Wayne L Silver

• Ph. D.
• Wake Forest University

Introduction Carbon dioxide (CO2) is a critical biological signal that is noxious to many animals at high concentrations. The earthworm Dendrobaena veneta lives in subterranean burrows containing high levels of CO2 and respires through its skin. Despite the ecological and agricultural importance of earthworms, relatively little is known about how t...

Carbon dioxide (CO 2 ) is a critical biological signal that is noxious to many animals at high concentrations. The earthworm Dendrobaena veneta lives in subterranean burrows containing high levels of CO 2 and respires through its skin. Despite the ecological and agricultural importance of earthworms, relatively little is known about how they make d...

Earthworms shape the biological and physicochemical qualities of the soil they choose to reside in, but our understanding of the specific chemicals that attract or repel a particular species of earthworm remains incomplete. Current research indicates that some species feed on and are attracted to fungi, such as Geotrichum candidum . In the present...

Earthworms have a profound effect on the soil they inhabit, but our current understanding of the chemical factors and molecular mechanisms that attract or repel earthworms from a specific area of soil is limited. In this study, we developed a soil T-maze assay allowing for the examination of earthworm behavioral responses to repellent chemicals. Th...

There has been disagreement over the functional roles of the painless gene product in the detection and subsequent behavioral aversion to the active ingredient in wasabi, allyl isothiocyanate (AITC). Originally, painless was reported to eliminate the behavioral aversion to AITC, although subsequent reports suggested that another trpA homolog, dTRPA...

PER responses to water in dTRPA1 and painless variants. Percentage of PER responses to water treatment alone in wild-type, painless, dTRPA1, and painless; dTRPA1 double mutants. There are no significant differences in the amount of positive PER responses to water alone (One Way ANOVA, P > 0.05), indicating that these genotypes aren’t differentially...

Expression of painless and dTRPA1 in the adult CNS. Adult brains and ventral nerve cords were dissected from offspring of a painless-GAL4 (left) and a dTRPA1-GAL4 (right) cross to a UAS-mCD8-GFP fly line. Along the ventral nerve cord, note that there are four neurons that appear similar and are labeled in both painless and dTRPA1-GAL4 lines (white...

Electrical silencing of painless and dTRPA1 neurons impacts PER frequencies and oviposition preferences. (A) Electrical silencing of either the painless-GAL or the dTRPA1-GAL4 expressing neurons leads to no reduction in PER frequecies at 5% sucrose upon presentation of AITC as opposed to parental control genotypes (One way ANOVA, GraphPad). (B) Ovi...

(A) Addition of vehicle to painless expressing neurons does not significantly alter GCaMP fluorescence. Mean responses of painless expressing neurons to vehicle addition, note the photobleaching and compare to responses shown in Figure 9. (B) Addition of AITC to neurons that do not express painless or dTRPA1 does not significantly alter GCaMP fluor...

(E)-2-alkenals are aldehydes containing an unsaturated bond between the alpha and beta carbons. 2-alkenals are produced by many organisms for defense against predators and secretions containing (E)-2-alkenals cause predators to stop attacking and allow the prey to escape. Chemical ecologists have described many alkenal compounds with 3–20 carbons c...

Chemesthesis is the stimulation of somatic sensory nerves by chemicals. These chemicals produce sensations described as spicy, piquant, pungent, cooling, buzzing, and irritating. This chapter presents an overview of the anatomy and physiology of the nose and the mouth as they relate to chemesthesis, including a description of the nerve fibers types...

Introduction Recent advancements in the study of nasal chemesthesis have primarily been achieved through in vitro, cellular, and molecular techniques, with a resultant shift of focus away from in vivo experimental methodology. Psychophysical and electrophysiological data derived from long-standing in vivo methods form our core understanding of trig...

Polymodal neurons of the trigeminal nerve innervate the nasal cavity, nasopharynx, oral cavity and cornea. Trigeminal nociceptive fibers express a diverse collection of receptors and are stimulated by a wide variety of chemicals. However, the mechanism of stimulation is known only for relatively few of these compounds. Capsaicin, for example, activ...

Acetic acid produces an irritating sensation that can be attributed to activation of nociceptors within the trigeminal ganglion that innervate the nasal or oral cavities. These sensory neurons sense a diverse array of noxious agents in the environment, allowing animals to actively avoid tissue damage. Although receptor mechanisms have been identifi...

The trigeminal nerve responds to a variety of nociceptive stimuli, including many chemicals that activate the olfactory system at lower concentrations. However, the mechanisms by which specific odorants activate the trigeminal nerve are largely undetermined. We used an integrative approach to determine whether TRPA1 channels were the target of eigh...

The upper respiratory tract is continually assaulted with harmful dusts and xenobiotics carried on the incoming airstream. Detection of such irritants by the trigeminal nerve evokes protective reflexes, including sneezing, apnea, and local neurogenic inflammation of the mucosa. Although free intra-epithelial nerve endings can detect certain lipophi...

