fMRI reveals large-scale network activation in minimally conscious patients

The sometimes pernicious role of theory in science

The role of theory in science is discussed in the context of understanding brain function. Historically, theories of brain functions have oscillated between localization and anti-localization beliefs. In the last 50 years, the important discoveries of the ascending reticular activating system (ARAS), feature extracting neurons and synaptic growth led many to orthodoxy. Research became more and more focused upon the elements comprising the nervous system and their interconnections. The mainstream belief became that many brain functions including consciousness were localized, certain kinds of brain injuries produced irreversible functional deficits. Contrary scientific challenges were discouraged by the omnipresence of such theory. Examples of theoretical "Einstellungen" in the areas of ARAS, coma, treatment of brain injuries and consciousness are given, as well as signs that the pendulum is swinging back to an approach to the system as a whole rather than a focus on its parts.

The experience of surviving traumatic brain injury

AIM

This paper reports a study describing the experience of surviving traumatic brain injury as narrated by individuals 1 year after injury.

BACKGROUND

The experience of surviving traumatic brain injury is an individual and invisible experience. Healing and resolution of grief is still problematic for many years after injury. This experience includes those with severe injury. There is limited literature focusing on the survivor.

METHODOLOGY

Sixty people with hospital admission diagnoses of traumatic brain injury were interviewed 1 year after injury using the Extended Glasgow Outcome Score questionnaire. Survivors then described their experiences of recovery. Data were collected through unstructured in-depth interviews, transcribed from audio-tapes and analysed into references. Qualitative content analysis was used to compile their frequencies from recurring themes.

FINDINGS

Sixty survivors with a median age of 35 years were enrolled in the study, with 100% follow-up. Twelve per cent returned to full preinjury functioning, 35% had residual psychosocial and physical sequelae, 38% had significant restrictions in lifestyle and work capacity, and 15% were unable to care for themselves throughout the 24-hour period. The common narratives were classified into five categories: 'regret and grief within self'; 'insensitivity of health professionals'; 'invisibility of self'; 'stranded self'; and 'recovery in self'. These self-narratives reflected renewed ways to view the self, which were conceptualized to be intact 'in spite of' or to be worthwhile 'because of' the traumatic brain injury.

CONCLUSIONS

Self-narratives could be a worthwhile focus of psychological intervention by substituting positive narratives for negative ones, demonstrating hope and a positive outlook on life in order to enhance self-reflection and improve mental health. They can assist people to minimize, avoid or overcome devaluation and, as such, provide a basis for considerable nursing rehabilitation practice, even in those with severe injury.

Prognostic value of evoked and event-related potentials in moderate to severe brain injury

Clinicians are often expected to project patients' clinical outcomes to allow effective planning for future care. This can be a challenge in patients with moderate to severe traumatic brain injury (TBI) who are often unable to participate reliably in clinical evaluations. With recent advances in computer instrumentation and signal processing, evoked potentials and event-related potentials show increasing promise as powerful tools for prognosticating the trajectory of recovery and ultimate outcome from the TBI. Short- and middle-latency evoked potentials can now effectively predict coma outcomes in patients with acute TBI. Long-latency event-related potential components hold promise in predicting recovery of higher order cognitive abilities.

Possible axonal regrowth in late recovery from the minimally conscious state

We used diffusion tensor imaging (DTI) to study 2 patients with traumatic brain injury. The first patient recovered reliable expressive language after 19 years in a minimally conscious state (MCS); the second had remained in MCS for 6 years. Comparison of white matter integrity in the patients and 20 normal subjects using histograms of apparent diffusion constants and diffusion anisotropy identified widespread altered diffusivity and decreased anisotropy in the damaged white matter. These findings remained unchanged over an 18-month interval between 2 studies in the first patient. In addition, in this patient, we identified large, bilateral regions of posterior white matter with significantly increased anisotropy that reduced over 18 months. In contrast, notable increases in anisotropy within the midline cerebellar white matter in the second study correlated with marked clinical improvements in motor functions. This finding was further correlated with an increase in resting metabolism measured by PET in this subregion. Aberrant white matter structures were evident in the second patient's DTI images but were not clinically correlated. We propose that axonal regrowth may underlie these findings and provide a biological mechanism for late recovery. Our results are discussed in the context of recent experimental studies that support this inference.

