Axosomatic contacts of pyramidal neurons and those of neurones of celiac ganglia in rats are characterized by diverse types of relationships and by many-component complexes. The metric parameters of axosomatic contacts of pyramidal neurons do not change with age but the proportion of active contacts increases. With age, the celiac ganglia show an increase in the diameter of contact axons and in the number of deeply invaginated contacts. Meanwhile the proportion of active contacts diminishes. These changes within the system of axosomatic contacts appear to develop in response to subsidence of neurons and their contacts with age and thus have a compensatory-adaptive significance.
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JCI Insight
December 2024
School of Biosciences, University of Sheffield, Sheffield, United Kingdom.
In the mammalian cochlea, sensory hair cells are crucial for the transduction of acoustic stimuli into electrical signals, which are then relayed to the central auditory pathway via spiral ganglion neuron (SGN) afferent dendrites. The SGN output is directly modulated by inhibitory cholinergic axodendritic synapses from the efferent fibers originating in the superior olivary complex. When the adult cochlea is subjected to noxious stimuli or aging, the efferent system undergoes major rewiring, such that it reestablishes direct axosomatic contacts with the inner hair cells (IHCs), which occur only transiently during prehearing stages of development.
View Article and Find Full Text PDFSci Adv
January 2021
Department of Anesthesiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
Hearing involves a stereotyped neural network communicating cochlea and brain. How this sensorineural circuit assembles is largely unknown. The cochlea houses two types of mechanosensory hair cells differing in function (sound transmission versus amplification) and location (inner versus outer compartments).
View Article and Find Full Text PDFJ Neurophysiol
March 2021
Auditory Neurophysiology Group, Department of Chemosensation, RWTH Aachen University, Aachen, Germany.
Spherical bushy cells (SBCs) in the anteroventral cochlear nucleus receive a single or very few powerful axosomatic inputs from the auditory nerve. However, SBCs are also contacted by small regular bouton synapses of the auditory nerve, located in their dendritic tree. The function of these small inputs is unknown.
View Article and Find Full Text PDFJ Physiol
October 2020
Department of Neuroscience, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, 3000 CA, The Netherlands.
Key Points: During development the giant, auditory calyx of Held forms a one-to-one connection with a principal neuron of the medial nucleus of the trapezoid body. While anatomical studies described that most of the target cells are temporarily contacted by multiple calyces, multi-calyceal innervation was only sporadically observed in in vivo recordings, suggesting a structure-function discrepancy. We correlated synaptic strength of inputs, identified in in vivo recordings, with post hoc labelling of the recorded neuron and synaptic terminals containing vesicular glutamate transporters (VGluT).
View Article and Find Full Text PDFJ Comp Neurol
June 2021
Department of Pharmacology, University of Maryland School of Medicine, Baltimore, Maryland, USA.
The chemical synapse is the principal form of contact between neurons of the central nervous system. These synapses are typically configured as presynaptic axon terminations onto postsynaptic dendrites or somata, giving rise to axo-dendritic and axo-somatic synapses, respectively. Beyond these common synapse configurations are less-studied, non-canonical synapse types that are prevalent throughout the brain and significantly contribute to neural circuit function.
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