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Tactile Stimuli (tactile + stimulus)
Selected AbstractsGlutamate drives the touch response through a rostral loop in the spinal cord of zebrafish embryosDEVELOPMENTAL NEUROBIOLOGY, Issue 12 2009Thomas Pietri Abstract Characterizing connectivity in the spinal cord of zebrafish embryos is not only prerequisite to understanding the development of locomotion, but is also necessary for maximizing the potential of genetic studies of circuit formation in this model system. During their first day of development, zebrafish embryos show two simple motor behaviors. First, they coil their trunks spontaneously, and a few hours later they start responding to touch with contralateral coils. These behaviors are contemporaneous until spontaneous coils become infrequent by 30 h. Glutamatergic neurons are distributed throughout the embryonic spinal cord, but their contribution to these early motor behaviors in immature zebrafish is still unclear. We demonstrate that the kinetics of spontaneous coiling and touch-evoked responses show distinct developmental time courses and that the touch response is dependent on AMPA-type glutamate receptor activation. Transection experiments suggest that the circuits required for touch-evoked responses are confined to the spinal cord and that only the most rostral part of the spinal cord is sufficient for triggering the full response. This rostral sensory connection is presumably established via CoPA interneurons, as they project to the rostral spinal cord. Electrophysiological analysis demonstrates that these neurons receive short latency AMPA-type glutamatergic inputs in response to ipsilateral tactile stimuli. We conclude that touch responses in early embryonic zebrafish arise only after glutamatergic synapses connect sensory neurons and interneurons to the contralateral motor network via a rostral loop. This helps define an elementary circuit that is modified by the addition of sensory inputs, resulting in behavioral transformation. © 2009 Wiley Periodicals, Inc. Develop Neurobiol 2009 [source] The vesicular integral protein-like gene is essential for development of a mechanosensory system in zebrafishDEVELOPMENTAL NEUROBIOLOGY, Issue 12 2008Mabel Chong Abstract The zebrafish hi472 mutation is caused by a retroviral insertion into the vesicular integral protein-like gene, or zVIPL, a poorly studied lectin implicated in endoplasmic reticulum (ER)-Golgi trafficking. A mutation in the shorter isoform of zVIPL (zVIPL-s) results in a reduction of mechanosensitivity and consequent loss of escape behavior. Here we show that motoneurons and hindbrain reticulospinal neurons, which normally integrate mechanosensory inputs, failed to fire in response to tactile stimuli in hi472 larvae, suggesting a perturbation in sensory function. The hi472 mutant larvae in fact suffered from a severe loss of functional neuromasts of the lateral line mechanosensory system, a reduction of zVIPL labeling in support cells, and a reduction or even a complete loss of hair cells in neuromasts. The Delta-Notch signaling pathway is implicated in cellular differentiation of neuromasts, and we observed an increase in Notch expression in neuromasts of hi472 mutant larvae. Treatment of hi472 mutant larvae with DAPT, an inhibitor of Notch signaling, or overexpression of the Notch ligand deltaB in hi472 mutant blastocysts produced partial rescue of the morphological defects and of the startle response behavior. We conclude that zVIPL-s is a necessary component of Delta-Notch signaling during neuromast development in the lateral line mechanosensory system. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008 [source] Neuronal disinhibition in the trigeminal nucleus caudalis in a model of chronic neuropathic painEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2010Yasmina B. Martin Abstract The mechanisms underlying neuropathic facial pain syndromes are incompletely understood. We used a unilateral chronic constriction injury of the rat infraorbital nerve (CCI-IoN) as a facial neuropathic model. Pain-related behavior of the CCI-IoN animals was tested at 8, 15 and 26 days after surgery (dps). The response threshold to mechanical stimulation with von Frey hairs on the injured side was reduced at 15 and 26 dps, indicating the presence of allodynia. We performed unitary recordings in the caudalis division of the spinal trigeminal nucleus (Sp5C) at 8 or 26 dps, and examined spontaneous activity and responses to mechanical and thermal stimulation of the vibrissal pad. Neurons were identified as wide dynamic range (WDR) or low-threshold mechanoreceptive (LTM) according to their response to tactile and/or