Sensitivity improvement device

Abstract

To provide a sensitivity improvement device which can improve a sensing function of oral cavity and pharynx using a phenomenon called stochastic resonance.SOLUTION: A sensitivity improvement device of the present invention includes an actuator 14 for generating a noise vibration. By applying the noise vibration to a skin of head and neck or a tongue of a biological body, the sensing function of the oral cavity or a pharynx is improved using a phenomenon called stochastic resonance. Further, threshold value setting means 20 is provided for setting a vibration level of the noise vibration. The threshold value setting means 20 applies different vibration levels to a user, causes the user to input the stimulated vibration level at which the noise vibration is sensed and a non-stimulated vibration level at which the noise vibration is not sensed, and sets a threshold value specific to the user based on the input stimulated vibration level and the non-stimulated vibration level.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sensitivity enhancement device that uses a phenomenon called stochastic resonance to enhance the sensory function of the oral cavity or pharynx. [Background technology]

[0002] Careful oral care not only improves oral sensory function, but also lowers the threshold for triggering the swallowing and coughing reflexes and enhances the ability to prevent aspiration. However, in nursing and care settings where time and manpower shortages are becoming increasingly serious, only a handful of facilities are able to provide oral care before every meal. The sensory function of the tongue is important not only for articulatory functions such as speech production, but also for swallowing functions such as recognizing the physical properties, shape, and location of food taken into the oral cavity, chewing, bolus formation, and transporting the bolus into the pharynx. The anterior two-thirds of the tongue are innervated by the lingual nerve, which is involved in the perception of food properties and shape, while the posterior one-third is innervated by the glossopharyngeal nerve, which is the same nerve innervated by the pharyngeal region, which is involved in the swallowing reflex. Therefore, improving the sensory function of the tongue directly contributes to improving the ability to prevent aspiration. Because the tongue is also involved in transporting the food bolus into the pharynx during swallowing, a decline in sensory function due to aging or disease increases the risk of aspiration and choking. Therefore, improving the tactile sensitivity of the tongue and improving food recognition and transport into the pharynx is thought to be effective in preventing aspiration and choking. However, treatments and training methods for restoring or improving sensory function have not been fully established. Against this background, stochastic resonance (SR), a phenomenon that can instantly improve human sensory functions, has attracted attention. SR is a phenomenon in which the application of weak noise vibrations improves the response performance of a system, making it possible to detect signals below the system's detection threshold. It has been confirmed that a similar phenomenon occurs in the sensory functions of human skin when appropriate noise vibrations are applied. For example, it has been reported that simply applying weak noise vibrations below the sensory threshold of mechanoreceptors to the side of a finger or distal to the wrist makes it possible to detect weak signals that are normally imperceptible at the fingertip. Non-Patent Document 1 reports the stochastic resonance phenomenon, in which the tactile sensitivity of the fingertips is improved by applying white noise vibration to the sides of the fingers or the wrist. US Patent No. 6,299,649 discloses a method and system for improving a subject's sensory, reflex, and / or motor mechanisms through auditory, tactile, or visual stimulation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5311229 [Non-patent literature]

[0004] [Non-Patent Document 1] Tetsuya Yokoyama, Yuki Hashimoto, "The Effect of Sensory Nerve Action Potential Spread on Finger Tactile Sensitivity," Transactions of the Virtual Reality Society of Japan, Vol. 27, No. 3, 2022, pp. 173-200 Summary of the Invention [Problem to be solved by the invention]

[0005] As disclosed in Non-Patent Document 1 and Patent Document 1, the effects of SR on parts of the body that are composed of skin, muscles, and skeleton, such as the fingers, have been verified, but it has not been clarified whether similar effects are also exhibited on oral sensations such as the tongue, which are important for forming a bolus and sending it to the pharynx, or on pharyngeal sensations, which are important for inducing the swallowing reflex and the resulting airway closure.

