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1.
Sci Rep ; 9(1): 10298, 2019 Jul 16.
Artículo en Inglés | MEDLINE | ID: mdl-31311957

RESUMEN

Inner ear sensory afferent connections establish sensory maps between the inner ear hair cells and the vestibular and auditory nuclei to allow vestibular and sound information processing. While molecular guidance of sensory afferents to the periphery has been well studied, molecular guidance of central projections from the ear is only beginning to emerge. Disorganized central projections of spiral ganglion neurons in a Wnt/PCP pathway mutant, Prickle1, suggest the Wnt/PCP pathway plays a role in guiding cochlear afferents to the cochlear nuclei in the hindbrain, consistent with known expression of the Wnt receptor, Frizzled3 (Fzd3) in inner ear neurons. We therefore investigated the role of Wnt signaling in central pathfinding in Fzd3 mutant mice and Fzd3 morpholino treated frogs and found aberrant central projections of vestibular afferents in both cases. Ear transplantations from knockdown to control Xenopus showed that it is the Fzd3 expressed within the ear that mediates this guidance. Also, cochlear afferents of Fzd3 mutant mice lack the orderly topological organization observed in controls. Quantification of Fzd3 expression in spiral ganglion neurons show a gradient of expression with Fzd3 being higher in the apex than in the base. Together, these results suggest that a gradient of Fzd3 in inner ear afferents directs projections to the correct dorsoventral column within the hindbrain.

2.
Front Cell Dev Biol ; 7: 59, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31069224

RESUMEN

Central nervous system neurons become postmitotic when radial glia cells divide to form neuroblasts. Neuroblasts may migrate away from the ventricle radially along glia fibers, in various directions or even across the midline. We present four cases of unusual migration that are variably connected to either pathology or formation of new populations of neurons with new connectivities. One of the best-known cases of radial migration involves granule cells that migrate from the external granule cell layer along radial Bergman glia fibers to become mature internal granule cells. In various medulloblastoma cases this migration does not occur and transforms the external granule cell layer into a rapidly growing tumor. Among the ocular motor neurons is one unique population that undergoes a contralateral migration and uniquely innervates the superior rectus and levator palpebrae muscles. In humans, a mutation of a single gene ubiquitously expressed in all cells, induces innervation defects only in this unique motor neuron population, leading to inability to elevate eyes or upper eyelids. One of the best-known cases for longitudinal migration is the facial branchial motor (FBM) neurons and the overlapping inner ear efferent population. We describe here molecular cues that are needed for the caudal migration of FBM to segregate these motor neurons from the differently migrating inner ear efferent population. Finally, we describe unusual migration of inner ear spiral ganglion neurons that result in aberrant connections with disruption of frequency presentation. Combined, these data identify unique migratory properties of various neuronal populations that allow them to adopt new connections but also sets them up for unique pathologies.

3.
F1000Res ; 82019.
Artículo en Inglés | MEDLINE | ID: mdl-30984379

RESUMEN

Interaction with the world around us requires extracting meaningful signals to guide behavior. Each of the six mammalian senses (olfaction, vision, somatosensation, hearing, balance, and taste) has a unique primary map that extracts sense-specific information. Sensory systems in the periphery and their target neurons in the central nervous system develop independently and must develop specific connections for proper sensory processing. In addition, the regulation of sensory map formation is independent of and prior to central target neuronal development in several maps. This review provides an overview of the current level of understanding of primary map formation of the six mammalian senses. Cell cycle exit, combined with incompletely understood molecules and their regulation, provides chemoaffinity-mediated primary maps that are further refined by activity. The interplay between cell cycle exit, molecular guidance, and activity-mediated refinement is the basis of dominance stripes after redundant organ transplantations in the visual and balance system. A more advanced level of understanding of primary map formation could benefit ongoing restoration attempts of impaired senses by guiding proper functional connection formations of restored sensory organs with their central nervous system targets.

