Classes of multichannel EEG microstates in light and deep hypnotic conditions

The study assessed the brain electric mechanisms of light and deep hypnotic conditions in the framework of EEG temporal microstates. Multichannel EEG of healthy volunteers during initial resting, light hypnosis, deep hypnosis, and eventual recovery was analyzed into temporal EEG microstates of four classes. Microstates are defined by the spatial configuration of their potential distribution maps ([Symbol: see text]potential landscapes') on the head surface. Because different potential landscapes must have been generated by different active neural assemblies, it is reasonable to assume that they also incorporate different brain functions. The observed four microstate classes were very similar to the four standard microstate classes A, B, C, D [Koenig, T. et al. Neuroimage, 2002;16: 41-8] and were labeled correspondingly. We expected a progression of microstate characteristics from initial resting to light to deep hypnosis. But, all three microstate parameters (duration, occurrence/second and %time coverage) yielded values for initial resting and final recovery that were between those of the two hypnotic conditions of light and deep hypnosis. Microstates of the classes B and D showed decreased duration, occurrence/second and %time coverage in deep hypnosis compared to light hypnosis; this was contrary to microstates of classes A and C which showed increased values of all three parameters. Reviewing the available information about microstates in other conditions, the changes from resting to light hypnosis in certain respects are reminiscent of changes to meditation states, and changes to deep hypnosis of those in schizophrenic states.

Microscale mapping of alteration conditions and potential biosignatures in basaltic-ultramafic rocks on early Earth and beyond

Subseafloor environments preserved in Archean greenstone belts provide an analogue for investigating potential subsurface habitats on Mars. The c. 3.5-3.4 Ga pillow lava metabasalts of the mid-Archean Barberton greenstone belt, South Africa, have been argued to contain the earliest evidence for microbial subseafloor life. This includes candidate trace fossils in the form of titanite microtextures, and sulfur isotopic signatures of pyrite preserved in metabasaltic glass of the c. 3.472 Ga Hooggenoeg Formation. It has been contended that similar microtextures in altered martian basalts may represent potential extraterrestrial biosignatures of microbe-fluid-rock interaction. But despite numerous studies describing these putative early traces of life, a detailed metamorphic characterization of the microtextures and their host alteration conditions in the ancient pillow lava metabasites is lacking. Here, we present a new nondestructive technique with which to study the in situ metamorphic alteration conditions associated with potential biosignatures in mafic-ultramafic rocks of the Hooggenoeg Formation. Our approach combines quantitative microscale compositional mapping by electron microprobe with inverse thermodynamic modeling to derive low-temperature chlorite crystallization conditions. We found that the titanite microtextures formed under subgreenschist to greenschist facies conditions. Two chlorite temperature groups were identified in the maps surrounding the titanite microtextures and record peak metamorphic conditions at 315 ± 40°C (XFe3+(chlorite) = 25-34%) and lower-temperature chlorite veins/microdomains at T = 210 ± 40°C (lower XFe3+(chlorite) = 40-45%). These results provide the first metamorphic constraints in textural context on the Barberton titanite microtextures and thereby improve our understanding of the local preservation conditions of these potential biosignatures. We suggest that this approach may prove to be an important tool in future studies to assess the biogenicity of these earliest candidate traces of life on Earth. Furthermore, we propose that this mapping approach could also be used to investigate altered mafic-ultramafic extraterrestrial samples containing candidate biosignatures.

Trends of periodontal conditions in two different randomly selected Swiss (Bernese) cohorts 25 years apart

AIM To assess the periodontal conditions of two randomly selected Swiss cohorts 25 years apart. MATERIAL AND METHODS Standardized examinations were performed to assess the periodontal conditions of two randomly selected populations of the Canton of Bern; oral cleanliness was evaluated using the plaque index (PlI) and the retention index (RI). Gingival health was scored according to the gingival index (GI). Periodontal conditions were evaluated by pocket probing depth (PPD) and loss of attachment (LA). RESULTS At the first examination in 1985, 206 out of 350 subjects were evaluated, while in the second examination in 2010, 134 out of 490 subjects attended the examinations. In 1985, subjects showed a mean PlI of 1.16, and 0.77 in 2010. RI was 0.81 and 0.36 in 1985 and 2010 respectively. Mean GI was 1.34 and 0.6. The mean proportion of PPD ≤3 mm was 72% in 1985 and 97.3% in 2010. PPD ≥ 6 mm affected 2.0% in 1985 and 0.3% in 2010. In 1985, subjects had an average of 20.7 teeth, while in 2010, the average was 24.6. In 1985, 7.3% of the subjects were edentulous, while in 2010, 4.5% had no teeth. CONCLUSIONS Trends to improvements resulting in more teeth in function and better periodontal conditions were recognized.