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1.
Sci Eng Ethics ; 30(5): 40, 2024 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-39251460

RESUMO

Ethics is central to scientific and engineering research and practice, but a key challenge for promoting students' ethical formation involves enhancing faculty members' ability and confidence in embedding positive ethical learning experiences into their curriculums. To this end, this paper explores changes in faculty members' approaches to and perceptions of ethics education following their participation in a multi-year interdisciplinary faculty learning community (FLC). We conducted and thematically analyzed semi-structured interviews with 11 participants following the second year of the FLC. Qualitative themes suggested that, following two years of FLC participation, faculty members (1) were better able to articulate their conceptualizations of ethics; (2) became cognizant of how personal experiences, views, and beliefs informed how they introduced ethics into their curriculum; and (3) developed and lived instructional principles that guided their ethics teaching. Results thus suggested that faculty members benefitted from exploring, discussing, and teaching ethics, which (in turn) enabled them to see new opportunities and become confident in integrating ethics into their courses in meaningful ways that aligned with their scholarly identities. Taken together, these data suggest faculty became agents of change for designing, implementing, and refining ethics-related instructional efforts in STEM. This work can guide others interested in designing faculty learning communities to promote instructional skill development, faculty members' awareness of their ethical values, and their ability and agency to design and integrate ethics learning activities alongside departmental peers in an intentional and continuous manner.


Assuntos
Currículo , Engenharia , Docentes , Aprendizagem , Humanos , Engenharia/ética , Engenharia/educação , Ensino , Ciência/ética , Ciência/educação , Ética Profissional/educação , Estudantes , Pesquisa Qualitativa , Atitude , Masculino , Feminino
2.
IEEE J Biomed Health Inform ; 27(5): 2178-2185, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-35816524

RESUMO

Running gait assessment and running shoe recommendation is important for the injury prevention of runners who exhibit different skill-levels and running styles. Traditionally, running gait assessment for shoe recommendation relies upon a combination of trained professionals (e.g., sports-therapists, physiotherapists) and complex equipment such as motion or pressure sensors, often incurring a high-cost to the consumer. Despite this, assessments are still prone to subjectivity, and may differ between assessors. Alternatively, methods to provide low-cost, reproduceable gait assessment has become a necessity, especially within a habitual (low-resource) context, with many traditional methods generally unavailable due to the need of professional assistance and more recently the COVID-19 pandemic. Fuzzy logic has shown to be an effective tool in the assessment and identification of gait by providing the potential for a high-accuracy methodology, while retaining a low computational cost; ideal for applications within embedded systems. Here, we present a novel shoe recommendation fuzzy inference system from the classification of two key running gait parameters, foot strike and pronation from a single foot mounted internet of thing (IoT) enabled wearable inertial measurement unit. The fuzzy approach provides excellent (ICC > 0.9) accuracy, while significantly increasing the resolution of the gait assessment technique, providing a more detailed running gait analysis.


Assuntos
COVID-19 , Corrida , Humanos , Análise da Marcha , Lógica Fuzzy , Pandemias , Marcha , Sapatos , Fenômenos Biomecânicos
3.
Annu Int Conf IEEE Eng Med Biol Soc ; 2021: 6818-6821, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34892673

RESUMO

Running gait assessment for shoe type recommendation to avoid injury often takes place within commercial premises. That is not representative of a natural running environment and may influence normal/usual running characteristics. Typically, assessments are costly and performed by an untrained biomechanist or physiotherapist. Thus, use of a low-cost assessment of running gait to recommend shoe type is warranted. Indeed, the recent impact of COVID has heightened the need for a shift toward remote assessment in general due to social-distancing guidelines and restriction of movement to bespoke assessment facilities. Mymo is a Bluetooth-enabled, inertial measurement unit (IMU) wearable worn on the foot. The wearable transmits inertial data via a smartphone application to the Cloud, where algorithms work to recommend a running shoe based upon the users/runner's pronation and foot-strike location/pattern. Here, an additional algorithm is presented to quantify ground contact time and swing/flight time within the Mymo platform to further inform the assessment of a runner's gait. A large cohort of healthy adult and adolescents (n=203, 91M:112F) were recruited to run on a treadmill while wearing the Mymo wearable. Validity of the inertial-based algorithm to quantify ground contact time was established through manual labelling of reference standard ground truth video data, with a presented accuracy between 96.6-98.7% across the two classes with respect to each foot.Clinical Relevance-This establishes the validity of a ground contact and swing times for runner with a low-cost IoT wearable.


