Organ donation after the circulatory determination of death requires the permanent cessation of circulation while organ donation after the brain determination of death requires the irreversible cessation of brain functions. The unified brain-based determination of death connects the brain and circulatory death criteria for circulatory death determination in organ donation as follows: permanent cessation of systemic circulation causes permanent cessation of brain circulation which causes permanent cessation of brain perfusion which causes permanent cessation of (...) brain function. The relevant circulation that must cease in circulatory death determination is that to the brain. Eliminating brain circulation from the donor ECMO organ perfusion circuit in thoracoabdominal NRP protocols satisfies the unified brain-based determination of death but only if the complete cessation of brain circulation can be proved. Despite its medical and physiologic rationale, the unified brain-based determination of death remains inconsistent with the Uniform Determination of Death Act. (shrink)

Abstract:Disturbing cases continue to be published of patients declared brain dead who later were found to have a few intact brain functions. We address the reasons for the mismatch between the whole-brain criterion and brain death tests, and suggest solutions. Many of the cases result from diagnostic errors in brain death determination. Others probably result from a tiny amount of residual blood flow to the brain despite intracranial circulatory arrest. Strategies to lessen the mismatch (...) include improving brain death determination training for physicians, mandating a test showing complete intracranial circulatory arrest, or revising the whole-brain criterion. (shrink)

“Brain death,” the determination of human death by showing the irreversible loss of all clinical functions of the brain, has become a worldwide practice. A biophilosophical account of brain death requires four sequential tasks: agreeing on the paradigm of death, a set of preconditions that frame the discussion; determining the definition of death by making explicit the consensual concept of death; determining the criterion of death that proves the definition has been fulfilled by being both necessary and (...) sufficient for death; and determining the tests of death for physicians to employ at the patient's bedside to demonstrate that the criterion of death has been fulfilled. The best definition of death is “the cessation of functioning of the organism as a whole.” The whole-brain criterion is the only criterion that is both necessary and sufficient for death. Brain death tests are used only in the unusual case in which a patient's ventilation is being supported. Brain death critics have identified weaknesses in its formulation. But despite its shortcomings, the whole-brain death formulation comprises a concept and public policy that make intuitive and practical sense and that has been well accepted by many societies. (shrink)

The publicity surrounding the recent McMath and Muñoz cases has rekindled public interest in brain death: the familiar term for human death determination by showing the irreversible cessation of clinical brain functions. The concept of brain death was developed decades ago to permit withdrawal of therapy in hopeless cases and to permit organ donation. It has become widely established medical practice, and laws permit it in all U.S. jurisdictions. Brain death has a biophilosophical justification as a (...) standard for determining human death but remains poorly understood by the public and by health professionals. The current controversies over brain death are largely restricted to the academy, but some practitioners express ambivalence over whether brain death is equivalent to human death. Brain death remains an accepted and sound concept, but more work is necessary to establish its biophilosophical justification and to educate health professionals and the public. (shrink)

The definition of death is one of the oldest and most enduring problems in biophilosophy and bioethics. Serious controversies over formally defining death began with the invention of the positive-pressure mechanical ventilator in the 1950s. For the first time, physicians could maintain ventilation and, hence, circulation on patients who had sustained what had been previously lethal brain damage. Prior to the development of mechanical ventilators, brain injuries severe enough to induce apnea quickly progressed to cardiac arrest from hypoxemia. (...) Before the 1950s, the loss of spontaneous breathing and heartbeat were perfect predictors of death because the functioning of the brain and of all other organs ceased rapidly and nearly simultaneously thereafter, producing a unitary death phenomenon. In the pretechnological era, physicians and philosophers did not have to consider whether a human being who had lost certain “vital functions” but had retained others was alive, because such cases were technically impossible. (shrink)

The concept of whole‐brain death is under attack again. Scholars are arguing that the concept of brain death per se—regardless of the focus on “higher,” “stem” or “whole”—is fundamentally flawed. These scholars have identified what they believe are serious discrepancies between the definition and criterion of brain death, and have pointed out that medical professionals and lay persons remain confused about its meaning. Yet whole‐brain death remains the standard for determining death in much of the Western (...) world and its defenders believe this concept best maps onto our everyday conception of death. (shrink)