4.
Int J Pharm Pract ; 27(3): 295-302, 2019 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-30648772

RESUMEN

OBJECTIVE: Increased demands from healthcare services have led to new roles for healthcare professionals (HCPs). Simulation based learning (SBL) can offer multidisciplinary HCPs and students a format to train for such emerging roles. The aim of this work was to adapt existing nursing SBL to involve pharmacy students and evaluate perceptions and effectiveness of SBL when used for interprofessional education (IPE). METHODS: Settings were a simulated hospital ward and a general practitioner (GP) practice. Participants were pharmacy and nursing students. Evaluation was by questionnaires and interviews. Ethical approval was obtained from the University Ethics Committee. KEY FINDINGS: A total of 440 students participated. The majority of respondents (317/330;96%) found the sessions useful. All elements were highly rated: briefing (315/340;93%), setting (301/321;94%), scenario (325/338;96%), feedback (303/327;93%), interaction with the "patient" (328/338;97%), interactions with other HCP trainee (293/329;89%). The majority (304/327;93%) agreed that they felt the sessions had enhanced their skills. Significant (p ≤ 0.05) enhancement in communication confidence was perceived by the students. Students gained understanding of each other's roles, and appreciated practicing communication and teamwork. CONCLUSIONS: Students recognised the importance, usefulness and need for IPE. SBL has the potential to support a variety of HCPs to facilitate uptake of new roles and working in multidisciplinary teams.


Asunto(s)
Educación en Enfermería/métodos , Educación en Farmacia/métodos , Comunicación Interdisciplinaria , Prácticas Interdisciplinarias/métodos , Entrenamiento Simulado/métodos , Medicina General , Humanos , Aprendizaje , Servicio de Farmacia en Hospital , Evaluación de Programas y Proyectos de Salud , Estudiantes de Enfermería/psicología , Estudiantes de Enfermería/estadística & datos numéricos , Estudiantes de Farmacia/psicología , Estudiantes de Farmacia/estadística & datos numéricos , Encuestas y Cuestionarios/estadística & datos numéricos , Lugar de Trabajo
5.
Front Neuroanat ; 12: 99, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30532697

RESUMEN

The inner ear and its two subsystems, the vestibular and the auditory system, exemplify how the identification of distinct cellular or anatomical elements ahead of elucidating their function, leads to a medley of anatomically defined and recognition oriented names that confused generations of students. Past attempts to clarify this unyielding nomenclature had incomplete success, as they could not yet generate an explanatory nomenclature. Building on these past efforts, we propose a somewhat revised nomenclature that keeps most of the past nomenclature as proposed and follows a simple rule: Anatomical and explanatory terms are combined followed, in brackets, by the name of the discoverer (see Table 1). For example, the "organ of Corti" will turn into the spiral auditory organ (of Corti). This revised nomenclature build as much as possible on existing terms that have explanatory value while keeping the recognition of discoverers alive to allow a transition for those used to the eponyms. Once implements, the proposed terminology should help future generations in learning the structure-function correlates of the ear more easily. To facilitate future understanding, leading genetic identifiers for a given structure have been added wherever possible.

6.
Sci Rep ; 8(1): 13819, 2018 09 14.
Artículo en Inglés | MEDLINE | ID: mdl-30218045

RESUMEN

Vertebrate inner ear neurons project into the correct brainstem nuclei region before target neurons become postmitotic, or even in their absence. Moreover, afferents from transplanted ears in frogs have been shown to navigate to vestibular nuclei, suggesting that ear afferents use molecular cues to find their target. We performed heterochronic, xenoplastic, and heterotopic transplantations in chickens to investigate whether inner ear afferents are guided by conserved guidance molecules. We show that inner ear afferents can navigate to the vestibular nuclei following a delay in afferent entry and when the ear was from a different species, the mouse. These data suggest that guidance molecules are expressed for some time and are conserved across amniotes. In addition, we show that chicken ears transplanted adjacent to the spinal cord project dorsally like in the hindbrain. These results suggest that inner ear afferents navigate to the correct dorsoventral brainstem column using conserved cues.


