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Using immunohistochemistry in combination with confocal laser scanning microscopy, we studied the ontogeny of neuropeptide Y-Y1 receptor (Y1-R) expression in the trigeminal system of the rat. The study was limited to the nerve fib...
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Using immunohistochemistry in combination with confocal laser scanning microscopy, we studied the ontogeny of neuropeptide Y-Y1 receptor (Y1-R) expression in the trigeminal system of the rat. The study was limited to the nerve fibers innervating the mystacial pad and the trigeminal ganglia. In the trigeminal ganglia, Y1-R-immunoreactive (IR) neurons were first observed at E16.5. At this same stage some nerve fibers in the trigeminal ganglia also exhibited Y1-R-like immunoreactivity (LI). Strongly Y1-R-IR nerve fibers innervating the follicles of the mystacial vibrissae were first observed at E18. After double labeling, the Y1-R-LI was found to be colocalized with the neuronal marker protein gene product 9.5. At P1 only weak labeling for the Y1-R was found around the vibrissae follicles, whereas the neurons in the trigeminal ganglia were intensely labeled. The same was true for the adult rat, but at this stage no Y1-R labeling at all was observed in nerve fibers around the vibrissal follicles. These results strongly support an axonal localization of the Y1-R at this developmental stage. The transient expression of the Y1-R during prenatal mystacial pad development suggests a role for the Y1-R in the functional development of the vibrissae.
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Of all mammalian vibrissae, those of certain species of pinnipeds are exceptional. Researchers believe that their curious undulating form evolved for hydrodynamic detection. Our understanding of how these whiskers work depends on ...
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Of all mammalian vibrissae, those of certain species of pinnipeds are exceptional. Researchers believe that their curious undulating form evolved for hydrodynamic detection. Our understanding of how these whiskers work depends on a geometrical model that captures the crucial pertinent features of the natural vibrissae including its tapering and curvature. It should also account for the form of the whisker when it flexes under external loading. We introduce and study a normal skeleton of a two-dimensional projection of a harbour seal whisker. The normal skeleton is a complete shape descriptor that involves reduction to the centreline equipped with a thickness function of the orthogonal cross-section. The contours of the whisker shape are extracted from a 2D greyscale scan. Our analysis reveals correspondence between the undulations of the width and oscillations of the centreline curvature as functions of arc length. We discuss two possible explanations for that remarkable feature: one based on consideration of growth and the other of plastic deformation. For the latter we employ a mechanical model to demonstrate appearance of curvature oscillations caused by extensive deflection of the undulating whisker due to external loading.
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Wally Welker died in Madison on 28 November 2007 after a long and innovative career at the University of Wisconsin—Madison. We were both influenced profoundly by his science and his approach to his science as a mentor and as a fr...
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Wally Welker died in Madison on 28 November 2007 after a long and innovative career at the University of Wisconsin—Madison. We were both influenced profoundly by his science and his approach to his science as a mentor and as a friend. Figure 1 shows us in photographs of the Laboratory of Neurophysiology in the Department of Physiology at the University of Wisconsin taken in the summers of 1962 and 1965. Figure 2 is a portrait of Wally taken more recently. It captures the "twinkle" that was often there in his eyes. We thank his widow and longtime partner Carol Dizak for this wonderful image and permission to include it here. What follows are our separate recollections of Wally's significant impact on the studies of "Vibrissae" and "Barrels" presented on 13 November 2008 at Barrels XXI in Baltimore, Maryland.
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Whisker sensors are a class of tactile sensors that have recently attracted attention. Inspired by mammals’ whiskers known as mystacial vibrissae, they have displayed tremendous potential in a variety of applications e.g., roboti...