In a seminal 1977 article, Rumelhart argued that perception required the simultaneous use of multiple sources of information, allowing perceivers to optimally interpret sensory information at many levels of representation in real time as information arrives. Building on Rumelhart's arguments, we present the Interactive Activation hypothesis—the idea that the mechanism used in perception and comprehension to achieve these feats exploits an interactive activation process implemented through the bidirectional propagation of activation among simple processing units. We then examine the interactive activation (...) model of letter and word perception and the TRACE model of speech perception, as early attempts to explore this hypothesis, and review the experimental evidence relevant to their assumptions and predictions. We consider how well these models address the computational challenge posed by the problem of perception, and we consider how consistent they are with evidence from behavioral experiments. We examine empirical and theoretical controversies surrounding the idea of interactive processing, including a controversy that swirls around the relationship between interactive computation and optimal Bayesian inference. Some of the implementation details of early versions of interactive activation models caused deviation from optimality and from aspects of human performance data. More recent versions of these models, however, overcome these deficiencies. Among these is a model called the multinomial interactive activation model, which explicitly links interactive activation and Bayesian computations. We also review evidence from neurophysiological and neuroimaging studies supporting the view that interactive processing is a characteristic of the perceptual processing machinery in the brain. In sum, we argue that a computational analysis, as well as behavioral and neuroscience evidence, all support the Interactive Activation hypothesis. The evidence suggests that contemporary versions of models based on the idea of interactive activation continue to provide a basis for efforts to achieve a fuller understanding of the process of perception. (shrink)

Nair-Collins and Joffe (2023) highlighted the noncongruence between the language of the Uniform Determination of Death Act (UDDA) and the accepted brain death bedside testing standard by showing th...

In this interview, James L. McClelland responds to questions regarding connectionist models of cognition, a theory inspired by information processing in the brain. McClelland explains the distinction between symbolic and non-symbolic processing for a better understanding of mental processes. He argues that connectionist models can perform the computations which we know the brain can perform. In addition, he responds to several general questions on the perspectives of computational models of cognition.

Notwithstanding these wise pronouncements, my project here is to characterize the biological phenomenon of death of the higher animal species, such as vertebrates. My claim is that the formulation of “whole- brain death ” provides the most congruent map for our correct understanding of the concept of death. This essay builds upon the foundation my colleagues and I have laid since 1981 to characterize the concept of death and refine when this event occurs. Although our society's well-accepted program of (...) multiple organ procurement for transplantation requires the organ donor first to be dead, the concept of brain death is not merely a social contrivance to permit us to obtain the benefits of organ procurement. Rather, the concept of whole- brain death stands independently as the most accurate biological representation of the demise of the human organism. (shrink)

Among the old and new controversies over brain death, none is more fundamental than whether brain death is equivalent to the biological phenomenon of human death. Here, I defend this equivalency by offering a brief conceptual justification for this view of brain death, a subject that Andrew Huang and I recently analyzed elsewhere in greater detail. My defense of the concept of brain death has evolved since Bernard Gert, Charles Culver, and I first addressed it in (...) 1981, a development that paralleled advances in intensive care unit treatment. The century‐old concept of the organism as a whole provides the fundamental justification for the equivalency of brain death and human death. In our technological age, in which increasing numbers of components and systems of an organism can be kept alive, and for longer intervals, the permanent cessation of functioning of the organism as a whole is the phenomenon that best corresponds to its death. (shrink)

Ariane Lewis provided an insightful review of several controversial cases of death by neurologic criteria (“brain death”) in the UK, focusing on Archie Battersbee, a boy whose tragic illness provok...

The Uniform Determination of Death Act (UDDA) provides that “an individual who has sustained either (1) irreversible cessation of circulatory and respiratory functions or (2) irreversible cessation of all functions of the entire brain, including the brain stem, is dead.” We show that the UDDA contains two conflicting interpretations of the phrase “cessation of functions.” By one interpretation, what matters for the determination of death is the cessation of spontaneous functions only, regardless of their generation by artificial means. (...) By the other, what matters is the cessation of both spontaneous and artificially supported functions. Because each UDDA criterion uses a different interpretation, the law is conceptually inconsistent. A single consistent interpretation would lead to the conclusion that conscious individuals whose respiratory and circulatory functions are artificially supported are actually dead, or that individuals whose brain is entirely and irreversibly destroyed may be alive. We explore solutions to mitigate the inconsistency. (shrink)

The locked-in syndrome is a state of profound paralysis with preserved awareness of self and environment who typically results from a brain stem stroke. Although patients in LIS have great difficulty communicating, their consciousness, cognition, and language usually remain intact. Medical decision-making by LIS patients is compromised, not by cognitive impairment, but by severe communication impairment. Former systems of communication that permitted LIS patients to make only “yes” or “no” responses to questions was sufficient to validate their consent for (...) simple medical decisions but not for consequential medical decisions such as whether to refuse further life-sustaining therapy. Emerging technologies including computer-tracking assistance of retained partial motor function and brain-computer interfaces promise to improve the communication ability of LIS patients and, when better developed, will allow them to fully exercise their right to actively participate in consequential medical decisions about their own medical care. Although so-called “covert cognition” patients clinically diagnosed as vegetative state that are shown to be aware by functional neuroimaging maybe metaphorically considered locked-in, it is nosologically more coherent not to categorize them formally as LIS. (shrink)

Different developmental anomalies produce contrasting deficits in a single, integrated system. In a network that inflects regular and exception verbs correctly, a disproportionate deficit with exceptions occurs if connections are deleted, whereas a disproportionate deficit with regulars occurs when an auditory deficit impairs perception of the regular inflection. In general, contrasting deficits do not license the inference of underlying modularity.