Asunto(s)
Vías Aferentes/fisiología , Oído Interno/inervación , Neuronas Aferentes/fisiología , Animales , Tronco Encefálico/fisiología , Embrión de Pollo , Pollos , Señales (Psicología) , Oído Interno/trasplante , Células Ciliadas Auditivas/fisiología , Ratones , Neuronas , Rombencéfalo/fisiología , Médula Espinal/fisiología , Nervio Vestibular/fisiología
7.
Front Cell Neurosci ; 12: 252, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30135646

RESUMEN

We review the evolution and development of organ of Corti hair cells with a focus on their molecular differences from vestibular hair cells. Such information is needed to therapeutically guide organ of Corti hair cell development in flat epithelia and generate the correct arrangement of different hair cell types, orientation of stereocilia, and the delayed loss of the kinocilium that are all essential for hearing, while avoiding driving hair cells toward a vestibular fate. Highlighting the differences from vestibular organs and defining what is known about the regulation of these differences will help focus future research directions toward successful restoration of an organ of Corti following long-term hair cell loss.

8.
Dev Neurobiol ; 78(11): 1064-1080, 2018 11.
Artículo en Inglés | MEDLINE | ID: mdl-30027559

RESUMEN

Numerous tissue transplantations have demonstrated that otocysts can develop into normal ears in any location in all vertebrates tested thus far, though the pattern of innervation of these transplanted ears has largely been understudied. Here, expanding on previous findings that transplanted ears demonstrate capability of local brainstem innervation and can also be innervated themselves by efferents, we show that inner ear afferents grow toward the spinal cord mostly along existing afferent and efferent fibers and preferentially enter the dorsal spinal cord. Once in the dorsal funiculus of the spinal cord, they can grow toward the hindbrain and can diverge into vestibular nuclei. Inner ear afferents can also project along lateral line afferents. Likewise, lateral line afferents can navigate along inner ear afferents to reach hair cells in the ear. In addition, transplanted ears near the heart show growth of inner ear afferents along epibranchial placode-derived vagus afferents. Our data indicate that inner ear afferents can navigate in foreign locations, likely devoid of any local ear-specific guidance cues, along existing nerves, possibly using the nerve-associated Schwann cells as substrate to grow along. However, within the spinal cord and hindbrain, inner ear afferents can navigate to vestibular targets, likely using gradients of diffusible factors that define the dorso-ventral axis to guide them. Finally, afferents of transplanted ears functionally connect to native hindbrain vestibular circuitry, indicated by eliciting a startle behavior response, and providing excitatory input to specific sets of extraocular motoneurons.


Asunto(s)
Vías Aferentes/fisiología , Oído Interno/inervación , Células Ciliadas Auditivas/fisiología , Neuronas Motoras/fisiología , Neuronas Aferentes/fisiología , Animales , Tronco Encefálico/fisiología , Rombencéfalo/fisiología , Células de Schwann/fisiología , Médula Espinal/fisiología
9.
Integr Comp Biol ; 58(2): 351-365, 2018 08 01.
Artículo en Inglés | MEDLINE | ID: mdl-29718413

