Intrinsic physiology of identified neurons in the prepositus hypoglossi and medial vestibular nuclei

Issue title: ARO 2010 Symposium on Signal Processing in First- and Second-Order Vestibular Neurons, Anaheim, CA, USA, 8 February 2010

Guest editors: Kenna D. Peusner

Article type: Research Article

Authors: Kolkman, Kristine E.^{a; b} | Moghadam, Setareh H.^b | du Lac, Sascha^{a; b; c; *}

Affiliations: [a] Neurosciences Graduate Program, University of California San Diego, San Diego, CA, USA | [b] The Salk Institute for Biological Studies, La Jolla, CA, USA | [c] Howard Hughes Medical Institute, La Jolla, CA, USA | Department of Anatomy and Regenerative Biology, The George Washington University Medical Center, 2300 I Street NW, Washington, DC, USA

Correspondence: [*] Corresponding author: Sascha du Lac, Howard Hughes Medical Institute, The Salk Institute for Biological Studies, Systems Neurobiology Laboratories, 10010 N. Torrey Pines Rd., La Jolla, CA 92037, USA. Tel.: +1 858 455 4100, x5877; Fax: +1 858 455 7933; E-mail: sascha@salk.edu

Abstract: Signal processing in the vestibular system is influenced by the intrinsic physiological properties of neurons that differ in neurotransmitters and circuit connections. Do membrane and firing properties differ across functionally distinct cell types? This study examines the intrinsic physiology of neurons in the medial vestibular nucleus (MVN) and nucleus prepositus hypoglossi (NPH) which express different neurotransmitters and have distinct axonal projections. NPH neurons expressing fluorescent proteins in glutamatergic, glycinergic, or GABAergic neurons were targeted for whole-cell patch recordings in brainstem slices obtained from transgenic mouse lines (YFP-16, GlyT2, and GIN). Recordings from MVN neurons projecting to the spinal cord, reticular formation, or oculomotor nucleus were obtained by targeting fluorescent neurons retrogradely labeled from tracer injections. Intrinsic physiological properties of identified neurons exhibited continuous variations but tended to differ between functionally defined cell types. Within the NPH, YFP-16 neurons had the narrowest action potentials and highest evoked firing rates and expressed high levels of Kv3.3 proteins, which speed repolarization. MVN neurons projecting to the spinal cord and oculomotor nucleus had similar action potential waveforms, but oculomotor-projecting neurons had higher intrinsic gains than those projecting to the spinal cord. These results indicate that intrinsic membrane properties are differentially tuned in MVN and NPH neurons subserving different functions.

Keywords: Glycinergic, GABAergic, glutamatergic, vestibulospinal, oculomotor

DOI: 10.3233/VES-2011-0394

Journal: Journal of Vestibular Research, vol. 21, no. 1, pp. 33-47, 2011