sensory pathway
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2022 ◽  
Vol 119 (3) ◽  
pp. e2110158119
Author(s):  
Hsueh-Ling Chen ◽  
Dorsa Motevalli ◽  
Ulrich Stern ◽  
Chung-Hui Yang

Sucrose is an attractive feeding substance and a positive reinforcer for Drosophila. But Drosophila females have been shown to robustly reject a sucrose-containing option for egg-laying when given a choice between a plain and a sucrose-containing option in specific contexts. How the sweet taste system of Drosophila promotes context-dependent devaluation of an egg-laying option that contains sucrose, an otherwise highly appetitive tastant, is unknown. Here, we report that devaluation of sweetness/sucrose for egg-laying is executed by a sensory pathway recruited specifically by the sweet neurons on the legs of Drosophila. First, silencing just the leg sweet neurons caused acceptance of the sucrose option in a sucrose versus plain decision, whereas expressing the channelrhodopsin CsChrimson in them caused rejection of a plain option that was “baited” with light over another that was not. Analogous bidirectional manipulations of other sweet neurons did not produce these effects. Second, circuit tracing revealed that the leg sweet neurons receive different presynaptic neuromodulations compared to some other sweet neurons and were the only ones with postsynaptic partners that projected prominently to the superior lateral protocerebrum (SLP) in the brain. Third, silencing one specific SLP-projecting postsynaptic partner of the leg sweet neurons reduced sucrose rejection, whereas expressing CsChrimson in it promoted rejection of a light-baited option during egg-laying. These results uncover that the Drosophila sweet taste system exhibits a functional division that is value-based and task-specific, challenging the conventional view that the system adheres to a simple labeled-line coding scheme.


Insects ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 25
Author(s):  
Torben Stemme ◽  
Sarah E. Pfeffer

Many arachnid taxa have evolved unique, highly specialized sensory structures such as antenniform legs in Amblypygi (whip spiders), for instance, or mesosomal pectines in scorpions. Knowledge of the neuroanatomy as well as functional aspects of these sensory organs is rather scarce, especially in comparison to other arthropod clades. In pseudoscorpions, no special sensory structures have been discovered so far. Nevertheless, these animals possess dominant, multifunctional pedipalps, which are good candidates for being the primary sensory appendages. However, only little is known about the anatomy of the nervous system and the projection pattern of pedipalpal afferents in this taxon. By using immunofluorescent labeling of neuronal structures as well as lipophilic dye labeling of pedipalpal pathways, we identified the arcuate body, as well as a comparatively small mushroom body, the latter showing some similarities to that of Solifugae (sun spiders and camel spiders). Furthermore, afferents from the pedipalps terminate in a glomerular and a layered neuropil. Due to the innervation pattern and structural appearance, we conclude that these neuropils are the first integration centers of the chemosensory and mechanosensory afferents. Within Arthropoda, but also other invertebrates or even vertebrates, sensory structures show rather similar neuronal arrangement. Thus, these similarities in the sensory systems of different evolutionary origin have to be interpreted as functional prerequisites of the respective modality.


2021 ◽  
Vol 17 (12) ◽  
pp. e1009654
Author(s):  
Andrea Ferrario ◽  
Andrey Palyanov ◽  
Stella Koutsikou ◽  
Wenchang Li ◽  
Steve Soffe ◽  
...  

How does the brain process sensory stimuli, and decide whether to initiate locomotor behaviour? To investigate this question we develop two whole body computer models of a tadpole. The “Central Nervous System” (CNS) model uses evidence from whole-cell recording to define 2000 neurons in 12 classes to study how sensory signals from the skin initiate and stop swimming. In response to skin stimulation, it generates realistic sensory pathway spiking and shows how hindbrain sensory memory populations on each side can compete to initiate reticulospinal neuron firing and start swimming. The 3-D “Virtual Tadpole” (VT) biomechanical model with realistic muscle innervation, body flexion, body-water interaction, and movement is then used to evaluate if motor nerve outputs from the CNS model can produce swimming-like movements in a volume of “water”. We find that the whole tadpole VT model generates reliable and realistic swimming. Combining these two models opens new perspectives for experiments.