RESUMEN

The mammalian hearing organ is a stereotyped cellular assembly with orderly innervation: two types of spiral ganglion neurons (SGNs) innervate two types of differentially distributed hair cells (HCs). HCs and SGNs evolved from single neurosensory cells through gene multiplication and diversification. Independent regulation of HCs and neuronal differentiation through expression of basic helix-loop-helix transcription factors (bHLH TFs: Atoh1, Neurog1, Neurod1) led to the evolution of vestibular HC assembly and their unique type of innervation. In ancestral mammals, a vestibular organ was transformed into the organ of Corti (OC) containing a single row of inner HC (IHC), three rows of outer HCs (OHCs), several unique supporting cell types, and a peculiar innervation distribution. Restoring the OC following long-term hearing loss is complicated by the fact that the entire organ is replaced by a flat epithelium and requires reconstructing the organ from uniform undifferentiated cell types, recapitulating both evolution and development. Finding the right sequence of gene activation during development that is useful for regeneration could benefit from an understanding of the OC evolution. Toward this end, we report on Foxg1 and Lmx1a mutants that radically alter the OC cell assembly and its innervation when mutated and may have driven the evolutionary reorganization of the basilar papilla into an OC in ancestral Therapsids. Furthermore, genetically manipulating the level of bHLH TFs changes HC type and distribution and allows inference how transformation of HCs might have happened evolutionarily. We report on how bHLH TFs regulate OHC/IHC and how misexpression (Atoh1-Cre; Atoh1f/kiNeurog1) alters HC fate and supporting cell development. Using mice with altered HC types and distribution, we demonstrate innervation changes driven by HC patterning. Using these insights, we speculate on necessary steps needed to convert a random mixture of post-mitotic precursors into the orderly OC through spatially and temporally regulated critical bHLH genes in the context of other TFs to restore normal innervation patterns.


Asunto(s)
Corrección de Deficiencia Auditiva/métodos , Evolución Molecular , Pérdida Auditiva/terapia , Mamíferos/fisiología , Órgano Espiral/crecimiento & desarrollo , Órgano Espiral/metabolismo , Animales , Diferenciación Celular , Humanos
10.
Br J Community Nurs ; 23(4): 174-178, 2018 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-29633877

RESUMEN

The education sector faces major challenges in providing learning experiences so that newly qualified nurses feel adequately prepared to work in a community setting. With this in mind, higher education institutions need to develop more innovative ways to deliver the community-nurse experience to student nurses. This paper presents and explores how simulation provides an opportunity for educators to support and evaluate student performance in an environment that models a complete patient encounter in the community. Following the simulation, evaluative data were collated and the answers analysed to identify key recommendations.


Asunto(s)
Competencia Clínica , Bachillerato en Enfermería/métodos , Enfermeras de Salud Comunitaria/educación , Desempeño de Papel , Entrenamiento Simulado/métodos , Adulto , Femenino , Humanos , Masculino , Investigación Cualitativa , Estudiantes de Enfermería , Reino Unido , Adulto Joven
11.
Dev Biol ; 444 Suppl 1: S14-S24, 2018 12 01.
Artículo en Inglés | MEDLINE | ID: mdl-29447907

RESUMEN

Wilhelm His (1831-1904) provided lasting insights into the development of the central and peripheral nervous system using innovative technologies such as the microtome, which he invented. 150 years after his resurrection of the classical germ layer theory of Wolff, von Baer and Remak, his description of the developmental origin of cranial and spinal ganglia from a distinct cell population, now known as the neural crest, has stood the test of time and more recently sparked tremendous advances regarding the molecular development of these important cells. In addition to his 1868 treatise on 'Zwischenstrang' (now neural crest), his work on the development of the human hindbrain published in 1890 provided novel ideas that more than 100 years later form the basis for penetrating molecular investigations of the regionalization of the hindbrain neural tube and of the migration and differentiation of its constituent neuron populations. In the first part of this review we briefly summarize the major discoveries of Wilhelm His and his impact on the field of embryology. In the second part we relate His' observations to current knowledge about the molecular underpinnings of hindbrain development and evolution. We conclude with the proposition, present already in rudimentary form in the writings of His, that a primordial spinal cord-like organization has been molecularly supplemented to generate hindbrain 'neomorphs' such as the cerebellum and the auditory and vestibular nuclei and their associated afferents and sensory organs.