Assuntos
COVID-19 , Corrida , Dispositivos Eletrônicos Vestíveis , Adolescente , Adulto , Algoritmos , Fenômenos Biomecânicos , Humanos , SARS-CoV-2
4.
Mil Med ; 178(11): 1196-201, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24183765

RESUMO

Despite improved body armor, hemorrhage remains the leading cause of preventable death on the battlefield. Trauma to the junctional areas such as pelvis, groin, and axilla can be life threatening and difficult to manage. The Abdominal Aortic Tourniquet (AAT) is a prehospital device capable of preventing pelvic and proximal lower limb hemorrhage by means of external aortic compression. The aim of the study was to evaluate the efficacy of the AAT. Serving soldiers under 25 years old were recruited. Basic demographic data, height, weight, blood pressure, and abdominal girth were recorded. Doppler ultrasound was used to identify blood flow in the common femoral artery (CFA). The AAT was applied while the CFA flow was continuously monitored. The balloon was inflated until flow in the CFA ceased or the maximum pressure of the device was reached. A total of 16 soldiers were recruited. All participants tolerated the device. No complications were reported. Blood flow in the CFA was eliminated in 15 out of 16 participants. The one unsuccessful subject was above average height, weight, body mass index, and abdominal girth. This study shows the AAT to be effective in the control of blood flow in the pelvis and proximal lower limb and potentially lifesaving.


Assuntos
Aorta Abdominal , Artéria Femoral/lesões , Hemorragia/terapia , Traumatismos da Perna/complicações , Pelve/lesões , Torniquetes , Adulto , Desenho de Equipamento , Hemorragia/etiologia , Humanos , Masculino , Militares , Resultado do Tratamento , Adulto Jovem
5.
PLoS One ; 6(5): e19214, 2011 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-21573228

RESUMO

BACKGROUND: Traumatic brain injury is a major cause of morbidity and mortality worldwide. Ameliorating the neurocognitive and physical deficits that accompany traumatic brain injury would be of substantial benefit, but the mechanisms that underlie them are poorly characterized. This study aimed to use diffusion tensor imaging to relate clinical outcome to the burden of white matter injury. METHODOLOGY/PRINCIPAL FINDINGS: Sixty-eight patients, categorized by the Glasgow Outcome Score, underwent magnetic resonance imaging at a median of 11.8 months (range 6.6 months to 3.7 years) years post injury. Control data were obtained from 36 age-matched healthy volunteers. Mean fractional anisotropy, apparent diffusion coefficient (ADC), and eigenvalues were obtained for regions of interest commonly affected in traumatic brain injury. In a subset of patients where conventional magnetic resonance imaging was completely normal, diffusion tensor imaging was able to detect clear abnormalities. Significant trends of increasing ADC with worse outcome were noted in all regions of interest. In the white matter regions of interest worse clinical outcome corresponded with significant trends of decreasing fractional anisotropy. CONCLUSIONS/SIGNIFICANCE: This study found that clinical outcome was related to the burden of white matter injury, quantified by diffusivity parameters late after traumatic brain injury. These differences were seen even in patients with the best outcomes and patients in whom conventional magnetic resonance imaging was normal, suggesting that diffusion tensor imaging can detect subtle injury missed by other techniques. An improved in vivo understanding of the pathology of traumatic brain injury, including its distribution and extent, may enhance outcome evaluation and help to provide a mechanistic basis for deficits that remain unexplained by other approaches.


