Texture signals in whisker vibrations (original) (raw)

Neuronal encoding of texture in the whisker sensory pathway. PLoS Biol 3: e17

2005

A major challenge of sensory systems neuroscience is to quantify brain activity underlying perceptual experiences and to explain this activity as the outcome of elemental neuronal response properties. Rats make extremely fine discriminations of texture by ‘‘whisking’ ’ their vibrissae across an object’s surface, yet the neuronal coding underlying texture sensations remains unknown. Measuring whisker vibrations during active whisking across surfaces, we found that each texture results in a unique ‘‘kinetic signature’ ’ defined by the temporal profile of whisker velocity. We presented these texture-induced vibrations as stimuli while recording responses of first-order sensory neurons and neurons in the whisker area of cerebral cortex. Each texture is encoded by a distinctive, temporally precise firing pattern. To look for the neuronal coding properties that give rise to texture-specific firing patterns, we delivered horizontal and vertical whisker movements that varied randomly in tim...

Encoding of whisker vibration by rat barrel cortex neurons: implications for texture discrimination

The Journal of neuroscience : the official journal of the Society for Neuroscience, 2003

Rats, using their whiskers, have excellent capabilities in texture discrimination. What is the representation of texture in rat somatosensory cortex? We hypothesize that as rats "whisk" over a surface, the spatial frequency of a grooved or pebbled texture is converted to a temporal frequency of whisker vibration. Surface features such as groove depth or grain size modulate the amplitude of this vibration. Validation of the hypothesis depends on showing that vibration parameters have distinct neuronal representations in cortex. To test this, we delivered sinusoidal vibrations to the whisker shaft and analyzed cortical neuronal activity. Seven amplitudes and seven frequencies were combined to construct 49 stimuli while recording activity through a 10 x 10 microelectrode array inserted into the middle layers of barrel cortex. We find that cortical neurons do not explicitly encode vibration frequency (f) or amplitude (A) by any coding measure (average spike counts over differe...

Novel, whisker-dependent texture discrimination task for mice

Behavioural Brain Research, 2013

Many mammals use their mystacial vibrissae to palpate objects in their environment and encode information such as size, shape and texture. We have developed a novel method to assess the sensitivity with which mice can discriminate textures using their mystacial vibrissae. Our texture discrimination task can be performed within 3 days, requiring approximately 1 h of handling time, per subject, over the entire testing period. No appetitive or aversive training is required. We have demonstrated that this novel texture discrimination task is dependent on intact mystacial vibrissae and can be performed by both young (2-month old) and older (6-month old) C57BL/6 mice. The parameters of the task can be adjusted to assess the sensitivity of mice using a gradient of textures with different roughness. We have developed a novel, efficient method to assess whisker-mediated texture discrimination in mice.

Sensing and processing whisker deflections in rodents

2021

The classical view of sensory information mainly flowing into barrel cortex at layer IV, moving up for complex feature processing and lateral interactions in layers II and III, then down to layers V and VI for output and corticothalamic feedback is becoming increasingly undermined by new evidence. We review the neurophysiology of sensing and processing whisker deflections, emphasizing the general processing and organisational principles present along the entire sensory pathway—from the site of physical deflection at the whiskers to the encoding of deflections in the barrel cortex. Many of these principles support the classical view. However, we also highlight the growing number of exceptions to these general principles, which complexify the system and which investigators should be mindful of when interpreting their results. We identify gaps in the literature for experimentalists and theorists to investigate, not just to better understand whisker sensation but also to better understa...