2021 ◽  
Vol 23 (5) ◽  
pp. 1005-1016
Author(s):  
A. A. Artemenkov

The review article analyzes literature data on the issues of immune response dysregulation during aging. It has been shown that impairment of innate and adaptive immune response in elderly and senile people under the conditions of spreading the new coronavirus infection is an aggravating factor in the course of the disease and recovery. Neuro-immuno-endocrine changes occurring in the organs of immune system, immunocompetent cells, molecules and receptor formations involved into the arising immune response have been traced. The imbalance of the brain-intestine-microbiota axis is considered in sufficient details, where a significant role is attributed to the changes occurring in hypothalamic-adrenal system under participation of biogenic neurotransmitters and neuromodulators. It is shown that intestinal microbiota may be involved into the neurodegeneration events, due to toxic effects on the brain via the neuro-immuno-endocrine and metabolic pathways. The data are presented, which show that adrenaline, norepinephrine, dopamine and serotonin are involved in the immune response dysregulation, thus making this process similar to the changes that occur during the general adaptation syndrome and stress response of the body. On the other hand, the review notes that chronic stress during aging not only alters the activity of macrophages, lymphocytes and dendritic cells, but also increases the level of proinflammatory cytokines in blood, thereby affecting permeability of the blood-brain barrier. The article emphasizes that with body aging, a neuroendocrine sensory pathway of immune response dysregulation is gradually formed. In this regard, it is noted that the afferent nerve endings and neurons of the vagus, adrenergic and peptidergic nerves are involved into dysfunction of immune system by affecting the processes occurring not only in thymus, but also in the brain. However, it is obvious that the pathodynamic “dysadapting circuit” formed in the higher compartments of nervous system is also involved in dysregulatory immune responses during aging. Hence, the work concludes that the signaling networks of the body's regulatory systems (nervous, immune and endocrine) are closely interconnected throughout the lifetime, but with aging and penetration of antigens into the body, this interaction is easily disrupted at different levels of organization of living matter, thus leading to dysregulation.


Pain ◽  
2021 ◽  
Vol Publish Ahead of Print ◽  
Author(s):  
Seung Min Shin ◽  
Francie Moehring ◽  
Brandon Itson-Zoske ◽  
Fan Fan ◽  
Cheryl L. Stucky ◽  
...  

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Vinicius M. Gadotti ◽  
Gerald W. Zamponi

AbstractWe have recently reported that the Cav3.2 T-type calcium channel which is well known for its key role in pain signalling, also mediates a critical function in the transmission of itch/pruritus. Here, we evaluated the effect of the clinically used anti-seizure medication ethosuximide, a well known inhibitor of T-type calcium channels, on male and female mice subjected to histaminergic- and non-histaminergic itch. When delivered intraperitoneally ethosuximide significantly reduced scratching behavior of mice of both sexes in response to subcutaneous injection of either histamine or chloroquine. When co-delivered subcutaneously together with either pruritogenic agent ethosuximide was also effective in inhibiting scratching responses in both male and female animals. Overall, our results are consistent with an important role of Cav3.2 T-type calcium channels in modulating histamine-dependent and histamine-independent itch transmission in the primary sensory pathway. Our findings also suggest that ethosuximide could be explored further as a possible therapeutic for the treatment of itch.


PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10730
Author(s):  
Thomas F. Burns ◽  
Ramesh Rajan

The classical view of sensory information mainly flowing into barrel cortex at layer IV, moving up for complex feature processing and lateral interactions in layers II and III, then down to layers V and VI for output and corticothalamic feedback is becoming increasingly undermined by new evidence. We review the neurophysiology of sensing and processing whisker deflections, emphasizing the general processing and organisational principles present along the entire sensory pathway—from the site of physical deflection at the whiskers to the encoding of deflections in the barrel cortex. Many of these principles support the classical view. However, we also highlight the growing number of exceptions to these general principles, which complexify the system and which investigators should be mindful of when interpreting their results. We identify gaps in the literature for experimentalists and theorists to investigate, not just to better understand whisker sensation but also to better understand sensory and cortical processing.


