2 days, 9 hours ago

Generally speaking, most people and plants are unconscious. But a small number of vegetative people are conscious. 

With the development of neuroimaging, scientists gradually have tools to detect human consciousness. In 2006, the journal Science 
 published a study on the detection of vegetative consciousness. In 2005, a 23-year-old young woman suffered from severe brain injury due to a car accident. Five months later, she was still in a state of no response to the outside world and met the clinical diagnostic criteria for vegetative patients. 

The researchers used functional magnetic resonance imaging (fMRI) to measure her brain's response to statements, such as "his coffee has milk and sugar," as compared to her response to another murmur of similar tones. It turns out that when she hears a regular sentence, the activated areas in her brain are the same as those in healthy people (see figure below). It was also surprising that when the sentence contained some ambiguous words, the lower left prefrontal area of the vegetative woman was activated, the same as that of healthy people. This means that the area of her brain that processes the meaning of words is working. 

 of course, this evidence is not so convincing, because many studies have found that humans also learn subconsciously when they are unconscious or sleeping. 

So the researchers conducted a second experiment, in which they instructed the woman to imagine two scenarios, one was to imagine herself playing tennis, and the other was that she started from the front door and visited every room in her house. When she imagined playing tennis (top left, below), her brain's auxiliary motor area (SMA) was significantly activated. When she imagined visiting the house (top right below), her hippocampal gyrus (PPA), posterior parietal cortex (PPC) and anterior lateral motor cortex (PMC) were all activated, which was consistent with that in healthy people (second row below). 

 adopted the same method as the previous study. 23 patients with vegetative state and 31 patients with critical state of consciousness (close to vegetative) were scanned by MRI. 

During the MRI scan, the patients were guided by the researcher's language to imagine a sports scene: standing on a tennis court and then swinging the ball. They also need to imagine the location of the space: visiting each room in their house and imagining themselves in that scene. 

In addition, one of the patients who had been diagnosed with permanent vegetative state by a professional team 17 months ago received an additional language communication test. The researchers would ask him 48 questions, such as "do you have a brother?". Then tell him if he is, imagine playing tennis, if not, imagine visiting the house. And then verify the answer according to the activated area of the patient's brain. 

The results showed that five out of 54 patients were able to consciously engage in brain activity (imagination). 

However, in the language test, the brain activation regions of the subjects were very similar to those of healthy people (as shown in the figure below), and they were asking questions related to themselves, such as "is your father called Alexander" (the patient answered "yes" - correctly), "is your father Thomas" (answer "no" - correct). 

 left: the activated area of the patient's brain; the right: the activated area of the brain of the healthy person 
 however, in clinical diagnosis, the patient fully meets the standards of vegetative people, indicating that the clinical diagnosis may not necessarily reflect the patient's inner state of consciousness. 

After that, studies on 
 showed plants familiar and unfamiliar face images, and asked them to imagine their parents' appearance, and found brain activation similar to that of healthy people. 

But in this state, is it lucky or unfortunate to have a certain degree of consciousness?


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