scholarly journals Probing the multimodal fungiform papilla: complex peripheral nerve endings of chorda tympani taste and mechanosensitive fibers before and after Hedgehog pathway inhibition

2021 ◽  
Author(s):  
Christopher R. Donnelly ◽  
Archana Kumari ◽  
Libo Li ◽  
Iva Vesela ◽  
Robert M. Bradley ◽  
...  
Keyword(s):  
Nerve Fibers ◽  
Nerve Endings ◽  
Merkel Cells ◽  
Chorda Tympani ◽  
Fungiform Papilla ◽  
Tactile Stimuli ◽  
Reporter Mice ◽  
Before And After ◽  
Pathway Inhibition ◽  
Synapsin 1

AbstractThe fungiform papilla (FP) is a gustatory and somatosensory structure incorporating chorda tympani (CT) nerve fibers that innervate taste buds (TB) and also contain somatosensory endings for touch and temperature. Hedgehog (HH) pathway inhibition eliminates TB, but CT innervation remains in the FP. Importantly, after HH inhibition, CT neurophysiological responses to taste stimuli are eliminated, but tactile responses remain. To examine CT fibers that respond to tactile stimuli in the absence of TB, we used Phox2b-Cre; Rosa26LSL−TdTomato reporter mice to selectively label CT fibers with TdTomato. Normally CT fibers project in a compact bundle directly into TB, but after HH pathway inhibition, CT fibers reorganize and expand just under the FP epithelium where TB were. This widened expanse of CT fibers coexpresses Synapsin-1, β-tubulin, S100, and neurofilaments. Further, GAP43 expression in these fibers suggests they are actively remodeling. Interestingly, CT fibers have complex terminals within the apical FP epithelium and in perigemmal locations in the FP apex. These extragemmal fibers remain after HH pathway inhibition. To identify tactile end organs in FP, we used a K20 antibody to label Merkel cells. In control mice, K20 was expressed in TB cells and at the base of epithelial ridges outside of FP. After HH pathway inhibition, K20 + cells remained in epithelial ridges but were eliminated in the apical FP without TB. These data suggest that the complex, extragemmal nerve endings within and disbursed under the apical FP are the mechanosensitive nerve endings of the CT that remain after HH pathway inhibition.

scholarly journals Cell non-autonomous requirement of p75 in the development of geniculate oral sensory neurons

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tao Tang ◽  
Christopher R. Donnelly ◽  
Amol A. Shah ◽  
Robert M. Bradley ◽  
Charlotte M. Mistretta ◽  
...  
Keyword(s):  
Sensory Neurons ◽  
Significant Loss ◽  
Taste Buds ◽  
Neurotrophin Receptor ◽  
P75 Neurotrophin Receptor ◽  
Chorda Tympani ◽  
Chorda Tympani Nerve ◽  
Tactile Stimuli ◽  
Oral Sensory ◽  
Nerve Recordings

AbstractDuring development of the peripheral taste system, oral sensory neurons of the geniculate ganglion project via the chorda tympani nerve to innervate taste buds in fungiform papillae. Germline deletion of the p75 neurotrophin receptor causes dramatic axon guidance and branching deficits, leading to a loss of geniculate neurons. To determine whether the developmental functions of p75 in geniculate neurons are cell autonomous, we deleted p75 specifically in Phox2b + oral sensory neurons (Phox2b-Cre; p75fx/fx) or in neural crest-derived cells (P0-Cre; p75fx/fx) and examined geniculate neuron development. In germline p75−/− mice half of all geniculate neurons were lost. The proportion of Phox2b + neurons, as compared to Phox2b-pinna-projecting neurons, was not altered, indicating that both populations were affected similarly. Chorda tympani nerve recordings demonstrated that p75−/− mice exhibit profound deficits in responses to taste and tactile stimuli. In contrast to p75−/− mice, there was no loss of geniculate neurons in either Phox2b-Cre; p75fx/fx or P0-Cre; p75fx/fx mice. Electrophysiological analyses demonstrated that Phox2b-Cre; p75fx/fx mice had normal taste and oral tactile responses. There was a modest but significant loss of fungiform taste buds in Phox2b-Cre; p75fx/fx mice, although there was not a loss of chemosensory innervation of the remaining fungiform taste buds. Overall, these data suggest that the developmental functions of p75 are largely cell non-autonomous and require p75 expression in other cell types of the chorda tympani circuit.

scholarly journals Training-induced plasticity enables visualizing sounds with a visual-to-auditory conversion device

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jacques Pesnot Lerousseau ◽  
Gabriel Arnold ◽  
Malika Auvray
Keyword(s):  
Individual Differences ◽  
Visual Information ◽  
Sensory Modality ◽  
Sensory Substitution ◽  
Visual Images ◽  
Visual Functions ◽  
Tactile Stimuli ◽  
Before And After ◽  
Visual Distractors ◽  
Auditory Processes

