Mouth Position Research Articles

Inter- and intra-basin phenotypic variation in two riverine cichlids from northeastern Brazil: potential eco-evolutionary damages of São Francisco interbasin water transfer

Intraspecific morphological variation can be generated by a set of historical and ecological processes, and can be induced by anthropogenic actions. One such activity that has large-scale environmental impacts in freshwater environments is interbasin water transfer. Brazil’s Mid-Northeastern Caatinga freshwater ecoregion is going through an interbasin diversion that will link waters from Sao Francisco ecoregion with the four major basins of Mid-Northeastern Caatinga. Here, we aimed to evaluate the morphological variation of two cichlids, Cichlasoma orientale and Crenicichla menezesi, from both ecoregions and test, whether this morphological variation is related to historical isolation among basins and/or to local water flow regimes, through mtDNA (cytb) and geometric morphometric approaches. Our results showed, for both species, significant morphological differences among basins. However, the comparisons between genetic and morphological differences among basins were not significant. Additionally, a significant shared morphological pattern between species (body depth and mouth position) among different habitats was found. These results reinforce a potential role of environmental pressures upon fish morphology, possibly through phenotypic plasticity. The evolutionary role of morphological responses in freshwater fish populations—especially in variable environments—is discussed, as well as the potential eco-evolutionary damages that might result from the artificial river connection.

Mahseers genera Tor and Neolissochilus (Teleostei: Cyprinidae) from southern Vietnam.

Two new species and two new basin records of mahseers in the genera Tor and Neolissochilus are described from the upper Krong No and middle Đồng Nai drainages of the Langbiang Plateau in southern Vietnam. These new species and new records are known from streams and rivers in montane mixed pine and evergreen forests between 140 and 1112 m. Their populations are isolated in the Sre Pok River of the Mekong basin, the middle of the Đồng Nai basin, and the An Lão River. Both new species are differentiated from their congeners by a combination of the following characters: 23-24 lateral scales, 9-10 predorsal scales, 2/7 or 1/8 pelvic-fin rays, mouth position, median lobe of lower lip, rostral hood, colour in life and by divergent mitochondrial DNA. Tor mekongensis sp. nov. is differentiated from Tor dongnaiensis sp. nov. by the number of transverse scale rows (3/1/2 vs. 4/1/2), number of pelvic-fin rays (2/7 vs. 1/8), a blunt rostral hood vs. pointed, caudal-fin lobes that are equal vs. unequal, and by mitochondrial DNA (0.7% sequence divergence). Molecular evidence identifies both species as members of the genus Tor and distinct from all congeners sampled (uncorrected sequence divergences >1.9% for all Tor species for which homologous COI sequences are available). Tor sinensis is recorded in the Krong No and the Sre Pok rivers, further south of its known distribution. Polymorphism is described in Neolissochilus stracheyi with a Tor-like morph and a Neolissochilus-like morph.

Influential feeding dynamics of sharks and mathematical formulas to estimate the power of biting by morphological data

The mouths of some bony and cartilaginous fishes are located in the anterior part of theirbodies, with a slight variation in sharks, which have theirs located in the abdominal part. Thisvariation is evolutionary over time. The force exerted by the jaws of sharks in order todismember their prey can be examined from two origins: .The determined force exerted by teethand muscles and the force as a result of torque arm through jaw distance. Although sharks applyless force compared to crocodile, their sharp teeth and mouth position provides much strongereffect. Moreover, several species are characterized with heavier upper jaw and this enhances thepower. A mouth located in the anterior part of the body would have less force exerted. On thecontrary, human jaw is shorter, which applies much more force. This paper relates the prebranchiallength and power with preying strength. According to this survey, a couple ofpredators were considered in terms of their mouth position, as well as different kind of feedingand ecological characteristics. Morphological data on several sharks were extracted andevaluated by MATLAB software to prove the following deductive hypothesis. The more thesupport distance (prebranchial length) to concentrated force was, the stronger the shark preyedon animals. The amount of torque had significant relationship with the lever distance andconcentrated force. Besides, several formulas have been recommended to estimate the bite forceand torque based on morphological characteristics.