2021 ◽  
Author(s):  
Meike M. Rogalla ◽  
Adina Seibert ◽  
K Jannis Hildebrandt

AbstractIn patients with severe sensory impairment due to compromised peripheral function, partial restoration can be achieved by implantation of sensory prostheses for the electrical stimulation of the central nervous system. However, these state of the art approaches suffer from the drawback of limited spectral resolution. Electrical field spread depends on the impedance of the surrounding medium, impeding spatially focused electrical stimulation in neural tissue. To overcome these technical limitations, optogenetic excitation could be applied in such prostheses to achieve enhanced resolution through precise and differential stimulation of nearby neuronal ensembles within the central sensory pathway. Previous experiments have provided a first proof for behavioral detectability of optogenetic excitation in the rodent auditory system. However, little is known about the generation of complex and behaviorally relevant sensory patterns involving differential excitation. In this study, we developed an optogenetic implant to excite two spatially separated points along the tonotopy of the murine central inferior colliculus (ICc). Using a newly-devised reward-based operant Go/No-Go paradigm for the evaluation of optogenetic excitation of the auditory midbrain in freely moving, behaving mice, we demonstrate that differential optogenetic excitation of a sub-cortical sensory pathway is possible and efficient. Here we demonstrate how animals which were previously trained in a frequency discrimination paradigm a) rapidly generalize between sound and optogenetic excitation, b) generally detect optogenetic excitation at two different neuronal ensembles, and c) discriminate between them. Our results demonstrate for the first time that optogenetic excitation at different points of the ICc tonotopy elicits a stable response behavior over time periods of several months. With this study, we provide the first proof of principle for sub-cortical differential stimulation of sensory systems using complex artificial cues in freely moving animals.


2021 ◽  
Author(s):  
Seung Min Shin ◽  
Francie Moehring ◽  
Brandon Itson-Zoske ◽  
Fan Fan ◽  
Cheryl L. Stucky ◽  
...  

AbstractPiezo2 mechanotransduction channel is a crucial mediator of sensory neurons for sensing and transducing touch, vibration, and proprioception. We here characterized Piezo2 expression and cell specificity in rat peripheral sensory pathway using a validated Piezo2 antibody. Immunohistochemistry using this antibody revealed Piezo2 expression in pan primary sensory neurons (PSNs) of dorsal rood ganglia (DRG) in naïve rats, which was actively transported along afferent axons to both central presynaptic terminals innervating the spinal dorsal horn (DH) and peripheral afferent terminals in skin. Piezo2 immunoreactivity (IR) was also detected in the postsynaptic neurons of the DH and in the motor neurons of the ventral horn, but not in spinal GFAP- and Iba1-positive glia. Notably, Piezo2-IR was clearly identified in peripheral non-neuronal cells, including perineuronal glia, Schwann cells in the sciatic nerve and surrounding cutaneous afferent endings, as well as in skin epidermal Merkel cells and melanocytes. Immunoblots showed increased Piezo2 in DRG ipsilateral to plantar injection of complete Freund’s adjuvant (CFA), and immunostaining revealed increased Piezo2-IR intensity in the DH ipsilateral to CFA injection. This elevation of DH Piezo2-IR was also evident in various neuropathic pain models and monosodium iodoacetate (MIA) knee osteoarthritis (OA) pain model, compared to controls. We conclude that 1) the pan neuronal profile of Piezo2 expression suggests that Piezo2 may function extend beyond simply touch/proprioception mediated by large-sized low-threshold mechanosensitive PSNs, 2) Piezo2 may have functional roles involving sensory processing in spinal cord, Schwann cells, and skin melanocytes, and 3) aberrant Piezo2 expression may contribute pain pathogenesis.


eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Alejandro Tabas ◽  
Glad Mihai ◽  
Stefan Kiebel ◽  
Robert Trampel ◽  
Katharina von Kriegstein

The subcortical sensory pathways are the fundamental channels for mapping the outside world to our minds. Sensory pathways efficiently transmit information by adapting neural responses to the local statistics of the sensory input. The long-standing mechanistic explanation for this adaptive behaviour is that neural activity decreases with increasing regularities in the local statistics of the stimuli. An alternative account is that neural coding is directly driven by expectations of the sensory input. Here, we used abstract rules to manipulate expectations independently of local stimulus statistics. The ultra-high-field functional-MRI data show that abstract expectations can drive the response amplitude to tones in the human auditory pathway. These results provide first unambiguous evidence of abstract processing in a subcortical sensory pathway. They indicate that the neural representation of the outside world is altered by our prior beliefs even at initial points of the processing hierarchy.


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