Changes in spatial self-consciousness elicit grid cell-like representation in the entorhinal cortex.

Grid cells in the entorhinal cortex (EC) encode an individual's location in space, integrating both environmental and multisensory bodily cues. Notably, body-derived signals are also primary signals for the sense of self. While studies have demonstrated that continuous application of visuo-tactile bodily stimuli can induce perceptual shifts in self-location, it remains unexplored whether these illusory changes suffice to trigger grid cell-like representation (GCLR) within the EC, and how this compares to GCLR during conventional virtual navigation. To address this, we systematically induced illusory drifts in self-location toward controlled directions using visuo-tactile bodily stimulation, while maintaining the subjects' visual viewpoint fixed (absent conventional virtual navigation). Subsequently, we evaluated the corresponding GCLR in the EC through functional MRI analysis. Our results reveal that illusory changes in perceived self-location (independent of changes in environmental navigation cues) can indeed evoke entorhinal GCLR, correlating in strength with the magnitude of perceived self-location, and characterized by similar grid orientation as during conventional virtual navigation in the same virtual room. These data demonstrate that the same grid-like representation is recruited when navigating based on environmental, mainly visual cues, or when experiencing illusory forward drifts in self-location, driven by perceptual multisensory bodily cues.

Numerosity estimation of virtual humans as a digital-robotic marker for hallucinations in Parkinson's disease.

Hallucinations are frequent non-motor symptoms in Parkinson's disease (PD) associated with dementia and higher mortality. Despite their high clinical relevance, current assessments of hallucinations are based on verbal self-reports and interviews that are limited by important biases. Here, we used virtual reality (VR), robotics, and digital online technology to quantify presence hallucination (vivid sensations that another person is nearby when no one is actually present and can neither be seen nor heard) in laboratory and home-based settings. We establish that elevated numerosity estimation of virtual human agents in VR is a digital marker for experimentally induced presence hallucinations in healthy participants, as confirmed across several control conditions and analyses. We translated the digital marker (numerosity estimation) to an online procedure that 170 PD patients carried out remotely at their homes, revealing that PD patients with disease-related presence hallucinations (but not control PD patients) showed higher numerosity estimation. Numerosity estimation enables quantitative monitoring of hallucinations, is an easy-to-use unobtrusive online method, reaching people far away from medical centers, translating neuroscientific findings using robotics and VR, to patients' homes without specific equipment or trained staff.

Cerebral venous sinus thrombosis presenting with subarachnoid hemorrhage: a series of 11 cases.

BACKGROUND AND PURPOSE: Cerebral venous sinus thrombosis (CVST) is a rare cerebrovascular disease with a wide spectrum of clinical manifestations. The aim of this study is to assess the presence of subarachnoid hemorrhage (SAH) in the context of CVST and to present its epidemiological, clinical and radiological/laboratory aspects. METHODS: Between October 2012 and October 2019, 43 patients with CVST were reviewed. Eleven (25.58%) cases presented SAH. RESULTS: A quarter of the patients evaluated with CVST had SAH. There were 9 women (81.82%) and 2 men, with a mean age at presentation of 37.7 years (range 28-49). The most common risk factor was the use of oral contraceptives and the most prevalent symptom was headache. Both sinuses, the superior sagittal sinus and the transverse sinus, were the most affected. There was no isolated involvement of the cortical vein. The SAH was limited to some sulci of cerebral convexity in 8 cases (72.73%). In one case, the location of SAH was in the cerebellum and in two cases in the Sylvian fissure. In two cases, there was an evolution to venous infarction; and in three cases, intraparenchymal hemorrhage was present. Seven patients (63.64%) improved considerably with anticoagulation after 6 months of treatment. CONCLUSIONS: This series found that 25.58% of patients with CVST had SAH. It is the highest incidence described in the literature so far. Findings of SAH located in the cerebral convexities, without affecting the base cisterns, should always lead to the suspicion of CVST.

Animated virtual characters to explore audio-visual speech in controlled and naturalistic environments.

Natural speech is processed in the brain as a mixture of auditory and visual features. An example of the importance of visual speech is the McGurk effect and related perceptual illusions that result from mismatching auditory and visual syllables. Although the McGurk effect has widely been applied to the exploration of audio-visual speech processing, it relies on isolated syllables, which severely limits the conclusions that can be drawn from the paradigm. In addition, the extreme variability and the quality of the stimuli usually employed prevents comparability across studies. To overcome these limitations, we present an innovative methodology using 3D virtual characters with realistic lip movements synchronized on computer-synthesized speech. We used commercially accessible and affordable tools to facilitate reproducibility and comparability, and the set-up was validated on 24 participants performing a perception task. Within complete and meaningful French sentences, we paired a labiodental fricative viseme (i.e. /v/) with a bilabial occlusive phoneme (i.e. /b/). This audiovisual mismatch is known to induce the illusion of hearing /v/ in a proportion of trials. We tested the rate of the illusion while varying the magnitude of background noise and audiovisual lag. Overall, the effect was observed in 40% of trials. The proportion rose to about 50% with added background noise and up to 66% when controlling for phonetic features. Our results conclusively demonstrate that computer-generated speech stimuli are judicious, and that they can supplement natural speech with higher control over stimulus timing and content.