noxious stimulation. Following CCI-IoN, WDR neurons, but not LTM neurons, increased their spontaneous activity at 8 and 26 dps, and both types of Sp5C neurons increased their responses to tactile stimuli. In addition, the on,off tactile response in neurons recorded after CCI-IoN was followed by afterdischarges that were not observed in control cases. Compared with controls, the response inhibition observed during paired-pulse stimulation was reduced after CCI-IoN. Immunohistochemical studies showed an overall decrease in GAD65 immunoreactivity in Sp5C at 26 dps, most marked in laminae I and II, suggesting that following CCI-IoN the inhibitory circuits in the sensory trigeminal nuclei are depressed. Consequently, our results strongly suggest that disinhibition of Sp5C neurons plays a relevant role in the appearance of allodynia after CCI-IoN. [source] Tactile responses of hindpaw, forepaw and whisker neurons in the thalamic ventrobasal complex of anesthetized ratsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2008J. Aguilar Abstract The majority of studies investigating responses of thalamocortical neurons to tactile stimuli have focused on the whisker representation of the rat thalamus: the ventral,posterior,medial nucleus (VPM). To test whether the basic properties of thalamocortical responses to tactile stimuli could be extended to the entire ventrobasal complex, we recorded single neurons from the whisker, forepaw and hindpaw thalamic representations. We performed a systematic analysis of responses to stereotyped tactile stimuli , 500 ms pulses (i.e. ON,OFF stimuli) or 1 ms pulses (i.e. impulsive stimuli) , under two different anesthetics (pentobarbital or urethane). We obtained the following main results: (i) the tuning of cells to ON vs. OFF stimuli displayed a gradient across neurons, so that two-thirds of cells responded more to ON stimuli and one-third responded more to OFF stimuli; (ii) on average, response magnitudes did not differ between ON and OFF stimuli, whereas latencies of response to OFF stimuli were a few milliseconds longer; (iii) latencies of response to ON and OFF stimuli were highly correlated; (iv) responses to impulsive stimuli and ON stimuli showed a strong correlation, whereas the relationship between the responses to impulsive stimuli and OFF stimuli was subtler; (v) unlike ON responses, OFF responses did not decrease when stimuli were moved from the receptive field center to a close location in the excitatory surround. We obtained the same results for hindpaw, forepaw and whisker neurons. Our results support the view of a neurophysiologically homogeneous ventrobasal complex, in which OFF responses participate in the structure of the spatiotemporal receptive field of thalamocortical neurons for tactile stimuli. [source] The rapidly adapting receptors in mammalian airways and their responses to changes in extravascular fluid volumeEXPERIMENTAL PHYSIOLOGY, Issue 4 2006C. Tissa Kappagoda In this short review, we shall focus on some recent findings on the physiological stimulus for the rapidly adapting receptors (RAR) of the airways. They are readily activated by a sustained inflation of the lungs and they are usually identified by their rapid adaptation to this stimulus. They are also activated by both tactile stimuli and irritant gases applied to the epithelium of the airways. The investigations reviewed here suggest that these receptors are activated by changes in extravascular fluid volume. The principal factors governing fluid flux from the microcirculation are identified in the Starling equation. These are the hydrostatic pressure, plasma oncotic pressure and capillary permeability. Findings from recent studies suggest that all these factors increase the activity of RAR. In addition, these receptors are also activated by obstruction of lymph drainage from the lung. Evidence is presented to show that manipulation of Starling forces also increases the extravascular fluid volume of the airways in areas where the RAR are located. On the basis of these findings, it is suggested that, along with mechanosensitivity to stimuli such as stretch, inflation and deflation, another physiological stimulus to the RAR is a change in extravascular fluid volume in the regions of the airways where these receptors are located. [source] Cold Exposure Enhances Tactile Allodynia Transiently In Mononeuropathic RatsJOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 2 2000T. Kauppila A laser and erythrosin-B-induced sciatic nerve injury decreases thresholds of a mechanically induced paw withdrawal reflex and enhances cold-induced withdrawal behavior of the affected limb. Exposure of the affected paw to a normally innocuous