Physiological and anatomical development of glycinergic inhibition in the mouse superior paraolivary nucleus following hearing onset

Rajaram, Ezhilarasan; Pagella, Sara; Grothe, Benedikt und Kopp-Scheinpflug, Conny (3. August 2020): Physiological and anatomical development of glycinergic inhibition in the mouse superior paraolivary nucleus following hearing onset. In: Journal of Neurophysiology, Bd. 24, Nr. 2: S. 471-483

Abstract

Neural circuits require balanced synaptic excitation and inhibition to ensure accurate neural computation. Our knowledge about the development and maturation of inhibitory synaptic inputs is less well developed than that concerning excitation. Here we describe the maturation of an inhibitory circuit within the mammalian auditory brainstem where counterintuitively, inhibition drives action potential firing of principal neurons. With the use of combined anatomical tracing and electrophysiological recordings from mice, neurons of the superior paraolivary nucleus (SPN) are shown to receive converging glycinergic input from at least four neurons of the medial nucleus of the trapezoid body (MNTB). These four axons formed 30.71 ± 2.72 (means ± SE) synaptic boutons onto each SPN neuronal soma, generating a total inhibitory conductance of 80 nS. Such strong inhibition drives the underlying postinhibitory rebound firing mechanism, which is a hallmark of SPN physiology. In contrast to inhibitory projections to the medial and lateral superior olives, the inhibitory projection to the SPN does not exhibit experience-dependent synaptic refinement following the onset of hearing. These findings emphasize that the development and function of neural circuits cannot be inferred from one synaptic target to another, even if both originate from the same neuron.

NEW & NOTEWORTHY Neuronal activity regulates development and maturation of neural circuits. This activity can include spontaneous burst firing or firing elicited by sensory input during early development. For example, auditory brainstem circuits involved in sound localization require acoustically evoked activity to form properly. Here we show, that an inhibitory circuit, involved in processing sound offsets, gaps, and rhythmically modulated vocal communication signals, matures before the onset of acoustically evoked activity.

• Dokumententyp: Zeitschriftenartikel
• Keywords: 3D reconstruction; auditory brain stem; development; tch clamp; synaptic inhibition
• Fakultät: Biologie > Department Biologie II > Neurobiologie
• Themengebiete: 500 Naturwissenschaften und Mathematik > 570 Biowissenschaften; Biologie
• Bemerkung: PubMed 32667247
• Sprache: Englisch