The Experts below are selected from a list of 30417 Experts worldwide ranked by ideXlab platform
Adrian M Owen - One of the best experts on this subject based on the ideXlab platform.
-
the assessment of Conscious Awareness in the vegetative state
The Neurology of Conciousness (Second Edition)#R##N#Cognitive Neuroscience and Neuropathology, 2016Co-Authors: Adrian M Owen, Nicholas D Schiff, Steven LaureysAbstract:The assessment of patients in the vegetative state is extremely complex and depends frequently on subjective interpretations of the observed spontaneous and volitional behavior. In recent years, a number of studies have demonstrated an important role for functional neuroimaging in the identification of residual cognitive function, and even Conscious Awareness, in some patients fulfilling the clinical criteria for vegetative state. Such studies, when successful, may be particularly useful where there is concern about the accuracy of the diagnosis and the possibility that residual cognitive function has remained undetected. However, use of these techniques in severely brain-injured persons is methodologically complex and requires careful quantitative analysis and interpretation.
-
anesthesia and neuroimaging investigating the neural correlates of unConsciousness
Trends in Cognitive Sciences, 2015Co-Authors: Alex A Macdonald, Lorina Naci, Penny A Macdonald, Adrian M OwenAbstract:In the past 15 years, rapid technological development in the field of neuroimaging has led to a resurgence of interest in the study of Consciousness. However, the neural bases of Consciousness and the boundaries of unConscious processing remain poorly understood. Anesthesia combined with functional neuroimaging presents a unique approach for studying neural responses as a function of Consciousness. In this review we summarize findings from functional neuroimaging studies that have used anesthetic drugs to study cognition at different levels of Conscious Awareness. We relate the results to those of psychophysical studies of cognition and explore their potential usefulness in interpreting clinical findings from studies of non-responsive patients.
-
functional imaging reveals movement preparatory activity in the vegetative state
Frontiers in Human Neuroscience, 2011Co-Authors: Tristan A Bekinschtein, Adrian M Owen, Facundo Manes, Mirta F Villarreal, Valeria DellamaggioreAbstract:The Vegetative State (VS) is characterized by the absence of Awareness of self or the environment and preserved autonomic functions. The diagnosis relies critically on the lack of consistent signs of purposeful behavior in response to external stimulation. Yet, given that patients with disorders of Consciousness often exhibit fragmented movement patterns, voluntary actions may go unnoticed. Here we designed a simple motor paradigm that could potentially detect residual Conscious Awareness in VS patients with mild to severe brain damage by examining the neural correlates of motor preparation in response to verbal commands. Twenty-four patients who met the diagnostic criteria for VS were recruited for this study. Eleven of these patients showing preserved auditory evoked potentials underwent functional magnetic resonance imaging (fMRI) to test for basic speech processing. Five of these patients, who showed word related activity, were included in a second fMRI study aimed at detecting functional changes in premotor cortex elicited by specific verbal instructions to move either their left or their right hand. Despite the lack of overt muscle activity, two patients out of five activated the dorsal premotor cortex contralateral to the instructed hand, consistent with movement preparation. Given that movement preparation in response to a motor command is a sign of purposeful behavior, our results are consistent with residual Conscious Awareness in these patients. We believe that the identification of positive results with fMRI using this simple task, may complement the clinical assessment by helping attain a more precise diagnosis in patients with disorders of Consciousness.
-
functional neuroimaging of the vegetative state
Nature Reviews Neuroscience, 2008Co-Authors: Adrian M Owen, Martin R ColemanAbstract:Functional MRI has shown that aspects of cognitive and emotional processing and even Conscious Awareness might be retained in some patients who have been diagnosed as vegetative. Owen and Coleman discuss the clinical, legal and scientific implications of these findings. 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.
-
using functional magnetic resonance imaging to detect covert Awareness in the vegetative state
JAMA Neurology, 2007Co-Authors: Adrian M Owen, Steven Laureys, Martin R Coleman, Melanie Boly, Matthew H Davis, John D PickardAbstract:ological 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.
Jian Kong - One of the best experts on this subject based on the ideXlab platform.
-
a neural mechanism for nonConscious activation of conditioned placebo and nocebo responses
Cerebral Cortex, 2015Co-Authors: Karin B. Jensen, Irving Kirsch, Ted J. Kaptchuk, Martin Ingvar, Jian Kong, Xiaoyan Chen, Randy L GollubAbstract:Fundamental aspects of human behavior operate outside of Conscious Awareness. Yet, theories of conditioned responses in humans, such as placebo and nocebo effects on pain, have a strong emphasis on Conscious recognition of contextual cues that trigger the response. Here, we investigated the neural pathways involved in nonConscious activation of conditioned pain responses, using functional magnetic resonance imaging in healthy participants. NonConscious compared with Conscious activationofconditionedplaceboanalgesiawasassociatedwithincreasedactivationoftheorbitofrontalcortex,astructurewith direct connections to affective brain regions and basic reward processing. During nonConscious nocebo, there was increased activation of the thalamus, amygdala, and hippocampus. In contrast to previous assumptions about conditioning in humans, our results show that conditioned pain responses can be elicited independentlyof Conscious Awareness and our results suggest a hierarchical activation of neural pathways for nonConscious and Conscious conditioned responses. Demonstrating that the human brain has a nonConscious mechanism for responding to conditioned cues has major implications for the role of associative learning in behavioral medicine and psychiatry. Our results may also open up for novel approaches to translational animal-to-human research since human Consciousness and animal cognition is an inherent paradox in all behavioral science.
