Whisking Kinematics Enables Object Localization in Head-Centered Coordinates Based on Tactile Information from a Single Vibrissa

Abstract

During active tactile exploration with their whiskers (vibrissae), rodents can rapidly orient to an object even though there are very few proprioceptors in the whisker muscles. Thus a long-standing question in the study of the vibrissal system is how the rat can localize an object in head-centered coordinates without muscle-based proprioception. We used a three-dimensional model of whisker bending to simulate whisking motions against a peg to investigate the possibility that the 3D mechanics of contact from a single whisker are sufficient for localization in head-centered coordinates. Results show that for nearly all whiskers in the array, purely tactile signals at the whisker base – as would be measured by mechanoreceptors, in whisker-centered coordinates – could be used to determine the location of a vertical peg in head-centered coordinates. Both the “roll” and the “elevation” components of whisking kinematics contribute to the uniqueness and resolution of the localization. These results offer an explanation for a behavioral study showing that rats can more accurately determine the horizontal angle of an object if one column, rather than one row, of whiskers is spared.

Surround Integration Organizes a Spatial Map during Active Sensation

“…Nonetheless, a map of scanned space, as was observed here, may contribute to the generation of an egocentric (head-centered) map of space downstream that is independent of the scanned region (or ‘field of view’). Based on prior evidence in non-human primates, the posterior parietal cortex is a brain area that may be involved in this transformation (Andersen et al, 1985), but likely builds on cues present even at the mechanoreceptors themselves (Yang and Hartmann, 2016). …”

“…Multiple mechanisms potentially contribute to their tuning. These include selectivity for the phase (Curtis and Kleinfeld, 2009), deflection angle (Knutsen et al, 2008), inter-contact interval (Crochet et al, 2011), or contact forces (Bagdasarian et al, 2013; Yang and Hartmann, 2016) at the moment of touch. These schemes can all operate at the single whisker level, and do not require multi-whisker integration, which is likely to occur in most natural contexts.…”

A system for tracking whisker kinematics and whisker shape in three dimensions

“…In whisker-centric coordinates, bending corresponds to changes in shape of b ( s ) in the x ’ − y ’ or x ’ − z ’ planes (with, respectively, component m z ’ defined in the direction of the positive z’ axis and m y ’ defined in the directions of the positive y’ axis) (Fig 5;(36)). Since b ( s ) is a quadratic curve, it has zero torsion and its curvature is entirely confined to the x ’ − y ’ plane: κ 3 D ( s ) is the curvature in this plane; the only non-zero component of bending moment is m z ’.…”

The Sensorimotor Basis of Whisker-Guided Anteroposterior Object Localization in Head-Fixed Mice

“…These models differ in the sensorimotor features gathered and used to construct location perception. In a roll angle model ( Figure 1B), rodents sense how much the whisker has rotated on its long axis at time of touch through a differing pattern of mechanoreceptor activation [22,26]. In a whisk latency model ( Figure 1C), rodents measure the time of touch referenced to the time from maximum retraction.…”