Assuntos
Lesões Encefálicas/patologia , Imagem de Tensor de Difusão/métodos , Adolescente , Adulto , Idoso , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
6.
Neuroimage ; 54(1): 103-12, 2011 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-20728553

RESUMO

The vegetative (VS) and minimally conscious (MCS) states are currently distinguished on the basis of exhibited behaviour rather than underlying pathology. Although previous histopathological studies have documented different degrees of diffuse axonal injury as well as damage to the thalami and brainstem regions in VS and MCS, these differences have not been assessed in vivo, and therefore, do not provide a measurable pathological marker to aid clinical diagnosis. Currently, the diagnostic decision-making process is highly subjective and prone to error. Indeed, previous work has suggested that up to 43% of patients in this group may be misdiagnosed. We used diffusion tensor imaging (DTI) to study the neuropathology of 25 vegetative and minimally conscious patients in vivo and to identify measures that could potentially distinguish the patients in these two groups. Mean diffusivity (MD) maps of the subcortical white matter, brainstem and thalami were generated. The MCS and VS patients differed significantly in subcortical white matter and thalamic regions, but appeared not to differ in the brainstem. Moreover, the DTI results predicted scores on the Coma Recovery Scale (p<0.001) and successfully classified the patients in to their appropriate diagnostic categories with an accuracy of 95%. The results suggest that this method may provide an objective and highly accurate method for classifying these challenging patient populations and may therefore complement the behavioural assessment to inform the diagnostic decision making process.


Assuntos
Estado de Consciência/fisiologia , Estado Vegetativo Persistente/patologia , Inconsciência/patologia , Adolescente , Adulto , Idoso , Encéfalo/fisiologia , Lesões Encefálicas/etiologia , Lesões Encefálicas/patologia , Lesões Encefálicas/fisiopatologia , Lesões Encefálicas/reabilitação , Imagem de Difusão por Ressonância Magnética/métodos , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Masculino , Pessoa de Meia-Idade , Estado Vegetativo Persistente/fisiopatologia , Estado Vegetativo Persistente/reabilitação , Reflexo de Sobressalto , Centros de Reabilitação , Movimentos Sacádicos , Inconsciência/fisiopatologia , Inconsciência/reabilitação , Ferimentos e Lesões , Adulto Jovem
7.
N Engl J Med ; 362(7): 579-89, 2010 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-20130250

RESUMO

BACKGROUND: The differential diagnosis of disorders of consciousness is challenging. The rate of misdiagnosis is approximately 40%, and new methods are required to complement bedside testing, particularly if the patient's capacity to show behavioral signs of awareness is diminished. METHODS: At two major referral centers in Cambridge, United Kingdom, and Liege, Belgium, we performed a study involving 54 patients with disorders of consciousness. We used functional magnetic resonance imaging (MRI) to assess each patient's ability to generate willful, neuroanatomically specific, blood-oxygenation-level-dependent responses during two established mental-imagery tasks. A technique was then developed to determine whether such tasks could be used to communicate yes-or-no answers to simple questions. RESULTS: Of the 54 patients enrolled in the study, 5 were able to willfully modulate their brain activity. In three of these patients, additional bedside testing revealed some sign of awareness, but in the other two patients, no voluntary behavior could be detected by means of clinical assessment. One patient was able to use our technique to answer yes or no to questions during functional MRI; however, it remained impossible to establish any form of communication at the bedside. CONCLUSIONS: These results show that a small proportion of patients in a vegetative or minimally conscious state have brain activation reflecting some awareness and cognition. Careful clinical examination will result in reclassification of the state of consciousness in some of these patients. This technique may be useful in establishing basic communication with patients who appear to be unresponsive.


