Distinguishing intentional from nonintentional actions through eeg and kinematic markers.

How can an intentional movement be distinguished from the same movement done nonintentionally? How can this distinction be drawn without asking the subject, or in patients who are unable to communicate? Here we address these questions, by focusing on blinking. This is one of the most frequent spontaneous actions in our daily life, but it can also be done intentionally. Furthermore, blinking is often spared in patients with severe brain injuries, and for some, it is the only way to report complex meanings. Using kinematic and EEG-based measures, we found that intentional and spontaneous blinking are preceded by different brain activities, even when they are indistinguishable. Unlike spontaneous ones, intentional blinks are characterized by a slow negative EEG drift, resembling the classic readiness potential. We investigated the theoretical implication of this finding in stochastic decision models as well as the practical significance of using brain-based signals to improve the discrimination between intentional and nonintentional actions. As proof of principle, we considered three brain-injured patients with rare neurological syndromes characterized by motor and communicative impairments. Although further research is needed, our results indicate that brain-based signals can offer a feasible way to infer intentionality even in absence of overt communication.

Sleep-like cortical OFF-periods disrupt causality and complexity in the brain of unresponsive wakefulness syndrome patients.

Unresponsive wakefulness syndrome (UWS) patients may retain intact portions of the thalamocortical system that are spontaneously active and reactive to sensory stimuli but fail to engage in complex causal interactions, resulting in loss of consciousness. Here, we show that loss of brain complexity after severe injuries is due to a pathological tendency of cortical circuits to fall into silence (OFF-period) upon receiving an input, a behavior typically observed during sleep. Spectral and phase domain analysis of EEG responses to transcranial magnetic stimulation reveals the occurrence of OFF-periods in the cortex of UWS patients (N = 16); these events never occur in healthy awake individuals (N = 20) but are similar to those detected in healthy sleeping subjects (N = 8). Crucially, OFF-periods impair local causal interactions, and prevent the build-up of global complexity in UWS. Our findings link potentially reversible local events to global brain dynamics that are relevant for pathological loss and recovery of consciousness.

Vascular impairment in patients with primary biliary cirrhosis.

Experimental and clinical observation suggest that patients with primary biliary cirrhosis (PBC) have endothelial dysfunction. Postischemic digital blood flow, nailfold capillaroscopy, von Willebrand factor (vWf) and tissue-type plasminogen activator (t-PA) plasma levels were examined in 59 PBC patients. Forty-six subjects (15 with liver diseases other than PBC, 11 hypercholesterolemics, 20 healthy subjects) served as controls. PBC versus healthy controls (209.8 +/- 1.4% and 16.54 +/- 1.44 ng/ml vs. 120.2 +/- 1.4% and 9.91 +/- 1.49 ng/ml; p<0.001) and related to bilirubin (r = 0.38, p<0.02; r = 0.47, p<0.0005, respectively). vWf was also increased in other liver diseases (249.9 +/- 1.7%; p<0.001) and related to bilirubin (r = 0.59, p<0.05). Postischemic finger blood flow negatively correlated with vWf(p<0.05 or less). Our data indicate that PBC patients have microvascular disease. Whether vessels other than those of the fingers were involved remained unclear. vWf and t-PA might reflect a dysfunction of teh hepatic vascular endothelium.