Amyotrophic Lateral Sclerosis (ALS), can affect everyone in a different way, causing lack of control of different parts of the body. While it is slightly uncommon, it is possible for a patient with ALS to enter the totally locked-in state (TLS), which causes them to lose function of all parts of their bodies, including their eyes . A study was done on a 73-year-old male with ALS in the TLS state, who had no “history of any neurological or psychiatric disease other than ALS” .
This study was done using near-infrared spectroscopy to attempt to “clarify the preserved abilities and reorganization of the motor system” of a patient with TLS . The main goal of the study was to determine if “cognitive functions can be preserved” in an TLS patient. The four key study tasks tested were, “dichotic listening, covert singing, word fluency, and motor imagery” . Both the dichotic listening task, and the word fluency task, consisted of “11 periods which alternated between a task period and a control period” .
In the dichotic listening task, the patient was given a speech and non-speech auditory target stimuli, alternating between the two .
The patient was asked to either track the target stimuli or target control tone. In the word fluency task, during the task period, the patient was told to state words with an assigned first syllable, during the control period, he was told to repeat the syllables a, e, I, o, and u . Analysis and calculations from both tasks focused on the concentrations of oxygenated hemoglobin, the areas stimulated, and temperature difference in RECO .
As a result of the dichotic listening and word fluency tasks, “significant activations were observed in bilateral prefrontal areas and bilateral sensorimotor areas” . The difference in temperature changes in RECO during both the tasks was also documented. During the dichotic listening task, the temperature decreased 5 seconds after the task period, peaked at 15 seconds, then decreased to the level of deactivation, and then 10 seconds later, increased to the background level . It was also documented that during the word fluency task, the temperature “peaked approximately 10 seconds after the onset of the task period, and then, within 30 seconds it decreased to the background level” . Both the activation of the areas and the RECO temperature changes point to the idea that “cognitive functions were preserved in this patient” .
The results of this experiment are important because it shows that patients who are in the TLS of ALS can think and process things normally because of their ability to maintain their cognitive functions. This not only shows that a person in the TLS can still understand and process things, but they are still the same person they were before the disease. Since cognitive functions were preserved in one of the patients in the TLS, it gives hope and opportunity as to the possibility that future patients can have their cognitive functions preserved as well. These results are also important in understanding the effect of ALS on the brain and on sensorimotor area. Since the sensorimotor area is “activated during language processing tasks” in this patient, this gives incentive for research to be done on “the effect of the progression of sickness on the sensorimotor activation”.
The research article is very informative and important in terms of attempting to truly understand ALS, specifically when a patient enters the totally locked-in state. I found it interesting how different parts of your brain can respond to different stimuli after a disease like ALS occurs. I want to know more about how the preservation of cognitive function in an ALS patient in the TLS can help them and how it can relate to preventing a victim of reaching the totally locked-in state. I believe that the researchers should have tested more patients on the effects of the study tasks, to show more of a proof that cognitive functions can be active in these patients. Despite not performing the study on more patients, the main findings of the study and the article itself are very informative and important for the research and understanding of amyotrophic lateral sclerosis.