Assuntos
Conscientização , Encéfalo/metabolismo , Comunicação , Imaginação , Estado Vegetativo Persistente/psicologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Processos Mentais , Pessoa de Meia-Idade , Estado Vegetativo Persistente/diagnóstico , Estado Vegetativo Persistente/metabolismo , Adulto Jovem
8.
Prog Brain Res ; 177: 191-200, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19818902

RESUMO

Transcranial magnetic stimulation (TMS) is a noninvasive means of investigating the function, plasticity, and excitability of the human brain. TMS induces a brief intracranial electrical current, which produces action potentials in excitable cells. Stimulation applied over the motor cortex can be used to measure overall excitability of the corticospinal system, somatotopic representation of muscles, and subsequent plastic changes following injury. The facilitation and inhibition characteristics of the cerebral cortex can also be compared using the modulatory effect of a conditioning stimulus preceding a test stimulus. So called paired-pulse protocols have been used in humans and animals to assess GABA (gamma-amino-butyric acid)-ergic function and may have a future role directing therapeutic interventions. Indeed, repetitive magnetic stimulation, where intracranial currents are induced by repetitive stimulation higher than 1 Hz, has been shown to modulate brain responses to sensory and cognitive stimulation. Here, we summarize information gathered using TMS with patients in coma, vegetative state, and minimally conscious state. Although in the early stages of investigation, there is preliminary evidence that TMS represents a promising tool by which to elucidate the pathophysiological sequelae of impaired consciousness and potentially direct future therapeutic interventions. We will discuss the methodology of work conducted to date, as well as debate the general limitations and pitfalls of TMS studies in patients with altered states of consciousness.


Assuntos
Transtornos da Consciência/patologia , Potencial Evocado Motor/fisiologia , Córtex Motor/fisiopatologia , Estimulação Magnética Transcraniana/métodos , Transtornos da Consciência/classificação , Transtornos da Consciência/fisiopatologia , Estimulação Elétrica/métodos , Eletromiografia/métodos , Humanos , Estimulação Magnética Transcraniana/classificação
9.
Prog Brain Res ; 177: 249-60, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19818906

RESUMO

One of the major challenges in the clinical evaluation of brain injury survivors is to comprehensively assess the level of preserved cognitive function in order to inform diagnostic decisions and suggest appropriate rehabilitation strategies. However, the limited (if any) capacity for producing behavior in some of these patients often limits the extent to which cognitive functions can be explored via standard bedside methods. We present a novel neuroimaging paradigm that allows the assessment of residual executive functions without requiring the patient to produce any behavioral output. In particular, we target processes such as active maintenance of information through time and willful adoption of "mind-sets" that have been proposed to require conscious awareness. Employing an fMRI block design paradigm, healthy volunteers were presented with a series of neutral (i.e., not emotionally salient) words, and alternatively instructed to listen to all the words, or to count the number of times a given target is repeated. Importantly, the perceptual stimulation in the passive listening and the counting tasks was carefully matched. Contrasted with passive listening, the counting task revealed a fronto-parietal network previously associated with target detection and working memory. Remarkably, when tested on this same procedure, a minimally conscious patient presented a highly similar pattern of activation. Furthermore, the activity in these regions appeared highly synchronous to the onset and offset of the counting blocks. Considering the close matching of sensory stimulation across the two tasks, these findings strongly suggest that the patient could willfully adopt differential "mind-sets" as a function of condition, and could actively maintain information across time. Neither cognitive function was apparent when the patient was (behaviorally) tested at the bedside. This paradigm thus exemplifies the potential for fMRI to explore high-level cognitive functions, and awareness, in the absence of any behavioral response.