Neuroethics: a modern context for ethics in neuroscience

Neuroethics, a recently modernized field at the intersection of bioethics and neuroscience, is founded on centuries of discussion of the ethical issues associated with mind and behavior. Broadly defined, neuroethics is concerned with ethical, legal and social policy implications of neuroscience, and with aspects of neuroscience research itself. Advances in neuroscience increasingly challenge long-held views of the self and the individual's relationship to society. Neuroscience also has led to innovations in clinical medicine that have not only therapeutic but also non-therapeutic dimensions that extend well beyond previously charted boundaries. The exponential increase in cross-disciplinary research, the commercialization of cognitive neuroscience, the impetus for training in ethics, and the increased attention being paid to public understanding of science all illuminate the important role of neuroethics in neuroscience.

Autonomic reactivity to sensory stimulation is related to consciousness level after severe traumatic brain injury

OBJECTIVE

To examine changes in the activity of the autonomic nervous system (ANS) that are related to recovery to consciousness in the post-acute phase after severe traumatic brain injury (sTBI).

METHODS

Skin conductance and heart rate reactivity to sensory stimulation were recorded every 2 weeks for an average period of 3.5 months in 16 adolescent patients, during the assessment of their level of consciousness (LoC), and their cognitive and functional behaviour.

RESULTS

Both heart rate variability (HRV) and skin conductance level (SCL) in reaction to sensory stimulation changed with recovery to consciousness. Indices of HRV and SCL that represent sympathetic activity of the autonomic nervous system (ANS) increased with recovery, whereas indices that represent parasympathetic activity decreased. In addition, we observed an increase in sympathovagal balance of the ANS with recovery.

CONCLUSIONS

Recovery to consciousness determined by clinical observation in sTBI in the post-acute phase is related to changes in SCL and HRV during sensory stimulation. ANS reactivity to environmental stimulation can therefore give objective supplementary information about the clinical state of sTBI patients, and can contribute to decision-making in the treatment policy of unresponsive patients.

SIGNIFICANCE

These findings demonstrate that autonomic reactivity can be informative concerning how a severely damaged nervous system reacts to environmental stimulation and how, in a recovering nervous system, this reactivity changes.

Neurorehabilitation issues in states of disordered consciousness following traumatic brain injury

The assessment and care of persons with disorders of consciousness (DOC) following catastrophic traumatic brain injury is often difficult and filled with both challenges and potential controversies. Rates of misdiagnosis of low-level neurological state (LLNS) patients with signs of awareness as being vegetative have been noted to be unacceptably high and call for better education and training regarding the assessment methodologies of individuals with DOC. Clinician knowledge regarding prognostication and neural recovery from LLNSs following traumatic brain injury is often lacking, as is awareness of the neurorehabilitative interventions that can potentially facilitate recovery, as well as minimize morbidity and mortality in this unique population of neurological patients.

Chronic disorders of consciousness

The vegetative state and the minimally conscious state are disorders of consciousness that can be acute and reversible or chronic and irreversible. Diffuse lesions of the thalami, cortical neurons, or the white-matter tracts that connect them cause the vegetative state, which is wakefulness without awareness. Functional imaging with PET and functional MRI shows activation of primary cortical areas with stimulation, but not of secondary areas or distributed neural networks that would indicate awareness. Vegetative state has a poor prognosis for recovery of awareness when present for more than a year in traumatic cases and for 3 months in non-traumatic cases. Patients in minimally conscious state are poorly responsive to stimuli, but show intermittent awareness behaviours. Indeed, findings of preliminary functional imaging studies suggest that some patients could have substantially intact awareness. The outcomes of minimally conscious state are variable. Stimulation treatments have been disappointing in vegetative state but occasionally improve minimally conscious state. Treatment decisions for patients in vegetative state or minimally conscious state should follow established ethical and legal principles and accepted practice guidelines of professional medical specialty societies.

The neuroscience of observing consciousness & mirror neurons in therapeutic hypnosis

Neuroscience documents the activity of "mirror neurons" in the human brain as a mechanism whereby we experience empathy and recognize the intentions of others by observing their behavior and automatically matching their brain activity. This neural basis of empathy finds support in research on dysfunctions in the mirror systems of humans with autism and fMRI research on normal subjects designed to assess intentionality, emotions, and complex cognition. Such empathy research now appears to be consistent with the historical and research literature on hypnotic induction, rapport, and many of the classical phenomena of suggestion. A preliminary outline of how mirror neurons may function as a rapport zone mediating between observing consciousness, the gene expression/protein synthesis cycle, and brain plasticity in therapeutic hypnosis and psychosomatic medicine is proposed. Brain plasticity is generalized in the theory, research, and practice of utilizing mirror neurons as an explanatory framework in developing and training new skill sets for facilitating an activity-dependent approach to creative problem solving, mind-body healing, and rehabilitation with therapeutic hypnosis.