Whisker Vibration Information Carried by Rat Barrel Cortex Neurons

Journal of Neuroscience, 2004

Rats can make extremely fine texture discriminations by "whisking" their vibrissa across the surface of an object. We have investigated one hypothesis for the neuronal basis of texture representation by measuring how clusters of neurons in the barrel cortex of anesthetized rats encode the kinetic features of sinusoidal whisker vibrations. Mutual information analyses of spike counts led to a number of findings. Information about vibration kinetics became available as early as 6 msec after stimulus onset and reached a peak at ϳ20 -30 msec. Vibration speed, proportional to the product of vibration amplitude (A) and frequency ( f), was the kinetic property most reliably reported by cortical neurons. Indeed, by measuring information when the complete stimulus set was collapsed into feature-defined groups, we found that neurons reduced the dimensionality of the stimulus from two features (A, f) to a single feature, the product Af. Moreover, because different neurons encode stimuli in the same manner, information loss was negligible even when the activity of separate neuronal clusters was pooled. This suggests a decoding scheme whereby target neurons could capture all available information simply by summating the signals from separate barrel cortex neurons. These results indicate that neuronal population activity provides sufficient information to allow nearly perfect discrimination of two vibrations, based on their deflection speeds, within a time scale comparable with that of a single whisking motion across a surface.

Sensing the Environment With Whiskers-Oxford Research Encyclopedia of Neuroscience

2020

Whiskers (vibrissae) are prominent on the snout of many mammals, both terrestrial and aquatic. The defining feature of whiskers is that they are rooted in large follicles with dense sensory innervation, surrounded by doughnut-shaped blood sinuses. Some species, including rats and mice, have elaborate muscular control of their whiskers and explore their environment by making rhythmic back-and-forth “whisking” movements. Whisking movements are purposefully modulated according to specific behavioral goals (“active sensing”). The basic whisking rhythm is controlled by a premotor complex in the interme­ diate reticular formation.

Texture discrimination and unit recordings in the rat whisker/barrel system

Physiology & Behavior, 2002

We have developed a semi-automated technique for acquiring neurophysiological data during whisker-based tactile discriminative behavior. Water-deprived, blindfolded rats are tethered by means of a harness vest that permits them to contact a rough (250 μm grooves) or smooth discriminandum with only their vibrissae. Discriminanda are mounted on a motor-driven carousel, and the rat indicates its choice (rough, smooth) by licking either a right or left water port located near the carousel. A narrow light beam detects general proximity of the animal's nose to the discriminandum, although actual whisker contact is monitored by a SuperVHS camera and measured offline using field-by-field videographic analysis. Rats can be trained within 3–6 weeks at which time they perform 100–150 trials/day at a level of 80% correct. Unit recording from the somatosensory cortex reveals that neurons increase their firing upon whisker contact of a discriminandum and that firing remains elevated during several hundred milliseconds of ongoing contact, even with the smooth surface. Nevertheless, despite the animal's ability to distinguish the rough and smooth surfaces, overall neuronal firing rates were indistinguishable for the two surfaces. In some cases, temporal firing patterns differed, although not in a consistent way across recording sites.

The Matrix: A new tool for probing the whisker-to-barrel system with natural stimuli

Journal of Neuroscience Methods, 2010

The whisker to barrel system in rodents has become one of the major models for the study of sensory processing. Several tens of whiskers (or vibrissae) are distributed in a regular manner on both sides of the snout. Many tactile discrimination tasks using this system need multiple contacts with more than one whisker to be solved. With the aim of mimicking those multi-whisker stimuli during electrophysiological recordings, we developed a novel mechanical stimulator composed of 24 independent multi-directional piezoelectric benders adapted to the five rows and the five caudal arcs of the rat whisker pad. The most widely used technology for producing mechanical deflections of the whiskers is based on piezoelectric benders that display a non-linear behavior when driven with high frequency input commands and, if not compensated, show high unwanted ringing at particular resonance frequencies. If not corrected, this nonlinear behavior precludes the application of high frequency deflections and the study of cortical responses to behaviorally relevant stimuli. To cope with the ringing problem, a mechanical and a software based solutions have been developed. With these corrections, the upper bound of the linear range of the bender is increased to 1 kHz. This new device allows the controlled delivery of large scale natural patterns of whisker deflections characterized by rapid high frequency vibrations of multiple whiskers.

Where' and 'what' in the whisker sensorimotor system

Nature Reviews Neuroscience, 2008

Texture relates to the surface pattern of objects. Roughness is one of the attributes of texture. The roughness of an irregular sandpaper-like surface texture is quantified by its grain size; the larger the grains, the coarser the texture.