Assuntos
Mapeamento Encefálico , Encéfalo/irrigação sanguínea , Função Executiva/fisiologia , Estado Vegetativo Persistente/diagnóstico , Estado Vegetativo Persistente/fisiopatologia , Estimulação Acústica/métodos , Percepção Auditiva/fisiologia , Encéfalo/fisiopatologia , Feminino , Lateralidade Funcional , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Masculino , Testes Neuropsicológicos , Oxigênio/sangue , Tempo de Reação/fisiologia , Estudos Retrospectivos , Fatores de Tempo , Vocabulário
10.
Nat Neurosci ; 12(10): 1343-9, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19767746

RESUMO

Pavlovian trace conditioning depends on the temporal gap between the conditioned and unconditioned stimuli. It requires, in mammals, functional medial temporal lobe structures and, in humans, explicit knowledge of the temporal contingency. It is therefore considered to be a plausible objective test to assess awareness without relying on explicit reports. We found that individuals with disorders of consciousness (DOCs), despite being unable to report awareness explicitly, were able to learn this procedure. Learning was specific and showed an anticipatory electromyographic response to the aversive conditioning stimulus, which was substantially stronger than to the control stimulus and was augmented as the aversive stimulus approached. The amount of learning correlated with the degree of cortical atrophy and was a good indicator of recovery. None of these effects were observed in control subjects under the effect of anesthesia (propofol). Our results suggest that individuals with DOCs might have partially preserved conscious processing, which cannot be mediated by explicit reports and is not detected by behavioral assessment.


Assuntos
Aprendizagem da Esquiva/fisiologia , Conscientização/fisiologia , Condicionamento Clássico/fisiologia , Transtornos da Consciência/diagnóstico , Transtornos da Consciência/fisiopatologia , Estimulação Acústica/métodos , Adulto , Análise de Variância , Atenção/fisiologia , Piscadela/fisiologia , Transtornos da Consciência/reabilitação , Variação Contingente Negativa/fisiologia , Eletromiografia/métodos , Potenciais Evocados/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Psicoacústica , Tempo de Reação/fisiologia , Adulto Jovem
11.
Ann N Y Acad Sci ; 1157: 81-9, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19351358

RESUMO

The accurate assessment of patients with impaired consciousness following a brain injury often remains a challenge to the most experienced clinician. A diagnosis of vegetative or minimally conscious state is made on the basis of the patient's clinical history and detailed behavioral examinations, which rely upon the patient being able to move or speak in order to demonstrate residual cognitive function. Recently, the development of noninvasive neuroimaging techniques has fostered a rapid increase in the exploration of residual cognitive abilities in these patient populations. However, while this body of literature is growing rapidly, at present the enterprise remains one of scientific endeavor with no inclusion in standard clinical practice. Correctly administered behavioral testing in survivors of brain injury may provide sufficient information to identify patients who are aware and are able to signal that this is the case via a recognized motor output. However, it remains possible that a subgroup of these patients may retain some level of awareness, but lack the ability to produce any motor output and are therefore mistakenly diagnosed as vegetative. It is in this latter situation that functional neuroimaging may prove to be most valuable, as a unique clinical tool for probing volition and residual cognition without necessarily assuming that the patient is able to produce any motor output.


Assuntos
Imageamento por Ressonância Magnética/métodos , Estado Vegetativo Persistente/diagnóstico , Estado Vegetativo Persistente/psicologia , Conscientização , Comportamento , Lesões Encefálicas/fisiopatologia , Lesões Encefálicas/psicologia , Coma Pós-Traumatismo da Cabeça/diagnóstico , Coma Pós-Traumatismo da Cabeça/fisiopatologia , Coma Pós-Traumatismo da Cabeça/prevenção & controle , Estado de Consciência , Humanos , Estado Vegetativo Persistente/fisiopatologia , Estimulação Física , Vigília
13.
Ann N Y Acad Sci ; 1129: 130-8, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18591475

RESUMO

The assessment of residual brain function in the vegetative state, is extremely difficult and depends frequently on subjective interpretations of observed spontaneous and volitional behaviors. For those patients who retain peripheral motor function, rigorous behavioral assessment supported by structural imaging and electrophysiology is usually sufficient to establish a patient's level of wakefulness and awareness. However, it is becoming increasingly apparent that, in some patients, damage to the peripheral motor system may prevent overt responses to command, even though the cognitive ability to perceive and understand such commands may remain intact. Advances in functional neuroimaging suggest a novel solution to this problem; in several recent cases, so-called "activation" studies have been used to identify residual cognitive function and even conscious awareness in patients who are assumed to be vegetative, yet retain cognitive abilities that have evaded detection using standard clinical methods.


