A Thalamic Reticular Circuit for Head Direction Cell Tuning and Spatial Navigation.

As we navigate in space, external landmarks and internal information guide our movement. Circuit and synaptic mechanisms that integrate these cues with head-direction (HD) signals remain, however, unclear. We identify an excitatory synaptic projection from the presubiculum (PreS) and the multisensory-associative retrosplenial cortex (RSC) to the anterodorsal thalamic reticular nucleus (TRN), so far classically implied in gating sensory information flow. In vitro, projections to TRN involve AMPA/NMDA-type glutamate receptors that initiate TRN cell burst discharge and feedforward inhibition of anterior thalamic nuclei. In vivo, chemogenetic anterodorsal TRN inhibition modulates PreS/RSC-induced anterior thalamic firing dynamics, broadens the tuning of thalamic HD cells, and leads to preferential use of allo- over egocentric search strategies in the Morris water maze. TRN-dependent thalamic inhibition is thus an integral part of limbic navigational circuits wherein it coordinates external sensory and internal HD signals to regulate the choice of search strategies during spatial navigation

Bladder cancer and occupational exposures

A hospital-based cas-referent study was carried out in Lyon with the purpose of generating hypotheses about the role of occupational exposures to 320 compounds in bladder carcinogenesis. Job histories were obtained by questionnaire for 116 cases and 232 reference patients with diseases other than cancer (one referent from the same hospital ward and one from another ward of the same hospital per case) ; the referents were matched for gender, hospital, age, and nationality. Systematic coding of exposures, with a blind analysis of job histories, was carried out by a team of experts in chemistry and occupational health. Significantly elevated odds ratios were observed for exposure to pyrolysis and combustion products [odds ratio (OR) 2.3, 95 % confidence interval (95 % CI) 1.0-4.0] when the general referents were used and for cutting fluids (OR 2.6, 95 % CI 1.2-5.4) when tobacco consumption was adjusted for. The latter was highest among the category consisting of blue-collar and unskilled workers, supervisors, and agricultural workers (OR 4.6, 95 % CI 2.0-10.6), while the odds ratio for the other category was 0.8 (95 % CI 0.3-2.7). An elevated odds ratio for exposure to inks was observed for the women (OR 14.0, 95 % CI 1.8-106.5) on the basis of 14 exposed cases, but confounding factors could have been responsible for this result. Odds ratios for several other exposures (rubber : OR 5.7, nitrates : OR 8.2, coke dust : OR 3.5, meat additives : OR 3.8) were also elevated, but not significantly so when based on a small number of exposed cases. The observations of this investigation should be tested in future studies, in particular since exposures to agents such as cutting fluids or pyrolysis products are ubiquitous in industrial settings and may present an important public health hazard. (Résumé d'auteur

Radiation exposure to the population of Europe following the Chernobyl accident

On the occasion of the 20th anniversary of the Chernobyl accident an attempt has been made to evaluate the impact of the Chernobyl accident on the global burden of human cancer in Europe. This required the estimation of radiation doses in each of the 40 European countries. Dose estimation was based on the analysis and compilation of data either published in the scientific literature or provided by local experts. Considerable variability has been observed in exposure levels among the European populations. The average individual doses to the thyroid from the intake of 131I for children aged 1 y were found to vary from ∼0.01 mGy in Portugal up to 750 mGy in Gomel Oblast (Belarus). Thyroid doses to adults were consistently lower than the doses received by young children. The average individual effective doses from external exposure and ingestion of long-lived radiocaesium accrued in the period 1986-2005 varied from ∼0 in Portugal to ∼10 mSv in Gomel Oblast (Belarus) and Bryansk Oblast (Russia). The uncertainties in the dose estimates were subjectively estimated on the basis of the availability and reliability of the radiation data that were used for dose reconstruction in each countr

Quantifying Infra-slow Dynamics of Spectral Power and Heart Rate in Sleeping Mice.

Three vigilance states dominate mammalian life: wakefulness, non-rapid eye movement (non-REM) sleep, and REM sleep. As more neural correlates of behavior are identified in freely moving animals, this three-fold subdivision becomes too simplistic. During wakefulness, ensembles of global and local cortical activities, together with peripheral parameters such as pupillary diameter and sympathovagal balance, define various degrees of arousal. It remains unclear the extent to which sleep also forms a continuum of brain states-within which the degree of resilience to sensory stimuli and arousability, and perhaps other sleep functions, vary gradually-and how peripheral physiological states co-vary. Research advancing the methods to monitor multiple parameters during sleep, as well as attributing to constellations of these functional attributes, is central to refining our understanding of sleep as a multifunctional process during which many beneficial effects must be executed. Identifying novel parameters characterizing sleep states will open opportunities for novel diagnostic avenues in sleep disorders. We present a procedure to describe dynamic variations of mouse non-REM sleep states via the combined monitoring and analysis of electroencephalogram (EEG)/electrocorticogram (ECoG), electromyogram (EMG), and electrocardiogram (ECG) signals using standard polysomnographic recording techniques. Using this approach, we found that mouse non-REM sleep is organized into cycles of coordinated neural and cardiac oscillations that generate successive 25-s intervals of high and low fragility to external stimuli. Therefore, central and autonomic nervous systems are coordinated to form behaviorally distinct sleep states during consolidated non-REM sleep. We present surgical manipulations for polysomnographic (i.e., EEG/EMG combined with ECG) monitoring to track these cycles in the freely sleeping mouse, the analysis to quantify their dynamics, and the acoustic stimulation protocols to assess their role in the likelihood of waking up. Our approach has already been extended to human sleep and promises to unravel common organizing principles of non-REM sleep states in mammals

Thalamic reticular control of local sleep in mouse sensory cortex.

Sleep affects brain activity globally, but many cortical sleep waves are spatially confined. Local rhythms serve cortical area-specific sleep needs and functions; however, mechanisms controlling locality are unclear. We identify the thalamic reticular nucleus (TRN) as a source for local, sensory-cortex-specific non-rapid-eye-movement sleep (NREMS) in mouse. Neurons in optogenetically identified sensory TRN sectors showed stronger repetitive burst discharge compared to non-sensory TRN cells due to higher activity of the low-threshold Ca <sup>2+</sup> channel Ca <sub>V</sub> 3.3. Major NREMS rhythms in sensory but not non-sensory cortical areas were regulated in a Ca <sub>V</sub> 3.3-dependent manner. In particular, NREMS in somatosensory cortex was enriched in fast spindles, but switched to delta wave-dominated sleep when Ca <sub>V</sub> 3.3 channels were genetically eliminated or somatosensory TRN cells chemogenetically hyperpolarized. Our data indicate a previously unrecognized heterogeneity in a powerful forebrain oscillator that contributes to sensory-cortex-specific and dually regulated NREMS, enabling local sleep regulation according to use- and experience-dependence