Development of functional innervation in the second and third order auditory nuclei of the chick

Development ◽  
1988 ◽  
Vol 104 (4) ◽  
pp. 575-588
Author(s):  
A.G. Pettigrew ◽  
A.D. Ansselin ◽  
J.R. Bramley
Keyword(s):  
Auditory Nerve ◽  
Current Source ◽  
Dorsal Surface ◽  
Synaptic Activity ◽  
Direct Stimulation ◽  
Final Destination ◽  
Functional Connections ◽  
Auditory Nerves ◽  
Dendritic Fields ◽  
Stimulation Of

The neurones that constitute the auditory nuclei of the brainstem in the chick (nuclei magnocellularis, NM, and laminaris, NL) are generated between days 2 and 4 of incubation. These neurones migrate towards the dorsal surface of the brainstem over the next few days and reach their final destination at about day 9 of incubation. We have examined the development of functional connections between the auditory nerve and neurones in NM and between neurones in NM and NL in embryos from stage 34 (day 8 of incubation) using electrophysiological techniques and electron and light microscopy. The earliest extracellular recordings of electrically evoked field and spike potentials were made in NM with stimulation of the ipsilateral auditory nerve and in NL with stimulation of the ipsilateral NM at stage 35 (day 9). No activity could be recorded in NL with stimulation of the auditory nerve at this stage. By stage 37 (day 11), direct stimulation of the contralateral NM evoked responses in NL and by stage 38 (day 12) stimulation of the auditory nerves evoked stable field potentials in NL. These potentials changed polarity as the electrode penetrated NL in a direction that was perpendicular to the laminar arrangement of neurone somas and parallel to the dendritic axes of these neurones. In 18 of 26 analyses of current-source density in NL of 12 preparations between stages 38 and 40 there was a sink of current associated with synaptic activity at levels both above and below the source of current (cell somas) following stimulation of the ipsilateral auditory nerve. In the remaining analyses, and in all 15 analyses from preparations older than stage 40, stimulation of the ipsilateral input evoked only a single sink of current above the level of the cell somas. In all preparations from embryos at stage 38 and older, stimulation of the contralateral auditory nerve was associated with a single sink of current below the level of the cell somas. The axon projections to the ipsilateral NL from neurones in NM were examined using HRP labelling between stages 38 and 40. The presence of terminal fields of single axons in both the dorsal and ventral dendritic regions of the ipsilateral NL at these ages was confirmed. Furthermore, dense vesicles within synaptic terminals in both the dorsal and ventral dendritic fields could be identified in preparations at stage 36 following injection of HRP into NL and stimulation of the ipsilateral NM.(ABSTRACT TRUNCATED AT 400 WORDS)

53: Direct Stimulation of the Auditory Nerve: Feasibility of a Thin-Film Microelectrode Array

1996 ◽  
Vol 115 (2) ◽  
pp. P94-P95
Author(s):  
Derek A. Jones ◽  
H. Alexander Arts ◽  
Steven M. Bierer ◽  
David J Anderson
Keyword(s):  
Thin Film ◽  
Auditory Nerve ◽  
Microelectrode Array ◽  
Direct Stimulation ◽  
Stimulation Of

scholarly journals Electrophysiology of Supramedullary Neurons in Spheroides maculatus

1959 ◽  
Vol 43 (1) ◽  
pp. 159-188 ◽  
Author(s):  
M. V. L. Bennett ◽  
S. M. Crain ◽  
H. Grundfest
Keyword(s):  
Action Potential ◽  
Cell Body ◽  
Cranial Nerves ◽  
Dorsal Surface ◽  
Compound Action Potential ◽  
Direct Stimulation ◽  
Afferent Pathways ◽  
Dorsal Roots ◽  
Indirect Stimulation ◽  
Stimulation Of