Implementation of Hand-Free Head Mouse Control System

As computer vision technology been developing, while camera becomes standard configuration for personal computer (PC) and computer calculating speed becomes faster and faster, Computer vision have been more popular used in people daily life, people can use computer as an eye to see and recognize the real world, In this paper, we will present a novel electronic head mouse control system which is based on human facial feature. Our system firstly detect human face from the input image by using face features in YUV Color model, and then for face candidate, use reversed relationship information between U and V cluster of face feature to detect mouth position. Then in the detected mouth region, mouth lip region gray level is usually lower than other region but V level higher than others, so we can reversal mouth region gray level and use associated threshold method to pick up mouth region pixels. Relationship between mouth position and face region boundary can be used to confirm human head rotation angles correspond to camera, which can be used to control mouse movement in screen. Then throughing analysising mouth shape information, we can confirm mouth motion command for mouse. We have simulated our algorithm on windows XP system to evaluate the effect of our algorithm. The simulation result showed that our algorithm can represent a good effect for head mouse control system.

Constructional morphology within the head of hammerhead sharks (sphyrnidae).

The study of functional trade-offs is important if a structure, such as the cranium, serves multiple biological roles, and is, therefore, shaped by multiple selective pressures. The sphyrnid cephalofoil presents an excellent model for investigating potential trade-offs among sensory, neural, and feeding structures. In this study, hammerhead shark species were chosen to represent differences in head form through phylogeny. A combination of surface-based geometric morphometrics, computed tomography (CT) volumetric analysis, and phylogenetic analyses were utilized to investigate potential trade-offs within the head. Hammerhead sharks display a diversity of cranial morphologies where the position of the eyes and nares vary among species, with only minor changes in shape, position, and volume of the feeding apparatus through phylogeny. The basal winghead shark, Eusphyra blochii, has small anteriorly positioned eyes. Through phylogeny, the relative size and position of the eyes change, such that derived species have larger, more medially positioned eyes. The lateral position of the external nares is highly variable, showing no phylogenetic trend. Mouth size and position are conserved, remaining relatively unchanged. Volumetric CT analyses reveal no trade-offs between the feeding apparatus and the remaining cranial structures. The few trade-offs were isolated to the nasal capsule volume's inverse correlation with braincase, chondrocranial, and total cephalofoil volume. Eye volume also decreased as cephalofoil width increased. These data indicate that despite considerable changes in head shape, much of the head is morphologically conserved through sphyrnid phylogeny, particularly the jaw cartilages and their associated feeding muscles, with shape change and morphological trade-offs being primarily confined to the lateral wings of the cephalofoil and their associated sensory structures.

Covariation of trophic and habitat‐related traits in chondrostoms (Cyprinidae): implications for repeated and diversifying evolutionary processes

AbstractThe tenet that ecological adaptation can lead to recurrent ecomorphological trends resulting from repetitive processes has long been a primary topic of investigation in evolutionary ecology. To explore this aspect further, this study provides an analysis of the morphological diversity in chondrostoms (Cyprinidae). This freshwater fish group shows a tendency towards bottom‐feeding specialization, which has led to evolutionary innovations in body and mouth shape traits, which are currently used for the classification of genera. Body, lower lip (LL) and corner ray shape were analysed for nine species in total. Allometric relationships among the three morphometric traits were considered to be responsible for LL shape variability and there was significant covariation between LL and body shape, which reflected habitat use. Smaller and opportunistic‐feeding species inhabiting stream or small‐sized rivers were characterized by a deeper body (increased feeding maneuverability), an arched LL and a terminal mouth position. Conversely, larger and diet‐specialized species were characterized by a fusiform body (increased swimming performance), a straight LL and an inframouth position on an elongated snout (optimized bottom feeding). The results suggest that interspecific mouth shape variability may have originated from two types of ‘deformation’ processes, both leading to a straight mouth shape and acting either jointly or independently. Also, given the plesiomorphic state of several of the species under study, the specialization towards a benthic lifestyle in chondrostoms from different phylogenetic lineages is thought to have occurred repeatedly to overcome a number of functional constraints, including foraging efficiency and swimming performance.

