Disentangling the vegetative state from the minimally conscious state is often difficult when relying only on behavioral observation. In this study, we explored a new active evoked-related potentials ...paradigm as an alternative method for the detection of voluntary brain activity.
The participants were 22 right-handed patients (10 traumatic) diagnosed as being in a vegetative state (VS) (n = 8) or in a minimally conscious state (MCS) (n = 14). They were presented sequences of names containing the patient's own name or other names, in both passive and active conditions. In the active condition, the patients were instructed to count her or his own name or to count another target name.
Like controls, MCS patients presented a larger P3 to the patient's own name, in the passive and in the active conditions. Moreover, the P3 to target stimuli was higher in the active than in the passive condition, suggesting voluntary compliance to task instructions like controls. These responses were even observed in patients with low behavioral responses (e.g., visual fixation and pursuit). In contrast, no P3 differences between passive and active conditions were observed for VS patients.
The present results suggest that active evoked-related potentials paradigms may permit detection of voluntary brain function in patients with severe brain damage who present with a disorder of consciousness, even when the patient may present with very limited to questionably any signs of awareness.
Abstract
The frontoparietal semantic network, encompassing the inferior frontal gyrus and the posterior middle temporal cortex, is considered to be involved in semantic control processes. The ...explicit versus implicit nature of these control processes remains however poorly understood. The present study examined this question by assessing regional brain responses to the semantic attributes of an unattended stream of auditory words while participants’ top–down attentional control processes were absorbed by a demanding visual search task. Response selectivity to semantic aspects of verbal stimuli was assessed via a functional magnetic resonance imaging response adaptation paradigm. We observed that implicit semantic processing of an unattended verbal stream recruited not only unimodal and amodal cortices in posterior supporting semantic knowledge areas, but also inferior frontal and posterior middle temporal areas considered to be part of the semantic control network. These results indicate that frontotemporal semantic networks support incidental semantic (control) processes.
Background
Verbal short‐term memory (STM) capacity has been considered to support vocabulary learning in typical children and adults, but evidence for this link is inconsistent for studies in ...individuals with Down syndrome (DS). The aim of this study was explore the role of processing demands on the association between verbal STM and vocabulary measures in DS, by comparing receptive vocabulary measures with high STM processing demands to productive vocabulary measures with low STM processing demands.
Method
Forty‐seven adults with Down syndrome were administered receptive vocabulary and productive vocabulary tasks, as well as measures of verbal STM abilities and intellectual efficiency.
Results
Bayesian regression analyses showed that verbal STM abilities were strongly and specifically associated with receptive vocabulary measures but not productive lexical abilities after controlling for intellectual efficiency, and this is despite the fact that vocabulary abilities as measured by receptive and productive vocabulary tasks were closely associated.
Conclusions
In Down syndrome, verbal STM abilities may be predictive of specific task demands associated with receptive vocabulary tasks rather than of vocabulary development per se.
Abstract
Objective
This study examined the spontaneous use of allocentric and egocentric frames of reference and their flexible use as a function of instructions.
Method
The computerized spatial ...reference task created by Heiz and Barisnikov (2015) was used. Participants had to choose a frame of reference according to three types of instructions: spontaneous, allocentric and egocentric. The performances of 16 Williams Syndrome participants between 10 and 41 years were compared to those of two control groups (chronological age and non-verbal intellectual ability).
Results
The majority of Williams Syndrome participants did not show a preference for a particular frame of reference. When explicitly inviting participants to use an allocentric frame of reference, all three groups showed an increased use of the allocentric frame of reference. At the same time, an important heterogeneity of type of frame of reference used by Williams Syndrome participants was observed.
Conclusion
Results demonstrate that despite difficulties in the spontaneous use of allocentric and egocentric frames of reference, some Williams Syndrome participants show flexibility in the use of an allocentric frame of reference when an explicit instruction is provided.