Brad Wyble - One of the best experts on this subject based on the ideXlab platform.
-
amnesia for object attributes failure to report attended information that had just reached Conscious Awareness
Psychological Science, 2015Co-Authors: Hui Chen, Brad WybleAbstract:People intuitively believe that when they become Consciously aware of a visual stimulus, they will be able to remember it and immediately report it. The present study provides a series of striking demonstrations of behavior that is inconsistent with such an intuition. Four experiments showed that in certain conditions, participants could not report an attribute (e.g., letter identity) of a stimulus even when that attribute had been attended and had reached a full state of Conscious Awareness just prior to being questioned about it. We term this effect attribute amnesia, and it occurs when participants repeatedly locate a target using one attribute and are then unexpectedly asked to report that attribute. This discovery suggests that attention to and Awareness of a stimulus attribute are insufficient to ensure its immediate reportability. These results imply that when attention is configured by using an attribute for target selection, that attribute will not necessarily be remembered.
Endel Tulving - One of the best experts on this subject based on the ideXlab platform.
-
event related brain potential correlates of two states of Conscious Awareness in memory
Proceedings of the National Academy of Sciences of the United States of America, 1997Co-Authors: Emrah Duzel, Andrew P Yonelinas, George R Mangun, Hansjochen Heinze, Endel TulvingAbstract:We report an event-related potential (ERP) experiment of human recognition memory that explored the relation between Conscious Awareness and electrophysiological activity of the brain. We recorded ERPs from healthy adults while they made “remember” and “know” recognition judgments about previously seen words. These two kinds of judgments reflect “autonoetic” and “noetic” Awareness, respectively. The ERP effects differed between the two kinds of Awareness while they were similar for “true” and “false” recognition. Noetic Awareness was associated with a temporoparietal positivity in the N400 range (325–600 ms) and a late (600–1,000 ms) frontocentral negativity, whereas autonoetic Awareness was associated with a widespread, late, bifrontal and left parietotemporal (600–1000 ms) positivity. In the very late (1,300–1,900 ms) time window, a right frontal positivity was observed for both remember and know judgments of both true and false targets. These results provide physiological evidence for two types of Conscious Awareness in episodic memory retrieval.
Karin B. Jensen - One of the best experts on this subject based on the ideXlab platform.
-
a neural mechanism for nonConscious activation of conditioned placebo and nocebo responses
Cerebral Cortex, 2015Co-Authors: Karin B. Jensen, Irving Kirsch, Ted J. Kaptchuk, Martin Ingvar, Jian Kong, Xiaoyan Chen, Randy L GollubAbstract:Fundamental aspects of human behavior operate outside of Conscious Awareness. Yet, theories of conditioned responses in humans, such as placebo and nocebo effects on pain, have a strong emphasis on Conscious recognition of contextual cues that trigger the response. Here, we investigated the neural pathways involved in nonConscious activation of conditioned pain responses, using functional magnetic resonance imaging in healthy participants. NonConscious compared with Conscious activationofconditionedplaceboanalgesiawasassociatedwithincreasedactivationoftheorbitofrontalcortex,astructurewith direct connections to affective brain regions and basic reward processing. During nonConscious nocebo, there was increased activation of the thalamus, amygdala, and hippocampus. In contrast to previous assumptions about conditioning in humans, our results show that conditioned pain responses can be elicited independentlyof Conscious Awareness and our results suggest a hierarchical activation of neural pathways for nonConscious and Conscious conditioned responses. Demonstrating that the human brain has a nonConscious mechanism for responding to conditioned cues has major implications for the role of associative learning in behavioral medicine and psychiatry. Our results may also open up for novel approaches to translational animal-to-human research since human Consciousness and animal cognition is an inherent paradox in all behavioral science.
-
Classical conditioning of analgesic and hyperalgesic pain responses without Conscious Awareness
Proceedings of the National Academy of Sciences of the United States of America, 2015Co-Authors: Karin B. Jensen, Irving Kirsch, Sara Odmalm, Ted J. Kaptchuk, Martin IngvarAbstract:Pain reduction and enhancement can be produced by means of conditioning procedures, yet the role of Awareness during the acquisition stage of classical conditioning is unknown. We used psychophysical measures to establish whether conditioned analgesic and hyperalgesic responses could be acquired by unseen (subliminally presented) stimuli. A 2 × 2 factorial design, including subliminal/supraliminal exposures of conditioning stimuli (CS) during acquisition/extinction, was used. Results showed significant analgesic and hyperalgesic responses (P < 0.001), and responses were independent of CS Awareness, as subliminal/supraliminal cues during acquisition/extinction led to comparable outcomes. The effect was significantly larger for hyperalgesic than analgesic responses (P < 0.001). Results demonstrate that Conscious Awareness of the CS is not required during either acquisition or extinction of conditioned analgesia or hyperalgesia. Our results support the notion that nonConscious stimuli have a pervasive effect on human brain function and behavior and may affect learning of complex cognitive processes such as psychologically mediated analgesic and hyperalgesic responses.