The role of gill rakers in the adaptation and habitat partitioning of Nicaraguan crater lake cichlid fishes

Event Abstract Back to Event The role of gill rakers in the adaptation and habitat partitioning of Nicaraguan crater lake cichlid fishes Marta Barluenga1*, Gema Aguilera1 and Melinda J. Hofmann1 1 Museo Nacional de Ciencias Naturales, CSIC, Dept. Biodiversity & Evolutionary Biology, Spain The coexistence of species is facilitated by niche partitioning. Resource competition is a major cause of phenotypic differentiation.The major axes of differentiation in closely related species occur along the two ecological dimensions habitat and diet. Adaptive radiations typically follow these axes of variation. Some of the most important traits in the radiations of freshwater fish are body size, body shape, and a few trophic features such as mouth position, teeth type or gill rakers. In some of the most famous temperate freshwater radiations (i.e., sticklebacks, whitefish) gill rakers play a pivotal role in the adaptation to novel prey types. Cichlids are the most famous textbook examples of fast and divergent adaptive radiations. Often species differ in adaptation to alternative prey types associated to particular trophic morphologies. Pharyngeal jaw shape, oral and pharyngeal teeth and mouth position are the main traits typically studied in cichlid radiations. Gill rakers have however rarely been consider when trying to understand cichlid adaptation to the environment. Here we assess the variation of gill rakers in the cichlid assemblage inhabiting the Nicaraguan large and crater lakes. We found marked differences among species, and found interesting correlations between gill raker traits and environmental features demonstrating their role in adaptation and diversification. Keywords: adaptation, niche partitioning, cichlid fishes, Crater lakes, Gill rakers Conference: XV European Congress of Ichthyology, Porto, Portugal, 7 Sep - 11 Sep, 2015. Presentation Type: Oral Presentation Topic: Ecology, Conservation and Invasive Species Citation: Barluenga M, Aguilera G and Hofmann MJ (2015). The role of gill rakers in the adaptation and habitat partitioning of Nicaraguan crater lake cichlid fishes. Front. Mar. Sci. Conference Abstract: XV European Congress of Ichthyology. doi: 10.3389/conf.FMARS.2015.03.00234 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 17 Dec 2015; Published Online: 19 Dec 2015. * Correspondence: Dr. Marta Barluenga, Museo Nacional de Ciencias Naturales, CSIC, Dept. Biodiversity & Evolutionary Biology, Madrid, 28006, Spain, marta.barluenga@mncn.csic.es Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Marta Barluenga Gema Aguilera Melinda J Hofmann Google Marta Barluenga Gema Aguilera Melinda J Hofmann Google Scholar Marta Barluenga Gema Aguilera Melinda J Hofmann PubMed Marta Barluenga Gema Aguilera Melinda J Hofmann Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Anatomical rationale for lingual nerve injury prevention during mandibular block

The topographic and anatomical study of lingual nerve structural features was done. It was revealed that during mandibular anesthesia possible lingual nerve injury can occur if puncture needle is lower than 1 cm. of molars occlusal surface level. The position of the lingual nerve varies withmandible movements. At the maximum open mouth lingual nerve is not mobile and is pressed against the inner surface of the mandibular ramus by the medial pterygoid muscle and the temporal muscle tendon. When closing the mouth to 1.25±0.2 cmfrom the physiological maximum, lingual nerve is displaced posteriorly from the internal oblique line of the mandible and gets mobile. On the basis of topographic and anatomic features of the lingual nervestructure the authors recommend the re-do of inferior alveolar nerve block, a semi-closed mouth position or the use the "high block techniques" (Torus anesthesia, Gow-Gates, Vazirani-Akinozi).

