Analysis of the Vibrissa Parametric Resonance Causing a Signal Amplification during Whisking Behaviour (original) (raw)
Related papers
The Journal of neuroscience : the official journal of the Society for Neuroscience, 2003
We investigated the natural resonance properties and damping characteristics of rat macrovibrissae (whiskers). Isolated whiskers rigidly fixed at the base showed first-mode resonance peaks between 27 and 260 Hz, principally depending on whisker length. These experimentally measured resonant frequencies were matched using a theoretical model of the whisker as a conical cantilever beam, with Young's modulus as the only free parameter. The best estimate for Young's modulus was approximately 3-4 GPa. Results of both vibration and impulse experiments showed that the whiskers are strongly damped, with damping ratios between 0.11 and 0.17. In the behaving animal, whiskers that deflected past an object were observed to resonate but were damped significantly more than isolated whiskers. The time course of damping varied depending on the individual whisker and the phase of the whisking cycle, which suggests that the rat may modulate biomechanical parameters that affect damping. No res...
2017
The tactile hairs of animals are used as paradigm for artificial tactile sensors. In the case of mystacial vibrissae, the animals can determine the distance to an object, recognize the shape of the object and detect the surface texture of the object. The goal is to design an artificial tactile sensor inspired by the natural paradigm. In the present work, the vibrissa and the follicle-sinus-complex are modeled as a one-sided clamped beam within the limits of the non-linear Euler-Bernoulli beam theory. The theoretical background of the function principle and the effects of typical properties of the natural vibrissa, e.g., a tapered shape and a pre-curvature while operating in surface texture detection are analyzed. The beam-surface contact is described by Coulomb’s law of friction. When the beam is in touch with the surface, a quasi-static displacement of the support takes place. As a consequence of the displacement the support reactions are changing. The resulting support reactions a...
A truncated conical beam model for analysis of the vibration of rat whiskers
Journal of Biomechanics, 2013
A truncated conical beam model is developed to study the vibration behaviour of a rat whisker. Translational and rotational springs are introduced to better represent the constraint conditions at the base of the whiskers in a living rat. Dimensional analysis shows that the natural frequency of a truncated conical beam with generic spring constraints at its ends is inversely proportional to the square root of the mass density. Under all the combinations of the classical free, pinned, sliding or fixed boundary conditions of a truncated conical beam, it is proved that the natural frequency can be expressed as
The mathematical whisker: A review of numerical models of the rat׳s vibrissa biomechanics
The vibrissal system of the rat refers to specialized hairs the animal uses for tactile sensory perception. Rats actively move their whiskers in a characteristic way called “whisking”. Interaction with the environment produces elastic deformation of the whiskers, generating mechanical signals in the whisker–follicle complex. Advances in our understanding of the vibrissal complex biomechanics is of interest not only for the biological research field, but also for biomimetic approaches. The recent development of whisker numerical models has contributed to comprehending its sophisticated movements and its interactions with the follicle. The great diversity of behavioral patterns and complexities of the whisker–follicle ensemble encouraged the creation of many different biomechanical models. This review analyzes most of the whisker biomechanical models that have been developed so far. This review was written so as to render it accessible to readers coming from different research areas.
Comparative Analysis of the Flexural Stiffness of Pinniped Vibrissae
PLOS ONE, 2015
Vibrissae are important components of the mammalian tactile sensory system and are used to detect vibrotactile stimuli in the environment. Pinnipeds have the largest and most highly innervated vibrissae among mammals, and the hair shafts function as a biomechanical filter spanning the environmental stimuli and the neural mechanoreceptors deep in the folliclesinus complex. Therefore, the material properties of these structures are critical in transferring vibrotactile information to the peripheral nervous system. Vibrissae were tested as cantilever beams and their flexural stiffness (EI) was measured to test the hypotheses that the shape of beaded vibrissae reduces EI and that vibrissae are anisotropic. EI was measured at two locations on each vibrissa, 25% and 50% of the overall length, and at two orientations to the point force. EI differed in orientations that were normal to each other, indicating a functional anisotropy. Since vibrissae taper from base to tip, the second moment of area (I) was lower at 50% than 25% of total length. The anterior orientation exhibited greater EI values at both locations compared to the dorsal orientation for all species. Smooth vibrissae were generally stiffer than beaded vibrissae. The profiles of beaded vibrissae are known to decrease the amplitude of vibrations when protruded into a flow field. The lower EI values of beaded vibrissae, along with the reduced vibrations, may function to enhance the sensitivity of mechanoreceptors to detection of small changes in flow from swimming prey by increasing the signal to noise ratio. This study builds upon previous morphological and hydrodynamic analyses of vibrissae and is the first comparative study of the mechanical properties of pinniped vibrissae.
