Posted By Dr. Anastasia Greenberg
For many, the term “vegetative state” brings to mind the American case of Terri Schiavo and her decade long legal battle (1992-2002) surrounding the “right-to-die”. Terri sustained serious brain damage in 1990 following a cardiac arrest, which led to an eventual diagnosis of a persistent vegetative state. Terri’s husband fought for the right to remove her feeding tube while her parents were desperate to keep her alive, believing she was conscious. Ultimately, Terri’s artificial life support was withdrawn in 2005, stirring an ongoing debate on the difficult ethical and legal implications in similar cases. Progress in neuroscience gives us hope in being able to answer key questions about brain and behaviour with direct relevance for the legislature and the courtroom.
Disorders of Consciousness
Vegetative state can be defined as “wakefulness without awareness”, in which patients show normal sleep-wake cycles (unlike a coma which is analogous to a deep sleep) but without any evidence of purposeful behaviour connected to awareness of the self or the environment. While wakefulness is straightforward to detect based on sustained eye opening and specific electroencephalogram (EEG) activity, the existence of awareness poses a much more complicated question.
In order to measure consciousness or awareness, we rely on behavioural evidence of “command following” as a proxy to make inferences about mental states. For example, locked-in syndrome patients have lost almost all ability to make voluntary movements but retain the ability to respond to “yes” or “no” questions by moving their eyes or eyelids in a consistent manner. This residual ability to form purposeful behaviour leaves no question that the patient is indeed conscious.
Advances in medical science have changed our understanding of consciousness in patients in a “vegetative” state. || (Source: Flickr // Presidencia de la República Mexicana)
Unfortunately, the difficulty with vegetative state patients is that they do not show any such meaningful behaviour or evidence of language comprehension. These patients will stare into space, move their eyes in an inconsistent manner and may even burst out into laugher or tears; however, none of these behaviours are linked to environmental stimuli.
For a long time, it was believed that such patients were completely unconscious. However, in the last decade this orthodox notion has faced serious scrutiny, regarding at least some of these patients, due in large part to the work of Canadian neuroscientist Dr. Adrian Owen from the University of Western Ontario.
Neural Activity as A Proxy for Behaviour
Dr. Owen’s research method allows certain patients who are labelled as vegetative to communicate solely by modulating their brain activity, recoded using functional magnetic resonance imaging (fMRI). fMRI makes inferences about brain activity indirectly by measuring blood flow, which is temporally linked to neural activity in that recently active cells require a fresh supply of oxygenated blood. This allows scientists to gauge which parts of the brain are involved in various cognitive tasks with high spatial resolution.
In a notable study, Dr. Owen’s team asked “vegetative state” patients in the fMRI scanner to imagine playing tennis or to imagine walking around their house from room to room. When healthy patients are asked to perform this same task, imagining playing tennis shows activation in a part of the brain called the supplementary motor area (SMA) while walking around the house activates parahippocampal corticies (PPA) which are involved in real and imaginary spatial navigation.
Remarkably, a portion of vegetative state patients (17%), diagnosed based on internationally recognized behavioural standards, show consistent SMA activity when instructed to imagine playing tennis and PPA activity in the case of walking around the house. Even more remarkably, they were then able to use imagining playing tennis or imagining walking around the house to respond “yes” or “no” to questions – with 100 percent accuracy. Using their imagination, this select group of vegetative state patients responded correctly to questions about their own name, their parents’ names, the current year, and so forth.
These findings make legal characterizations pertaining to the decision to withdraw nutrition and hydration even more complicated. In a personal communication with Dr. Owen, he mentioned that one such patient was asked whether he wished to continue living. He responded: “yes”. This is exciting news in the context of legal decision-making; perhaps we could simply ask the fMRI-responsive patients to decide their own fate.
fMRI scans allow doctors to prompt and make inferences about neural activity in patients in a “vegetative” state, in some cases enabling a limited channel of communication. || (Source: Flickr // NIH Image Gallery)
But what can be said for the remaining 83% of patients? Can we conclude that they are simply not conscious, and thus truly fit their derogatory label of “vegetative”? The problem with such a conclusion is one of false negatives. When someone consistently “responds” to high-level questions with their brain activity, we can be sure of their consciousness – arguably to the same extent as someone who is saying “yes” and “no” in plain English (or French).