The Effectiveness of Occlusal Splint for the Treatment of Temporomandibular Joint Dislocation

Temporomandibular joint (TMJ) dislocation is defined that the disc-condyle complex is positioned anterior to the articular eminence in the open mouth position, and is unable to return to a normal closed mouth position without a manipulative maneuver. TMJ dislocation can recur habitually and result several problems to patients such as discomfort, pain, fear, and anxiety. The only definitive treatment for TMJ dislocation is surgical alteration of the joint itself. In most cases, however, a surgical procedure is far too aggressive for the symptoms experienced by the patient. In addition, the effect of surgical treatment may be insufficient, and the recurrence have been reported. It is also possible to develop several complications after surgical treatment. Therefore much effort should be directed at supportive therapy in an attempt to eliminate the disorder or at least reduce the symptom to tolerable levels. Through this cases the authors present favorable treatment outcome using occlusal splint with the patient of TMJ dislocation. Occlusal splint therapy can be considered as easy, safe, and useful non-invasive modality to treatment of TMJ dislocation.

Efficacy of Interpositional Arthroplasty with Temporalis Myofascia Flap in Treatment of TMJ Ankylosis

Aims and objective: The present study was done to evaluate the efficacy of interpositional arthroplasty with temporalis muscle and fascia (myofascia) flap in preventing the re-ankylosis, to evaluate the growth of mandible, and to assess Al-Kayat and Bramley’s incision for its versatility in allowing muscle transfer and excellent exposure of the joint. Materials and Methods: Fifteen patients with ankylosis were treated with interpositional arthroplasty with temporalis myofascia flap. Maximum Interincisal Opening (MIO) was measured at different periods, i.e. preoperative, intraoperative, immediate post operative, 1 month post-operative, 6 month post-operative, 1 year post-operative. Pain was measured using Visual analogue scales in closed mouth position (spontaneously) & on mouth opening. Six cephalometric points were taken for evaluating the mandibular growth. Results: A statistically significant difference of 30.73 mm (p<0.001) was obtained between pre-operative and post-operative interincisal opening after a period of one year follow up. The pain score at different periods of time revealed that the pain incidence significantly reduced to almost zero post-operatively (p<0.5 for closed mouth, p<0.01 for open mouth).

Adaptive divergence between lake and stream populations of an East African cichlid fish.

Divergent natural selection acting in different habitats may build up barriers to gene flow and initiate speciation. This speciation continuum can range from weak or no divergence to strong genetic differentiation between populations. Here, we focus on the early phases of adaptive divergence in the East African cichlid fish Astatotilapia burtoni, which occurs in both Lake Tanganyika (LT) and inflowing rivers. We first assessed the population structure and morphological differences in A.burtoni from southern LT. We then focused on four lake-stream systems and quantified body shape, ecologically relevant traits (gill raker and lower pharyngeal jaw) as well as stomach contents. Our study revealed the presence of several divergent lake-stream populations that rest at different stages of the speciation continuum, but show the same morphological and ecological trajectories along the lake-stream gradient. Lake fish have higher bodies, a more superior mouth position, longer gill rakers and more slender pharyngeal jaws, and they show a plant/algae and zooplankton-biased diet, whereas stream fish feed more on snails, insects and plant seeds. A test for reproductive isolation between closely related lake and stream populations did not detect population-assortative mating. Analyses of F1 offspring reared under common garden conditions indicate that the detected differences in body shape and gill raker length do not constitute pure plastic responses to different environmental conditions, but also have a genetic basis. Taken together, the A.burtoni lake-stream system constitutes a new model to study the factors that enhance and constrain progress towards speciation in cichlid fishes.

Spatial variability of prodeltaic undulations on the Guadalfeo River prodelta: support to the genetic interpretation as hyperpycnal flow deposits