[0006] The present invention aims to provide a sensitivity enhancement device that uses a phenomenon called stochastic resonance or stochastic resonance to improve the sensory function of the oral cavity or pharynx. [Means for solving the problem]

[0007] The sensitivity enhancement device of the present invention described in claim 1 is a sensitivity enhancement device that uses a phenomenon called stochastic resonance or stochastic resonance to improve the sensory function of the oral cavity or pharynx, and is characterized in that it is equipped with an actuator 14 that generates noise vibrations, and the noise vibrations are applied to the skin of the head and neck or to the tongue of a living body. The present invention as set forth in claim 2 is characterized in that in the sensitivity improving device as set forth in claim 1, the noise vibration is applied to the skin below the jaw of the living body. The present invention as set forth in claim 3 is characterized in that, in the sensitivity improving device as set forth in claim 1, the noise vibration is applied from above the suprahyoid muscle group of the living body located directly below the tongue. The present invention described in claim 4 is characterized in that, in the sensitivity enhancement device described in claim 1, it is provided with a threshold setting means 20 for setting the vibration intensity of the noise vibration, and the threshold setting means 20 gives different vibration intensities to the wearer, has the wearer input the stimulation vibration intensity at which the noise vibration begins to be felt and the stimulation non-vibration intensity at which the noise vibration no longer is felt, and sets the wearer's unique threshold from the stimulation vibration intensity and the stimulation non-vibration intensity inputted. The present invention as set forth in claim 5 is characterized in that in the sensitivity enhancing device as set forth in claim 1, a white noise vibration is used as the noise vibration, in which the vibration intensity is approximately the same at all vibration frequencies. The present invention as set forth in claim 6 is characterized in that, in the sensitivity improving device as set forth in claim 1, the vibration frequency band of the white noise vibration is set within a range of 350 Hz or less. The present invention as set forth in claim 7 is characterized in that, in the sensitivity enhancing device as set forth in claim 1, the tactile sensitivity of the tongue is enhanced. [Effects of the Invention]

[0008] According to the present invention, the sensory function of the oral cavity or pharynx can be improved by applying noise vibration to the skin of the head and neck or to the tongue of a living body. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing the configuration of a sensitivity enhancement device according to an embodiment of the present invention; [Figure 2] FIG. 10 is a diagram showing an image of how the sensitivity improving device is attached in this embodiment. [Figure 3] 1 is a diagram showing a method for generating noise vibrations in a sensitivity improvement device according to the present embodiment; [Figure 4] FIG. 10 is a diagram showing a method for setting a threshold value of a sensitivity enhancing device in this embodiment. [Figure 5] Diagram showing measurement of tactile sensitivity [Figure 6] An overview of the stochastic resonance (SR) jig [Figure 7] Diagram showing the outline of the sensitivity test jig [Figure 8] Overview of the experimental environment for Verification 1 [Figure 9] Figure showing the experimental results for Verification 1 [Figure 10] Overview of the experimental environment for Verification 2 [Figure 11] Figure showing the experimental results for Verification 2 [Figure 12] Image showing the position of the sensitivity enhancement device in Verification 3 and Verification 4 [Figure 13] An explanatory diagram showing the static inspection method in Verification 3 [Figure 14] Figure showing the experimental results for Verification 3 [Figure 15] Diagram explaining considerations regarding the effects of Verification 3 [Figure 16] An explanatory diagram showing the dynamic inspection method in Verification 4 [Figure 17] An explanatory diagram showing the dynamic inspection method in Verification 4 [Figure 18] Figure showing the experimental results for Verification 4 [Figure 19] A diagram explaining the considerations regarding the effects of Verification 4 [Figure 20] Diagram showing the structure of the suprahyoid muscles DETAILED DESCRIPTION OF THE INVENTION

[0010] A sensitivity enhancing device according to a first embodiment of the present invention includes an actuator that generates noise vibrations and applies the noise vibrations to the head and neck skin or tongue of a living body. According to this embodiment, applying the noise vibrations to the head and neck skin or tongue of a living body can improve the sensory function of the oral cavity or pharynx.