Psychiatric Medicine has been accused justly of making its diagnoses on the patient's report of symptoms and the physician's subjective observations of the patient. The main problem has been the lack of reliable data compounded by the stigma of a mental diagnosis. More recently, third-party pressures have become an added threat to objectivity. New knowledge of brain function, especially neurotransmitters, and more specific and effective medication have made the need for accurate diagnoses more acute. Psychiatry has responded by frequent (...) and often controversial changes in its diagnostic criteria. Much of the controversy stems from a lack of accurate measurements to validate the diagnoses, thereby allowing for differences of opinion of a highly subjective nature. The problem is complicated by the chronic, but irrational, belief that there is a separation between mental and somatic illness. Keywords: calibration, diagnoses, objective vs. subjective, stigma, third-party CiteULike Connotea Del.icio.us What's this? (shrink)

Andrews et al. criticize Gould and colleagues for (1) failing to provide evidentiary criteria for accepting exaptationist alternatives to adaptationist explanations, and (2) seeing exaptations and spandrels as being far more frequent than adaptations in the evolutionary history of modern humans. I argue that the first of these criticisms is wrong, and the second reflects a bias for the classical version of Darwinian evolutionary theory, which Gould was trying to expand by proposing concepts like exaptation and spandrels.

We share with Anderson & Lebiere (A&L) (and with Newell before them) the goal of developing a domain-general framework for modeling cognition, and we take seriously the issue of evaluation criteria. We advocate a more focused approach than the one reflected in Newell's criteria, based on analysis of failures as well as successes of models brought into close contact with experimental data. A&L attribute the shortcomings of our parallel-distributed processing framework to a failure to acknowledge a symbolic level of thought. (...) Our framework does acknowledge a symbolic level, contrary to their claim. What we deny is that the symbolic level is the level at which the principles of cognitive processing should be formulated. Models cast at a symbolic level are sometimes useful as high-level approximations of the underlying mechanisms of thought. The adequacy of this approximation will continue to increase as symbolic modelers continue to incorporate principles of parallel distributed processing. (shrink)

Although death statutes permitting physicians to declare brain death are relatively uniform throughout the United States, academic debate persists over the equivalency of human death and brain death. Alan Shewmon showed that the formerly accepted integration rationale was conceptually incomplete by showing that brain-dead patients demonstrated a degree of integration. We provide a more complete rationale for the equivalency of human death and brain death by defending a deeper understanding of the organism as a whole and (...) by using a novel strategy with shared objectives to justify death determination criteria. Our OaaW account describes different types of OaaW, defining human death as the loss of status as a human OaaW. We defend human death as similar to nonhuman death in terms of wakefulness, but also distinct in terms of the sui generis properties, particularly conscious awareness. We thereby defend the equivalency of brain death and human death using a resulting neurocentric rationale. (shrink)

In this prcis we focus on phenomena central to the reaction against similarity-based theories that arose in the 1980s and that subsequently motivated the approach to semantic knowledge. Specifically, we consider (1) how concepts differentiate in early development, (2) why some groupings of items seem to form or coherent categories while others do not, (3) why different properties seem central or important to different concepts, (4) why children and adults sometimes attest to beliefs that seem to contradict their direct experience, (...) (5) how concepts reorganize between the ages of 4 and 10, and (6) the relationship between causal knowledge and semantic knowledge. The explanations our theory offers for these phenomena are illustrated with reference to a simple feed-forward connectionist model. The relationships between this simple model, the broader theory, and more general issues in cognitive science are discussed. (shrink)

Page's proposal to stipulate representations in which individual units correspond to meaningful entities is too unconstrained to support effective theorizing. An approach combining general computational principles with domain-specific assumptions, in which learning is used to discover representations that are effective in solving tasks, provides more insight into why cognitive and neural systems are organized the way they are.