Assuntos
Conscientização/fisiologia , Estado Vegetativo Persistente/fisiopatologia , Cognição/fisiologia , Humanos , Imageamento por Ressonância Magnética , Fala/fisiologia
14.
Nat Rev Neurosci ; 9(3): 235-43, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18285801

RESUMO

A number of recent studies have demonstrated a role for state-of-the-art neuroimaging methods in the assessment of patients in the vegetative state and other so-called 'disorders of consciousness'. In several cases, functional MRI has been used to show that aspects of speech perception, emotional processing, language comprehension and even conscious awareness might be retained in some patients who behaviourally meet all of the criteria that define the vegetative state. This work has profound implications for clinical care, diagnosis, prognosis and medical-legal decision making (relating to the prolongation, or otherwise, of life after severe brain injury), as well as for more basic scientific questions about the nature of consciousness and the neural representation of our own thoughts and intentions.


Assuntos
Mapeamento Encefálico , Encéfalo , Diagnóstico por Imagem/métodos , Estado Vegetativo Persistente/patologia , Estado Vegetativo Persistente/fisiopatologia , Conscientização/fisiologia , Encéfalo/irrigação sanguínea , Encéfalo/patologia , Encéfalo/fisiopatologia , Humanos , Processamento de Imagem Assistida por Computador/métodos
15.
Funct Neurol ; 23(4): 189-94, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-19331781

RESUMO

The assessment of residual brain function in the vegetative state is extremely difficult and depends frequently on subjective interpretations of observed spontaneous and volitional behaviours. For those patients who retain peripheral motor function, rigorous behavioural assessment supported by structural imaging and electrophysiology is usually sufficient to establish a patient's level of wakefulness and awareness. However, it is becoming increasingly apparent that, in some patients, damage to the peripheral motor system may prevent overt responses to commands, even though the cognitive ability to perceive and understand such commands may remain intact. Advances in functional neuroimaging suggest a novel solution to this problem; in several recent cases, so-called activation studies have been used to identify residual cognitive function and even conscious awareness in patients who are assumed to be vegetative, yet retain cognitive abilities that have evaded detection using standard clinical methods.


Assuntos
Conscientização/fisiologia , Encéfalo/fisiopatologia , Transtornos da Consciência/diagnóstico , Transtornos da Consciência/fisiopatologia , Diagnóstico por Imagem/métodos , Mapeamento Encefálico , Humanos
16.
Curr Opin Neurol ; 20(6): 632-7, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17992081

RESUMO

PURPOSE OF REVIEW: We discuss recent developments in the use of neuroimaging and, in particular, functional MRI, in the assessment of patients diagnosed as vegetative state or minimally conscious state. RECENT FINDINGS: In the last year, there has been a substantial increase in the number of research studies published which have used state-of-the-art neuroimaging methods to assess residual cognitive functioning in patients diagnosed with disorders of consciousness. Work using functional MRI has demonstrated aspects of retained speech processing, emotional processing, comprehension and even conscious awareness in a small number of patients behaviourally meeting the criteria defining the vegetative and minimally conscious states. SUMMARY: The assessment of patients with disorders of consciousness relies heavily upon the subjective and consequently fallible interpretation of observed behaviour. Recent studies have demonstrated an important role for functional MRI in the identification of residual cognitive function in these patients. Such studies may be particularly useful when there is concern about the accuracy of the diagnosis and the possibility that residual cognitive function has remained undetected. In our opinion, the future use of functional MRI will substantially increase our understanding of disorders of consciousness following severe brain injury.


