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Using paraclinical assessments to detect consciousness and communicate with severely brain-injured patients
Published in Camille Chatelle, Steven Laureys, Assessing Pain and Communication in Disorders of Consciousness, 2015
Camille Chatelle, Damien Lesenfants
Finally, extensive research on attention involving healthy subjects has suggested that the P3 response should be deconstructed into separable subcomponents represented by the P3a and P3b. The early frontally centered novelty P3a would be associated with exogenous attention, triggered by stimulus novelty (“bottom-up”) that may be task-irrelevant, whereas the later parietally focused P3b, on the other hand, is seen as a marker of volitional endogenous attention to task-relevant targets necessary for consolidation into working memory and for conscious access (“top down”) (Polich, 2007). Chennu et al. (2013) developed a paradigm aiming to engender exogenous or endogenous attention (i.e., P3a and P3b EEG response), respectively, in response to a pair of word stimuli presented auditorily among distracters. Among the 21 patients included in the study, none of the seven patients showing command-following at the bedside generated a P3b (false negative rate: 100%), three patients generated only early nondiscriminative responses to targets (including two patients showing command-following at the bedside – false negative rate: 71%), and one patient in VS/UWS generated both a P3a and a P3b response. Interestingly, 20 of these patients were also administered the fMRI paradigm developed by Owen et al. (Monti et al., 2010; Owen et al., 2006). In six patients in whom no discernible P3a/P3b response could be elicited, a response to command using fMRI tennis imagery task could be detected. This discrepancy may be explained by fluctuation of arousal or heterogeneity in terms of the preservation of specific neural structures and the cognitive resources available (Gibson et al., 2014). It also suggests that the level of difficulty required by this attention task is too high to enable a good rate of detection of conscious patients. However, the VS/UWS patient who showed P3a/P3b responses did also show a response to command with the fMRI, supporting the idea that the presence of a P3a and P3b may highlight a well-preserved volitional attention process.
Consciousness in a Rotor? Science and Ethics of Potentially Conscious Human Cerebral Organoids
Published in AJOB Neuroscience, 2023
Federico Zilio, Andrea Lavazza
In this sense, an HCO should probably be able to develop long-range neuronal projections in order to distribute and share the information globally. However, according to this theory, external outputs (body and environment) play only an accessory role, since consciousness can be mainly described as a process of unification, selection, representation, and broadcasting of information, that is, brain-wide information sharing (Dehaene 2014). The stimuli come into the brain through the sensory system and then are processed and globally orchestrated by a set of systems from a specific group of integrative brain regions (perception, memory, attention, etc.), that is, the global workspace (Deco, Vidaurre, and Kringelbach 2021). The event related potential P300 is one of the neuronal markers used to determine the above-mentioned level of information availability, and in particular the P3b, whereas the P3a component may relate to automatic and non-conscious attention) (Dehaene, Changeux, and Naccache 2011).
MEG reveals preference specific increases of sexual-image-evoked responses in paedophilic sexual offenders and healthy controls
Published in The World Journal of Biological Psychiatry, 2021
Marina Krylova, Inka Ristow, Vanessa Marr, Viola Borchardt, Meng Li, Joachim Witzel, Krasimira Drumkova, Joseph A. Harris, Norman Zacharias, Kolja Schiltz, Till Amelung, Klaus M. Beier, Tillmann H. C. Kruger, Jorge Ponseti, Boris Schiffer, Henrik Walter, Christian Kärgel, Martin Walter
The P300 is most commonly referred to in the context of attentional switch and information processing, more specifically in updating working memory and problem-solving (Dinteren et al. 2014). Typically, P300 is subdivided into the P3a and P3b component, with the P3a involved in early attention-related processes (‘novelty detection’) served by the frontal cortex and the hippocampus (Huster et al. 2010), and the P3b crucial for later attention-related processes and working memory, served by the temporal and parietal lobes, and cingulate cortex. In the P3a window, present sources of activity were observed in occipital, parietal and temporal areas as well as in orbitofrontal cortex in both HC and P + CSO. P + CSO exhibited increased amplitudes in response to child images in the P3a window in middle orbital and middle frontal gyrus (Supplementary Table 1). These effects could be interpreted in terms of dorsal and ventral stream of the visual pathways. Especially, the P + CSO show activation regarding ventral stream, which is associated with form recognition and object representation, with storage of long-term memory subsequent cognitive operations (Goodale and Milner 1992).
AUDITORY EVOKED POTENTIALS EVIDENCE FOR DIFFERENCES IN INFORMATION PROCESSING BETWEEN HIGH AND LOW HYPNOTIZABLE SUBJECTS
Published in International Journal of Clinical and Experimental Hypnosis, 2019
Anna V. Kirenskaya, Zinaida I. Storozheva, Svetlana V. Solntseva, Vladimir Yu Novototsky-Vlasov, Mikhail N. Gordeev
Overall increase of P300 amplitude in HH subjects (comparatively to LH subjects) with maximal amplitude in frontal region was revealed. The P300 is generally considered to be a multicomponent phenomenon (Huang et al., 2015; Polich, 2007). Intermittent, task-irrelevant (i.e., novel) stimuli result in P300 component with a frontal-central distribution (usually termed P3a). The P3a can occur independently of prior attention to the stimuli and likely reflects the orientation of attention to them. Attended target stimuli, such as the target stimuli in the present study, produce a larger central-parietal maximum of P300 amplitude (termed P3b), which has an amplitude that is inversely related to factors such as stimulus probability, the information provided by the stimulus event, and perceptual certainty (Huang et al., 2015; Polich, 2007). It is generally accepted that this component also reflects high-order processing associated with the contextual evaluation of attended stimuli.