The commentaries reflect three core themes that pertain not just to our theory, but to the enterprise of connectionist modeling more generally. The first concerns the relationship between a cognitive theory and an implemented computer model. Specifically, how does one determine, when a model departs from the theory it exemplifies, whether the departure is a useful simplification or a critical flaw? We argue that the answer to this question depends partially upon the model's intended function, and we suggest that connectionist (...) models have important functions beyond the commonly accepted goals of fitting data and making predictions. The second theme concerns perceived in-principle limitations of the connectionist approach to cognition, and the specific concerns these perceived limitations raise for our theory. We argue that the approach is not in fact limited in the ways our critics suggest. One common misconception, that connectionist models cannot address abstract or relational structure, is corrected through new simulations showing directly that such structure can be captured. The third theme concerns the relationship between parallel distributed processing (PDP) models and structured probabilistic approaches. In this case we argue that there the difference between the approaches is not merely one of levels. Our PDP approach differs from structured statistical approaches at all of Marr's levels, including the characterization of the goals of cognitive computations, and of the representations and algorithms used. (shrink)

Mitchell et al. describe many fascinating studies, and in the process, propose what they consider to be a unified framework for human learning in which effortful, controlled learning results in propositional knowledge. However, it is unclear how any of their findings privilege a propositional account, and we remain concerned that embedding all knowledge in propositional representations obscures the tight interdependence between learning from experiences and the use of the results of learning as a basis for action.

Expectations can facilitate rapid fear conditioning and this may explain some phenomena that have been attributed to preparedness. However, preparedness remains the best explanation for some aspects of clinical phobias and the difficulty of creating fears of modern dangers. Rapid fear conditioning based on expectancy is not an alternative to an evolutionary explanation, but has, like preparedness, been shaped by natural selection.

The fundamental determinant of death in donation after circulatory determination of death is the cessation of brain circulation and function. We therefore propose the term donation after brain circulation determination of death [DBCDD]. In DBCDD, death is determined when the cessation of circulatory function is permanent but before it is irreversible, consistent with medical standards of death determination outside the context of organ donation. Safeguards to prevent error include that: 1] the possibility of auto-resuscitation has elapsed; 2] no (...) brain circulation may resume after the determination of death; 3] complete circulatory cessation is verified; and 4] the cessation of brain function is permanent and complete. Death should be determined by the confirmation of the cessation of systemic circulation; the use of brain death tests is invalid and unnecessary. Because this concept differs from current standards, consensus should be sought among stakeholders. The patient or surrogate should provide informed consent for organ donation by understanding the basis of the declaration of death. In cases of circulatory cessation, such as occurs in DBCDD, death can be defined as the permanent cessation of brain functions, determined by the permanent cessation of brain circulation. (shrink)

The application of neuroimaging technology to the study of the injured brain has transformed how neuroscientists understand disorders of consciousness, such as the vegetative and minimally conscious states, and deepened our understanding of mechanisms of recovery. This scientific progress, and its potential clinical translation, provides an opportunity for ethical reflection. It was against this scientific backdrop that we convened a conference of leading investigators in neuroimaging, disorders of consciousness and neuroethics. Our goal was to develop an ethical frame to (...) move these investigative techniques into mature clinical tools. This paper presents the recommendations and analysis of a Working Meeting on Ethics, Neuroimaging and Limited States of Consciousness held at Stanford University during June 2007. It represents an interdisciplinary approach to the challenges posed by the emerging use of neuroimaging technologies to describe and characterize disorders of consciousness. (shrink)

The application of neuroimaging technology to the study of the injured brain has transformed how neuroscientists understand disorders of consciousness, such as the vegetative and minimally conscious states, and deepened our understanding of mechanisms of recovery. This scientific progress, and its potential clinical translation, provides an opportunity for ethical reflection. It was against this scientific backdrop that we convened a conference of leading investigators in neuroimaging, disorders of consciousness and neuroethics. Our goal was to develop an ethical frame to (...) move these investigative techniques into mature clinical tools. This paper presents the recommendations and analysis of a Working Meeting on Ethics, Neuroimaging and Limited States of Consciousness held at Stanford University during June 2007. It represents an interdisciplinary approach to the challenges posed by the emerging use of neuroimaging technologies to describe and characterize disorders of consciousness. (shrink)

We suggest that the phenomenon of uncertainty monitoring in nonhuman animals contributes richly to the conception of nonhuman animals' self-monitoring. We propose that uncertainty may play a role in the emergence of new forms of behavior that are adaptive. We recommend that Smith et al. determine the extent to which the uncertain response transfers immediately to other test paradigms.

What processes underlie the formation of new memories? What determines their strength? Where are the changes underlying memory located? With contributions from leading experts, this book offers the most up-to-date attempts to answer these and many more critical questions.

In the target article, Bowers et al. dispute deep artificial neural network (ANN) models as the currently leading models of human vision without producing alternatives. They eschew the use of public benchmarking platforms to compare vision models with the brain and behavior, and they advocate for a fragmented, phenomenon-specific modeling approach. These are unconstructive to scientific progress. We outline how the Brain-Score community is moving forward to add new model-to-human comparisons to its community-transparent suite of benchmarks.

For all its popularity as a psychological construct, willpower is irremediably polysemous. A more helpful construct is self-control, defined as the self-regulation of conflicting impulses. We show how the process model of self-control provides a principled framework for examining how undesirable impulses may be weakened and desirable impulses may be strengthened.