Hi, Achilleas. I guess it depends on the resting tone of the muscle. When lying down some facial muscles have this constantly whereas those muscles in the rest of the body do not. To improve the sub-mental EMG you should use three electrodes. Two are placed over the bilateral mandible and one is placed underneath the chin just off the midline. You can then record between one electrode on the mandible and the one underneath the chin. If one falls off you can use the second electrode.
To apply palpate underneath their chin to find a soft mass and ask your participant to swallow the muscle will move. I recommend prepping the skin like you would any electrode and using an electrode glue such as collodion to keep it in place. Furthermore, a simple cup electrode with 10-20 paste may be preferable in people with hair underneath their chin. It's not as easy to apply but you will get a better recording as the paste acts as an extension of the electrode.
In regards to other muscles to record EMG from it is easier, I would recommend the deltoids and tibialis anterior. Nevertheless, you will struggle to record background EMG tone and you will only record hypnic jerks (NREM) and possibly phasic bursts (phasic REM). It important to note that it depends on the position of the subject during the recording. You should also remember that REM atonia is more like hypotonia. Muscle activity may still be apparent however it is reduced relative to EMG activity in NREM sleep.
Hope this helps.
Why submental? Refer to the Bibliography in the R&K Manual:
Berger, R. J. (1961). Tonus of Extrinsic Laryngeal Muscles during Sleep and Dreaming. Science (New York, N.Y.), 134(3482), 840. http://doi.org/10.1126/science.134.3482.840
The tonus of extrinsic laryngeal muscles was studied in sleeping humans by means of electromyograms. A striking decrease in the muscle tonus was observed at the onset of each phase of electroencephalographic light sleep, rapid eye movements, and dreaming.
Jacobson, A., Kales, A., Lehmann, D., & S, F. (1964). Muscle tone in human subjects during sleep and dreaming. Experimental Neurology, 10(5), 418–424. http://doi.org/10.1016/0014-4886(64)90033-0
It has been shown that dreams occur during EEG sleep stage I-rapid eye movement periods, and that simultaneously the tonus of some neck muscles decreases. To determine the activity of other somatic muscle groups, the tonic electrical activity of 29 muscle areas was recorded from cutaneous bipolar electrodes on sleeping human Ss. The EEG and the eye movements were recorded simultaneously. Indeed, tonus of most head and neck muscles studied decreased with the onset of EEG stage I-rapid eye movement sleep. Yet, trunk and limb muscles exhibited stable levels of tonic activity throughout the night with no change of level associated with rapid eye movement periods.
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