Active Spatial Perception in the Vibrissa Scanning Sensorimotor System

Abstract

Haptic perception is an active process that provides an awareness of objects that are encountered as an organism scans its environment. In contrast to the sensation of touch produced by contact with an object, the perception of object location arises from the interpretation of tactile signals in the context of the changing configuration of the body. A discrete sensory representation and a low number of degrees of freedom in the motor plant make the ethologically prominent rat vibrissa system an ideal model for the study of the neuronal computations that underlie this perception. We found that rats with only a single vibrissa can combine touch and movement to distinguish the location of objects that vary in angle along the sweep of vibrissa motion. The patterns of this motion and of the corresponding behavioral responses show that rats can scan potential locations and decide which location contains a stimulus within 150 ms. This interval is consistent with just one to two whisk cycles and provides constraints on the underlying perceptual computation. Our data argue against strategies that do not require the integration of sensory and motor modalities. The ability to judge angular position with a single vibrissa thus connects previously described, motion-sensitive neurophysiological signals to perception in the behaving animal.

Temporal Activity Patterns in Thermosensory Neurons of Freely Moving Caenorhabditis elegans Encode Spatial Thermal Gradients

“…Sophisticated examples of active perception have been studied in the whisking behavior of rodents, which scan objects by actively sweeping their sensory vibrissa across surfaces (Mehta et al, 2007), and of bats, which use their sonar-related vocalizations during flight to locate targets in complex environments (Moss et al, 2006). However, a rudimentary form of active perception may be found in the nematode C. elegans as it navigates chemical and thermal gradients.…”

Vibrissa-Based Object Localization in Head-Fixed Mice

“…4C; two mice only have two data points after trimming). Therefore, head-fixed mice can use a single whisker for object localization, indicating that the brain combines information about position of the whiskers and contact between whisker and object to compute object distance (Knutsen et al, 2006;Mehta et al, 2007;Diamond et al, 2008).…”

“…Rats and mice move their large vibrissae (whiskers) through the space surrounding the head, often in a rhythmic pattern, to locate landmarks (Hutson and Masterton, 1986;Knutsen et al, 2006;Mehta et al, 2007) and identify textures (Guić-Robles et al, 1989;Carvell and Simons, 1990;Diamond et al, 2008). Whiskers arise from an array of follicles within the mystacial pad (Dörfl, 1982).…”

“…Here we trained head-fixed mice to locate objects in the posteroanterior (horizontal) direction, similar to previous tasks in freely moving (Knutsen et al, 2006) and partially restrained (Mehta et al, 2007) rats. Mice learned the task after 1-2 weeks of training and performed hundreds of trials per session.…”

A Microsaccadic Rhythm Modulates Gamma-Band Synchronization and Behavior

“…Rhythmic behavior is prominent also in sensory systems, in which it typically scans the sensory surface across the environment and thereby constitutes so-called active sensation. Active sensation has received much attention in the rodent vibrissal system, in which the vibrissae are moved across the input space rhythmically (Kleinfeld et al, 2006;Mehta et al, 2007;Lee et al, 2008). Such rhythmic exploration has also been suggested for the visual system and it has been pointed out that the high-frequency rhythmic microtremor of the eyes might constitute a scanning of the visual environment (Ahissar and Arieli, 2001).…”