However, when a vegetative patient fails to show any meaningful fMRI responses, we cannot be certain that they are not conscious. Consider, for example, patients that have lost function in their auditory cortex and thus cannot hear the task instruction nor questions – not to mention many more nuanced neural complications that may prevent successful performance despite consciousness.
Legal Applications for Neuroscience Data
Dr. Owen’s work has received enormous media attention and, most relevant to the legal context, Dr. Owen recently submitted an affidavit that was admitted into evidence by the Supreme Court of British Columbia (BC) in Ng v Ng (2013). Kenny Ng was involved in a motor vehicle collision that left him in a minimally conscious state (higher functioning than vegetative) from 2005 onward. Kenny’s wife, who was entitled to give substitute consent for Kenny under BC’s Patient’s Property Act (PPA) and Health Care (Consent) and Care Facility (Admission) Act (HCCFA), decided to take Kenny off of life support in spite of opposition from his siblings.
In a personal communication with Dr. Owen, he mentioned that one such patient was asked whether he wished to continue living. He responded: “yes”.
Dr. Owen’s affidavit could not speak specifically to Kenny’s case given that Kenny never participated in any studies by Dr. Owen’s team. However, it suggested that Kenny could potentially fall into the category of those with awareness and is a good candidate for further study. Ultimately, though, the court ruled in favour of Kenny’s wife since she held the decision-making authority pursuant to legislation and since the removal of feeding was found to be reasonable given the available medical evidence supporting Kenny’s poor clinical prognosis. The court had no legal mechanism by which to order that Kenny be tested by Dr. Owen, a neuroscientist, and set aside the recommendations of Kenny’s team of medical doctors.
An Eye to the Future
The potential applications of neuroscientific evidence in courtrooms and in end-of-life legislation are exponentially increasing. Publications in the developing study of neuroscience and law, coined “neurolaw”, have spiked since 2006. Both neuroscientists and legal scholars express optimism, but they also emphasize erring on the side of caution when admitting flashy neuroscience into court. While the direct legal relevance of Dr. Owen’s work for use in a courtroom setting is persuasive, it also presents many opportunities for abuse, or innocent misinterpretation, of neuroscientific information.
US courts have admitted brain scans (including fMRI) into evidence in criminal cases involving insanity defenses (called defense of mental disorder in Canada), as well as highly controversial fMRI lie-detection evidence. In Canada, fMRI data has not yet seen its day in court and may raise serious Charter issues in relation to brain privacy. Dr. Owen’s affidavit in Ng v Ng is one of only two Canadian cases to ever mention fMRI in more than an incidental way. In a controversial ruling in Italy, a court reduced a sentence for murder after being presented with neuroscientific evidence in the form of brain scans and genetic evidence that suggested links to poor impulse control.
Legislators and the courts will have to grapple with the risks and benefits of allowing the adducement of neuroscientific evidence before a judge. || (Source: Flickr // Jordan Schulz)
A deep understanding of neuroscientific technology and methodology is invaluable in drawing valid conclusions based on the data presented. A jury may interpret a colourful fMRI image as analogous to an X-ray – being able to “see” brain activity – when in fact the image is created through a series of inferential steps involving complicated statistical analyses performed on the data. These steps are peppered with human decisions about which statistical thresholds are to be used, which behavioural conditions should be compared, and so forth. Concerns over “overclaim syndrome” relate to the persuasive “wow” factor neuroscientific evidence evokes. In one study, mock jurors were more likely to give a verdict of “not guilty” if a defense of mental disorder was presented along with MRI images.
Neuroscientific evidence also has the potential to influence end-of-life legislation, such as BC’s PPA and HCCFA that were used to transfer consent to Kenny’s wife, by requiring neuroscientific interventions before transferring consent. Currently, however, such a provision can only exist in the parliament of dreams, as neuroscientific tests of consciousness are far from routine procedures.
Neuroscience and law have begun to converge, developing the field of neurolaw with international neurolaw conferences and societies bringing scholars and practitioners from both disciplines together to explore their mutual interests. Professor Henry T Greely of Stanford Law School predicts that neuroscience will revolutionize the law: while the consequences of this neurolaw revolution carry serious risks, a future that offers a “window into the mind” may prove more conducive to justice. For those conscious patients trapped behind a “vegetative” label, neuroscientific evidence may provide sufficient weight to tip the scales of justice.
Dr. Greenberg holds a PhD in Neuroscience from the University of Alberta, and recently began studies at the McGill Faculty of Law.