This series of three papers presents data on a system of neurons, the large supramedullary cells (SMC) of the puffer, Spheroides maculatus, in terms of the physiological properties of the individual cells, of their afferent and efferent connections, and of their interconnections. Some of these findings are verified by available anatomical data, but others suggest structures that must be sought for in the light of the demonstration that these cells are not sensory neurons. Analysis on so broad a scale was made possible by the accessibility of the cells in a compact cluster on the dorsal surface of the spinal cord. Simultaneous recordings were made intracellularly and extracellularly from individual cells or from several, frequently with registration of the afferent or efferent activity as well. The passive and active electrical properties of the SMC are essentially similar to those of other neurons, but various response characteristics have been observed which are related to different excitabilities of different parts of the neuron, and to specific anatomical features. The SMC produce spikes to direct stimuli by intracellular depolarization, or by indirect synaptic excitation from many afferent paths, including tactile stimulation of the skin. Responses that were evoked by intracellular stimulation of a single cell cause an efferent discharge bilaterally in many dorsal roots, but not in the ventral. Sometimes several distinct spikes occurred in the same root, and behaved independently. Thus, a number of axons are efferent from each neuron. They are large unmyelinated fibers which give rise to the elevation of slowest conduction in the compound action potential of the dorsal root. A similar component is absent in the ventral root action potential. Antidromic stimulation of the axons causes small potentials in the cell body, indicating that the antidromic spikes are blocked distantly to the soma, probably in the axon branches. The failure of antidromic invasion is correlated with differences in excitability of the axons and the neurite from which they arise. As recorded in the cell body, the postsynaptic potentials associated with stimulation of afferent fibers in the dorsal roots or cranial nerves are too small to discharge the soma spike. The indirect spike has two components, the first of which is due to the synaptically initiated activity of the neurite and which invades the cell body. The second component is then produced when the soma is fired. The neurite impulse arises at some distance from the cell body and propagates centrifugally as well as centripetally. An indirect stimulus frequently produces repetitive spikes which are observed to occur synchronously in all the cells examined at one time. Each discharge gives rise to a large efferent volley in each of the dorsal roots and cranial nerves examined. The synchronized responses of all the SMC to indirect stimulation occur with slightly different latencies. They are due to a combination of excitation by synaptic bombardment from the afferent pathways and by excitatory interconnections among the SMC. Direct stimulation of a cell may also excite all the others. This spread of activity is facilitated by repetitive direct excitation of the cell as well as by indirect stimulation.

The Role of the Organ of Corti in Auditory Nerve Stimulation

1973 ◽  
Vol 82 (4) ◽  
pp. 464-472 ◽  
Author(s):  
Merle Lawrence ◽  
Lars-Göran Johnsson
Keyword(s):  
Auditory Nerve ◽  
Dynamic Range ◽  
Ganglion Cells ◽  
Organ Of Corti ◽  
Nerve Fibers ◽  
Nerve Degeneration ◽  
Direct Stimulation ◽  
Afferent Nerve Fibers ◽  
Stimulation Of

An analysis of the contribution to hearing made by the presence of a normal organ of Corti as compared to direct electric stimulation of the nerve leads to the following conclusions: The portion of the basal turn of the cochlea which can be stimulated contains activity regions primarily limited to frequencies above 5000 Hz. Electrical stimulation of sensory afferent nerve fibers gives rise to sensations of very limited dynamic range compared to normal adequate stimulation through the organ of Corti. Following destruction of the organ of Corti, the speed of nerve degeneration in man is not known, but appears to be slow. Some ganglion cells almost always persist but it is doubtful that these are excitable. The severe nerve degeneration known to be present in most cases of human deafness raises critical questions about the feasibility and logic of a direct stimulation of the auditory nerve in these patients. The unavoidable damage to the capillaries and endosteum of the walls of the scala tympani by insertion of a wire is certain to produce further degeneration and new bone formation.

scholarly journals The Role of BMP Signaling in Osteoclast Regulation

2021 ◽  
Vol 9 (3) ◽  
pp. 24
Author(s):  
Brian Heubel ◽  
Anja Nohe
Keyword(s):  
Bone Formation ◽  
Bone Morphogenetic Proteins ◽  
Bone Diseases ◽  
Bmp Signaling ◽  
Bone Homeostasis ◽  
Direct Stimulation ◽  
Federal Drug Administration ◽  
Bmp Pathway ◽  
Stimulation Of

The osteogenic effects of Bone Morphogenetic Proteins (BMPs) were delineated in 1965 when Urist et al. showed that BMPs could induce ectopic bone formation. In subsequent decades, the effects of BMPs on bone formation and maintenance were established. BMPs induce proliferation in osteoprogenitor cells and increase mineralization activity in osteoblasts. The role of BMPs in bone homeostasis and repair led to the approval of BMP2 by the Federal Drug Administration (FDA) for anterior lumbar interbody fusion (ALIF) to increase the bone formation in the treated area. However, the use of BMP2 for treatment of degenerative bone diseases such as osteoporosis is still uncertain as patients treated with BMP2 results in the stimulation of not only osteoblast mineralization, but also osteoclast absorption, leading to early bone graft subsidence. The increase in absorption activity is the result of direct stimulation of osteoclasts by BMP2 working synergistically with the RANK signaling pathway. The dual effect of BMPs on bone resorption and mineralization highlights the essential role of BMP-signaling in bone homeostasis, making it a putative therapeutic target for diseases like osteoporosis. Before the BMP pathway can be utilized in the treatment of osteoporosis a better understanding of how BMP-signaling regulates osteoclasts must be established.