The trigeminal nerve (TN) provides sensory information from the eyes, nose, and mouth. A subset of trigeminal nerve fibers, particularly those containing the neuropeptides substance P and calcitonin gene-related peptide (CGRP), responds to chemical irritants in the environment. Axons in the ethmoid and nasopalatine branches of the trigeminal nerve...

Nasal solitary chemoreceptor cells (SCCs) are a population of specialized chemosensory epithelial cells presumed to broaden trigeminal chemoreceptivity in mammals (Finger et al. [2003] Proc Natl Acad Sci USA 100:8981-8986). SCCs are innervated by peptidergic trigeminal nerve fibers (Finger et al. [2003]) but it is currently unknown if intact innerv...

The trigeminal nerve responds to a wide variety of irritants. Trigeminal nerve fibers express several receptors that respond to chemicals, including TRPV1 (vanilloid) receptors, acid-sensing ion channels, P2X (purinergic) receptors, and nicotinic acetylcholine receptors. In order to assess whether TRPV1 plays a role in responses to a broad array of...

Inhalation of irritating substances leads to activation of the trigeminal nerve, triggering protective reflexes that include apnea or sneezing. Receptors for trigeminal irritants are generally assumed to be located exclusively on free nerve endings within the nasal epithelium, requiring that trigeminal irritants diffuse through the junctional barri...

The nasal epithelium is richly invested with peptidergic (substance P and calcitonin gene-related peptide [CGRP]) trigeminal polymodal nociceptors, which respond to numerous odorants as well as irritants. Peptidergic trigeminal sensory fibers also enter the glomerular layer of the olfactory bulb. To test whether the trigeminal fibers in the olfacto...

This collaborative laboratory exercise integrates two upper division laboratory courses (Developmental Biology and Neurobiology) offered to biology majors at Wake Forest University. The laboratory exercise involves the use of the Xenopus oocyte expression system to study the function of specific membrane receptors and ligand-activated channels. cDN...

The peripheral chemoreceptors of the trigeminal system in the nasal cavity are presumed to be free nerve endings arising from Adelta and C fibers. These fibers appear to be scattered throughout the nasal epithelium, and arise from the nasopalatine and ethmoid branches of the trigeminal nerve. In the present study, the effects of nicotinic acetylcho...

Complaints about unpleasant environmental odorants, both outdoor and indoor, are increasingly being reported. The main complaints of health symptoms from environmental odorants are eye, nose and throat irritation, headache and drowsiness. Complaints may arise from the stimulation of olfactory receptors or trigeminal chemoreceptors. Stimulation of c...

Olfactory and trigeminal sensitivities to vapor-phase nicotine were assessed by using psychophysical studies with normal and anosmic human subjects and using electrophysiological studies with rats and pigeons. This work showed that 1) psychophysical estimates of sensitivity are approximately tenfold higher (i.e., lower thresholds) than those based...

The nasal cavity embraces a wide variety of chemoreceptors, including those of the olfactory, vomeronasal, and trigeminal systems. Chemical stimulation of nasal trigeminal receptors is usually associated with pain or irritation. Accordingly, trigeminal fibers sensitive to chemical irritants have been considered part of the common chemical sense [1]...

Electrophysiological, multi-unit responses from the ethmoid branch of the trigeminal nerve to chemical stimuli (amyl acetate, d-carvone, l-carvone, l-menthol and toluene) were examined, using self- and cross-adaptation paradigms, to address the question of whether different chemical stimuli may stimulate trigeminal nerve fibers using different ‘rec...

Trigeminal nerve fibers in the nasal cavity respond to a variety of volatile chemical stimuli. Some of these trigeminal nerve fibers have been suggested to be capsaicin-sensitive and thus belong to a class of pain receptor rather than constituting a separate class of chemoreceptor. Our current results confirm this suggestion. Trigeminal nerve respo...

The olfactory organ of the striped eel catfish,Plotosus lineatus (Thunberg), obtained off Kyushu Island, Japan, was examined both morphologically and electrophysiologically. The olfactory organ ofP. lineatus differs from that of most other catfishes, possessing a small olfactory rosette containing only relatively few lamellae, a well-developed olfa...

An apparatus was developed which permits the automated delivery of volatile chemical stimuli for use in neurophysiology experiments. A computer-controlled olfactometer, incorporating electronic mass flow controllers (EMFCs) and Teflon-lined solenoid valves, generated and delivered clean or odorized air. Neural and respiratory signals from the anima...

The respiratory and olfactory mucosae of rats and mice were examined at ultrastructural levels for the presence of intraepithelial nerve endings. Immunocytochemical studies utilizing antisera directed against substance P and calcitonin gene-related peptide (CGRP) revealed numerous intraepithelial peptide-immunoreactive fibers near the basal region...

