Patients who are vegetative and patients who are in a coma will both show brain activity in a brain scanner (e.g. MRI), although there are key differences between these two conditions. Put simply, a comatose patient will typically have closed eyes, and will be entirely non-responsive to any form of external stimulation (for example, if you ask them to squeeze your hand, they will not). Vegetative state patients will also be entirely non-responsive, but they may open their eyes, they may have roving eye movements (that is, their gaze will drift around the room), and they may have sleeping and waking cycles. The vegetative state typically follows a period of coma – that is, after some period in a coma, patients may “awake”, but remain non-responsive. At that point they will likely be diagnosed as being in a vegetative state, but there is no clear difference in brain activity between these two conditions. I suspect that when you were referring to "vegetative state meaning no brain activity" you were actually thinking about patients who are diagnosed as being “brain-dead“. In that case, you would expect no, or very little, brain activity.

The vegetative state is often referred to as a condition of “wakefulness without awareness”. That is to say, these patients will open their eyes and they may have sleeping and waking cycles, but they will show no responses to any form of external stimulation (for example, if you ask them to squeeze your hand they will not do it). Because they lack any responses to external stimulation it is assumed that they are entirely unaware (that is, unaware of who they are, where they are and the predicament they are in). In many ways minimally conscious patients look very similar, clinically, to vegetative state patients. However to be classed as minimally conscious you must show some, albeit inconsistent, responses to external stimulation. For example, if you were to ask a minimally conscious patient to squeeze your hand they may do it, often enough for you to know that they have some level of awareness, but not so consistently that you can be confident that they are entirely aware all of the time (hence, “minimally conscious”). But importantly, there is a big gray zone between the two conditions. Many minimally conscious patients are barely responsive (and so, almost impossible to distinguish from vegetative state patients), while others can respond more consistently. As a result there is a very high level of misdiagnosis (40%+) between the two conditions (e.g. many patients assumed to be vegetative can be shown to be minimally conscious when examined by experienced doctors).

The short answer is, it is very difficult. Generally, the only way that we can know that somebody is conscious is if they are able to tell us that. Most people will be familiar with the scenario where a doctor will ask a patient to “squeeze my hand if you can hear me“. If the patient responds by squeezing the doctor’s hand then it is clear that they are conscious. Clinically, this is what is referred to as “command following" and it is the way that doctors around the world determine whether somebody has a conscious brain or an unconscious one. However, in 2006 my team and I (then in Cambridge UK), invented a new technique for differentiating between a conscious brain and an unconscious brain based not on behavioural responses (like the squeeze of a hand) but on brain responses. While lying in a brain scanner, we asked a patient who was assumed to be in a vegetative state to imagine playing a game of tennis. When we did this, we saw the parts of her brain activate that we know are involved in imagining vigorous arm movements (just as if she were actually playing tennis). In fact her brain responses looked identical to those of healthy participants who imagined playing tennis while lying in the scanner. On this basis, we were able to determine that she was conscious despite being entirely unable to make any physical responses. In many ways, I think of this technique as being a version of “command following”, except instead of responding with part of the body, the patient is required to respond using only their brain. Versions of our original technique have been adapted and applied to thousands of patients worldwide in many different laboratories and it is now clear that this is a very effective method for differentiating a conscious brain from an unconscious one. For your interest, I am attaching a copy of the scientific paper that we published in 2006 in the journal Science.

Consciousness is, perhaps, the most intimate of human mental experiences, and yet the hardest to explain. It is the faculty that allows us to read this sentence, to remember yesterday’s events, to derive pleasure from music and art, and to daydream about plans for tomorrow. It provides our experience of the world and yet is mysteriously altered, or absent altogether, when we fall asleep at night. Although consciousness is an essential property of being human, until recently, we have had almost no understanding of what it is and how it is created. Some of the work that we and others are doing, using modern advances in cognitive neuroscience has provided us with tools and concepts that are helping us to understand how consciousness emerges from the neural machinery of the brain. More specifically, some of our studies have provided important new clues about how best to measure consciousness. Until recently, the only way we could know that another human being was conscious was to ask them; no specific neuroimaging technique could tell you unequivocally that someone was conscious. However, some of the tools that we have developed recently allow you to do exactly that; simply by looking at the pattern of activity coming from someone's brain when they, say, watch a movie, we can now tell whether they are conscious of that experience or not.

A brain is really dead when it shows no activity at all and has no potential for becoming active ever again. This is what happens in a condition that is known as “brain death”. Patients who are brain dead are in a quite different situation to patients who are in a vegetative state, or in a minimally conscious state. Vegetative and minimally conscious patients do show brain activity – it is often not entirely normal and sometimes resembles the brain activity seen in somebody who is either asleep or deeply sedated with an anaesthetic agent. However, brain activity is clearly present. Patients who are brain dead never recover. On the other hand, patients who are vegetative or minimally conscious do, occasionally, recover, although it is rather rare.

