scholarly journals Kinematics of unconstrained tactile texture exploration

2015 ◽  
Vol 113 (7) ◽  
pp. 3013-3020 ◽  
Author(s):  
Thierri Callier ◽  
Hannes P. Saal ◽  
Elizabeth C. Davis-Berg ◽  
Sliman J. Bensmaia
Keyword(s):  
Neural Coding ◽  
Scanning Speed ◽  
Perceptual Task ◽  
Textured Surfaces ◽  
Cutaneous Mechanoreceptors ◽  
Texture Information ◽  
Different Types ◽  
Exploratory Movements

A hallmark of tactile texture exploration is that it involves movement between skin and surface. When we scan a surface, small texture-specific vibrations are produced in the skin, and specialized cutaneous mechanoreceptors convert these vibrations into highly repeatable, precise, and informative temporal spiking patterns in tactile afferents. Both texture-elicited vibrations and afferent responses are highly dependent on exploratory kinematics, however; indeed, these dilate or contract systematically with decreases or increases in scanning speed, respectively. These profound changes in the peripheral response that accompany changes in scanning speed and other parameters of texture scanning raise the question as to whether exploratory behaviors change depending on what surface is explored or what information is sought about that surface. To address this question, we measure and analyze the kinematics as subjects explore textured surfaces to evaluate different types of texture information, namely the textures' roughness, hardness, and slipperiness. We find that the exploratory movements are dependent both on the perceptual task, as has been previously shown, but also on the texture that is scanned. We discuss the implications of our findings regarding the neural coding and perception of texture.

scholarly journals Emergence of an invariant representation of texture in primate somatosensory cortex

2019 ◽  
Author(s):  
Justin D. Lieber ◽  
Sliman J. Bensmaia
Keyword(s):  
Cortical Neurons ◽  
Rhesus Macaques ◽  
Scanning Speed ◽  
Nerve Fibers ◽  
Invariant Representation ◽  
Major Function ◽  
Neural Representations ◽  
Wide Range ◽  
Sensory Modalities ◽  
Exploratory Movements

ABSTRACTA major function of sensory processing is to achieve neural representations of objects that are stable across changes in context and perspective. Small changes in exploratory behavior can lead to large changes in signals at the sensory periphery, thus resulting in ambiguous neural representations of objects. Overcoming this ambiguity is a hallmark of human object recognition across sensory modalities. Here, we investigate how the perception of tactile texture remains stable across exploratory movements of the hand, including changes in scanning speed, despite the concomitant changes in afferent responses. To this end, we scanned a wide range of everyday textures across the fingertips of Rhesus macaques at multiple speeds and recorded the responses evoked in tactile nerve fibers and somatosensory cortical neurons. We found that individual cortical neurons exhibit a wider range of speed-sensitivities than do nerve fibers. The resulting representations of speed and texture in cortex are more independent than are their counterparts in the nerve and account for speed-invariant perception of texture. We demonstrate that this separation of speed and texture information is a natural consequence of previously described cortical computations.

scholarly journals Laser surface texturing of tool steel: textured surfaces quality evaluation

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Peter Šugár ◽  
Jana Šugárová ◽  
Martin Frnčík
Keyword(s):  
Laser Beam ◽  
Tool Steel ◽  
Surface Texturing ◽  
Scanning Speed ◽  
Laser Surface ◽  
Laser Surface Texturing ◽  
Fibre Laser ◽  
Textured Surfaces ◽  
Machined Surface ◽  
Ytterbium Fibre Laser

Abstract In this experimental investigation the laser surface texturing of tool steel of type 90MnCrV8 has been conducted. The 5-axis highly dynamic laser precision machining centre Lasertec 80 Shape equipped with the nano-second pulsed ytterbium fibre laser and CNC system Siemens 840 D was used. The planar and spherical surfaces first prepared by turning have been textured. The regular array of spherical and ellipsoidal dimples with a different dimensions and different surface density has been created. Laser surface texturing has been realized under different combinations of process parameters: pulse frequency, pulse energy and laser beam scanning speed. The morphological characterization of ablated surfaces has been performed using scanning electron microscopy (SEM) technique. The results show limited possibility of ns pulse fibre laser application to generate different surface structures for tribological modification of metallic materials. These structures were obtained by varying the processing conditions between surface ablation, to surface remelting. In all cases the areas of molten material and re-cast layers were observed on the bottom and walls of the dimples. Beside the influence of laser beam parameters on the machined surface quality during laser machining of regular hemispherical and elipsoidal dimple texture on parabolic and hemispherical surfaces has been studied.

scholarly journals Analysis of visual processing capabilities and neural coding strategies of a detailed model for laminar cortical microcircuits in mouse V1