Vibrissa-based design of tapered tactile sensors for object sensing
2017
Numerous mammals possess whiskers (tactile hairs, also known as vibrissae) to explore their environment. These complex mechano-sensitive vibrissae are located, e.g. in the snout region (mystacial vibrissae). Because of the deformation of the vibrissa by contact with objects and obstacles, the animal gets additional information about the environment. Despite different morphology of animal vibrissae (e.g., cylindrically or conically shaped, precurved, multi-layer structure), these biological tactile hairs are modeled in a mechanical way to develop and analyze models concerning their bending behavior with a glance to get hints for a technical implementation as a technical sensor. At first, we investigate the bending behavior of cylindrically shaped and tapered rods which are one-sided clamped and are under the load of an external force, using the Euler-Bernoulli non-linear bending theory. Then, a quasi-static sweep of these rods along various obstacle profiles is used for an obstacle p...
Birdwell JA, Solomon JH, Thajchayapong M, Taylor MA, Cheely M, Towal RB, Conradt J, Hartmann MJZ. Biomechanical models for radial distance determination by the rat vibrissal system. . Rats use active, rhythmic movements of their whiskers to acquire tactile information about three-dimensional object features. There are no receptors along the length of the whisker; therefore all tactile information must be mechanically transduced back to receptors at the whisker base. This raises the question: how might the rat determine the radial contact position of an object along the whisker? We developed two complementary biomechanical models that show that the rat could determine radial object distance by monitoring the rate of change of moment (or equivalently, the rate of change of curvature) at the whisker base. The first model is used to explore the effects of taper and inherent whisker curvature on whisker deformation and used to predict the shapes of real rat whiskers during deflections at different radial distances. Predicted shapes closely matched experimental measurements. The second model describes the relationship between radial object distance and the rate of change of moment at the base of a tapered, inherently curved whisker. Together, these models can account for recent recordings showing that some trigeminal ganglion (Vg) neurons encode closer radial distances with increased firing rates. The models also suggest that four and only four physical variables at the whisker base-angular position, angular velocity, moment, and rate of change of moment-are needed to describe the dynamic state of a whisker. We interpret these results in the context of our evolving hypothesis that neural responses in Vg can be represented using a state-encoding scheme that includes combinations of these four variables.
Unilateral vibrissa contact: changes in amplitude but not timing of rhythmic whisking
Somatosensory & Motor Research, 2003
Electromyographic recordings from the mystacial pad of rats were used to assess the effect of unilateral vibrissa contact on the bilateral movement of the vibrissae. A first group of animals was trained to whisk freely in air and served to establish the baseline variability in bilateral symmetry. We observed that the electromyogram (EMG) activity across the two mystacial pads was rhythmic and synchronous to within 2 ms on a whisk-by-whisk basis; this value is small in comparison with the 50msrequiredforprotractionduringthewhiskcycle.Asecondgroupofanimalswastrainedtousetheirvibrissaetocontactasensorthatwaslocatedononesideofthehead.TheaverageEMGactivityacrossthetwopadswassynchronousatthetimeofvibrissacontact,albeitwithhighervariabilitythanforthecaseoffreewhisking.Incontrast,theaverageamplitudeoftheactivityonthecontactvsnoncontactsideofthefacewastransientlygreater,by2550 ms required for protraction during the whisk cycle. A second group of animals was trained to use their vibrissae to contact a sensor that was located on one side of the head. The average EMG activity across the two pads was synchronous at the time of vibrissa contact, albeit with higher variability than for the case of free whisking. In contrast, the average amplitude of the activity on the contact vs noncontact side of the face was transiently greater, by 25% or 50msrequiredforprotractionduringthewhiskcycle.Asecondgroupofanimalswastrainedtousetheirvibrissaetocontactasensorthatwaslocatedononesideofthehead.TheaverageEMGactivityacrossthetwopadswassynchronousatthetimeofvibrissacontact,albeitwithhighervariabilitythanforthecaseoffreewhisking.Incontrast,theaverageamplitudeoftheactivityonthecontactvsnoncontactsideofthefacewastransientlygreater,by2510 , at the time of contact. These data show that the amplitude of the vibrissae on the two sides of the face can be controlled independently, while the timing of vibrissa movement is largely synchronous.