Residual cognitive function in comatose, vegetative and minimally conscious states

PURPOSE OF REVIEW

The clinical evaluation of cognition in non-communicative severely brain-damaged patients is inherently difficult. In addition to novel behavioural 'consciousness-scales', the role of para-clinical markers of consciousness, such as event related potentials and functional neuroimaging is reviewed.

RECENT FINDINGS

New behavioural scales for vegetative and minimally conscious patients have been shown to reduce diagnostic error but regrettably remain underused in clinical routine. Electrophysiological studies have confirmed their role in estimating outcome and possibly cognition. Several recent functional neuroimaging studies have shown residual cortical function in undeniably vegetative patients. This cortical activation, however, seems limited to primary 'low-level' areas and does not imply 'higher-order' integration, considered necessary for conscious perception. Minimally conscious patients show large-scale high-order cerebral activation, apparently dependent upon the emotional relevance of the stimulation.

SUMMARY

Careful clinical assessment of putative 'conscious behaviour' in vegetative and minimally conscious patients is the first requirement for their proper diagnosis and management. Complementary functional neuroimaging and electrophysiological studies will have a major impact on future clinical decision making and may guide selective therapeutic options. At present, more experimental evidence and the elucidation of methodological and ethical controversies are awaited prior to their routine clinical use.

Science and society: death, unconsciousness and the brain

The concept of death has evolved as technology has progressed. This has forced medicine and society to redefine its ancient cardiorespiratory centred diagnosis to a neurocentric diagnosis of death. The apparent consensus about the definition of death has not yet appeased all controversy. Ethical, moral and religious concerns continue to surface and include a prevailing malaise about possible expansions of the definition of death to encompass the vegetative state or about the feared bias of formulating criteria so as to facilitate organ transplantation.

The neural correlate of (un)awareness: lessons from the vegetative state

Consciousness has two main components: wakefulness and awareness. The vegetative state is characterized by wakefulness without awareness. Recent functional neuroimaging results have shown that some parts of the cortex are still functioning in 'vegetative' patients. External stimulation, such as a painful stimulus, still activates 'primary' sensory cortices in these patients but these areas are functionally disconnected from 'higher order' associative areas needed for awareness. Such studies are disentangling the neural correlates of the vegetative state from the minimally conscious state, and have major clinical consequences in addition to empirical importance for the understanding of consciousness.

Clinical diagnosis of prolonged states of impaired consciousness in adults

A prolonged state of impaired consciousness is a devastating consequence of severe structural brain injury but fortunately is uncommon. Patients may be diagnosed as being in a persistent vegetative state, having akinetic mutism, or being in a minimally conscious state. These conditions can be distinguished from each other by a comprehensive clinical neurologic examination. Recovery is determined by age, cause, and time in such state. For patients diagnosed as being in a permanent (irreversible) vegetative state, hope for a clinically meaningful recovery is unrealistic after 1 year. Prolonged survival is possible only with meticulous care and aggressive medical intervention to prevent and treat systemic complications.

Raising consciousness

The national debate over Terri Schiavo exposed a critical gap between emotional fervor about brain-injured patients and the medical science that informs standards of care for them. Some of the questions raised in the public and legal forums point to a need for research and enhanced understanding of the mechanisms of recovery from disorders of consciousness.

Modeling the minimally conscious state: measurements of brain function and therapeutic possibilities

The minimally conscious state (MCS) defines a functional level of recovery following severe brain injuries. Patients in MCS demonstrate unequivocal evidence of response to their environment yet fail to recover the ability to communicate. Drawing on recent functional brain-imaging studies, pathological data, and neurophysiological investigations, models of brain function in MCS are proposed. MCS models are compared and contrasted with models of the vegetative state (VS), a condition characterized by wakeful appearance and unconsciousness. VS reflects a total loss of cognitive function and failure to recover basic aspects of the normal physiologic brain state associated with wakefulness. MCS may represent a recovery of the minimal dynamic architecture required to organize behavioral sets and respond to sensory stimuli. Several pathophysiological mechanisms that might limit further recovery in MCS patients are considered. Implications for future research directions and possible therapeutic strategies are reviewed.

