Representation of braille characters in human nerve fibres

Phillips, J. R.; Johansson, Roland S.; Johnson, Kenneth O.

doi:10.1007/bf02423508

Cited by 118 publications

(66 citation statements)

References 19 publications

(23 reference statements)

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“…These studies have produced reconstructed neural images based on both peripheral recordings and central recordings in Sf (Phillips, Johansson, & Johnson, 1990;Phillips, Johnson, & Hsiao, 1988). At present, researchers have examined interactions only between relatively simple patterns; however, as both stimulus control and recording techniques become more sophisticated, it should be possible to present pairs of spatial patterns in rapid succession to the same area of skin.…”

Section: Methodsmentioning

confidence: 99%

Vibrotactile masking: The role of response competition

Craig

1995

Perception & Psychophysics

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When two tactile patterns, a target and a nontarget pattern, are presented in dose temporal proximity to the same location, the nontarget pattern may interfere with the identification of the target. A series of experiments examined the extent to which the interference in target identification results from masking (interference in the representation of the target at an early stage of processing) or from response competition. A response competition view of pattern perception holds that both the target and nontarget are fully processed to the level of evoking responses. Interference is produced when subjects select the nontarget rather than the target. This view was tested with a paradigm developed in studies of selective attention. Pairs of tactile patterns were presented to subjects' left index fingerpads. The amount of interference produced by a nontarget that is physically different from a target depends on whether the nontarget is associated with the same response as the target or a different response. The amount of masking also depends on the set of target and nontarget patterns that are used. The results support the conclusion that subjects have available a representation of both the target and the nontarget and that a substantial portion of the interference previously attributed to masking may be due to response competition.

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Section: Methodsmentioning

confidence: 99%

Vibrotactile masking: The role of response competition

Craig

1995

Perception & Psychophysics

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“…This may be particularly evident in women or men with smaller fingers where the more densely packed receptors have been suggested to improve acuity (Peters et al 2009). Second, Merkel receptors have the highest acuity (Phillips et al 1990) but are the only lowthreshold receptors in the glabrous skin of the hand for which a role in fine motor control could not be demonstrated (McNulty et al 1999;McNulty and Macefield 2001). This suggests that Merkel receptors may have stronger connections to the somatosensory cortex than other low-threshold mechanoreceptors and so provide a learnt attentional focus to cutaneous inputs (McNulty and Macefield 2001).…”

Section: Changes Across the Handmentioning

confidence: 99%

Age-related changes in cutaneous sensation in the healthy human hand

Bowden

McNulty

2012

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Cutaneous sensation deteriorates with age. It is not known if this change is consistent over the entire hand or if sensation is affected by changes in skin mechanics. Cutaneous perceptual thresholds were tested at eight sites in the glabrous skin and two in the hairy skin of both hands in 70 subjects (20-88 years), five male and five female per decade, using calibrated von Frey filaments, two-point discrimination, and texture discrimination. Venous occlusion at the wrist (40±10 mmHg) and moisturizer were used to alter skin mechanics. Cutaneous thresholds increased significantly with age (p<0.001); von Frey thresholds were 0.04 g [0.02-0.07] (median and interquartile range) in the 20s and 0.16 g [0.04-0.4] in the 80s, with differences between hands for older females (p00.044) but not males. The pattern of changes in cutaneous sensation varied according to the site tested with smaller changes on the fingers compared to the palm. Two-point discrimination deteriorated with age (p00.046), but with no interaction between sex, handedness, or changes in skin mechanics. There were no significant differences for texture discrimination. Changes in skin mechanics improved cutaneous thresholds in the oldest males after moisturizing (p00.001) but not otherwise. These results emphasize the complex pattern of age-related deterioration in cutaneous sensation with differences between sexes, the hands, sites on the hand, and the mode of testing. As the index fingertip is not a sensitive indicator of sensory decline, the minimum assessment of age-related changes in cutaneous sensation should include both hands, and sites on the palm.

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“…Ongoing activity in the absence of externally applied stimulation is probably attributable to the inherent mechanical tension in the tissues where the receptors are located (Johansson, 1978). Importantly, the spatial low-pass filtering properties of the link between the skin surface and the nerve endings prevents an accurate representation of "fine-form" geometric features, such as Braille-like patterns in SA-II afferents (Phillips et al, 1990(Phillips et al, , 1992.…”

Section: What Do the Sa-iinail Afferents Tell The Cns?mentioning

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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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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Representation of braille characters in human nerve fibres

Cited by 118 publications

References 19 publications

Vibrotactile masking: The role of response competition

Vibrotactile masking: The role of response competition

Age-related changes in cutaneous sensation in the healthy human hand

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

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