2021 ◽  
Author(s):  
Guozhang Chen ◽  
Franz Scherr ◽  
Wolfgang Maass
Keyword(s):  
Visual Processing ◽  
Neural Coding ◽  
Noise Model ◽  
Projection Neurons ◽  
Detailed Model ◽  
Power Law Decay ◽  
Different Types ◽  
Cortical Microcircuits ◽  
Explained Variance ◽  
Spatial Locations

AbstractThe neocortex is a network of rather stereotypical cortical microcircuits that share an exquisite genetically encoded architecture: Neurons of a fairly large number of different types are distributed over several layers (laminae), with specific probabilities of synaptic connections that depend on the neuron types involved and their spatial locations. Most available knowledge about this structure has been compiled into a detailed model [Billeh et al., 2020] for a generic cortical microcircuit in the primary visual cortex, consisting of 51,978 neurons of 111 different types. We add a noise model to the network that is based on experimental data, and analyze the results of network computations that can be extracted by projection neurons on layer 5. We show that the resulting model acquires through alignment of its synaptic weights via gradient descent training the capability to carry out a number of demanding visual processing tasks. Furthermore, this weight-alignment induces specific neural coding features in the microcircuit model that match those found in the living brain: High dimensional neural codes with an arguably close to optimal power-law decay of explained variance of PCA components, specific relations between signal- and noise-coding dimensions, and network dynamics in a critical regime. Hence these important features of neural coding and dynamics of cortical microcircuits in the brain are likely to emerge from aspects of their genetically encoded architecture that are captured by this data-based model in combination with learning processes. In addition, the model throws new light on the relation between visual processing capabilities and details of neural coding.

scholarly journals Effect of scanning speed on texture-elicited vibrations

2020 ◽  
Vol 17 (167) ◽  
pp. 20190892
Author(s):  
Charles M. Greenspon ◽  
Kristine R. McLellan ◽  
Justin D. Lieber ◽  
Sliman J. Bensmaia
Keyword(s):  
Root Mean Square ◽  
Laser Doppler Vibrometer ◽  
Scanning Speed ◽  
Mean Square ◽  
Root Mean Square Velocity ◽  
Dependent Change ◽  
Fine Surface ◽  
Neuronal Representation ◽  
Human Participants ◽  
Exploratory Movements

To sense the texture of a surface, we run our fingers across it, which leads to the elicitation of skin vibrations that depend both on the surface and on exploratory parameters, particularly scanning speed. The transduction and processing of these vibrations mediate the ability to discern fine surface features. The objective of the present study is to characterize the effect of changes in scanning speed on texture-elicited vibrations to better understand how the exploratory movements shape the neuronal representation of texture. To this end, we scanned a variety of textures across the fingertip of human participants at a variety of speeds (10–160 mm s −1 ) while measuring the resulting vibrations using a laser Doppler vibrometer. First, we found that the intensity of the vibrations—as indexed by root-mean-square velocity—increases with speed but that the skin displacement remains constant. Second, we found that the frequency composition of the vibrations shifts systematically to higher frequencies with increases in scanning speed. Finally, we show that the speed-dependent shift in frequency composition accounts for the speed-dependent change in intensity.

scholarly journals Assessment the Sliding Wear Behavior of Laser Microtexturing Ti6Al4V under Wet Conditions

Coatings ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 67 ◽  
Author(s):  
Juan Vazquez Martinez ◽  
Irene Del Sol Illana ◽  
Patricia Iglesias Victoria ◽  
Jorge Salguero
Keyword(s):  
Wear Behavior ◽  
Strong Dependence ◽  
Scanning Speed ◽  
Processing Parameters ◽  
Textured Surfaces ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Dry Conditions ◽  
Titanium Alloy Ti6al4v ◽  
Microscopy Techniques

Laser micro-texturing processes, compared to untreated surfaces, can improve the friction, wear and wettability behavior of sliding parts. This improvement is related to the micro-geometry and the dimensions of the texture which is also dependent on the processing parameters. This research studied the effect of laser textured surfaces on the tribological behavior of titanium alloy Ti6Al4V. The influence of processing parameters was analyzed by changing the scanning speed of the beam and the energy density of pulse. First, the characterization of dimensional and geometrical features of the texturized tracks was carried out. Later, their influence on the wetting behavior was also evaluated through contact angle measurements using water as a contact fluid. Then, the tribological performance of these surfaces was analyzed using a ball-on-flat reciprocating tribometer under wet and dry conditions. Finally, wear mechanisms were identified employing electronic and optical microscopy techniques capable to evaluate the wear tracks on Ti surfaces and WC–Co spheres. These analyses had determined a strong dependence between the wear behavior and the laser patterning parameters. Wear friction effects were reduced by up to a 70% replacing conventional untreated surfaces of Ti6Al4V alloy with laser textured surfaces.

