Tactile Semiautomatic Passive-Finger Angle Stimulator (TSPAS)

Summary

Presented is the tactile semiautomated passive-finger angle stimulator TSPAS, a new way to assess tactile spatial acuity and tactile angle discrimination using a computer-controlled tactile stimulus system that applies raised angle stimuli to a subject's passive fingerpad, while controlling for movement speed, distance, and contact duration.

Abstract

Passive tactile perception is the ability to passively and statically perceive stimulus information coming from the skin; for example, the ability to sense spatial information is the strongest in the skin on the hands. This ability is termed tactile spatial acuity, and is measured by the tactile threshold or discrimination threshold. At present, the two-point threshold is extensively used as a measure of tactile spatial acuity, although many studies have indicated that critical deficits exist in two-point discrimination. Therefore, a computer-controlled tactile stimulus system was developed, the tactile semiautomated passive-finger angle stimulator (TSPAS), using the tactile angle discrimination threshold as a new measure for tactile spatial acuity. The TSPAS is a simple, easily operated system that applies raised angle stimuli to a subject's passive fingerpad, while controlling movement speed, distance, and contact duration. The components of the TSPAS are described in detail as well as the procedure to calculate the tactile angle discrimination threshold.

Introduction

Touch perception is a fundamental form of the sensations processed by the somatosensory system, including haptic perception and tactile perception. Passive tactile perception, as opposed to active exploration, means that the object is moved to make contact with static skin^1,2. As in other senses, spatial resolution in tactile perception, also termed tactile spatial acuity, is usually represented by the tactile threshold, detection threshold, or discrimination threshold^2,3. In the past 100 years, the two-point threshold has commonly been used as a measu....

Protocol

Written informed consent was obtained from the subjects in compliance with the policies of the local medical ethics committee of Okayama University. The testing procedures gained review and consent from the local medical ethics committee of Okayama University.

1. Detailed composition and function of equipment

1. Tactile angle stimuli
   1. The TSPAS uses two-dimensional (2D) raised angles to slide passively across the skin and form a tactile spatial representation of the angles (Figure 2). The tactile angles consist of plastic lines and square bases, which are both made from a transparent acrylic....

Results

In this study, the 3AFC (3-alternative forced-choice) technique and the logistic curve were used to estimate the tactile AD threshold. Participants were instructed to orally report the larger of the two angles perceived, or if they did not detect the difference, they could indicate the same. The equation of the logistic curve, which has been commonly applied to psychophysical experiments to measure thresholds^27,28,29 is:

Discussion

A new measure for tactile spatial acuity, tactile AD, is presented. In this system a pair of angles passively slides across the immobilized index fingerpad of a subject. AD combines the advantages of GO and TPD, reducing the impact of intensive cues and the neural peak impulse rate of a single point. This study shows that there is a gradual change in perceptual discrimination as the angle difference changes between the reference angle and the comparison angle⁴. In addition to the age effect, train.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Acrylic sheet (3 mm)	MonotaRO Co.,Ltd.	33159874	Good Material
Acrylic sheet (1 mm)	MonotaRO Co.,Ltd.	45547101	Good Material
EZ limo (easy linear motion motor)	ORIENTAL MOTOR CO., LTD. Made in Japan	EZS3	Good Motorized Linear Slides
Data Editing Software	ORIENTAL MOTOR CO., LTD. Made in Japan	EZED2	easy to use
Operating Manual (Orientalmotor)	ORIENTAL MOTOR CO., LTD. Made in Japan	HL-17151-2	Good Guidebook