Trigeminal receptors can respond to a wide variety of chemical stimuli, but it is unknown whether these receptors mediate discrimination between chemical stimuli matched for equal perceptual intensity. The present electrophysiological and behavioral experiments address this issue using tiger salamanders, Ambystoma tigrinum, and four compounds (amyl...

Capsaicin injections severely reduced or eliminated nasal trigeminal responses to 3 odorants (Experiment 1). However, capsaicin treated animals exhibited no deficits in locating buried food, in odor avoidance learning, or in operant odor detection and discrimination (Experiments 2 and 3). In addition, capsaicin desensitization did not affect respon...

Odorant molecules can stimulate nasal trigeminal receptors, but the properties of such molecules which make them effective stimuli are largely unknown. In the present study, we obtained integrated multiunit responses from the ethmoid branch of the rat trigeminal nerve to a homologous series of aliphatic alcohols. Our aim was to determine whether li...

Recent experimental data on the influence of non-olfactory nasal chemoreception in physiology, sensation and behavior suggest the following, (i) The vomeronasal system may be a detector for pre-programmed chemical signals, especially for pheromones that trigger hormonal and behavioral responses. As animals gain experience with particular chemical s...

Electro-olfactograms (EOGs) were used to assess olfactory responding by aquatic larval and terrestrial adult tiger salamanders (Ambystoma tigrinum) to airborne volatile compounds, and volatile and non-volatile compounds in aqueous solution. Both forms of salamander showed saturation effects to presentations of airborne stimuli (Fig. 2). Saturation...

Electro-olfactograms (EOGs) were used to assess olfactory responding by aquatic larval and terrestrial adult tiger salamanders (Ambystoma tigrinum) to airborne volatile compounds, and volatile and non-volatile compounds in aqueous solution. Both forms of salamander showed saturation effects to presentations of airborne stimuli (Fig. 2). Saturation...

The diuretic, amiloride, is a potent yet reversible inhibitor of passive sodium transport in many epithelia. It has been shown to inhibit sodium transport in dorsal lingual epithelia and to inhibit both psychophysical and neural measures of salt taste. The present results demonstrate that amiloride's action as an inhibitor of integrated whole chord...

Experiment 1 showed that capsaicin injections severely reduced or eliminated nasal trigeminal responses to 3 odorants. Experiments 2 and 3 investigated whether desensitized animals could behaviorally detect and discriminate odors. Capsaicin treated animals had no measurable deficits in locating buried food, in odor aversion learning, or in operant...

1. Electrophysiological responses to chemical stimuli were recorded from the spinal nerves innervating the free fin rays of the searobin,Prionotus carolinus. These modified pectoral fin rays are capable of detecting chemical stimuli although they contain neither taste buds nor olfactory receptors. 2. Squid extract elicited a vigorous response and o...

Electrophysiological and psychophysical evidence has demonstrated that trigeminal receptors in the nasal cavity respond to odorants. Despite these demonstrations of trigeminal chemoreception, it is not clear whether naso-trigeminal stimulation can be used to mediate learned behaviors in contexts such as feeding. Here, we report that starlings will...

Electrophysiological recordings demonstrated strong olfactory receptor responses to intravascularly injected odorants in tracheotomized animals. This disproves the belief that such odorants reach olfactory receptors only via exhaled air and strongly suggests that blood-borne odorants can stimulate receptors by diffusing from nasal capillaries. Bloo...

1. Electrophysiological responses were obtained from the peripheral olfactory system of the American eel,Anguilla rostrata, using three different recording methods: averaged multiunit activity from the olfactory mucosa (MNR), averaged multiunit activity from bundles of olfactory nerve axons (NTR), and the underwater electro-olfactogram (EOG). 2. Fo...

Electrophysiological responses to odorants delivered via an air dilution olfactometer were recorded from the ethmoid branch of the trigeminal nerve innervating the nasal cavity. Thresholds were obtained for nine compounds with those for heptanol (21-137 ppm) and propionic acid (39-49) ppm consistently being the lowest. Not all odorants e.g., phenet...

Nasal and oral trigeminal chemoreception are discussed with a focus on their functions, responses, and interactions with olfaction and gustation. Trigeminal stimulation elicits a number of physiological reflexes which are shown to have several possible effects on the olfactory and gustatory systems. Based on psychophysical and electrophysiological...

Underwater electro‐olfactogram (EOG) responses were recorded from the olfactory organ of the Atlantic stingray, Dasyatis sabina. Amino acids were shown to be effective stimuli with thresholds determined to be between 10 and 10 M. The five most stimulatory compounds tested were l‐glutamic acid γ methylester, l‐ethionine, l‐serine, l‐glutamic acid, a...

Recording the olfactory receptor activity of marine fishes presents problems due to the shunting of the electrical signals by the highly conductive sea water, which results in significant signal loss. By recording the large signal-to-noise ratio D. C. potentials using the underwater electro-olfactogram (EOG), we were able to study olfactory recepto...

Thesis--Florida State University. Includes bibliographical references (leaves 157-166).

Incluye bibliografía e índice