Del Mar Photonics

Pflugers Arch. 2009 Jul;458(3):459-69. Epub 2009 Feb 24.

Glycinergic interneurons are functionally integrated into the inspiratory network of mouse medullary slices.
Winter SM, Fresemann J, Schnell C, Oku Y, Hirrlinger J, Hülsmann S.

Abt Neuro- und Sinnesphysiologie, Zentrum Physiologie und Pathophysiologie, Georg-August-Universität, Göttingen, Germany.

 

Visualizing neuronal activity using multiphoton imaging is one of the growing applications of femtosecond lasers.

Abstract
Neuronal activity in the respiratory network is functionally dependent on inhibitory synaptic transmission. Using two-photon excitation microscopy, we analyzed the integration of glycinergic neurons in the isolated inspiratory pre-Bötzinger complex-driven network of the rhythmic slice preparation. Inspiratory (96%) and 'tonic' expiratory neurons (4%) were identified via an increase or decrease, respectively, of the cytosolic free calcium concentration during the inspiratory-related respiratory burst. Furthermore, in BAC-transgenic mice expressing EGFP under the control of the GlyT2-promoter, 50% of calcium-imaged inspiratory neurons were glycinergic. Inspiratory bursting of glycinergic neurons in the slice was confirmed by whole-cell recording. We also found glycinergic neurons that receive phasic inhibition from other glycinergic neurons. Our calcium imaging data show that glycinergic neurons comprise a large population of inspiratory neurons in the pre-Bötzinger complex-driven network of the rhythmic slice preparation.
 

Del Mar Photonics - Newsletter Fall 2010 - Newsletter Winter 2010

Del Mar Photonics supplies multi-photon lasers and systems based on cost effective femtosecond sources:

Science. 2009 Dec 4;326(5958):1419-24.

GABAergic hub neurons orchestrate synchrony in developing hippocampal networks.
Bonifazi P, Goldin M, Picardo MA, Jorquera I, Cattani A, Bianconi G, Represa A, Ben-Ari Y, Cossart R.

Institut de Neurobiologie de la Méditerranée INSERM U901, Universitéde la Méditerranée, Parc Scientifique de Luminy, Boîte Postale 13, 13273 Marseille Cedex 9, France.

Abstract
Brain function operates through the coordinated activation of neuronal assemblies. Graph theory predicts that scale-free topologies, which include "hubs" (superconnected nodes), are an effective design to orchestrate synchronization. Whether hubs are present in neuronal assemblies and coordinate network activity remains unknown. Using network dynamics imaging, online reconstruction of functional connectivity, and targeted whole-cell recordings in rats and mice, we found that developing hippocampal networks follow a scale-free topology, and we demonstrated the existence of functional hubs. Perturbation of a single hub influenced the entire network dynamics. Morphophysiological analysis revealed that hub cells are a subpopulation of gamma-aminobutyric acid-releasing (GABAergic) interneurons possessing widespread axonal arborizations. These findings establish a central role for GABAergic interneurons in shaping developing networks and help provide a conceptual framework for studying neuronal synchrony.

PMID: 19965761 [PubMed - indexed for MEDLINE]


Publication Types, MeSH Terms, SubstancesPublication Types: In VitroResearch Support, Non-U.S. Gov'tMeSH Terms:Action PotentialsAnimalsAxons/ultrastructureCA3 Region, Hippocampal/cytologyCA3 Region, Hippocampal/physiology*Calcium/metabolismDendrites/ultrastructureExcitatory Postsynaptic PotentialsHippocampus/cytologyHippocampus/physiology*Interneurons/physiology*Interneurons/ultrastructureMiceNerve Net/physiology*Patch-Clamp TechniquesPyramidal Cells/physiologyRatsRats, WistarSynapses/physiologygamma-Aminobutyric Acid/physiology*Substances:gamma-Aminobutyric AcidCalcium
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