Asunto(s)
Cresta Neural/citología , Rombencéfalo/citología , Rombencéfalo/embriología , Animales , Evolución Biológica , Tipificación del Cuerpo , Diferenciación Celular , Cerebelo , Ganglios Espinales , Estratos Germinativos , Historia del Siglo XVII , Historia del Siglo XVIII , Humanos , Cresta Neural/embriología , Tubo Neural , Neuronas , Organogénesis , Rombencéfalo/fisiología
12.
Nurse Educ Pract ; 30: 7-12, 2018 May.
Artículo en Inglés | MEDLINE | ID: mdl-29459316

RESUMEN

Like any skill in nursing, preparing students for the changes in technology needs to be incorporated into the curriculum. Electronic Patient Records (EPR) are an example of technological innovation in health care. This article presents a case study of how one faculty of healthcare, working collaboratively with a web designer, created and implemented a simulation activity to enable student nurses to develop their skills in using EPRs. An evaluation study was undertaken into students' perceptions of undertaking the simulation activity and using EPRs in the simulation activity. Findings showed that students were positive about the simulation activity and using the EPR app in the simulation, and felt well-prepared for using EPR in practice.


Asunto(s)
Bachillerato en Enfermería/métodos , Registros Electrónicos de Salud , Entrenamiento Simulado , Estudiantes de Enfermería/psicología , Curriculum , Bachillerato en Enfermería/organización & administración , Inglaterra , Humanos , Aplicaciones Móviles , Investigación en Educación de Enfermería , Investigación en Evaluación de Enfermería
13.
Neuropsychol Rehabil ; 28(8): 1375-1391, 2018 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-27788615

RESUMEN

The impact of vegetative state (VS) and minimally conscious states (MCSs) on an individual is devastating. VS and MCSs may be transitional towards recovery, but may become permanent. Although devastating for the individual the nature of these conditions also has a profound effect on the family. This study examined the impact on the family member and the changes in the individuals' occupation. Six participants (spouses, partners or parents) were recruited to the study. Mixed methods were adopted to meet the requirements of the research and participants. Data were collected at 6 and 12 months post-injury, using time diaries, a questionnaire and semi-structured interviews. At 6 months post-injury the greatest amount of carers' time was allocated to occupations involving the person in a Disorder of Consciousness and less time to social and leisure activities. Participants had difficulty viewing the future, lacked the desire or capacity to engage in previously enjoyed activities. At 12 months those impacts were still evident although changing. The transition to balanced occupational activity is slow, requiring a number of catalysts to change. A conceptual framework for a return to balance is provided, and guidance on advice from family members to families in a similar situation is given.


Asunto(s)
Trastornos de la Conciencia , Empleo , Familia/psicología , Adolescente , Adulto , Anciano , Trastornos de la Conciencia/terapia , Empleo/psicología , Humanos , Entrevistas como Asunto , Estudios Longitudinales , Persona de Mediana Edad , Investigación Cualitativa , Encuestas y Cuestionarios , Factores de Tiempo , Adulto Joven
14.
Dev Neurobiol ; 77(12): 1385-1400, 2017 12.
Artículo en Inglés | MEDLINE | ID: mdl-29030893

RESUMEN

Sonic hedgehog (Shh) signaling plays a major role in vertebrate development, from regulation of proliferation to the patterning of various organs. In amniotes, Shh affects dorsoventral patterning in the inner ear but affects anteroposterior patterning in teleost ears. It remains unknown how altered function of Shh relates to morphogenetic changes that coincide with the evolution of limbs and novel auditory organs in the ear. In this study, we used the tetrapod, Xenopus laevis, to test how increasing concentrations of the Shh signal pathway antagonist, Vismodegib, affects ear development. Vismodegib treatment dose dependently alters the development of the ear, hypaxial muscle, and indirectly the Mauthner cell through its interaction with the inner ear afferents. Together, these phenotypes have an effect on escape response. The altered Mauthner cell likely contributes to the increased time to respond to a stimulus. In addition, the increased hypaxial muscle in the trunk likely contributes to the subtle change in animal C-start flexion angle. In the ear, Vismodegib treatment results in decreasing segregation between the gravistatic sensory epithelia as the concentration of Vismodegib increases. Furthermore, at higher doses, there is a loss of the horizontal canal but no enantiomorphic transformation, as in bony fish lacking Shh. Like in amniotes, Shh signaling in frogs affects dorsoventral patterning in the ear, suggesting that auditory sensory evolution in sarcopterygians/tetrapods evolved with a shift of Shh function in axis specification. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1385-1400, 2017.