Yes it can. In 2011 we published a paper in the medical journal The Lancet showing that EEG can be used to determine consciousness in patients who are assumed to be in a vegetative state. I would caution that it is not possible to do this successfully in every patient – like most techniques, there will always be so-called 'false negatives' (i.e. the results suggest that the patient is unconscious when in reality they are conscious), but the paper shows that it is certainly possible using EEG. I am attaching the paper for your interest.

You can survive for many years. Several of the patients described in my book have been in a vegetative state for almost 20 years, but it can certainly be longer than that. As long as patients are fed and hydrated (and medicated when needed) there is no direct reason why they would not live long lives. But typically they succumb to infections (like pneumonia) or die from complications stemming from their original brain injury.

Comatose patients appear to be unconscious. In many ways, they look like someone who has been deeply sedated using an anaesthetic agent like propofol. They do not respond to touch, sound or pain, and nothing can be done to awaken them. Because of this, it is very hard to say "what it is like" to be in a coma. My best guess would be that it is similar to being under a general anaesthetic; that is, there is nothing.....nothing to experience, nothing to understand and nothing to remember. That is what a profound state on unconsciousness must be like. The brains of comatose patients often show no signs of the normal sleep-wakefulness cycle, which means they are unlikely to be dreaming.

That’s a very good question and one that requires a very nuanced answer. It depends what you mean exactly by “can people in comas hear?” What we and others have shown is that when auditory stimuli such as speech are played to some patients who are comatose, the parts of the brain that are responsible for hearing (and processing speech), react normally. So in that sense, yes, people in comas can “hear”. However, whether any of them have any conscious experience of what their brains are responding to is an entirely different matter. We really don’t know. There are some clues that can be gleaned from studies in healthy participants. For example, some years ago my colleagues and I sedated healthy participants using the anaesthetic agent propofol. Just like the comatose patients, when we played these sedated healthy participants sounds, their brains responded just like an entirely conscious person’s brain would respond. Yet when they recovered consciousness, they had no memory of ever hearing any sounds. So rather like the comatose patients, although their brains certainly did “hear”, we do not know what that experience of “hearing” was like.

Yes there is. In 2010 my team and I published a paper in The New England Journal of Medicine, showing how it is possible to communicate with some patients who appear to be vegetative using a technique called functional magnetic resonance imaging (fMRI). While in the scanner, we asked a patient (who had appeared to be vegetative for five years) a series of simple questions that had “yes” and “no” answers. We asked him to imagine playing tennis if the answer to the question was “yes“ and to imagine walking from room to room in his house if the answer to the question was “no“. Because we are able to detect with fMRI whether someone is imagining playing tennis or imagining moving from room to room in their house, we were able to decode the patient’s “yes” and “no” answers. Despite appearing to be completely vegetative and unaware, he was perfectly able to correctly answer the questions, simply by changing his pattern brain activity. This was the first time anyone communicated with a patient who appeared to be vegetative, but was aware, although we have done it with quite a few patients since. We now commonly ask patients to tell us whether they are in pain, for example, and what their preferences are for watching TV, listening to music etc. I am attaching the paper for your interest.

Yes I have. I think our original discovery in 2006 that some patients who appear to be entirely vegetative may actually be conscious and aware made people realise that you can never really be sure about the conscious state of the patient. Even if they are entirely behaviourally non-responsive, they may still be in there, aware of every conversation in their presence, every decision that has ever been made about them, and every visitor they have ever had. I have seen this widely acknowledged now, and I believe it has changed the way people think about (and treat) this population of patients.

You might be surprised to learn that many people who have sustained a serious brain injury rate their “quality-of-life” much higher than we would imagine. I am attaching a paper that examines this issue and provides quite compelling evidence that just because a patient looks to be seriously brain damaged, it does not necessarily mean that they are also miserable. This concept is extremely important for my research program because we have found over the years that making assumptions about someone’s quality-of-life, based on what we think it must be like, is often incorrect and can be very harmful to the patient's general welfare. That is why, through my research program, we work hard to try to understand every patient as best we can and to communicate with them when we can, in order to find out what their wishes and desires may be. In doing so, we try as best we can to give them their “second best life”.

Near death experiences are not my area of expertise, so my reply here is from the perspective of someone who works with critically ill patients, but has not studied near death experiences directly. One point to remember is that when a patient is critically ill (for example, in the ICU with serious brain damage), they are more often than not very confused and disoriented. Indeed, delirium is extremely common in this patient population. We don’t know why this occurs exactly, but the original brain injury, the high doses of sedative drugs that these patients receive, and disrupted sleep may all play a role. Suffice it to say, with all this going on, it is not surprising to me that some patients will interpret events that happen, either in the outside world, or in their dreams and visions, to be a little 'supernatural' (for want of a better word).

