@article {32, title = {Behavioral study of whisker-mediated vibration sensation in rats}, journal = {Proceedings of the National Academy of Sciences of USA}, volume = {109}, year = {2012}, pages = {971{\textendash}976}, abstract = {

Rats use their vibrissal sensory system to collect information about the nearby environment. They can accurately and rapidly identify object location, shape, and surface texture. Which features of whisker motion does the sensory system extract to construct sensations? We addressed this question by training rats to make discriminations between sinusoidal vibrations simultaneously presented to the left and right whiskers. One set of rats learned to reliably identify which of two vibrations had higher frequency (f1 vs. f2) when amplitudes were equal. Another set of rats learned to reliably identify which of two vibrations had higher amplitude (A1 vs. A2) when frequencies were equal. Although these results indicate that both elemental features contribute to the rats{\textquoteright} sensation, a further test found that the capacity to discriminate A and f was reduced to chance when the difference in one feature was counterbalanced by the difference in the other feature: Rats could not discriminate amplitude or frequency whenever A1f1 = A2f2. Thus, vibrations were sensed as the product Af rather than as separable elemental features, A and f. The product Af is proportional to a physical entity, the mean speed. Analysis of performance revealed that rats extracted more information about differences in Af than predicted by the sum of the information in elemental differences. These behavioral experiments support the predictions of earlier physiological studies by demonstrating that rats are {\textquotedblleft}blind{\textquotedblright} to the elemental features present in a sinusoidal whisker vibration; instead, they perceive a composite feature, the speed of whisker motion.

}, keywords = {barrel cortex, coding}, doi = {10.1073/pnas.1116726109}, author = {Mehdi Adibi and Mathew E. Diamond and Ehsan Arabzadeh} } @article {34, title = {Unsupervised quantification of whisking and head movement in freely moving rodents}, journal = {Journal of Neurophysiology}, volume = {105}, year = {2011}, pages = {1950-1962}, abstract = {

The rodent whisker system has become the leading experimental paradigm for the study of active sensing. Thanks to more sophisticated behavioral paradigms, progressively better neurophysiological methods, and improved video hardware/software, there is now the prospect of defining the precise connection between the sensory apparatus and brain activity in awake, exploring animals. Achieving this ambitious goal requires quantitative, objective characterization of head and whisker kinematics. This study presents the methodology and potential uses of a new automated motion analysis routine. The program provides full quantification of head orientation and translation, as well as the angle, frequency, amplitude, and bilateral symmetry of whisking. The system operates without any need for manual tracing by the user. Quantitative comparison to whisker detection by expert humans indicates that the program{\textquoteright}s correct detection rate is at \>95\% even on animals with all whiskers intact. Particular attention has been paid to obtaining reliable performance under nonoptimal lighting or video conditions and at frame rates as low as 100. Variation of the zoom across time is compensated for without user intervention. The program adapts automatically to the size and shape of different species. The outcome of our testing indicates that the program can be a valuable tool in quantifying rodent sensorimotor behavior.

}, keywords = {head tracking, snout tracking, whisker tracking}, doi = {10.1152/jn.00764.2010}, author = {Igor Perkon and Andrej Kosir and Pavel M Itskov and Jurij Tasic and Mathew E. Diamond} } @article {33, title = {Whisking and whisker kinematics during a texture classification task}, journal = {Philosophical Transactions of the Royal Society B}, volume = {366}, year = {2011}, pages = {3058-3069}, abstract = {

Rats explore objects by rhythmically whisking with their vibrissae. The goal of the present study is to learn more about the motor output used by rats to acquire texture information as well as the whisker motion evoked by texture contact. We trained four rats to discriminate between different grooved textures and used high-speed video to characterize whisker motion during the task. The variance in whisking parameters among subjects was notable. After whisker trimming, the animals changed their behaviour in ways that appear consistent with an optimization of whisker movement to compensate for lost information. These results lead to the intriguing notion that the rats use an information-seeking {\textquoteleft}cognitive{\textquoteright} motor strategy, instead of a rigid motor programme. Distinct stick/slip events occurred during texture palpation and their frequency increased in relation to the spatial frequency of the grooves. The results allow a preliminary assessment of three candidate texture-coding mechanisms{\textemdash}the number of grooves encountered during each touch, the temporal difference between groove contacts and the spatial pattern of groove contacts across the whiskers.

}, keywords = {stick/slip, texture classification task, touch, vibrissae, whisking}, doi = {10.1098/rstb.2011.0161}, author = {Yanfang Zuo and Igor Perkon and Mathew E. Diamond} }