Two fields of prodeltaic undulations located off the Guadalfeo River were studied by integrating surficial (multibeam bathymetry, backscatter, sediment samples) and sub-surface (seismic profiles, sediment cores) data. Our main motivation was to analyze the along- and across-shelf variability of the seafloor undulations, in order to obtain useful insights into genetic mechanisms. A geostatistical analysis was performed, based on the determination of characteristic parameters and derived relationships. The undulations occur over a concave-upward surface which shows a seaward-decreasing slope. Most of the undulations are symmetrical to asymmetrically-oriented toward the coast. Two main fields are correlated with the present and previous river mouths. The western field, associated with the modern river mouth, is highly symmetrical, with the higher undulations in an axial position and diminishing the width/height relationship both laterally and downslope. In contrast, the eastern field, associated with an historic river mouth, shows lower-amplitude undulations, the width/height changes are less pronounced, and the undulations are more elongated. The two undulation fields exhibit subseafloor reflections that are subparallel to the seafloor, with peaks that migrate upslope upward in the stratigraphic column and which appear to correlate with coarse-grained layers. We support the contention that prodeltaic undulations off the Guadalfeo River should be regarded as sediment waves. Assuming a sediment-wave process, a strong normal-to-contour sediment flows with a riverine origin (e.g., hyperpycnal flows) may have been active during undulation generation. Both morphometric parameters of the river basin and estimations of sediment concentration during exceptional flood events are in agreement with an episodic activity of high freshwater discharges. Most of the geomorphic parameters and stratigraphic observations indicate a change of sediment supply conditions related to the shift in river mouth position, attributed to a temporal change in the activity of hyperpycnal flows.

Bidirectional control of a one-dimensional robotic actuator by operant conditioning of a single unit in rat motor cortex.

The design of efficient neuroprosthetic devices has become a major challenge for the long-term goal of restoring autonomy to motor-impaired patients. One approach for brain control of actuators consists in decoding the activity pattern obtained by simultaneously recording large neuronal ensembles in order to predict in real-time the subject's intention, and move the prosthesis accordingly. An alternative way is to assign the output of one or a few neurons by operant conditioning to control the prosthesis with rules defined by the experimenter, and rely on the functional adaptation of these neurons during learning to reach the desired behavioral outcome. Here, several motor cortex neurons were recorded simultaneously in head-fixed awake rats and were conditioned, one at a time, to modulate their firing rate up and down in order to control the speed and direction of a one-dimensional actuator carrying a water bottle. The goal was to maintain the bottle in front of the rat's mouth, allowing it to drink. After learning, all conditioned neurons modulated their firing rate, effectively controlling the bottle position so that the drinking time was increased relative to chance. The mean firing rate averaged over all bottle trajectories depended non-linearly on position, so that the mouth position operated as an attractor. Some modifications of mean firing rate were observed in the surrounding neurons, but to a lesser extent. Notably, the conditioned neuron reacted faster and led to a better control than surrounding neurons, as calculated by using the activity of those neurons to generate simulated bottle trajectories. Our study demonstrates the feasibility, even in the rodent, of using a motor cortex neuron to control a prosthesis in real-time bidirectionally. The learning process includes modifications of the activity of neighboring cortical neurons, while the conditioned neuron selectively leads the activity patterns associated with the prosthesis control.

Measurement of oxygen concentration delivered via nasal cannulae by tracheal sampling

Oxygen is used in many clinical scenarios, however the variable performance of nasal cannulae makes determining the precise fraction of inspired oxygen (FiO2 ) difficult. We developed a novel method for measurement of the tracheal FiO2 using a catheter placed via bronchoscopy. We investigate the effects of oxygen delivery, respiratory rate, mouth position and estimated minute ventilation (VE ) on the FiO2 delivered by nasal cannulae. The catheter was placed in 20 subjects. Tracheal gas concentrations were analysed during six 5-min treatments controlling for oxygen delivery rate, respiratory rate and mouth position. Ventilation was monitored with respiratory inductive plethysmography (RIP). The FiO2 delivered by nasal cannulae was compared between treatments, and we investigated the relationships among the FiO2 , alveolar partial pressure of oxygen (PA O2 ) and VE . The FiO2 increased by 0.038/L/min of oxygen. Respiratory rate had a significant effect on the FiO2 . A normal respiratory rate of 15 breaths/min and oxygen supplementation via nasal cannula at 2 L/min resulted in an FiO2 of 0.296; however, FiO2 decreased by 0.012 at 20 breaths/min and 0.004 at 10 breaths/min. The mean FiO2 decreased by 0.024 with the mouth open. The FiO2 and PA O2 were observed to decrease with increasing VE . Continuous measurement of the FiO2 using a transtracheal catheter provides detailed insight into inspiratory changes of the FiO2 delivered by nasal cannulae. Our study confirms that respiratory rate, VE and mouth position significantly influence the inspired oxygen concentration. These parameters should be accounted for when prescribing oxygen.