[0011] In the second embodiment of the present invention, in the sensitivity improving device according to the first embodiment, noise vibration is applied to the skin under the jaw of a living body. According to this embodiment, by applying noise vibration to the skin under the jaw of a living body, the sensory function of the oral cavity or pharynx can be improved.

[0012] In the third embodiment of the present invention, noise vibration is applied from above the suprahyoid muscles of a living body in the sensitivity improving device according to the first embodiment. According to this embodiment, by applying noise vibration from above the suprahyoid muscles of a living body, the sensory function of the oral cavity or pharynx can be improved.

[0013] A fourth embodiment of the present invention is a sensitivity enhancement device according to the first embodiment, further comprising a threshold setting means for setting the vibration intensity of noise vibration, wherein the threshold setting means applies different vibration intensities to the wearer, prompts the wearer to input the stimulus vibration intensity at which the noise vibration begins to be felt and the stimulus vibration intensity at which the noise vibration is no longer felt, and sets the wearer's unique threshold from the input stimulus vibration intensity and stimulus vibration intensity. If the noise vibration is too large, the original signal will be buried in the noise vibration, and if it is too weak, no effect will be achieved because the threshold will not be exceeded even if the noise vibration is added. However, according to this embodiment, it is possible to apply a noise vibration that is appropriate for the wearer or a noise vibration that is appropriate for the wearing, thereby achieving the effect of improving sensory function through a phenomenon called stochastic resonance or stochastic resonance.

[0014] The fifth embodiment of the present invention is a sensitivity enhancement device according to the first embodiment, in which a white noise vibration having the same vibration intensity at all vibration frequencies is used as the noise vibration. According to this embodiment, noise vibration of any magnitude can be applied by changing the value of the noise intensity σ.

[0015] The sixth embodiment of the present invention is the sensitivity improvement device according to the fifth embodiment, in which the vibration frequency band of the white noise vibration is set to a range of 350 Hz or less. According to this embodiment, the vibration frequency to which the device reacts most sensitively can be used.

[0016] The seventh embodiment of the present invention is directed to enhancing the tactile sensitivity of the tongue in the sensitivity enhancing device according to the first embodiment. This embodiment is expected to enhance the tactile sensitivity of the tongue, thereby improving the recognition of food and the function of sending food to the pharynx. [Example]

[0017] An embodiment of the sensitivity enhancing device of the present invention will be described below. FIG. 1 is a diagram showing the configuration of a sensitivity enhancement device according to an embodiment of the present invention. The sensitivity enhancing device in this embodiment comprises a noise vibration generating means 10, a threshold setting means 20, a mounting means 30, and an input means 40.

[0018] The noise vibration generating means 10 includes a signal generating unit 11 that generates a noise vibration signal, a D / A converter 12 that converts the noise vibration signal generated by the signal generating unit 11 into an analog signal, an amplifier 13 that amplifies the converted analog signal, and an actuator 14 that generates noise vibration and applies it to the skin of a living body. A piezoelectric actuator can be used as the actuator 14. The attachment means 30 attaches the sensitivity enhancing device to the living body by bringing the actuator 14 into contact with the skin of the living body. The noise vibration from the actuator 14 is applied to the skin of the head and neck or to the tongue of the living body.

