True or false? Activations of language-related areas in patients with disorders of consciousness

Disorders of Consciousness: Painless or Painful Conditions?—Evidence from Neuroimaging Studies

“…Whether it is the impairment of this core consciousness which is being referred to when we talk about UWS/VS is still questionable [17]. However, most of the recent studies investigating the presence of preserved islands of consciousness in brain-injured patients were exclusively aimed at revealing the presence of a covert higher-level reflective self-awareness through the use of fMRI associated with specific cognitive tasks [18,19,20,21]. For instance, during fMRI scanning, patients are asked to imagine playing tennis or moving around their home or to listen to factually correct vs. factually incorrect sentences, and their fMRI patterns are compared to those obtained from healthy subjects [18,19,20,21].…”

“…However, most of the recent studies investigating the presence of preserved islands of consciousness in brain-injured patients were exclusively aimed at revealing the presence of a covert higher-level reflective self-awareness through the use of fMRI associated with specific cognitive tasks [18,19,20,21]. For instance, during fMRI scanning, patients are asked to imagine playing tennis or moving around their home or to listen to factually correct vs. factually incorrect sentences, and their fMRI patterns are compared to those obtained from healthy subjects [18,19,20,21]. When the patterns of patients significantly resemble those of healthy subjects, the conclusion is that behaviourally unresponsive patients are, indeed, covertly conscious but unable to convey their preserved mental performances into perceived motor outputs, due to the aforementioned cognitive motor dissociation [7,18,19,20,21].…”

“…For instance, during fMRI scanning, patients are asked to imagine playing tennis or moving around their home or to listen to factually correct vs. factually incorrect sentences, and their fMRI patterns are compared to those obtained from healthy subjects [18,19,20,21]. When the patterns of patients significantly resemble those of healthy subjects, the conclusion is that behaviourally unresponsive patients are, indeed, covertly conscious but unable to convey their preserved mental performances into perceived motor outputs, due to the aforementioned cognitive motor dissociation [7,18,19,20,21]. To date, these studies seem to be the most promising way to reach a better understanding of the pathophysiology of DOCs: however, one should remember that processing a stimulus does not necessarily imply being conscious of it.…”

“…This observation overturns the traditional view about the prevailing involvement of grey matter in post-anoxic damage, due to the higher energy demand of grey matter and its higher density of glutamate receptors, and suggests investigating both grey and white matter in future neuroimaging studies [30]. Other studies focused on the possible activation of high-level cortical areas in patients with DOCs in response to specific cognitive paradigms, thus stressing the role of a neuropathological overlap between grey and white matter lesions and their combined action in causing consciousness impairment [20,31]. …”

“…The high occurrence of bedside underestimation of consciousness in these patients may be partly due to these concomitant impairments limiting the behavioural repertoire [33]. Indeed, in a small percentage of patients behaviourally diagnosed as having UWS/VS, neuroimaging has uncovered previously undetected functional communication, in the form of willful brain activity in response to verbal instructions [18,19,20,21,35]. More routine use of neuroimaging investigations may therefore help to bring to light cases of functional locked-in syndrome [9].…”