Modeling and Control of Lip Based on Double-Layer Muscle

Lip model plays an important role in virtual facial expression and speech simulation. However, the structures and movements of existing lip models are very simple, and the common motions such as protruding, pouting and sipping are failed to totally realize. In order to solve these problems, this paper presents a new double-layer muscle-controlled lip model. This method adopts the approach from anatomy to classify lip muscles into deep and superficial ones. The deep muscle is employed to control the corners of the mouth position and the size of mouth fissure. The superficial muscle is treated as a new arc muscle, and it uses catenary function to fix the parameters under different shrinkages and fit the process of protruding and sipping etc. The experiments show that the method can control the model flexibly and simulate some lip movements that accord with physiological motion characteristics.

Influence of oral stabilization appliances in intra-articular pressure of the temporomandibular joint

Aims:This study analyzed the intra-articular pressure in the upper compartment of the temporomandibular joint (TMJ) under different functional conditions. The influence of stabilization appliances on intra-articular pressure was studied.Methodology:Seventy-four joints from 64 patients (55 women and 9 men; mean age: 43·2±11·86 years; range: 19–61 years) with TMJ disorders were examined. Only 50 joints passed the inclusion criteria. Intra-articular pressure was measured using a 21G needle inserted into the joint and connected to a pressure transducer. Pressure was measured with the jaw in the following positions: at rest, maximal mouth opening, clenching in maximal intercuspal position, and clenching with an oral interoclusal appliance.Results:Fifty joints were included in the study (without blood reflux), mean pressure at rest was negative (–6·06±4·55 mmHg); when the mouth was opened to its maximal position the pressure was lower (−26·09±6·42 mmHg). Mean intra-articular pressure was higher in the maximal intercuspal position (58·56±24·90 mmHg). When an interoclusal appliance device was fitted, mean intra-articular pressure reduced its value by 31·24%, which reached a mean value of 40·56±18·84 mmHg (P<0·001). There were no significant differences in sex. The group over 45 years old had higher pressure values in maximal open mouth position than the group of patients under 45 years old (P<0·02).Conclusions:Interoclusal appliances can reduce pressure in the upper compartment of the TMJ and improve functional status of the joint.

Force relaxation of 3/16 inch heavy orthodontic latex elastics used in maxillofacial trauma in simulated jaw fracture situation

Introduction: Orthodontic elastic has been investigated for tooth movement. Study about their use in treatment of jaw fractures is limited. This study is designed to measure force relaxation of 3/16 inch heavy latex orthodontic elastics in jaw fracture treatment simulated conditions. Materials and Methods: This study is designed to study the force relaxation of 45 heavy 3/16 inch orthodontic elastic (American Orthodontist, AO) (4/8 mm internal diameter) were measured using Zwick testing machine (Zwick GmbH & Ulm Germany) in 0, 1, and 14 days of immersion in simulated oral environment. In each of these three occasions, 15 specimens were placed in jigs with metallic pins that inserted 15 mm and 20 mm apart that is equivalent to the normal inter-arch space in a closed mouth position. The jigs were incubated in 37°C and each 24 hours they received 10 thermal cycles of 55°C and 5°C for 30 seconds in a thermocycle. The distribution of the data was evaluated by Klomogrov-Simirnov test and after confirmation of a normal distribution; data was analyzed using analysis of variance (ANOVA). Results: Mean force decay at 15 mm stretch was significantly differ between 0-1 days and 0-14 days (P < 0.05) but was not significantly differ between 1-14 days. The same relations exist for 20 mm stretch. Conclusions: This study creates scientific basis for use of orthodontic elastics in treatment of fractured jaws.