AbstractSensory substitution devices aim at restoring visual functions by converting visual information into auditory or tactile stimuli. Although these devices show promise in the range of behavioral abilities they allow, the processes underlying their use remain underspecified. In particular, while an initial debate focused on the visual versus auditory or tactile nature of sensory substitution, since over a decade, the idea that it reflects a mixture of both has emerged. In order to investigate behaviorally the extent to which visual and auditory processes are involved, participants completed a Stroop-like crossmodal interference paradigm before and after being trained with a conversion device which translates visual images into sounds. In addition, participants' auditory abilities and their phenomenologies were measured. Our study revealed that, after training, when asked to identify sounds, processes shared with vision were involved, as participants’ performance in sound identification was influenced by the simultaneously presented visual distractors. In addition, participants’ performance during training and their associated phenomenology depended on their auditory abilities, revealing that processing finds its roots in the input sensory modality. Our results pave the way for improving the design and learning of these devices by taking into account inter-individual differences in auditory and visual perceptual strategies.

scholarly journals Visual body size adaptation and estimation of tactile distance

2020 ◽  
Author(s):  
Regine Zopf ◽  
Veronika Kosourikhina ◽  
Kevin R. Brooks ◽  
Vince Polito ◽  
Ian Stephen
Keyword(s):  
Body Size ◽  
Adaptation Effect ◽  
The Body ◽  
Size Perception ◽  
Visual Adaptation ◽  
Social Environments ◽  
Body Images ◽  
Tactile Stimuli ◽  
Before And After ◽  
Adaptation Effects

Estimating the size of bodies is crucial for interactions with physical and social environments. Body size perception is malleable and can be altered using visual adaptation paradigms. However, it is unclear whether such visual adaptation effects also transfer to other modalities and influence, for example, the perception of tactile distances. In this study we employed a visual adaptation paradigm. Participants were exposed to images of expanded or contracted versions of self- or other-identity bodies. Before and after this adaptation they were asked to manipulate the width of body images to appear as “normal” as possible. We replicated an effect of visual adaptation, such that the body size selected as most “normal” was larger after exposure to expanded and thinner after exposure to contracted adaptation stimuli. In contrast, we did not find evidence that this adaptation effect transfers to distance estimates for paired tactile stimuli delivered to the abdomen. A Bayesian analysis showed that our data provide moderate evidence that there is no effect of visual body size adaptation on the estimation of spatial parameters in a tactile task. This suggests that visual body size adaptation effects do not transfer to somatosensory body size representations.

Barbiturates depress vagal motor pathway to ferret trachea at ganglia

1982 ◽  
Vol 53 (1) ◽  
pp. 253-257 ◽  
Author(s):  
B. E. Skoogh ◽  
M. J. Holtzman ◽  
J. R. Sheller ◽  
J. A. Nadel
Keyword(s):  
Neuromuscular Junction ◽  
Vagus Nerve ◽  
Muscle Tension ◽  
Postsynaptic Membrane ◽  
Nerve Fibers ◽  
Motor Pathway ◽  
Parasympathetic Ganglia ◽  
Before And After ◽  
Nerve Muscle

To determine which site in the vagal motor pathway to airway smooth muscle is most sensitive to depression by barbiturates, we recorded isometric muscle tension in vitro and stimulated the vagal motor pathway at four different sites before and after exposure to barbiturates. In isolated tracheal rings from ferrets, we stimulated muscarinic receptors in the neuromuscular junction by exogenous acetylcholine, postganglionic nerve fibers by electrical fluid stimulation, and the postsynaptic membrane in ganglia by 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP). We also developed a tracheal nerve-muscle preparation to stimulate preganglionic fibers in the vagus nerve electrically. Activation of ganglia by DMPP or by vagus nerve stimulation was depressed by barbiturates at 10-fold lower concentrations than those depressing the activation of postganglionic nerves or the neuromuscular junction. These findings suggest that the postsynaptic membrane in parasympathetic ganglia is the site in the vagal motor pathway most sensitive to depression by barbiturates.

