Pain perception has evolved as a warning mechanism to alert organisms to tissue damage and dangerous environments. In humans, however, undesirable, excessive or chronic pain is a common and major societal burden for which available medical treatments are currently suboptimal. New therapeutic options have recently been derived from studies of individuals with congenital insensitivity to pain (CIP). Here we identified 10 different homozygous mutations in PRDM12 (encoding PRDI-BF1 and RIZ homology domain-containing protein 12) in subjects with CIP from 11 families. Prdm proteins are a family of epigenetic regulators that control neural specification and neurogenesis. We determined that Prdm12 is expressed in nociceptors and their progenitors and participates in the development of sensory neurons in Xenopus embryos. Moreover, CIP-associated mutants abrogate the histone-modifying potential associated with wild-type Prdm12. Prdm12 emerges as a key factor in the orchestration of sensory neurogenesis and may hold promise as a target for new pain therapeutics.

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Hypodontia and malformation are almost regular dental characteristics in patients suffering from ectodermal dysplasia. The distribution of absent teeth deviates remarkably from the general population. Treatment requires an interdisciplinary approach including orthodontics, prosthodontics and oral surgery.

We demonstrate the existence of generalized synchronization in systems that act as mediators between two dynamical units that, in turn, show complete synchronization with each other. These are the so-called relay systems. Specifically, we analyze the Lyapunov spectrum of the full system to elucidate when complete and generalized synchronization appear. We show that once a critical coupling strength is achieved, complete synchronization emerges between the systems to be synchronized, and at the same point, generalized synchronization with the relay system also arises. Next, we use two nonlinear measures based on the distance between phase-space neighbors to quantify the generalized synchronization in discretized time series. Finally, we experimentally show the robustness of the phenomenon and of the theoretical tools here proposed to characterize it. Synchronization is a common phenomenon in a diversity of natural and technological systems [1]. Synchrony, however, is not always achieved spontaneously, and reaching or maintaining a synchronous state often requires an external action. An elegant way to enhance synchronization is the use of relay units between the systems to be synchronized [see Fig. 1(a)]. Relay synchronization (RS) consists of achieving complete synchronization (CS) of two dynamical systems by indirect coupling through a relay unit, whose dynamics does not necessary join the synchronous state. RS is especially useful in bidirectionally coupled systems with a certain delay in the coupling line. In these cases, indeed, the coupling delay may induce instability of the synchronous state [2], which can be restored again thanks to a relay system. Lasers [3,4] and electronics circuits [5] have been the benchmark for experimental demonstration of the feasibility of RS, showing its robustness against noise or parameter mismatch. In semiconductor lasers, for instance, zero-lag synchronization between two delaycoupled oscillators can be achieved by relaying the dynamics via a third mediating element, which surprisingly lags behind the synchronized outer elements. With electronic circuits, RS has been used as a technique for transmitting and recovering encrypted messages, which can be sent bidirectionally and simultaneously [6]. Apart from its technological applications, RS has also been proposed as a possible mechanism at the basis of isochronous synchronization between distant areas of the brain [7]. Despite such evidence of RS, there are still open questions of a fundamental nature. The main issue is to characterize properly the relationship, established in RS, between the dynamics of the relay system and that of the synchronized systems. When a certain delay is introduced in the coupling lines, lag synchronization has been reported [3,4]. Nevertheless, relay units may have certain parameter mismatch [8] or even be completely different systems [5], thus having dynamics with unclear a priori relationship with the systems they are synchronizing.In this paper, we give evidence that RS in fact corresponds to t...

The dynamics of neurons is characterized by a variety of different spiking patterns in response to external stimuli. One of the most important transitions in neuronal response patterns is the transition from tonic firing to burst discharges, i.e., when the neuronal activity changes from single spikes to the grouping of spikes. An increased number of interspike-interval sequences of specific temporal correlations was detected in anticipation of temperature induced tonic-to-bursting transitions in both, experimental impulse recordings from hypothalamic brain slices and numerical simulations of a stochastic model. Analysis of the modelling data elucidates that the appearance of such patterns can be related to particular system dynamics in the vicinity of the period-doubling bifurcation. It leads to a nonlinear response on de- and hyperpolarizing perturbations introduced by noise. This explains why such particular patterns can be found as reliable precursors of the neurons' transition to burst discharges.

BackgroundFor treating deep caries lesions, selective or stepwise (one- and two-step) incomplete excavation seems advantageous compared with complete caries removal. However, current evidence regarding the success, as defined by not requiring any retreatments, or survival of teeth after different excavations is insufficient for definitive recommendation, especially when treating deciduous teeth. Moreover, restoration integrity has not been comparatively analyzed longitudinally, and neither patients’, dentists’ or parents’ preferences nor the clinical long-term costs emanating from both initial and retreatments have been reported yet.Methods/DesignThe planned study is a prospective multicenter, two-arm parallel group, randomized controlled clinical trial comparing selective and stepwise excavation in deciduous molars with deep, active caries lesions without pulpal symptoms. We will recruit 300 children aged between three and nine-years-old with a minimum of one such molar. Patients participating in another study, or those with systemic diseases, disabilities or known allergies to used materials as well patients with teeth expected to exfoliate within the next 18 months will be excluded. After inclusion, sequence generation will be performed. Initial treatment will follow dental routine. During excavation, leathery, moist and reasonably soft dentin will be left in proximity to the pulp followed by adhesive restoration of the cavity. Afterwards, patients’, dentists’ and parents’ subjective assessment of the treatment will be recorded using visual analogue or Likert scales. Re-examination will be performed after six months, and only then teeth will be allocated to one of the two interventions. Selectively excavated teeth will not be treated further, whilst for stepwise caries removal, a second excavation will be performed until only hard dentin remains. Clinical re-evaluations will be performed after 12, 24 and 36 months. Restorations will be reassessed using modified Ryge criteria. Objectively or subjectively required retreatments will determine success and survival. Retreatments will be evaluated both subjectively and regarding generated costs.DiscussionBased on the results of the trial, decision-making for treating deep caries lesions in deciduous molars based on multiple criteria should be feasible.Trial registrationClinicaltrials.gov identifier: NCT02232828 (registered on 29 November 2014).

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We study the role of the strength of subthreshold currents in a four-dimensional Hodgkin-Huxley-type model of mammalian cold receptors. Since a total diminution of subthreshold activity corresponds to a decomposition of the model into a slow, subthreshold, and a fast, spiking subsystem, we first elucidate their respective dynamics separately and draw conclusions about their role for the generation of different spiking patterns. These results motivate a numerical bifurcation analysis of the effect of varying the strength of subthreshold currents, which is done by varying a suitable control parameter. We work out the key mechanisms which can be attributed to subthreshold activity and furthermore elucidate the dynamical backbone of different activity patterns generated by this model.