Introduction In the late 20th century, Woolsey and Van der Loos discovered a specific projection map in the rodent somatosensory cortex corresponding to the contralateral face whiskers, designated barrel. Because rodents are nocturnal animals, their whiskers serve to recognize the external world, similar to our eyes and fingers. Each barrel is associated with an individual whisker on the snout,...

The rodent whisker system is widely used as a model system for investigating sensorimotor integration, neural mechanisms of complex cognitive tasks, neural development, and robotics. The whisker pathways to the barrel cortex have received considerable attention. However, many subcortical structures are paramount to the whisker system. They contribute to important processes, like filtering out s...

Studies of the rodent whisker system indicate that somatosensory cortical circuitry operates at a millisecond timescale to transform sensory afferent signals from the thalamus. We measured axon conduction times and whisker-evoked responses of 48 thalamocortical (TC) neurons in the rat whisker-to-barrel pathway. Conduction times were derived from spike-triggered averages of local field potential...

Sensation involves active movement of sensory organs, but it remains unknown how position or movement of sensory organs is encoded in cortex. In the rat whisker system, each whisker is represented by an individual cortical (barrel) column. Here, we quantified in awake, head-fixed rats the impact of natural whisker movements on action potential frequencies of single (identified) neurons located ...

Many rodents tactually sense the world through active motions of their vibrissae (whiskers), which are regularly arranged in rows and columns (arcs) on the face. The present study quantifies several geometric parameters of rat whiskers that determine the tactile information acquired. Findings include the following. 1) A meta-analysis of seven studies shows that whisker base diameter varies with...

Editor's Note: These short reviews of a recent paper in the Journal, written exclusively by graduate students or postdoctoral fellows, are intended to mimic the journal clubs that exist in your own departments or institutions. For more information on the format and purpose of the Journal Club, please see Review of Stüttgen et al. Like the digits of the human hand, the whiskers on the mystacial ...

Some rodent species show rhythmic bouts of vibrissal protractions and retractions, referred to as whisking, that are among the fastest movements performed by mammals. To better understand the muscular basis of whisking, we compared (1) whisker movements of two whisking species (mouse, rat) and a non-whisking species (guinea pig), (2) the muscle fiber composition of intrinsic whisker muscles of ...

The responsiveness of cortical neurons is strongly and rapidly influenced by changes in the level of local network activity. In rodent somatosensory cortex, increases in network activity increase neuronal responsiveness to the intracellular injection of brief conductance stimuli but paradoxically decrease responsiveness to brief whisker deflections. However, whisker stimulation frequently evoke...

The brain's sensory processing systems are modified during perceptual learning. To learn more about the spatial organization of learning-related modifications, we trained rats to utilize the sensory signal from a single intact whisker to carry out a behavioral task. Once a rat had mastered the task, we clipped its "trained" whisker and attached a "prosthetic" one to a different whisker stub. We...

Whisker deflection is an effective conditioned stimulus (CS) for trace eyeblink conditioning that has been shown to induce a learning-specific expansion of whisker-related cortical barrels, suggesting that memory storage for an aspect of the trace association resides in barrel cortex. To examine the role of the barrel cortex in acquisition and retrieval of trace eyeblink associations, the barre...