Pattern Classification of Volitional Functional Magnetic Resonance Imaging Responses in Patients With Severe Brain Injury

Bardin, Jonathan C.; Schiff, Nicholas D.; Voss, Henning U.

doi:10.1001/archneurol.2011.892

Cited by 55 publications

(50 citation statements)

References 18 publications

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“…Previous neuroimaging studies have established that brain function can serve as a proxy for overt behavior in patients who are aware, yet unable to produce any overt physical responses (2)(3)(4)(5)(6)(7)(8)36). To date, these studies have relied on a response according to instruction, albeit a brain response, to establish that a significant minority of patients (∼19%) (6, 7) can follow commands and, in some cases, communicate with the outside world (2, 3, 7).…”

Section: Decoding Conscious Experiences In Behaviorally Nonresponsivementioning

confidence: 99%

A common neural code for similar conscious experiences in different individuals

Naçi¹,

Cusack²,

Anello

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

179

208

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The interpretation of human consciousness from brain activity, without recourse to speech or action, is one of the most provoking and challenging frontiers of modern neuroscience. We asked whether there is a common neural code that underpins similar conscious experiences, which could be used to decode these experiences in the absence of behavior. To this end, we used richly evocative stimulation (an engaging movie) portraying real-world events to elicit a similar conscious experience in different people. Common neural correlates of conscious experience were quantified and related to measurable, quantitative and qualitative, executive components of the movie through two additional behavioral investigations. The movie's executive demands drove synchronized brain activity across healthy participants' frontal and parietal cortices in regions known to support executive function. Moreover, the timing of activity in these regions was predicted by participants' highly similar qualitative experience of the movie's moment-to-moment executive demands, suggesting that synchronization of activity across participants underpinned their similar experience. Thus we demonstrate, for the first time to our knowledge, that a neural index based on executive function reliably predicted every healthy individual's similar conscious experience in response to real-world events unfolding over time. This approach provided strong evidence for the conscious experience of a brain-injured patient, who had remained entirely behaviorally nonresponsive for 16 y. The patient's executive engagement and moment-to-moment perception of the movie content were highly similar to that of every healthy participant. These findings shed light on the common basis of human consciousness and enable the interpretation of conscious experience in the absence of behavior.fMRI | brain injury | disorders of consciousness A lthough consciousness is a part of all of our lives, we are not privy to the conscious experiences of others. Indeed, our ability to understand and appreciate their experiences depends largely on their self-report, or ability to describe those experiences (1). However, in recent years a population of patients has been identified who are demonstrably conscious, but entirely unable to speak or move willfully in any way, precluding any systematic investigation of their conscious experience of the world (2-8). It remains unknown whether there is a common neural code that can account for how different individuals might form similar conscious experiences and, if so, whether it could be used to interpret those experiences without recourse to self-report.The "executive" function of the brain refers to those processes that coordinate and schedule a host of other more basic cognitive operations, such as monitoring and analyzing information from the environment and integrating it with internally generated goals, as well as planning and adapting new behavioral schemas to take account of this information (9-11). As such, executive function is integral to our con...

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Section: Decoding Conscious Experiences In Behaviorally Nonresponsivementioning

confidence: 99%

A common neural code for similar conscious experiences in different individuals

Naçi¹,

Cusack²,

Anello

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

179

208

View full text Add to dashboard Cite

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“…Several recent neuroimaging studies have demonstrated that, despite the apparent absence of external signs of consciousness, a significant small proportion of behaviorally nonresponsive patients with disorders of consciousness can respond to commands by willfully modulating their brain activity according to instruction. [7][8][9][10][11] Despite these advances, little is known about the mental life of such patients with regard to whether they can have any coherent thoughts. One fundamental mental function, critical for coherent thinking, is the ability to pay attention.…”

mentioning

confidence: 99%

Making Every Word Count for Nonresponsive Patients

2013

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IMPORTANCE Despite the apparent absence of external signs of consciousness, a significant small proportion of patients with disorders of consciousness can respond to commands by willfully modulating their brain activity, even respond to yes or no questions, by performing mental imagery tasks. However, little is known about the mental life of such responsive patients, for example, with regard to whether they can have coherent thoughts or selectively maintain attention to specific events in their environment. The ability to selectively pay attention would provide evidence of a patient's preserved cognition and a method for brain-based communication, thus far untested with functional magnetic resonance imaging in this patient group.OBJECTIVE To test whether selective auditory attention can be used to detect conscious awareness and communicate with behaviorally nonresponsive patients. DESIGN, SETTING, AND PARTICIPANTSCase study performed in 3 patients with severe brain injury, 2 diagnosed as being in a minimally conscious state and 1 as being in a vegetative state. The patients constituted a convenience sample. MAIN OUTCOMES AND MEASURESFunctional magnetic resonance imaging data were acquired as the patients were asked to selectively attend to auditory stimuli, thereby conveying their ability to follow commands and communicate.RESULTS All patients demonstrated command following according to instructions. Two patients (1 in a minimally conscious state and 1 in a vegetative state) were also able to guide their attention to repeatedly communicate correct answers to binary (yes or no) questions. CONCLUSIONS AND RELEVANCETo our knowledge, we show for the first time with functional magnetic resonance imaging that behaviorally nonresponsive patients can use selective auditory attention to convey their ability to follow commands and communicate. One patient in a minimally conscious state was able to use attention to establish functional communication in the scanner, despite his inability to produce any communication responses in repeated bedside examinations. More important, 1 patient, who had been in a vegetative state for 12 years before the scanning and subsequent to it, was able to use attention to correctly communicate answers to several binary questions. The technique may be useful in establishing basic communication with patients who appear unresponsive to bedside examinations and cannot respond with existing neuroimaging methods.

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“…Moreover, stronger signs of awareness were found through active paradigms, i.e. when the patient had to volitionally modulate his or her cerebral activity in response to specific instructions (Owen et al, 2006, Monti et al, 2010, Bardin et al, 2012, Naci and Owen, 2013, Vogel et al, 2013. A well-known example involves UWS or MCS patients who were asked to imagine either pursuing or stopping sedative infusions.…”

Section: Introductionmentioning

confidence: 99%

“…In the study by Monti et al (Monti et al, 2010), the authors suggest and advocate comparing similarities between the cerebral activations obtained during the communication tasks to those resulting from the explicit imagery tasks. However, this method has not been compared with other detection methods, such as analyses based on the use of support vector machines (Bardin et al, 2012). The efficacy of each method for detecting patterns of volitional activations must thus be explored and compared.…”

Section: Introductionmentioning

confidence: 99%