[0019] The threshold setting means 20 sets the vibration intensity of the noise vibration, and sets the wearer's inherent threshold, and further adjusts this inherent threshold to a vibration intensity that improves tactile sensitivity. The threshold setting means 20 includes a storage means 21, a vibration intensity changing means 22, and a specific threshold adjusting means 23. The threshold setting means 20 applies different vibration intensities to the wearer using the vibration intensity changing means 22, and has the wearer input, via the input means 40, the stimulus vibration intensity at which the wearer begins to feel noise vibration and the non-stimulus vibration intensity at which the wearer no longer feels noise vibration. In other words, the wearer distinguishes between when they begin to feel noise vibration and when they no longer feel noise vibration, and inputs these values ​​via the input means 40. The input stimulus vibration intensity and non-stimulus vibration intensity are stored in the storage means 21. The threshold setting means 20 sets the wearer's inherent threshold from the stored stimulation vibration intensity and non-stimulation vibration intensity. The set unique threshold value of the wearer is stored in the storage means 21. The inherent threshold adjusting means 23 adjusts the vibration intensity to obtain the SR effect using the wearer's inherent threshold that has been set. The noise vibration generating means 10 generates noise vibration with the vibration intensity adjusted by the inherent threshold adjusting means 23.

[0020] FIG. 2 is a diagram showing an image of how the sensitivity improving device in this embodiment is attached. The sensitivity enhancing device in this embodiment brings the actuator 14 into contact with the skin of the living body by means of the attachment means 30. The head and neck region includes the anterior neck region, lateral neck region, submandibular region, chin region, and sub-ear region. It is preferable to apply the noise vibrations to the skin under the jaw of the living body, and the attachment means 30 brings the actuator 14 into contact with the skin under the jaw of the living body. By bringing the actuator 14 into contact with the skin under the jaw of the living body in this way, the noise vibrations can be applied to the suprahyoid muscles of the living body located directly below the tongue. The structure of the suprahyoid muscles is as shown in Figure 20. In this way, by applying noise vibrations to the skin of the head and neck or to the tongue of a living body, the sensory function of the oral cavity or pharynx can be improved. Although FIG. 2 shows a case where the noise vibration is applied to the skin below the jaw of the living body, when the noise vibration is applied to the tongue, an intraoral appliance such as a mouthpiece is used as the attachment means 30.

[0021] FIG. 3 is a diagram showing a method for generating noise vibrations in the sensitivity enhancing device in this embodiment. The white noise required to generate stochastic resonance (SR) is noise that has the same intensity at all vibration frequencies, and can be generated, for example, by the Box-Muller method shown in Figure 3(a). Figure 3(b) shows an image of the case where the noise intensity σ is 1.0, but as shown in Figure 3(c), by changing the value of the noise intensity σ, it is possible to apply white noise vibration of any magnitude. Each human being has a vibration frequency band to which they are most sensitive. To ensure that the vibration frequency band is one that humans can perceive sensitively on the skin, the device is equipped with a function that applies a low-pass filter to the generated white noise vibration so that the vibration frequency band is 0 to 350 Hz, taking into account the response frequency characteristics of tactile receptors.

[0022] FIG. 4 is a diagram showing a method for setting a threshold value of the sensitivity improving device in this embodiment. In order to improve sensory function through stochastic resonance (SR), it is necessary to apply white noise vibrations of an appropriate magnitude. If the applied noise vibration is too large, the original signal will be buried in the noise vibration, and if it is too weak, the noise vibration will not exceed the threshold even when added, and no effect will be seen. To set the wearer's specific threshold, it is necessary to know the threshold, which differs from person to person. Figure 4(a) shows the results of applying different vibration intensities (stimulus intensity σ) to the wearer and asking them to input the stimulus vibration intensity (Yes) at which they began to feel noise vibration and the non-stimulus vibration intensity (No) at which they no longer felt noise vibration. The stimulation intensity σ is gradually increased from a low level at which the wearer does not perceive noise vibrations, and when the stimulation intensity σ reaches a level at which the wearer perceives noise vibrations, the intensity of the noise vibrations is reduced, and when the stimulation intensity σ reaches a level at which the wearer does not perceive noise vibrations, the intensity of the noise vibrations is increased again. By repeating this process, the wearer's inherent threshold can be obtained. Note that the inherent threshold of a wearer will differ depending on the wearing position, wearing method, actuator type, etc., even for the same wearer, so it is preferable to set the inherent threshold each time the device is worn. FIG. 4(b) shows the input means 40 for inputting the stimulus vibration intensity (Yes) at which the noise vibration begins to be felt and the stimulus vibration intensity (No) at which the noise vibration is no longer felt, and also shows the input results. The wearer's inherent threshold σ th Set.