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Whisker sensors are a class of tactile sensors that have recently attracted attention. Inspired by mammals’ whiskers known as mystacial vibrissae, they have displayed tremendous potential in a variety of applications e.g., robotics, underwater vehicles, minimally invasive surgeries, and leak detection. This paper provides a supplement to the recent tactile sensing techniques’ designs of whiskers that only sense at their base, as well as the materials employed, and manufacturing techniques. The article delves into the technical specifications of these sensors, such as the resolution, measurement range, sensitivity, durability, and recovery time, which determine their performance. The sensors’ sensitivity varies depending on the measured physical quantity; for example, the pressure sensors had an intermediate sensitivity of 58%/Pa and a response time of around 90 ms, whereas the force sensors that function based on piezoelectric effects exhibited good linearity in the measurements with a resolution of 3 μN and sensitivity of 0.1682 mV/μN. Some sensors were used to perform spatial mapping and the identification of the geometry and roughness of objects with a reported resolution of 25 nm. The durability and recovery time showed a wide range of values, with the maximum durability being 10,000 cycles and the shortest recovery time being 5 ms. Furthermore, the paper examines the fabrication of whiskers at the micro- and nanoscales, as well as their contributions to mechanical and thermal behavior. The commonly used manufacturing techniques of 3D printing, PDMS casting, and screen printing were used in addition to several micro and nanofabrication techniques such as photolithography, etching, and chemical vapor deposition. Lastly, the paper discusses the main potential applications of these sensors and potential research gaps in this field. In particular, the operation of whisker sensors under high temperatures or high pressure requires further investigation, as does the design of sensors to explore larger topologies.
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Nowhere is the sparse nature of neuronal coding more evident than in the sensory cortex, where neuronal response becomes increasingly tuned to specific features of the sensory environment. For such situations, where rate modulatio...
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Nowhere is the sparse nature of neuronal coding more evident than in the sensory cortex, where neuronal response becomes increasingly tuned to specific features of the sensory environment. For such situations, where rate modulation schemes do not accurately describe the neuronal response to sensory stimuli, statistical descriptions based on point process events are particularly appropriate. Here, intensity measures derived from experimental data in the rat somatosensory cortex enable the direct analysis of statistical structure within spike trains, as well as interrelationships between tactile stimuli and neuronal response. Intensity measures capture structure in spontaneous as well as driven activity, reflecting the interplay between excitatory and suppressive influences on neuronal firing. Second-order intensity estimates reveal strong dependencies upon patterns of tactile stimulation, which define the neuronal response characteristics to temporally structured stimuli.
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Understanding how whisker-based tactile information is represented in the nervous system requires quantification of sensory input and observation of neural activity during whisking and whisker touch. Chronic electrophysiological m...
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Understanding how whisker-based tactile information is represented in the nervous system requires quantification of sensory input and observation of neural activity during whisking and whisker touch. Chronic electrophysiological methods have long been available to study neural responses in awake and behaving animals; however, methods to quantify the sensory input on whiskers have not yet been developed. Here we describe an unsupervised algorithm to track whisker movements in high-speed video recordings and to quantify the statistics of the tactile information on whiskers in freely behaving animals during haptic object exploration. The algorithm does not require human identification of whiskers, nor does it assume the shape, location, orientation, length of whiskers, or direction of the whisker movements. The algorithm performs well on temporary loss of whisker visibility and under low-light/low-contrast conditions even with inherent anisotropic noise and non-Gaussian variability in the signal. Using this algorithm, we define the speed [protraction (P), 1,081 +/- 322; retraction (R), 1,564 +/- 549 degrees /s], duration (P, 34 +/- 10; R, 24 +/- 8 ms), amplitude (P = R, 40 +/- 13 degrees ), and frequency (19 +/- 7 Hz) of active whisking in freely behaving mice. We furthermore quantify whisker deflection induced changes in whisking kinematics and calculate the statistics (i.e., speed, amplitude and duration) of whisker touch and finally show that whisker deprivation does not alter whisking kinematics during haptic exploration.
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We present evidence that resonance properties of rat vibrissae differentially amplify high-frequency and complex tactile signals. Consistent with a model of vibrissa mechanics, optical measurements of vibrissae revealed that their...
