Demonstration of three-dimensional contact point determination and contour reconstruction during active whisking behavior of an awake rat.

The rodent vibrissal (whisker) system has been studied for decades as a model of active touch sensing. There are no sensors along the length of a whisker; all sensing occurs at the whisker base. Therefore, a large open question in many neuroscience studies is how an animal could estimate the three-dimensional (3D) location at which a whisker makes contact with an object.

Tactile Sensing with Whiskers of Various Shapes: Determining the Three-Dimensional Location of Object Contact Based on Mechanical Signals at the Whisker Base.

Almost all mammals use their mystacial vibrissae (whiskers) as important tactile sensors. There are no sensors along the length of a whisker: all sensing is performed by mechanoreceptors at the whisker base. To use artificial whiskers as a sensing tool in robotics, it is essential to be able to determine the three-dimensional (3D) location at which a whisker has made contact with an object.

Decoupling kinematics and mechanics reveals coding properties of trigeminal ganglion neurons in the rat vibrissal system.

Tactile information available to the rat vibrissal system begins as external forces that cause whisker deformations, which in turn excite mechanoreceptors in the follicle. Despite the fundamental mechanical origin of tactile information, primary sensory neurons in the trigeminal ganglion (Vg) have often been described as encoding the kinematics (geometry) of object contact. Here we aimed to determine the extent to which Vg neurons encode the kinematics vs.

Simulations of a Vibrissa Slipping along a Straight Edge and an Analysis of Frictional Effects during Whisking.

During tactile exploration, rats sweep their whiskers against objects in a motion called whisking. Here, we investigate how a whisker slips along an object's edge and how friction affects the resulting tactile signals. First, a frictionless model is developed to simulate whisker slip along a straight edge and compared with a previous model that incorporates friction but cannot simulate slip.

Tactile signals transmitted by the vibrissa during active whisking behavior.

The rodent vibrissal-trigeminal system is one of the most widely used models for the study of somatosensation and tactile perception, but to date the field has been unable to quantify the complete set of mechanical input signals generated during natural whisking behavior. In this report we show that during whisking behavior of awake rats (Rattus norvegicus), the whisker will often bend out of its plane of rotation, generating sizeable mechanical (tactile) signals out of the plane. We then develop a model of whisker bending that allows us to compute the three-dimensional tactile signals at the vibrissal base during active whisking behavior.

The search space of the rat during whisking behavior.

Rodents move their vibrissae rhythmically to tactually explore their surroundings. We used a three-dimensional model of the vibrissal array to quantify the rat's 'search space' during whisking. Search space was quantified either as the volume encompassed by the array or as the surface formed by the vibrissal tips.

Modeling forces and moments at the base of a rat vibrissa during noncontact whisking and whisking against an object.

During exploratory behavior, rats brush and tap their whiskers against objects, and the mechanical signals so generated constitute the primary sensory variables upon which these animals base their vibrissotactile perception of the world. To date, however, we lack a general dynamic model of the vibrissa that includes the effects of inertia, damping, and collisions. We simulated vibrissal dynamics to compute the time-varying forces and bending moment at the vibrissa base during both noncontact (free-air) whisking and whisking against an object (collision).