Effect of dementia severity and age on posterior cingulate cortex metabolism in Alzheimer's disease

in Journal of Neurology (2007, May), 254(Suppl. 3), 146

Cerebral response to patient's own name in the vegetative and minimally conscious states

in Neurology (2007), 68(12), 895-899

Background: A challenge in the management of severely brain- damaged patients with altered states of consciousness is the differential diagnosis between the vegetative state ( VS) and the minimally ... [more ▼]

Background: A challenge in the management of severely brain- damaged patients with altered states of consciousness is the differential diagnosis between the vegetative state ( VS) and the minimally conscious state ( MCS), especially for the gray zone separating these clinical entities. Objective: To evaluate the differences in brain activation in response to presentation of the patient's own name spoken by a familiar voice ( SON- FV) in patients with VS and MCS. Methods: By using fMRI, we prospectively studied residual cerebral activation to SON- FV in seven patients with VS and four with MCS. Behavioral evaluation was performed by means of standardized testing up to 3 months post- fMRI. Results: Two patients with VS failed to show any significant cerebral activation. Three patients with VS showed SON- FV induced activation within the primary auditory cortex. Finally, two patients with VS and all four patients with MCS not only showed activation in primary auditory cortex but also in hierarchically higher order associative temporal areas. These two patients with VS showing the most widespread activation subsequently showed clinical improvement to MCS observed 3 months after their fMRI scan. Conclusion: The cerebral responses to patient's own name spoken by a familiar voice as measured by fMRI might be a useful tool to preclinically distinguish minimally conscious state - like cognitive processing in some patients behaviorally classified as vegetative. [less ▲]

Locked-in syndrome et états de conscience altérée: comment détecter la conscience?

in Pellas, Frederique; Kiefer, C; Weiss, JJ (Eds.) et al Eveil de coma et états limites (2007)

Evaluation cognitive chez le patient en locked-in syndrome

in Pellas, Frederique; Kiefer, C; Weiss, JJ (Eds.) et al Entretiens de Médecine Physique et de Réadaptation (2007)

Evaluation comportementale et par neuroimagerie fonctionnelle des patients en état végétatif

in Revue Médicale de Liège (2007), 62 Spec No

Currently, there remains a high rate of misdiagnosis of the vegetative state. This should incite clinicians to use the most sensitive "coma scales" to detect signs of consciousness in these patients. The ... [more ▼]

Currently, there remains a high rate of misdiagnosis of the vegetative state. This should incite clinicians to use the most sensitive "coma scales" to detect signs of consciousness in these patients. The gold standard remains the Glasgow Coma Scale (GCS, Teasdale and Jennet, 1974), with the Glasgow Liege Scale (GLS, Born, 1988) adding standardized assessment of brainstem reflexes. New sensible behavioral assessment tools for use in the acute neurocritical care setting include the Full Outline of UnResponsiveness (FOUR, Wijdicks et al., 2005). The Coma Recovery Scale-Revised (CRS-R, Giacino and Kalmar, 2004) specifically tests the diagnostic criteria differentiating vegetative from minimally conscious patients. Detecting signs of consciousness also depends on the employed methodology. We showed that for the assesment of the presence of visual pursuit, using a moving mirror is better suited than using a moving object or person. The clinical diagnosis can be confirmed by cerebral positron emission tomography studies objectively quantifying residual metabolic activity in vegetative and minimally conscious patients. Ongoing studies evaluate the prognostic value of functional magnetic resonance imaging studies in these challenging patient populations. [less ▲]

The challenge of disentangling reportability and phenomenal consciousness in post-comatose states

in Behavioral And Brain Sciences (2007), 30(5-6), 529-530

Determining whether or not noncommunicative patients are phenomenally conscious is a major clinical and ethical challenge. Clinical assessment is usually limited to the observation of these patients ... [more ▼]

Determining whether or not noncommunicative patients are phenomenally conscious is a major clinical and ethical challenge. Clinical assessment is usually limited to the observation of these patients' motor responses. Recent neuroimaging technology and brain computer interfaces help clinicians to assess whether patients are conscious or not, and to avoid diagnostic errors. [less ▲]