scholarly journals Incerto-thalamic modulation of fear via GABA and dopamine

2021 ◽  
Author(s):  
Archana Venkataraman ◽  
Sarah C. Hunter ◽  
Maria Dhinojwala ◽  
Diana Ghebrezadik ◽  
JiDong Guo ◽  
...  
Keyword(s):  
Brain Regions ◽  
Zona Incerta ◽  
Dependent Manner ◽  
Post Traumatic Stress ◽  
Functional Roles ◽  
Functional Connections ◽  
Optogenetic Stimulation ◽  
Fear Generalization ◽  
Stimulation Of

AbstractFear generalization and deficits in extinction learning are debilitating dimensions of Post-Traumatic Stress Disorder (PTSD). Most understanding of the neurobiology underlying these dimensions comes from studies of cortical and limbic brain regions. While thalamic and subthalamic regions have been implicated in modulating fear, the potential for incerto-thalamic pathways to suppress fear generalization and rescue deficits in extinction recall remains unexplored. We first used patch-clamp electrophysiology to examine functional connections between the subthalamic zona incerta and thalamic reuniens (RE). Optogenetic stimulation of GABAergic ZI → RE cell terminals in vitro induced inhibitory post-synaptic currents (IPSCs) in the RE. We then combined high-intensity discriminative auditory fear conditioning with cell-type-specific and projection-specific optogenetics in mice to assess functional roles of GABAergic ZI → RE cell projections in modulating fear generalization and extinction recall. In addition, we used a similar approach to test the possibility of fear generalization and extinction recall being modulated by a smaller subset of GABAergic ZI → RE cells, the A13 dopaminergic cell population. Optogenetic stimulation of GABAergic ZI → RE cell terminals attenuated fear generalization and enhanced extinction recall. In contrast, optogenetic stimulation of dopaminergic ZI → RE cell terminals had no effect on fear generalization but enhanced extinction recall in a dopamine receptor D1-dependent manner. Our findings shed new light on the neuroanatomy and neurochemistry of ZI-located cells that contribute to adaptive fear by increasing the precision and extinction of learned associations. In so doing, these data reveal novel neuroanatomical substrates that could be therapeutically targeted for treatment of PTSD.

Electrical stimulation of retinal neurons in epiretinal and subretinal configuration using a multicapacitor array

2012 ◽  
Vol 107 (10) ◽  
pp. 2742-2755 ◽  
Author(s):  
Max Eickenscheidt ◽  
Martin Jenkner ◽  
Roland Thewes ◽  
Peter Fromherz ◽  
Günther Zeck
Keyword(s):  
Electrical Stimulation ◽  
Ganglion Cells ◽  
Ex Vivo ◽  
Biophysical Model ◽  
Retinal Neurons ◽  
Direct Stimulation ◽  
Tungsten Electrode ◽  
Partial Restoration ◽  
Low Amplitude ◽  
Stimulation Of

Electrical stimulation of retinal neurons offers the possibility of partial restoration of visual function. Challenges in neuroprosthetic applications are the long-term stability of the metal-based devices and the physiological activation of retinal circuitry. In this study, we demonstrate electrical stimulation of different classes of retinal neurons with a multicapacitor array. The array—insulated by an inert oxide—allows for safe stimulation with monophasic anodal or cathodal current pulses of low amplitude. Ex vivo rabbit retinas were interfaced in either epiretinal or subretinal configuration to the multicapacitor array. The evoked activity was recorded from ganglion cells that respond to light increments by an extracellular tungsten electrode. First, a monophasic epiretinal cathodal or a subretinal anodal current pulse evokes a complex burst of action potentials in ganglion cells. The first action potential occurs within 1 ms and is attributed to direct stimulation. Within the next milliseconds additional spikes are evoked through bipolar cell or photoreceptor depolarization, as confirmed by pharmacological blockers. Second, monophasic epiretinal anodal or subretinal cathodal currents elicit spikes in ganglion cells by hyperpolarization of photoreceptor terminals. These stimuli mimic the photoreceptor response to light increments. Third, the stimulation symmetry between current polarities (anodal/cathodal) and retina-array configuration (epi/sub) is confirmed in an experiment in which stimuli presented at different positions reveal the center-surround organization of the ganglion cell. A simple biophysical model that relies on voltage changes of cell terminals in the transretinal electric field above the stimulation capacitor explains our results. This study provides a comprehensive guide for efficient stimulation of different retinal neuronal classes with low-amplitude capacitive currents.

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