Interactions between the neural correlates of short-term memory (STM) and attention have been actively studied in the visual STM domain but much less in the verbal STM domain. Here we show that the ...same attention mechanisms that have been shown to shape the neural networks of visual STM also shape those of verbal STM. Based on previous research in visual STM, we contrasted the involvement of a dorsal attention network centered on the intraparietal sulcus supporting task-related attention and a ventral attention network centered on the temporoparietal junction supporting stimulus-related attention. We observed that, with increasing STM load, the dorsal attention network was activated while the ventral attention network was deactivated, especially during early maintenance. Importantly, activation in the ventral attention network increased in response to task-irrelevant stimuli briefly presented during the maintenance phase of the STM trials but only during low-load STM conditions, which were associated with the lowest levels of activity in the dorsal attention network during encoding and early maintenance. By demonstrating a trade-off between task-related and stimulus-related attention networks during verbal STM, this study highlights the dynamics of attentional processes involved in verbal STM.
We studied a patient in a minimally conscious state using PET and cognitive evoked potentials. Cerebral metabolism was below half of normal values. Auditory stimuli with emotional valence (infant ...cries and the patient's own name) induced a much more widespread activation than did meaningless noise; the activation pattern was comparable with that previously obtained in controls. Cognitive potentials showed preserved P300 responses to the patient's own name.
The management and treatment of acute pain is very difficult in non-communicative patients with disorders of consciousness (
i.e.
, vegetative state/unresponsive wakefulness syndrome (VS/UWS) and ...minimally conscious state), creating an ethical dilemma for caregivers and an emotional burden among both relatives and caregivers. In this review, we summarize recent findings about the neural substrates of nociception and pain in VS/UWS patients as well as recent behavioral assessment methods of nociception specifically designed for patients in altered states of consciousness. We will finally discuss implications for pain treatment in these patients.
Observations of neutral-current nu interactions on deuterium in the Sudbury Neutrino Observatory are reported. Using the neutral current (NC), elastic scattering, and charged current reactions and ...assuming the standard 8B shape, the nu(e) component of the 8B solar flux is phis(e) = 1.76(+0.05)(-0.05)(stat)(+0.09)(-0.09)(syst) x 10(6) cm(-2) s(-1) for a kinetic energy threshold of 5 MeV. The non-nu(e) component is phi(mu)(tau) = 3.41(+0.45)(-0.45)(stat)(+0.48)(-0.45)(syst) x 10(6) cm(-2) s(-1), 5.3sigma greater than zero, providing strong evidence for solar nu(e) flavor transformation. The total flux measured with the NC reaction is phi(NC) = 5.09(+0.44)(-0.43)(stat)(+0.46)(-0.43)(syst) x 10(6) cm(-2) s(-1), consistent with solar models.
This study explored the validity of an attentional account for the involvement of the left intraparietal sulcus (IPS) in visual STM tasks. This account considers that during STM tasks, the IPS acts ...as an attentional modulator, maintaining activation in long-term memory networks that underlie the initial perception and processing of the specific information to be retained. In a recognition STM paradigm, we presented sequences of unfamiliar faces and instructed the participants to remember different types of information: either the identity of the faces or their order of presentation. We hypothesized that, if the left IPS acts as an attentional modulator, it should be active in both conditions, but connected to different neural networks specialized in serial order or face identity processing. Our results showed that the left IPS was activated during both order and identity encoding conditions, but for different reasons. During order encoding, the left IPS showed functional connectivity with order processing areas in the right IPS, bilateral premotor and cerebellar cortices, reproducing earlier results obtained in a verbal STM experiment. During identity encoding, the left IPS showed preferential functional connectivity with right temporal, inferior parietal and medial frontal areas involved in detailed face processing. These results not only support an attentional account of left IPS involvement in visual STM, but given their similarity with previous results obtained for a verbal STM task, they further highlight the importance of the left IPS as an attentional modulator in a variety of STM tasks.
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