Asunto(s)
Anilidas/farmacología , Tipificación del Cuerpo/efectos de los fármacos , Oído Interno/crecimiento & desarrollo , Oído Interno/metabolismo , Regulación del Desarrollo de la Expresión Génica/efectos de los fármacos , Proteínas Hedgehog/antagonistas & inhibidores , Proteínas Hedgehog/metabolismo , Piridinas/farmacología , Animales , Tipificación del Cuerpo/fisiología , Dextranos/metabolismo , Relación Dosis-Respuesta a Droga , Reacción de Fuga/efectos de los fármacos , Femenino , Imagen Tridimensional , Larva , Locomoción/efectos de los fármacos , Locomoción/fisiología , Miosina Tipo IV/metabolismo , Mucosa Olfatoria/efectos de los fármacos , Mucosa Olfatoria/crecimiento & desarrollo , Epitelio Pigmentado Ocular/efectos de los fármacos , Epitelio Pigmentado Ocular/crecimiento & desarrollo , Pigmentación/efectos de los fármacos , Natación , Xenopus laevis
15.
Dev Biol ; 431(1): 3-15, 2017 11 01.
Artículo en Inglés | MEDLINE | ID: mdl-28866362

RESUMEN

We review the development and evolution of the ear neurosensory cells, the aggregation of neurosensory cells into an otic placode, the evolution of novel neurosensory structures dedicated to hearing and the evolution of novel nuclei in the brain and their input dedicated to processing those novel auditory stimuli. The evolution of the apparently novel auditory system lies in duplication and diversification of cell fate transcription regulation that allows variation at the cellular level [transforming a single neurosensory cell into a sensory cell connected to its targets by a sensory neuron as well as diversifying hair cells], organ level [duplication of organ development followed by diversification and novel stimulus acquisition] and brain nuclear level [multiplication of transcription factors to regulate various neuron and neuron aggregate fate to transform the spinal cord into the unique hindbrain organization]. Tying cell fate changes driven by bHLH and other transcription factors into cell and organ changes is at the moment tentative as not all relevant factors are known and their gene regulatory network is only rudimentary understood. Future research can use the blueprint proposed here to provide both the deeper molecular evolutionary understanding as well as a more detailed appreciation of developmental networks. This understanding can reveal how an auditory system evolved through transformation of existing cell fate determining networks and thus how neurosensory evolution occurred through molecular changes affecting cell fate decision processes. Appreciating the evolutionary cascade of developmental program changes could allow identifying essential steps needed to restore cells and organs in the future.


Asunto(s)
Evolución Biológica , Oído Interno/crecimiento & desarrollo , Animales , Vías Auditivas/crecimiento & desarrollo , Vías Auditivas/fisiología , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/fisiología , Oído Interno/anatomía & histología , Oído Interno/fisiología , Evolución Molecular , Duplicación de Gen , Células Ciliadas Auditivas/citología , Células Ciliadas Auditivas/fisiología , Audición/genética , Audición/fisiología , Mecanorreceptores/citología , Mecanorreceptores/fisiología , Modelos Biológicos , Células Receptoras Sensoriales/citología , Células Receptoras Sensoriales/fisiología
16.
Cell Tissue Res ; 370(2): 195-209, 2017 11.
Artículo en Inglés | MEDLINE | ID: mdl-28856468