cold stimulus results in a transient decrease in the threshold of the mechanically evoked paw withdrawal reflex in neuropathic but not in intact rats. The present data suggest that in an experimental neuropathic state a normally innocuous cold stimulus may further sensitize spinally mediated withdrawal reflexes to stimuli of another stimulus modality, in this case, to innocuous tactile stimuli. Therefore, testing mechanical allodynia in neuropathic rats immediately after testing cold allodynia may produce artifactual results. [source] Identification of a de novo Lys304Gln mutation in the glycine receptor ,-1 subunit gene in a Korean infant with hyperekplexiaMOVEMENT DISORDERS, Issue 4 2008Hoon-Chul Kang MD Abstract Startle disease or hyperekplexia (STHE; MIM 149400) is a rare disorder that is characterized by marked muscular hypertonia in infancy and an exaggerated startle response to unexpected acoustic or tactile stimuli. Mutations in the gene encoding the ,-1 subunit of the inhibitory glycine receptor (GLRA1) were reported as causes of STHE. Recently, we encountered a Korean male infant with generalized stiffness that was observed from the first 3 days of life. The abnormal startle response was evident from the fourth week of life, and he showed marked improvement in the startle response and muscle hypertonia after being administered phenobarbital and clonazepam. Direct sequencing analysis of the infant and his parents revealed a de novo variation (c.910A>C) in the GLRA1 gene, resulting in a novel Lys304Gln missense mutation. © 2007 Movement Disorder Society [source] Cortical processing of near-threshold tactile stimuli: An MEG studyPSYCHOPHYSIOLOGY, Issue 3 2010Anja Wühle Abstract In the present study we tested the applicability of a paired-stimulus paradigm for the investigation of near-threshold (NT) stimulus processing in the somatosensory system using magnetoencephalography. Cortical processing of the NT stimuli was studied indirectly by investigating the impact of NT stimuli on the source activity of succeeding suprathreshold test stimuli. We hypothesized that cortical responses evoked by test stimuli are reduced due to the preactivation of the same finger representation by the preceding NT stimulus. We observed attenuation of the magnetic responses in the secondary somatosensory (SII) cortex, with stronger decreases for perceived than for missed NT stimuli. Our data suggest that processing in the primary somatosensory cortex including recovery lasts for <200 ms. Conversely, the occupancy of SII lasts ,500 ms, which points to its role in temporal integration and conscious perception of sensory input. [source] Sexual selection research on spiders: progress and biasesBIOLOGICAL REVIEWS, Issue 3 2005Bernhard A. Huber ABSTRACT The renaissance of interest in sexual selection during the last decades has fuelled an extraordinary increase of scientific papers on the subject in spiders. Research has focused both on the process of sexual selection itself, for example on the signals and various modalities involved, and on the patterns, that is the outcome of mate choice and competition depending on certain parameters. Sexual selection has most clearly been demonstrated in cases involving visual and acoustical signals but most spiders are myopic and mute, relying rather on vibrations, chemical and tactile stimuli. This review argues that research has been biased towards modalities that are relatively easily accessible to the human observer. Circumstantial and comparative evidence indicates that sexual selection working via substrate-borne vibrations and tactile as well as chemical stimuli may be common and widespread in spiders. Pattern-oriented research has focused on several phenomena for which spiders offer excellent model objects, like sexual size dimorphism, nuptial feeding, sexual cannibalism, and sperm competition. The accumulating evidence argues for a highly complex set of explanations for seemingly uniform patterns like size dimorphism and sexual cannibalism. Sexual selection appears involved as well as natural selection and mechanisms that are adaptive in other contexts only. Sperm competition has resulted in a plethora of morphological and behavioural adaptations, and simplistic models like those linking reproductive morphology with behaviour and sperm priority patterns in a straightforward way are being replaced by complex models involving an array of parameters. Male mating costs are increasingly being documented in spiders, and sexual selection by male mate choice is discussed as a potential result. Research on sexual selection in spiders has come a long way since Darwin, whose spider examples are reanalysed in the