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We present evidence that resonance properties of rat vibrissae differentially amplify high-frequency and complex tactile signals. Consistent with a model of vibrissa mechanics, optical measurements of vibrissae revealed that their first mechanical resonance frequencies systematically varied from low (60-100 Hz) in longer, posterior vibrissae to high ( approximately 750 Hz) in shorter, anterior vibrissae. Resonance amplification of tactile input was observed in vivo and ex vivo, and in a variety of boundary conditions that are likely to occur during perception, including stimulation of the vibrissa with moving complex natural stimuli such as sandpaper. Vibrissae were underdamped, allowing for sharp tuning to resonance frequencies. Vibrissa resonance constitutes a potentially useful mechanism for perception of high-frequency and complex tactile signals. Amplification of small amplitude signals by resonance could facilitate detection of stimuli that would otherwise fail to drive neural activity. The systematic map of frequency sensitivity across the face could facilitate texture discrimination through somatotopic encoding of frequency content. These findings suggest strong parallels between vibrissa tactile processing and auditory encoding, in which the cochlea also uses resonance to amplify low-amplitude signals and to generate a spatial map of frequency sensitivity.
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The motion of isolated rat vibrissae due to low frequency sound has been modeled and measured with good agreement (within a factor of 2) between the data and the model's predictions. As had been done in previous studies on the res...
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The motion of isolated rat vibrissae due to low frequency sound has been modeled and measured with good agreement (within a factor of 2) between the data and the model's predictions. As had been done in previous studies on the response of rat vibrissae to tactile stimulation [Hartmann, M. J. , Johnson, N. J., Towal, R. B., and Assad, C., J. Neurosci 23, 6510-6519 (2003) and Neimark, M. A., Andermann, A. L., Hopfield, J. J., and Moore, C. I., J. Neurosci 23, 6449-6509 (2003)] the vibrissae were modeled as thin conical beams. The force of the vibrating air on a vibrissa was modeled using the exact solution for a vibrating infinite cylinder in linear fluid. A finite element method was used to model the motion of a single vibrissa fixed at its base, using the aforementioned fluid force. Values for Young's modulus and vibrissa mass density were taken from a previous study [ Neimark et al. (above)]. The model had no freely fitted parameters. Motion of isolated vibrissae was measured using a video camera with microscope. The sound stimulation was created using a stereo speaker connected to a signal generator. The tuning was found to be sharp, with quality factors that varied between 3 and 7, much sharper than the motion of cricket cereal hairs or in vitro inner ear hair bundles.
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The 32nd Annual Barrels meeting was hosted at the Northwestern University Feinberg School of Medicine in Chicago, Illinois on October 17th and 18th, 2019. The annual meeting brings together researchers who utilize the rodent whisk...
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The 32nd Annual Barrels meeting was hosted at the Northwestern University Feinberg School of Medicine in Chicago, Illinois on October 17th and 18th, 2019. The annual meeting brings together researchers who utilize the rodent whisker-to-barrel system as a means to understand cortical function and development. This year's meeting focussed on social behaviours, development and cerebellar functions within the barrel system and beyond.
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The 23rd annual Barrels meeting was held on the University of California, San Diego campus and highlighted the latest advances in the whisker-to-barrel pathway and beyond. The annual meeting brought together investigators from a d...
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The 23rd annual Barrels meeting was held on the University of California, San Diego campus and highlighted the latest advances in the whisker-to-barrel pathway and beyond. The annual meeting brought together investigators from a dozen countries to present their data in posters and short talks. The meeting focused on several themes, first the barrel system was used as a model to study the consequences that result from alterations in the normal pattern(s) of development. A second session focused on what happens to whisker information once it leaves the layer IV barrel. A third session addressed issues of coding within the barrel system and a final session highlighted the latest advances in the engineering of transgenic mouse lines. The meeting highlighted the utility of the barrel system to study cortical circuitry in the normal and pathological state.
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