RESUMEN

Several concepts developed in the nineteenth century have formed the basis of much of our neuroanatomical teaching today. Not all of these were based on solid evidence nor have withstood the test of time. Recent evidence on the evolution and development of the autonomic nervous system, combined with molecular insights into the development and diversification of motor neurons, challenges some of the ideas held for over 100 years about the organization of autonomic motor outflow. This review provides an overview of the original ideas and quality of supporting data and contrasts this with a more accurate and in depth insight provided by studies using modern techniques. Several lines of data demonstrate that branchial motor neurons are a distinct motor neuron population within the vertebrate brainstem, from which parasympathetic visceral motor neurons of the brainstem evolved. The lack of an autonomic nervous system in jawless vertebrates implies that spinal visceral motor neurons evolved out of spinal somatic motor neurons. Consistent with the evolutionary origin of brainstem parasympathetic motor neurons out of branchial motor neurons and spinal sympathetic motor neurons out of spinal motor neurons is the recent revision of the organization of the autonomic nervous system into a cranial parasympathetic and a spinal sympathetic division (e.g., there is no sacral parasympathetic division). We propose a new nomenclature that takes all of these new insights into account and avoids the conceptual misunderstandings and incorrect interpretation of limited and technically inferior data inherent in the old nomenclature.


Asunto(s)
Sistema Nervioso Autónomo/citología , Evolución Biológica , Neuronas Motoras/clasificación , Neuronas Motoras/citología , Médula Espinal/citología , Animales , Sistema Nervioso Autónomo/anatomía & histología , Sistema Nervioso Autónomo/embriología , Tipificación del Cuerpo , Tronco Encefálico/anatomía & histología , Tronco Encefálico/citología , Tronco Encefálico/embriología , Ganglios/anatomía & histología , Ganglios/citología , Ganglios/embriología , Humanos , Cresta Neural/anatomía & histología , Cresta Neural/citología , Cresta Neural/embriología , Médula Espinal/anatomía & histología , Médula Espinal/embriología
17.
J Exp Anal Behav ; 108(1): 113-124, 2017 07.
Artículo en Inglés | MEDLINE | ID: mdl-28653338

RESUMEN

Prolonged space flight, specifically microgravity, presents a problem for space exploration. Animal models with altered connections of the vestibular ear, and thus altered gravity sensation, would allow the examination of the effects of microgravity and how various countermeasures can establish normal function. We describe an experimental apparatus to monitor the effects of ear manipulations to generate asymmetric gravity input on the tadpole escape response. To perform the movement pattern analysis, an imaging apparatus was developed that uses a high-speed camera to obtain time-resolved, high-resolution images of tadpole movements. Movements were recorded in a temperature-controlled test chamber following mechanical stimulation with a solenoid actuator, to elicit a C-start response. Temperature within the test cell was controlled with a recirculating water bath. Xenopus laevis embryos were obtained using a standard fertilization technique. Tadpole response to a controlled perturbation was recorded in unprecedented detail and the approach was validated by describing the distinct differences in response between normal and one-eared tadpoles. The experimental apparatus and methods form an important element of a rigorous investigation into the response of the tadpole vestibular system to mechanical and biochemical manipulations, and can ultimately contribute to improved understanding of the effects of altered gravity perception on humans.


Asunto(s)
Larva/fisiología , Movimiento/fisiología , Reflejo de Sobresalto/fisiología , Xenopus laevis/fisiología , Animales , Sensación de Gravedad/fisiología , Temperatura Ambiental
18.
Front Cell Neurosci ; 11: 114, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28484373