Image-Computable Ideal Observers for Tasks with Natural Stimuli

2020 ◽  
Vol 6 (1) ◽  
pp. 491-517 ◽  
Author(s):  
Johannes Burge
Keyword(s):  
Visual Processing ◽  
Visual Information ◽  
Neural Coding ◽  
Ideal Observer ◽  
Perceptual Task ◽  
Vision Science ◽  
Natural Stimuli ◽  
Ideal Observers ◽  
Perceptual Performance ◽  
And Performance

An ideal observer is a theoretical model observer that performs a specific sensory-perceptual task optimally, making the best possible use of the available information given physical and biological constraints. An image-computable ideal observer (pixels in, estimates out) is a particularly powerful type of ideal observer that explicitly models the flow of visual information from the stimulus-encoding process to the eventual decoding of a sensory-perceptual estimate. Image-computable ideal observer analyses underlie some of the most important results in vision science. However, most of what we know from ideal observers about visual processing and performance derives from relatively simple tasks and relatively simple stimuli. This review describes recent efforts to develop image-computable ideal observers for a range of tasks with natural stimuli and shows how these observers can be used to predict and understand perceptual and neurophysiological performance. The reviewed results establish principled links among models of neural coding, computational methods for dimensionality reduction, and sensory-perceptual performance in tasks with natural stimuli.

Influence of Different Types of Physical Fatigue on a Visual Detection Task

1981 ◽  
Vol 53 (3) ◽  
pp. 723-730 ◽  
Author(s):  
Michelle Fleury ◽  
Chantal Bard ◽  
Jean Jobin ◽  
Lise Carrière
Keyword(s):  
Repeated Measures ◽  
Visual Detection ◽  
Detection Task ◽  
Perceptual Task ◽  
Mask Condition ◽  
Physical Fatigue ◽  
Significant Difference ◽  
Different Types ◽  
Type Of Exercise ◽  
Experimental Treatments

The present study was designed to investigate the effects of different types of physical fatigue—past demand for exertion—on the performance of a visual detection task performed with and without masking. 31 male subjects were first administered a VO2 max test and familiarized with the detection task. They were divided into two groups to control potential effects of masking. They were subjected to three experimental treatments involving the utilization of different sources of energy: (a) a short anaerobic alactacid effort recruiting phosphocreatine, (b) a supramaximal effort (anaerobic lactacid) recruiting glycogen without oxygen, and (c) a progressive (partially anaerobic) effort recruiting glycogen and oxygen. All three were performed on a treadmill. Blood samples were collected for the anaerobic lactacid and the partially anaerobic exercises. Once fatigued, all subjects undertook the detection task. A2 × 3 × 2 × 8 analysis of variance, with repeated measures on the last three factors, was applied to the data (mask/no mask × type of exercise × pre-post performance measures × location of the letter to be detected). No significant difference was found for either the main effects or interactions, except for the location of the letter and the mask/no-mask condition. It appears therefore that a physically fit population (X̅V̇O2max = 62.39 ml kg−1 × min−1) shows no detectable decrement in a perceptual task performed after fatiguing exercises recruiting various types of energy sources.

scholarly journals Neural Coding Mechanisms Underlying Perceived Roughness of Finely Textured Surfaces

2001 ◽  
Vol 21 (17) ◽  
pp. 6905-6916 ◽  
Author(s):  
Takashi Yoshioka ◽  
Barbara Gibb ◽  
Andrew K. Dorsch ◽  
Steven S. Hsiao ◽  
Kenneth O. Johnson
Keyword(s):  
Neural Coding ◽  
Textured Surfaces

scholarly journals Emergence of an Invariant Representation of Texture in Primate Somatosensory Cortex

2019 ◽  
Vol 30 (5) ◽  
pp. 3228-3239 ◽  
Author(s):  
Justin D Lieber ◽  
Sliman J Bensmaia
Keyword(s):  
Cortical Neurons ◽  
Rhesus Macaques ◽  
Scanning Speed ◽  
Nerve Fibers ◽  
Invariant Representation ◽  
Major Function ◽  
Neural Representations ◽  
Wide Range ◽  
Brodmann Areas ◽  
Exploratory Movements

Abstract A major function of sensory processing is to achieve neural representations of objects that are stable across changes in context and perspective. Small changes in exploratory behavior can lead to large changes in signals at the sensory periphery, thus resulting in ambiguous neural representations of objects. Overcoming this ambiguity is a hallmark of human object recognition across sensory modalities. Here, we investigate how the perception of tactile texture remains stable across exploratory movements of the hand, including changes in scanning speed, despite the concomitant changes in afferent responses. To this end, we scanned a wide range of everyday textures across the fingertips of rhesus macaques at multiple speeds and recorded the responses evoked in tactile nerve fibers and somatosensory cortical neurons (from Brodmann areas 3b, 1, and 2). We found that individual cortical neurons exhibit a wider range of speed-sensitivities than do nerve fibers. The resulting representations of speed and texture in cortex are more independent than are their counterparts in the nerve and account for speed-invariant perception of texture. We demonstrate that this separation of speed and texture information is a natural consequence of previously described cortical computations.

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