Detecting Awareness in the Vegetative State

in Science (2006)

Offline persistence of memory-related cerebral activity during active wakefulness

in PLoS Biology (2006), 4(4), 100

Much remains to be discovered about the fate of recent memories in the human brain. Several studies have reported the reactivation of learning-related cerebral activity during post-training sleep ... [more ▼]

Much remains to be discovered about the fate of recent memories in the human brain. Several studies have reported the reactivation of learning-related cerebral activity during post-training sleep, suggesting that sleep plays a role in the offline processing and consolidation of memory. However, little is known about how new information is maintained and processed during post-training wakefulness before sleep, while the brain is actively engaged in other cognitive activities. We show, using functional magnetic resonance imaging, that brain activity elicited during a new learning episode modulates brain responses to an unrelated cognitive task, during the waking period following the end of training. This post-training activity evolves in learning-related cerebral structures, in which functional connections with other brain regions are gradually established or reinforced. It also correlates with behavioral performance. These processes follow a different time course for hippocampus-dependent and hippocampus-independent memories. Our experimental approach allowed the characterization of the offline evolution of the cerebral correlates of recent memories, without the confounding effect of concurrent practice of the learned material. Results indicate that the human brain has already extensively processed recent memories during the first hours of post-training wakefulness, even when simultaneously coping with unrelated cognitive demands. [less ▲]

One's Own Face Is Hard to Ignore

in Quarterly Journal of Experimental Psychology (2006), 59(1), 46-52

One's own face possesses two properties that make it prone to grab attention: It is a face, and, in addition, it is a self-referential stimulus. The question of whether the self-face is actually an ... [more ▼]

One's own face possesses two properties that make it prone to grab attention: It is a face, and, in addition, it is a self-referential stimulus. The question of whether the self-face is actually an especially attention-grabbing stimulus was addressed by using a face-name interference paradigm. We investigated whether interference from a flanking self-face on the processing of a target classmate's name was stronger than interference from a classmate's flanking face on the processing of one's own name as the target. In a control condition a third familiar face served as the flanker for both decisions from the participant's own name and from the classmate's name. The presentation of the self-face as a flanker produced significantly more interference on the identification of a classmate's name than the presentation of that classmate's face did on the identification of one's own name. This result was due to the interfering power of the self-face and not to a particular resistance of one's name to interfering facial stimuli. We argue that the emotional value or the high familiarity of one's own face may explain its attention-grabbing property. [less ▲]

A prominent role for amygdaloid complexes in the Variability in Heart Rate (VHR) during Rapid Eye Movement (REM) sleep relative to wakefulness.

in NeuroImage (2006), 32(3), 1008-1015

Rapid eye movement sleep (REMS) is associated with intense neuronal activity, rapid eye movements, muscular atonia and dreaming. Another important feature in REMS is the instability in autonomic ... [more ▼]

Rapid eye movement sleep (REMS) is associated with intense neuronal activity, rapid eye movements, muscular atonia and dreaming. Another important feature in REMS is the instability in autonomic, especially in cardiovascular regulation. The neural mechanisms underpinning the variability in heart rate (VHR) during REMS are not known in detail, especially in humans. During wakefulness, the right insula has frequently been reported as involved in cardiovascular regulation but this might not be the case during REMS. We aimed at characterizing the neural correlates of VHR during REMS as compared to wakefulness and to slow wave sleep (SWS), the other main component of human sleep, in normal young adults, based on the statistical analysis of a set of (H2O)-O-15 positron emission tomography (PET) sleep data acquired during SWS, REMS and wakefulness. The results showed that VHR correlated more tightly during REMS than during wakefulness with the rCBF in the right amygdaloid complex. Moreover, we assessed whether functional relationships between amygdala and any brain area changed depending the state of vigilance. Only the activity within in the insula was found to covary with the amygdala, significantly more tightly during wakefulness than during REMS in relation to the VHR. The functional connectivity between the amygdala and the insular cortex, two brain areas involved in cardiovascular regulation, differs significantly in REMS as compared to wakefulness. This suggests a functional reorganization of central cardiovascular regulation during REMS. (c) 2006 Elsevier Inc. All rights reserved. [less ▲]