RESUMEN

All craniate chordates have inner ears with hair cells that receive input from the brain by cholinergic centrifugal fibers, the so-called inner ear efferents (IEEs). Comparative data suggest that IEEs derive from facial branchial motor (FBM) neurons that project to the inner ear instead of facial muscles. Developmental data showed that IEEs develop adjacent to FBMs and segregation from IEEs might depend on few transcription factors uniquely associated with IEEs. Like other cholinergic terminals in the peripheral nervous system (PNS), efferent terminals signal on hair cells through nicotinic acetylcholine channels, likely composed out of alpha 9 and alpha 10 units (Chrna9, Chrna10). Consistent with the evolutionary ancestry of IEEs is the even more conserved ancestry of Chrna9 and 10. The evolutionary appearance of IEEs may reflect access of FBMs to a novel target, possibly related to displacement or loss of mesoderm-derived muscle fibers by the ectoderm-derived ear vesicle. Experimental transplantations mimicking this possible aspect of ear evolution showed that different motor neurons of the spinal cord or brainstem form cholinergic synapses on hair cells when ears replace somites or eyes. Transplantation provides experimental evidence in support of the evolutionary switch of FBM neurons to become IEEs. Mammals uniquely evolved a prestin related motor system to cause shape changes in outer hair cells regulated by the IEEs. In summary, an ancient motor neuron population drives in craniates via signaling through highly conserved Chrna receptors a uniquely derived cellular contractility system that is essential for hearing in mammals.

19.
Front Neural Circuits ; 11: 25, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28450830

RESUMEN

We investigate the importance of the degree of peripheral or central target differentiation for mouse auditory afferent navigation to the organ of Corti and auditory nuclei in three different mouse models: first, a mouse in which the differentiation of hair cells, but not central auditory nuclei neurons is compromised (Atoh1-cre; Atoh1f/f ); second, a mouse in which hair cell defects are combined with a delayed defect in central auditory nuclei neurons (Pax2-cre; Atoh1f/f ), and third, a mouse in which both hair cells and central auditory nuclei are absent (Atoh1-/-). Our results show that neither differentiated peripheral nor the central target cells of inner ear afferents are needed (hair cells, cochlear nucleus neurons) for segregation of vestibular and cochlear afferents within the hindbrain and some degree of base to apex segregation of cochlear afferents. These data suggest that inner ear spiral ganglion neuron processes may predominantly rely on temporally and spatially distinct molecular cues in the region of the targets rather than interaction with differentiated target cells for a crude topological organization. These developmental data imply that auditory neuron navigation properties may have evolved before auditory nuclei.


Asunto(s)
Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/deficiencia , Diferenciación Celular/genética , Células Ciliadas Auditivas/fisiología , Malformaciones del Sistema Nervioso/patología , Factor de Transcripción PAX2/deficiencia , Rombencéfalo/patología , Ganglio Espiral de la Cóclea , Animales , Animales Recién Nacidos , Vías Auditivas/embriología , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Núcleo Coclear/citología , Núcleo Coclear/embriología , Núcleo Coclear/crecimiento & desarrollo , Embrión de Mamíferos , Ratones , Ratones Noqueados , Malformaciones del Sistema Nervioso/genética , Factor de Transcripción PAX2/genética , Ganglio Espiral de la Cóclea/embriología , Ganglio Espiral de la Cóclea/crecimiento & desarrollo , Ganglio Espiral de la Cóclea/patología , beta-Galactosidasa/genética , beta-Galactosidasa/metabolismo
20.
Methods Mol Biol ; 1427: 243-62, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27259931

RESUMEN

The inner ear has long been at the cutting edge of tract tracing techniques that have shaped and reshaped our understanding of the ear's innervation patterns. This review provides a historical framework to understand the importance of these techniques for ear innervation and for development of tracing techniques in general; it is hoped that lessons learned will help to quickly adopt transformative novel techniques and their information and correct past beliefs based on technical limitations. The technical part of the review presents details of our protocol as developed over the last 30 years. We also include arguments as to why these recommendations work best to generate the desired outcome of distinct fiber and cell labeling, and generate reliable data for any investigation. We specifically focus on two tracing techniques, in part developed and/or championed for ear innervation analysis: the low molecular multicolor dextran amine tract tracing technique and the multicolor tract tracing technique with lipophilic dyes.


Asunto(s)
Oído/inervación , Técnicas de Trazados de Vías Neuroanatómicas/métodos , Animales , Dextranos/química , Oído/anatomía & histología , Colorantes Fluorescentes/química , Ratones
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