There are several answers to that question and it depends what you are doing to the person, or expecting of the person, while they are in the scanner. If you are just scanning them with fMRI while they lie passively in the scanner, then there is no specific activity in the brain that will definitively indicate awareness. However, if you ask them to imagine certain scenarios such as playing a game of tennis, then activity in the premotor cortex (the part of the brain that is involved in imagining and setting up sequences of movements) can be used as evidence that they are aware. However, it is also important that activity in this region occurs exactly when the patient is asked to imagine playing tennis. Activity in the premotor cortex at any other time could be a chance occurrence, but when it happens immediately after you ask them to imagine playing tennis, it is clear that it is a 'response to command' (by analogy, if a vegetative patient moves their hand spontaneously then it could be a chance occurrence, but if they move their hand immediately after you ask them to, then it is likely a sign of awareness).

I think the answer to this question comes down to reliability and specificity. What I mean by this is that if a patient smiled once, but never again, it might well be a reflex or a muscle twitch and not indicative of any inner happy thoughts. But if a patient repeatedly smiled when his or her mother entered the room, then it might suggest that this was meaningful. That is where specificity comes in. If a patient were to smile at absolutely everyone and everything (including her/his mother), then again, it might suggest that there is not a true conscious emotion, or meaning, behind it. But a smile directed at a loved one, but not at a stranger, might suggest something more.

There is no simple answer to this question and it probably varies from patient to patient. The brain often shows incredible plasticity. What we mean by that is that, following an injury, it has an amazing ability to reorganise itself. It is likely that in some patients, recovery occurs because the functions of parts of the brain that were damaged get taken over by other non-damaged parts of the brain. We know this from studying stroke patients (who are not in a vegetative state); through long and dedicated rehabilitation, some stroke patients who have lost the use of a limb are able to regain use of that limb. In those cases, parts of the brain that were not previously dedicated to moving the limb take over that function from the damaged parts of the brain that were previously responsible for limb movement. Something similar may occur in some vegetative patients who experience recovery. The other possibility, of course, is that the damage parts of the brain are only temporarily damaged and after a period of time function can be gradually restored. This is rather similar to the concept of recovering from a general anaesthetic; in that case, the brain functions that are responsible for wakefulness and awareness are suppressed by the anaesthetic agent, yet as it wears off they come back online and regain their function. The reason why recovery is more common in the earlier days following a brain injury is because early recovery probably suggests less severe brain damage in the first place. If a patient survives more than 6 months or a year, yet is still in a vegetative state, the brain damage is likely to be so severe that they will never make a full recovery. However, having said all that, it is very important to remember that most patients who enter the vegetative state do not recover fully and, at best, experience very minor improvements in their medical condition, sometimes over many years.

I understand this position, but it’s one that I disagree with quite strongly. The first step in developing a treatment for any condition is to fully understand that condition. Until you really know what the underlying situation is, and what the cause is, it’s impossible to know how to begin to identify treatments. The comparison I often use it with cancer – in the 1970s and the 1980s, many types of cancer were completely untreatable and one might have argued back then that these people should just have been left to die because there was nothing we could do for them. However, many scientists worked very hard to try to understand those cancers and by understanding them, they were able to develop therapies to treat them. And now, many of those cancers are completely treatable. Similarly, many of us are working very hard to try to fully understand conditions like the vegetative state and other disorders of consciousness, in order to develop therapies that might eventually lead to effective treatments. Indeed, many potential therapeutic interventions are already been tried in various laboratories around the world and this is only possible because of the work that many scientists have done to understand these challenging conditions. To put it bluntly, no medical condition was ever cured by just leaving the affected patients alone and hoping that a cure would come along. On the other hand, hundreds of the worst ailments to have affected humankind have been eradicated by careful scientific examination and documentation of those patients who are most affected.

The vegetative state and locked in syndrome are very different conditions. In the vegetative state the patient is said to be “awake but unaware“. That is to say, they have sleeping and waking cycles, they may spontaneously open their eyes, but they show no signs whatsoever of any awareness. If you ask them to blink, for example, they will not blink. The assumption is that they have no residual consciousness (although as we have shown through our studies, sometimes that assumption can be incorrect).The locked in syndrome can appear to be similar in some respects to the vegetative state. Locked in patients also cannot speak or move and this can give the impression that they are not conscious. However, often they can still move their eyes or blink, and it is through these methods that they are able to convey that they are in fact conscious and aware. Indeed, for many locked in patients (unlike vegetative state patients) consciousness and all other aspects of thinking and reasoning are entirely preserved.