Imaging or imagining? A neuroethics challenge informed by genetics

From a twenty-first century partnership between bioethics and neuroscience, the modern field of neuroethics is emerging, and technologies enabling functional neuroimaging with unprecedented sensitivity have brought new ethical, social and legal issues to the forefront. Some issues, akin to those surrounding modern genetics, raise critical questions regarding prediction of disease, privacy and identity. However, with new and still-evolving insights into our neurobiology and previously unquantifiable features of profoundly personal behaviors such as social attitude, value and moral agency, the difficulty of carefully and properly interpreting the relationship between brain findings and our own self-concept is unprecedented. Therefore, while the ethics of genetics provides a legitimate starting point--even a backbone--for tackling ethical issues in neuroimaging, they do not suffice. Drawing on recent neuroimaging findings and their plausible real-world applications, we argue that interpretation of neuroimaging data is a key epistemological and ethical challenge. This challenge is two-fold. First, at the scientific level, the sheer complexity of neuroscience research poses challenges for integration of knowledge and meaningful interpretation of data. Second, at the social and cultural level, we find that interpretations of imaging studies are bound by cultural and anthropological frameworks. In particular, the introduction of concepts of self and personhood in neuroimaging illustrates the interaction of interpretation levels and is a major reason why ethical reflection on genetics will only partially help settle neuroethical issues. Indeed, ethical interpretation of such findings will necessitate not only traditional bioethical input but also a wider perspective on the construction of scientific knowledge.

Currents in contemporary ethics. The confidentiality and privacy implications of functional magnetic resonance imaging

Advances in science and technology frequently raise new ethical, legal, and social issues, and developments in neuroscience and neuroimaging technology are no exception. Within the field of neuroethics, leading scientists, ethicists, and humanists are exploring the implications of efforts to image, study, treat, and enhance the human brain.

This article focuses on one aspect of neuroethics: the confidentiality and privacy implications of advances in functional magnetic resonance imaging (“fMRI”). Following a brief orientation to fMRI and an overview of some of its current and proposed uses, this article highlights key confidentiality and privacy issues raised by fMRI in the contexts of health care, research, employment, insurance, criminal justice, litigation, and cognitive privacy.

Functional neuroimaging during altered states of consciousness: how and what do we measure?

The emergence of functional neuroimaging has extended the doctrine of functional specificity of the brain beyond the primary stages of perception, language, and motor systems to high-level cognitive, personality, and affective systems. This chapter applies functional magnetic resonance imaging to another high-level realm of cognition and neurology to characterize cortical function in patients with disorders of consciousness. At first pass, this objective appears paradoxical because conventional investigations of a cognitive process require experimental manipulation. For example, to map the location of language-sensitive cortex, a language-related task is performed according to a temporal sequence that alternates the task with rest (no-task) periods. Application of this approach to the study of consciousness would require that levels of consciousness be similarly varied, this is an unlikely technique. Alternatively, another strategy is presented here where the focus is on functional brain activity elicited during various passive stimulations of patients who are minimally conscious. Comparisons between patients with altered states of consciousness due to brain injury and healthy subjects may be employed to infer readiness and potential to sustain awareness. As if a behavioral microscope, fMRI enables a view of occluded neural processes to inform medical practitioners about the health of the neurocircuity-mediating cognitive processes. An underlying point of view is that assessment of recovery potential can be enhanced by neuroimaging techniques that reveal the status of residual systems specialized for essential cognitive and volitional tasks for each patient. Thus, development of imaging techniques that assess the functional status of individual unresponsive patients is a primary goal. The structural integrity of injured brains is often compromised depending on the specific traumatic event, and, therefore, images cannot be grouped across patients, as is the standard practice for investigations of cognitive systems in healthy volunteers. This chapter addresses these challenges and discusses technique adaptations associated with passive stimulation, paradigm selection, and individual patient assessments, where there is "zero tolerance for error," and confidence in the results must meet the highest standards of care. Similar adaptations have been previously developed for the purpose of personalized planning for neurosurgical procedures by mapping the locations of essential functional systems such as language, perception, and sensory-motor functions for each individual patient. Rather than addressing the question of "how does the brain do consciousness" with these techniques, this chapter presents methods for assessment of neurocognitive health in specific patients with disorders of consciousness.

Clinicians, patients, and the brain

This chapter focuses on where and how several key neuroethical issues converge and diverge in diagnosis and treatment. First, it examines the broad obstacles that exist to addressing neuroethical problems optimally in clinical settings. Secondly, it explores ways that these barriers manifest themselves specifically in diagnostic tests that use neuroimaging and neurogenomics, and other clinical scenarios that involve treatment interventions. It discusses several sets of predicaments that appear likely to emerge, although others will no doubt confront clinicians as neurotechnology continues to advance.