Dendritic Ca2+ responses in neonatal lateral superior olive neurons elicited by glycinergic/GABAergic synapses and action potentials.

During development, GABA/glycinergic connections from the medial nucleus of the trapezoid body (MNTB) to the lateral superior olive (LSO) gradually change from being depolarizing to being hyperpolarizing. Previous studies have shown that depolarizing MNTB-LSO synapses can trigger action potentials and increase the concentration of intracellular calcium. In the present study we used confocal calcium imaging combined with whole-cell patch clamp recordings to investigate how depolarizing MNTB inputs in neonatal rats and mice increase the calcium concentration in the dendrites of LSO neurons. Our results show that subthreshold synaptic responses can elicit local dendritic calcium responses while suprathreshold responses reliably generate global calcium responses that are observed in all dendritic processes. The amplitude of global dendritic calcium responses increased with distance from the soma. Global calcium responses were blocked by tetrodotoxin and could not be recovered by somatic injection of action potential waveforms indicating that global calcium responses are generated by back-propagating sodium action potentials.

Dynamic Clamp Analysis of Synaptic Integration in Sympathetic Ganglia.

Advances in modern neuroscience require the identification of principles that connect different levels of experimental analysis, from molecular mechanisms to explanations of cellular functions, then to circuits, and, ultimately, to systems and behavior. Here, we examine how synaptic organization of the sympathetic ganglia may enable them to function as use-dependent amplifiers of preganglionic activity and how the gain of this amplification may be modulated by metabotropic signaling mechanisms. The approach combines a general computational model of ganglionic integration together with experimental tests of the model using the dynamic clamp method. In these experiments, we recorded intracellularly from dissociated bullfrog sympathetic neurons and then mimicked physiological synapses with virtual computer-generated synapses. It thus became possible to analyze the synaptic gain by recording cellular responses to complex patterns of synaptic activity that normally arise in vivo from convergent nicotinic and muscarinic synapses. The results of these studies are significant because they illustrate how gain generated through ganglionic integration may contribute to the feedback control of important autonomic behaviors, in particular to the control of the blood pressure. We dedicate this paper to the memory of Professor Vladimir Skok, whose rich legacy in synaptic physiology helped establish the modern paradigm for connecting multiple levels of analysis in studies of the nervous system.

Soarian--workflow management applied for health care.

OBJECTIVES: To describe and comment on functionality and architecture of the software product Soarian developed by Siemens, to identify key differentiators to related products, and to comment on predecessor systems and beta versions. This has been done in the framework of a conference on health information systems of the IMIA. METHODS: Analyzing existing literature. Site visit of a predecessor system at Haukeland Sykehus, Bergen. Pilot of a beta version at the Erlangen University Medical Center, elaborating on major characteristics in discussion rounds. RESULTS: Soarian is a functional comprehensive, clinically oriented software product to support health care processes and to be used for health care professional workstations. It is a software product, designed and written completely new. Three major key differentiators were identified in comparison to related software products: Soarian's workflow engine, its embedded analytics, and its 'smart' user interface. The targeted reduced installation time is stated to be 12 months or less. CONCLUSIONS: Soarian has good chances to become one of the major software products for health care professional workstations in the international market to support patient-centered, shared care. Its global design may help to better support and maintain national or language specific versions. The first installations of Soarian will be critical, as they will show how the system will be accepted. To use such software products efficiently, organizational aspects within hospitals as well as between health care institutions have to be considered, e.g. strategic IT planning.

Glycinergic/GABAergic synapses in the lateral superior olive are excitatory in neonatal C57Bl/6J mice.

The lateral superior olive (LSO), a nucleus involved in sound localization, receives tonotopically organized, inhibitory input from the medial nucleus of the trapezoid body (MNTB). To better understand the development of this glycinergic/GABAergic pathway, we used Gramicidin-perforated patch clamp recordings to characterize MNTB-evoked postsynaptic potentials in LSO neurons of neonatal C57Bl/6J mice. We found that during the first postnatal week, MNTB-evoked responses change from being depolarizing to being hyperpolarizing. Most interestingly, depolarizing glycinergic/GABAergic synaptic potentials were able to trigger action potentials, demonstrating that the MNTB-LSO pathway can act as a true excitatory pathway. This transient excitatory action of immature MNTB-LSO synapses might play an important role in activity-dependent sharpening of the tonotopic organization of inhibitory connections in the LSO.