Assuntos
Encéfalo/patologia , Encéfalo/fisiopatologia , Transtornos da Consciência/diagnóstico , Transtornos da Consciência/fisiopatologia , Avaliação da Deficiência , Imageamento por Ressonância Magnética/normas , Cognição/fisiologia , Estado de Consciência/fisiologia , Diagnóstico Diferencial , Humanos , Imageamento por Ressonância Magnética/métodos , Valor Preditivo dos Testes , Sensibilidade e Especificidade , Percepção da Fala/fisiologia
17.
Proc Natl Acad Sci U S A ; 104(41): 16032-7, 2007 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-17938125

RESUMO

We used functional MRI and the anesthetic agent propofol to assess the relationship among neural responses to speech, successful comprehension, and conscious awareness. Volunteers were scanned while listening to sentences containing ambiguous words, matched sentences without ambiguous words, and signal-correlated noise (SCN). During three scanning sessions, participants were nonsedated (awake), lightly sedated (a slowed response to conversation), and deeply sedated (no conversational response, rousable by loud command). Bilateral temporal-lobe responses for sentences compared with signal-correlated noise were observed at all three levels of sedation, although prefrontal and premotor responses to speech were absent at the deepest level of sedation. Additional inferior frontal and posterior temporal responses to ambiguous sentences provide a neural correlate of semantic processes critical for comprehending sentences containing ambiguous words. However, this additional response was absent during light sedation, suggesting a marked impairment of sentence comprehension. A significant decline in postscan recognition memory for sentences also suggests that sedation impaired encoding of sentences into memory, with left inferior frontal and temporal lobe responses during light sedation predicting subsequent recognition memory. These findings suggest a graded degradation of cognitive function in response to sedation such that "higher-level" semantic and mnemonic processes can be impaired at relatively low levels of sedation, whereas perceptual processing of speech remains resilient even during deep sedation. These results have important implications for understanding the relationship between speech comprehension and awareness in the healthy brain in patients receiving sedation and in patients with disorders of consciousness.


Assuntos
Conscientização , Compreensão , Percepção da Fala , Adulto , Anestesia , Anestésicos Intravenosos/administração & dosagem , Encéfalo/fisiologia , Feminino , Humanos , Hipnóticos e Sedativos/administração & dosagem , Imageamento por Ressonância Magnética , Masculino , Memória , Propofol/administração & dosagem , Psicolinguística , Semântica
18.
Brain ; 130(Pt 10): 2494-507, 2007 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17827174

RESUMO

A diagnosis of vegetative state is made if a patient demonstrates no evidence of awareness of self or environment, no evidence of sustained, reproducible, purposeful or voluntary behavioural response to sensory stimuli and critically no evidence of language comprehension. For those patients who retain peripheral motor function, rigorous behavioural assessment is usually able to determine retained function. However, some patients do not retain the ability to respond overtly to command and it is becoming increasingly accepted that assessment of these patients should include techniques, which do not rely on any 'motor action' on the part of the patient. Here, we apply a hierarchical functional magnetic resonance imaging (fMRI) auditory processing paradigm to determine the extent of retained language processing in a group of 14 aetiologically heterogeneous patients who met the diagnostic criteria for either the vegetative state (n = 7), the minimally conscious state (n = 5), or who were in a severely disabled condition having emerged from a minimally conscious state (n = 2). Three different levels of speech processing were assessed: (i) Low-level auditory responses were measured using a contrast between a set of auditory stimuli and a silence baseline; (ii) mid-level speech perception processing abilities were assessed by comparing intelligible speech to unintelligible noise stimuli and (iii) high-level semantic aspects of speech processing were assessed by comparing sentences that were made difficult to understand by the presence of words that were semantically ambiguous compared to matched low-ambiguity sentences. As expected the two severely disabled, but conscious patients showed preserved speech processing at all three levels. However, contrary to the diagnostic criteria defining the vegetative state, three patients (1 traumatic, 2 non-traumatic aetiology) demonstrated some evidence of preserved speech processing. The remaining four patients (1 traumatic, 3 non-traumatic aetiology) with a diagnosis of vegetative state showed no significant activation in response to sound compared with silence. These results provide further evidence that a subset of patients fulfilling the behavioural criteria for the vegetative state retain islands of preserved cognitive function.