Operant conditioning of single units in rat motor cortex allows graded control of a prosthetic device

Operant control of a prosthesis by neuronal cortical activity is one of the successful strategies for implementing brain-machine interfaces, by which the subject learns to exert a volitional control of goal-directed movements. Here, several motor cortex neurons were recorded simultaneously in head-fixed awake rats and were trained, one at a time, to modulate their firing in order to control the speed and direction of a 1D actuator carrying a water bottle. In the first phase of the experiment, the bottle could only move in one direction and this was triggered by an increase in firing rate. Most neurons submitted to this conditioning successfully increased their activity during trials, and this effect was enhanced across sessions. Once trained, the neuron chosen to control the operant behavior reacted consistently more rapidly than the other recorded neurons after trial onset. We observed also that the firing rate variability increased in an anticipatory way before trial onset, specifically for the neurons that could be conditioned successfully. However, this effect was observed only in the initial phases of the conditioning. In the second phase of the experiment, neurons modulated their firing rate up or down in order to control the direction and speed of the water bottle. The bottle could thus move bilaterally, and the goal was to maintain the bottle in front of the rat's mouth in order to allow drinking. All conditioned neurons adapted their firing rate to the instantaneous bottle position so that the drinking time was increased relative to chance. The mean firing rate averaged over all trajectories depended on position, so that the mouth position operated as an attractor (at least for the bottle starting side). Again, the conditioned neuron reacted on average faster than the other neurons and led to a better bottle control than if trajectories were simulated using the activity of simultaneously recorded neurons. Overall, our results demonstrate that conditioning single neurons is a suitable approach to control a prosthesis in real-time, and that these neurons occupy a lead position after learning, acting as master neurons in the network.

Use of heated humidified high‐flow nasal cannula oxygen in neonates: a UK wide survey

Heated humidified high-flow nasal cannula (HHHFNC) oxygen is a relatively new form of respiratory support and is increasing in popularity despite lack of supportive evidence and amid safety concerns. We investigated the prevalence of its use in tertiary neonatal units in the UK. Electronic survey. A total of 57 units were contacted and replies received from 44 (77%). HHHFNC was used in 34/44 (77%) units. Vapotherm 2000i and Fisher and Paykel RT329 were the most popular devices. 39% units used HHHFNC without policies. Most reported use in infants of any gestation (24/34, 71%) and weight (26/34, 77%) and for a variety of indications including as an alternative to CPAP (26/34, 77%), weaning off CPAP (24/34, 71%) and postextubation (18/34, 53%). The flow rates, cannula size and mouth position varied widely. The popularity of HHHFNC appeared to be its perceived ease of use and improved access to the baby. This survey demonstrates that HHHFNC is a widely used modality in UK neonatal units. Its current use appears to be without clear criteria and mostly based on individual preference. In view of doubts about its efficacy and concerns regarding safety, this study highlights the urgent need for research to evaluate its use in newborns.

Effects of open mouth and rubber dam on upper airway patency and breathing

Rubber dams increase the quality and safety of dental treatment. However, the condition of a rubber dam over an open mouth may also obstruct the route for respiration. We tested whether an open mouth with or without a rubber dam would affect upper airway patency and breathing pattern. Twenty young healthy volunteers were imaged with a magnetic resonance (MR) system under three conditions: mouth closed, mouth open, and rubber dam with mouth open. Respiration was concurrently monitored with plethysmography. MRI slices of the upper airway were obtained at 5-mm thicknesses, and the size of the cross-sectional area of the upper airway was measured by image analysis software. Respiratory cycle duration and tidal volume were also measured with digital signal analysis software. The volume of the upper airway became significantly decreased with the mouth open. Analysis of each cross-sectional area of the upper airway revealed that while the oropharyngeal area was significantly narrower with an open mouth, the retropalatal and hypopharyngeal areas were not affected. Placing a rubber dam had no additional influence on upper airway patency but was seen to significantly shorten mean respiratory duration and decrease tidal volume. Open mouth position plays the largest role in decreased upper airway patency, and open mouth position with a rubber dam may further disrupt breathing pattern. Breathing pattern may become deteriorated by airway obstruction during dental treatments requiring a rubber dam.