Uncovering EEG Correlates of Covert Attention in Soccer Goalkeepers: Towards Innovative Sport Training Procedures.

Advances in sports sciences and neurosciences offer new opportunities to design efficient and motivating sport training tools. For instance, using NeuroFeedback (NF), athletes can learn to self-regulate specific brain rhythms and consequently improve their performances. Here, we focused on soccer goalkeepers' Covert Visual Spatial Attention (CVSA) abilities, which are essential for these athletes to reach high performances. We looked for Electroencephalography (EEG) markers of CVSA usable for virtual reality-based NF training procedures, i.e., markers that comply with the following criteria: (1) specific to CVSA, (2) detectable in real-time and (3) related to goalkeepers' performance/expertise. Our results revealed that the best-known EEG marker of CVSA-increased α-power ipsilateral to the attended hemi-field- was not usable since it did not comply with criteria 2 and 3. Nonetheless, we highlighted a significant positive correlation between athletes' improvement in CVSA abilities and the increase of their α-power at rest. While the specificity of this marker remains to be demonstrated, it complied with both criteria 2 and 3. This result suggests that it may be possible to design innovative ecological training procedures for goalkeepers, for instance using a combination of NF and cognitive tasks performed in virtual reality.

Sequential intra-arterial infusion of 90Y-resin microspheres and mitomycin C in chemo refractory liver metastatic breast cancer patients: a single centre pilot study.

Background The aim of the study was to evaluate the safety and feasibility of intra-arterial mitomycin C (MMC) infusion after selective internal radiation therapy (SIRT) using Yttrium-90 (90Y) resin microspheres in liver metastatic breast cancer (LMBC) patients. Patients and methods The prospective pilot study included LMBC patients from 2012-2018. Patients first received infusion of 90Y resin microspheres, after 6-8 weeks response to treatment was assessed by MRI, 18F-FDG PET/CT and laboratory tests. After exclusion of progressive disease, MMC infusion was administrated 8 weeks later in different dose cohorts; A: 6 mg in 1 cycle, B: 12 mg in 2 cycles, C: 24 mg in 2 cycles and D: maximum of 72 mg in 6 cycles. In cohort D the response was evaluated after every 2 cycles and continued after exclusion of progressive disease. Adverse events (AE) were reported according to CTCAE version 5.0. Results Sixteen patients received 90Y treatment. Four patients were excluded for MMC infusion, because of extra hepatic disease progression (n = 3) and clinical and biochemical instability (n = 1). That resulted in the following number of patient per cohort; A: 2, B: 1, C: 3 and D: 6. In 4 of the 12 patients (all cohort D) the maximum dose of MMC was adjusted due biochemical toxicities (n = 2) and progressive disease (n = 2). One grade 3 AE occurred after 90Y treatment consisting of a gastrointestinal ulcer whereby prolonged hospitalization was needed. Conclusions Sequential treatment of intra-arterial infusion of MMC after 90Y SIRT was feasible in 75% of the patients when MMC was administrated in different escalating dose cohorts. However, caution is needed to prevent reflux after 90Y SIRT in LMBC patients.

"Do You Feel in Control?": Towards Novel Approaches to Characterise, Manipulate and Measure the Sense of Agency in Virtual Environments.

While the Sense of Agency (SoA) has so far been predominantly characterised in VR as a component of the Sense of Embodiment, other communities (e.g., in psychology or neurosciences) have investigated the SoA from a different perspective proposing complementary theories. Yet, despite the acknowledged potential benefits of catching up with these theories a gap remains. This paper first aims to contribute to fill this gap by introducing a theory according to which the SoA can be divided into two components, the feeling and the judgment of agency, and relies on three principles, namely the principles of priority, exclusivity and consistency. We argue that this theory could provide insights on the factors influencing the SoA in VR systems. Second, we propose novel approaches to manipulate the SoA in controlled VR experiments (based on these three principles) as well as to measure the SoA, and more specifically its two components based on neurophysiological markers, using ElectroEncephaloGraphy (EEG). We claim that these approaches would enable us to deepen our understanding of the SoA in VR contexts. Finally, we validate these approaches in an experiment. Our results (N=24) suggest that our approach was successful in manipulating the SoA as the modulation of each of the three principles induced significant decreases of the SoA (measured using questionnaires). In addition, we recorded participants' EEG signals during the VR experiment, and neurophysiological markers of the SoA, potentially reflecting the feeling and judgment of agency specifically, were revealed. Our results also suggest that users' profile, more precisely their Locus of Control (LoC), influences their level of immersion and SoA.