Assuntos
Compreensão , Idioma , Estado Vegetativo Persistente/psicologia , Percepção da Fala , Estimulação Acústica/métodos , Adulto , Idoso , Lesões Encefálicas/complicações , Lesões Encefálicas/psicologia , Mapeamento Encefálico/métodos , Feminino , Escala de Coma de Glasgow , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Estado Vegetativo Persistente/etiologia , Semântica
19.
Arch Neurol ; 64(8): 1098-102, 2007 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17698699

RESUMO

The assessment of patients with disorders of consciousness, including the vegetative state, is difficult and depends frequently on subjective interpretations of the observed spontaneous and volitional behavior. For those patients who retain peripheral motor function, rigorous behavioral assessment supported by structural imaging and electrophysiological findings is usually sufficient to establish a patient's level of wakefulness and awareness. However, it is becoming increasingly apparent that in some patients damage to the peripheral motor system may prevent overt responses to command although the cognitive ability to perceive and understand such commands may remain intact. Recent advances in functional neuroimaging suggest a novel solution to this problem; in several cases, so-called activation studies have been used to identify residual cognitive function and conscious awareness in patients who are assumed to be in a vegetative state yet retain cognitive abilities that have evaded detection using standard clinical methods.


Assuntos
Conscientização , Imageamento por Ressonância Magnética , Estado Vegetativo Persistente/diagnóstico , Estado Vegetativo Persistente/psicologia , Encéfalo/fisiopatologia , Feminino , Humanos , Neurologia/métodos , Neurologia/tendências , Neurociências/métodos , Neurociências/tendências , Estado Vegetativo Persistente/fisiopatologia
20.
Crit Care Med ; 35(2): 568-78, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17205016

RESUMO

OBJECTIVE: To determine whether hyperventilation exacerbates cerebral ischemia and compromises oxygen metabolism (CMRO2) following closed head injury. DESIGN: A prospective interventional study. SETTING: A specialist neurocritical care unit. PATIENTS: Ten healthy volunteers and 30 patients within 10 days of closed head injury. INTERVENTIONS: Subjects underwent oxygen-15 positron emission tomography imaging of cerebral blood flow, cerebral blood volume, CMRO2, and oxygen extraction fraction. In patients, positron emission tomography studies, somatosensory evoked potentials, and jugular venous saturation (SjO2) measurements were obtained at Paco2 levels of 36+/-3 and 29+/-2 torr. MEASUREMENTS AND MAIN RESULTS: We estimated the volume of ischemic brain and examined the efficiency of coupling between oxygen delivery and utilization using the sd of the oxygen extraction fraction distribution. We correlated CMRO2 to cerebral electrophysiology and examined the effects of hyperventilation on the amplitude of the cortical somatosensory evoked potential response. Patients showed higher ischemic brain volume than controls (17+/-22 vs. 2+/-3 mL; p

Assuntos
Isquemia Encefálica/complicações , Isquemia Encefálica/metabolismo , Encéfalo/metabolismo , Traumatismos Craniocerebrais/complicações , Traumatismos Craniocerebrais/metabolismo , Hiperventilação/complicações , Hiperventilação/metabolismo , Adolescente , Adulto , Idoso , Encéfalo/diagnóstico por imagem , Encéfalo/fisiopatologia , Isquemia Encefálica/diagnóstico por imagem , Isquemia Encefálica/fisiopatologia , Traumatismos Craniocerebrais/diagnóstico por imagem , Traumatismos Craniocerebrais/fisiopatologia , Eletrofisiologia , Feminino , Humanos , Hiperventilação/diagnóstico por imagem , Hiperventilação/fisiopatologia , Masculino , Pessoa de Meia-Idade , Oxirredução , Tomografia por Emissão de Pósitrons , Estudos Prospectivos
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