Encoding of Direction of Fingertip Forces by Human Tactile Afferents

Birznieks, Ingvars; Jenmalm, Per; Goodwin, Antony W.; Johansson, Roland S.

doi:10.1523/jneurosci.21-20-08222.2001

Cited by 304 publications

(226 citation statements)

References 72 publications

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“…Mechanical stimuli were delivered to the tip of the receptor-bearing finger (i.e., right index, middle, or ring finger) using a custom-built computer-controlled stimulator that allowed control of force or position in three dimensions. A previous report describes in detail the apparatus used to deliver the mechanical stimuli (Birznieks et al, 2001).…”

Section: Methodsmentioning

confidence: 99%

“…Given their abundance, in the present study we asked whether the SA-IInail afferents might contribute important information about mechanical events at volar skin areas of the fingertips that directly contact objects during natural use of the digits. Because widespread complex stresses and strains occur all over the fingertip when it deforms in response to forces applied on objects, tactile afferents not only in the skin area contacting an object, but also at the end and sides of the fingertip, can convey information about contact forces (Bisley et al, 2000;Birznieks et al, 2001;Jenmalm et al, 2003;Johansson and Birznieks, 2004). We hypothesized that also SA-IInail afferents might encode fingertip forces because of significant changes of the tension in collagenous fiber strands of the paronychium where their end organs are situated.…”

Section: Introductionmentioning

confidence: 99%

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Slowly Adapting Mechanoreceptors in the Borders of the Human Fingernail Encode Fingertip Forces

Birznieks¹,

Macefield²,

Westling³

et al. 2009

J. Neurosci.

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There are clusters of slowly adapting (SA) mechanoreceptors in the skin folds bordering the nail. These "SA-IInail" afferents, which constitute nearly one fifth of the tactile afferents innervating the fingertip, possess the general discharge characteristics of slowly adapting type II (SA-II) tactile afferents located elsewhere in the glabrous skin of the human hand. Little is known about the signals in the SA-IInail afferents when the fingertips interact with objects. Here we show that SA-IInail afferents reliably respond to fingertip forces comparable to those arising in everyday manipulations. Using a flat stimulus surface, we applied forces to the finger pad while recording impulse activity in 17 SA-IInail afferents. Ramp-and-hold forces (amplitude 4 N, rate 10 N/s) were applied normal to the skin, and at 10, 20, or 30°f rom the normal in eight radial directions with reference to the primary site of contact (25 force directions in total). All afferents responded to the force stimuli, and the responsiveness of all but one afferents was broadly tuned to a preferred direction of force. The preferred directions among afferents were distributed all around the angular space, suggesting that the population of SA-IInail afferents could encode force direction. We conclude that signals in the population of SA-IInail afferents terminating in the nail walls contain vectorial information about fingertip forces. The particular tactile features of contacted surfaces would less influence force-related signals in SA-IInail afferents than force-related signals present in afferents terminating in the volar skin areas that directly contact objects.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Slowly Adapting Mechanoreceptors in the Borders of the Human Fingernail Encode Fingertip Forces

Birznieks¹,

Macefield²,

Westling³

et al. 2009

J. Neurosci.

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show abstract

“…Furthermore, when judging stickiness, subjects do not substantially vary the normal forces they apply on the surface, but the applied tangential forces tend to vary across surfaces, suggesting that tangential forces are critical in the perception of stickiness (Smith and Scott 1996). As SA2 fibers are sensitive to skin stretch (Witt and Hensel 1959;Iggo 1966;Knibestöl 1975), this population of mechanoreceptive afferent fibers may provide the peripheral signals underlying stickiness perception, although recent evidence suggests that other mechanoreceptive afferents also convey information about forces exerted on the skin (Birznieks et al 2001). Vibratory cues may also be a factor in the perception of stickiness: as the skin skitters across a sticky surface, vibrations are produced in the skin (likely transduced and processed within the Pacinian system) which may contribute to the perception of stickiness (Bensmaia and Hollins 2005).…”

Section: Neural Mechanisms Of Texture Perceptionmentioning

confidence: 99%

Texture perception through direct and indirect touch: An analysis of perceptual space for tactile textures in two modes of exploration

Yoshioka

Bensmaı̈a

Craig

et al. 2007

Somatosensory & Motor Research

183

122

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Considerable information about the texture of objects can be perceived remotely through a probe. It is not clear, however, how texture perception with a probe compares with texture perception with the bare finger. Here we investigate the perception of a variety of textured surfaces encountered daily (e.g., corduroy, paper, and rubber) using the two scanning modes-direct touch through the finger and indirect touch through a probe held in the hand-in two tasks. In the first task, subjects rated the overall pair-wise dissimilarity of the textures. In the second task, subjects rated each texture along three continua, namely, perceived roughness, hardness, and stickiness of the surfaces, shown previously as the primary dimensions of texture perception in direct touch. From the dissimilarity judgment experiment, we found that the texture percept is similar though not identical in the two scanning modes. From the adjective rating experiments, we found that while roughness ratings are similar, hardness and stickiness ratings tend to differ between scanning conditions. These differences between the two modes of scanning are apparent in perceptual space for tactile textures based on multidimensional scaling (MDS) analysis. Finally, we demonstrate that three physical quantities, vibratory power, compliance, and friction carry roughness, hardness, and stickiness information, predicting perceived dissimilarity of texture pairs with indirect touch. Given that different types of texture information are processed by separate groups of neurons across direct and indirect touch, we propose that the neural mechanisms underlying texture perception differ between scanning modes.

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“…Lashley [22] argued that, in the rapid sequences of articulation, sensory control is unlikely to play a role; rapid sequences of course also occur in music. It is of interest, however, that single tactile afferents may encode delicate fingertip forces, as demonstrated by Birzniek et al [5]. Furthermore, it was concluded that, during speech, b. .…”

Section: Feedforward and Feedback In Motor Control Of Music Performancementioning

confidence: 98%

Coordination of bowing and fingering in violin playing

Baader

Kazennikov

Wiesendanger

2005

Cognitive Brain Research

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Playing string instruments implies motor skills including asymmetrical interlimb coordination. How special is musical skill as compared to other bimanually coordinated, non-musical skillful performances? We succeeded for the first time to measure quantitatively bimanual coordination in violinists playing repeatedly a simple tone sequence. A motion analysis system was used to record finger and bow trajectories for assessing the temporal structure of finger-press, finger-lift (left hand), and bow stroke reversals (right arm). The main results were: (1) fingering consisted of serial and parallel (anticipatory) mechanisms; (2) synchronization between finger and bow actions varied from À12 ms to 60 ms, but these derrorsT were not perceived. The results suggest that (1) bow-finger synchronization varied by about 50 ms from perfect simultaneity, but without impairing auditory perception; (2) the temporal structure depends on a number of combinatorial mechanisms of bowing and fingering. These basic mechanisms were observed in all players, including all amateurs. The successful biomechanical measures of fingering and bowing open a vast practical field of assessing motor skills. Thus, objective assessment of larger groups of string players with varying musical proficiency, or of professional string players developing movement disorders, may be helpful in music education.Theme: Control of posture and movement Topic: Cognition

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Encoding of Direction of Fingertip Forces by Human Tactile Afferents

Cited by 304 publications

References 72 publications

Slowly Adapting Mechanoreceptors in the Borders of the Human Fingernail Encode Fingertip Forces

Slowly Adapting Mechanoreceptors in the Borders of the Human Fingernail Encode Fingertip Forces

Texture perception through direct and indirect touch: An analysis of perceptual space for tactile textures in two modes of exploration

Coordination of bowing and fingering in violin playing

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