Functional organization of ciliary muscle in the cat

1962 ◽  
Vol 203 (5) ◽  
pp. 857-859 ◽  
Author(s):  
Harris Ripps ◽  
Irwin M. Siegel ◽  
William B. Getz
Keyword(s):  
Functional Organization ◽  
Muscle Cells ◽  
Nerve Fibers ◽  
Fixed Number ◽  
Ciliary Muscle ◽  
Frequency Variation ◽  
Efferent Nerve ◽  
Ocular Accommodation ◽  
Before And After ◽  
Stimulation Of

Ocular accommodation was elicited by electric stimulation of the ciliary ganglion in cats. The responses to frequency variation were recorded before and after cutting a branch of the postganglionic motor supply to the ciliary muscle. At all stimulus frequencies the responses obtained after section were shown to be a constant fraction of those obtained in the intact preparation. This suggests that a fixed number of muscle cells are affected when a portion of the efferent nerve fibers is cut. It was concluded that smooth ciliary muscle is organized as independent functional units, akin to the motor-unit arrangement of skeletal muscle; a given nerve fiber influences the response of a limited number of muscle cells.

Amiloride sensitivity of chorda tympani response to NaCl in Fischer 344 and Wistar rats

1991 ◽  
Vol 261 (2) ◽  
pp. R329-R333 ◽  
Author(s):  
I. L. Bernstein ◽  
A. Longley ◽  
E. M. Taylor
Keyword(s):  
Sodium Transport ◽  
Wistar Rats ◽  
Strain Differences ◽  
Chorda Tympani ◽  
Gustatory System ◽  
Electrophysiological Response ◽  
Fischer 344 ◽  
Electrophysiological Responses ◽  
Before And After ◽  
Amiloride Hydrochloride

Fischer 344 (F-344) rats fail to prefer NaCl solutions to water at any concentration and avoid NaCl solutions preferred by other strains, including Wistar rats. Behavioral and electrophysiological responses of the mammalian gustatory system to NaCl have been shown to depend on a sodium transport system that is specifically blocked by lingual application of the sodium-transport blocker amiloride. The present study examined whether strain differences exist between F-344 and Wistar rats in the amiloride sensitivity of the chorda tympani (CT) electrophysiological response to NaCl. Whole nerve CT recordings were obtained from adult F-344 and Wistar rats during chemical stimulation of the anterior tongue. Responses to NaCl solutions ranging from 0.01 to 1.0 M were examined both before and after pretreatment with amiloride hydrochloride. Integrated whole nerve responses to NaCl solutions were expressed relative to the response to 0.5 M NH4Cl. Strain differences in the response to NaCl solutions emerged, with F-344 animals showing a significantly larger amplitude of the tonic response to NaCl, relative to NH4Cl, than Wistars. F-344 rats were also more sensitive to the sodium-channel blocker amiloride. These results suggest that strain differences in amiloride sensitive signals mediated by the CT nerve may contribute to the NaCl aversion displayed by F-344 rats.

Growth of Nerve Fibers to Merkel Cells Observed in Co-Culture of Sensory Ganglia and Sinus Hair Follicles

2003 ◽  
pp. 113-120
Author(s):  
Jun Fukuda ◽  
Hisako Ishimine ◽  
Kazuko Keino-Masu ◽  
Yoshiaki Masaki
Keyword(s):  
Nerve Fibers ◽  
Hair Follicles ◽  
Sensory Ganglia ◽  
Merkel Cells

scholarly journals Distinguishing hair cell from neural potentials recorded at the round window

2014 ◽  
Vol 111 (3) ◽  
pp. 580-593 ◽  
Author(s):  
Mathieu Forgues ◽  
Heather A. Koehn ◽  
Askia K. Dunnon ◽  
Stephen H. Pulver ◽  
Craig A. Buchman ◽  
...  
Keyword(s):  
Hair Cell ◽  
Kainic Acid ◽  
Hair Cells ◽  
Phase Locking ◽  
Round Window ◽  
Nerve Fibers ◽  
Neural Firing ◽  
Low Frequencies ◽  
Before And After ◽  
Different Sources

Almost all patients who receive cochlear implants have some acoustic hearing prior to surgery. Electrocochleography (ECoG), or electrophysiological measures of cochlear response to sound, can identify remaining auditory nerve activity that is the basis for this residual hearing and can record potentials from hair cells that are no longer functionally connected to nerve fibers. The ECoG signal is therefore complex, being composed of both hair cell and neural signals. To identify signatures of different sources in the recorded potentials, we collected ECoG data across frequency and intensity from the round window of gerbils before and after treatment with kainic acid, a neurotoxin. Distortions in the recorded waveforms were produced by different sources over different ranges of frequency and intensity. In response to tones at low frequencies and low-to-moderate intensities, the major source of distortion was from neural phase-locking that was sensitive to kainic acid. At high intensities at all frequencies, the distortion was not sensitive to kainic acid and was consistent with asymmetric saturation of the hair cell transducer current. In addition to loss of phase-locking, changes in the envelope after kainic acid treatment indicate that sustained neural firing combines with receptor potentials from hair cells to produce the envelope of the response to tones. These results provide baseline data to interpret comparable recordings from human cochlear implant recipients.

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