context of contemporary knowledge, but the same biases and methodological constraints have persisted almost unchanged through the current boom of research. [source] A tactile display using phantom sensation with apparent movement togetherELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 12 2008Shintaro Ueda Abstract When two and more stimuli are arranged in the space, an illusion such as phantom sensation and apparent movement appear in the sense of touch. The foundation research to build a system for presenting two-dimensional information by using phantom sensation and apparent movement is done in this research. When apparent movement is used, information in the direction can be expressed between two elements of tactile stimulus in two-dimensional vector information. In this report, the authors propose the technique of information expression using three elements for tactile stimulus that the apparent movement is used with the phantom sensation together. By this technique, two-dimensional vector information can be expressed by three elements of tactile stimulus. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 91(12): 29,38, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10000 [source] Development of Tactile Responses in Human Preterm and Full-Term Infants From 30 to 40 Weeks Postconceptional AgeINFANCY, Issue 1 2002Isabel Fearon Maturation of tactile sensitivity prior to term was examined in 36 preterm and 13 full-term infants using a fixed-trial, habituation procedure. Each infant was presented with a series of 8 habituation (arm stroke), 2 novel (arm lift), and 2 recovery (arm stroke) stimulus trials while heart rate and body movements were recorded. Maturation was observed with a gradual increase in the magnitude of the stimulus-elicited cardiac acceleration and cardiac-movement coupling from 30 to 40 weeks postconceptional age. The majority of infants displayed habituation,an excitatory response (heart rate acceleration and body movement),to the initial presentation of a tactile stimulus, response decline with repeated stimulations, and renewed response to a novel stimulus. A substantial number of infants (40%) failed to respond initially to the tactile stimulus, increased responding over several stimulus presentations, and failed to discriminate the presentation of a novel stimulus. We speculate that these differences in response patterns observed over all ages represent individual difference in the perception of stimulus intensity. [source] Early Responsiveness to Stimuli Paired With Different Stages Within the State of Alcohol IntoxicationALCOHOLISM, Issue 5 2002Ricardo M. Pautassi Background: Infant rats quickly learn to avoid a sensory cue paired with alcohol as an unconditioned stimulus, particularly when the drug reaches peak blood concentrations. In this study, a tactile cue paired with the onset of alcohol intoxication preceded subsequent presentations of a gustatory conditioned stimulus (CS). The goal was to address the possibility of differential conditioning depending on when stimuli were introduced during the course of the toxic state. Methods: In experiment 1, rat pups received sequential presentations of a salient texture (sandpaper) and a gustatory cue (saccharin) while intoxicated with a 2.5 g/kg alcohol dose or after receiving saline. Texture location tests and saccharin intake assessments were then performed. A third modality of assessment was defined by a saccharin intake test while pups simultaneously experienced sandpaper. In experiment 2, alcohol-mediated conditioning was followed by tests similar to those of experiment 1, but after pups were re-exposed to either the tactile CS or the alcohol-unconditioned stimulus. Results: Conditioned taste aversions, due to pairing saccharin and the later stage of alcohol intoxication, were reliably established in both experiments. Also in both experiments, this excitatory aversive response was dramatically inhibited when the association between the texture CS and the earlier stage of alcohol intoxication was activated. There were no indications of conditioned motor responses to the tactile CS that might compete with intake behavior of saccharin or distort measurement of an appetitive memory derived from pairing the texture and the earlier stage of intoxication. Conclusions: Rat pups' expression of an association between a taste signaling aversive consequences of alcohol was eliminated by the presence of a tactile stimulus that originally had signaled the absence of aversive consequences of alcohol intoxication. The results suggest the interaction of inhibitory and excitatory conditioning involving the aversive properties of alcohol. [source] | |||||||||||||