[0023] (verification) FIG. 5 shows the measurement of tactile sensitivity. Tactile sensitivity verification When white noise vibration is presented, it is necessary to confirm whether the tactile sensitivity of the tongue is improved by stochastic resonance (SR) and to what extent. Therefore, to determine whether sensitivity has changed, we use the threshold (the minimum perceptible level) as a criterion. Specifically, we measure and compare the tactile threshold of the tongue to sine wave vibration, expressed by the equation shown in Figure 5(a), when white noise vibration is presented and when it is not presented. If the tactile threshold decreases, we consider the tactile sensitivity to have improved. Furthermore, we examine how the noise intensity σ of the equation shown in Figure 3(a) affects the change in the tactile sensitivity of the tongue by changing the vibration strength of the actuator 14 and presenting it. We also examine the vibration intensity at which tactile sensitivity is most improved.

[0024] The tactile threshold was measured using the up-and-down method, which has also been used in previous studies. Specifically, the measurement procedure begins with an ascending series of vibration stimuli, gradually increasing in intensity from an imperceptible intensity. When the subject reports feeling the vibration, the measurement cycle returns to a predetermined cycle, and then gradually decreases in intensity. This cycle is repeated until a predetermined number of cycles are reached. Finally, the average of the stimulus intensities at the cycle points is defined as the threshold. An example of the defined threshold measurement is shown in Figure 5(b). A cross (×) in Figure 5(b) indicates that the vibration stimulus was not perceived, while a circle (○) indicates that it was perceived. In this example, the cycle points are the five cycles from the fourth to the eighth trials, and the average of these five stimulus intensities, 6.8, is the threshold. Furthermore, the tactile threshold for white noise vibration was measured by varying the noise intensity σ in the equation shown in Figure 3(a), and the tactile threshold for sine wave vibration was measured by varying the amplitude A in the equation shown in Figure 5(a).

[0025] (Verification 1: Verification of the stochastic resonance (SR) effect caused by noise vibration on the tip of the tongue) In experiments using noise vibrations on the tongue tip, white noise vibrations are presented to the tongue tip to verify whether stochastic resonance (SR) occurs in the tongue. Furthermore, because the dorsum of the tongue, the anterior part of the tongue, is primarily involved in recognizing the physical properties, shape, and position of food taken into the oral cavity, the dorsum of the tongue is used as the location for verifying the effect of improving tactile sensitivity. The verification location can also be the tongue tip instead of the dorsum of the tongue, or the posterior third of the tongue (a region innervated by the same glossopharyngeal nerve as the pharynx, which is involved in eliciting the swallowing reflex). It is also possible to examine the effect of SR on the entire tongue and to examine the spatial distribution of tactile sensitivity across the entire tongue and the changes in that distribution due to SR.

[0026] Vibration presentation jig To evaluate changes in the tactile sensitivity of the tongue, this experiment presented sine wave vibrations to the dorsum of the tongue and compared the tactile threshold for sine wave vibrations at that site with and without white noise and for each vibration intensity. Furthermore, white noise vibrations must be presented to generate stochastic resonance (SR). Therefore, a jig is required to present these vibrations to the tongue, and safety and hygiene considerations must be considered for use within the oral cavity. Therefore, in this experiment, we fabricated components made of biocompatible resin that can be autoclaved, and attached an actuator 14 to the jig, enabling vibration presentation to the tongue.

[0027] Stochastic Resonance (SR) Jig An overview of the stochastic resonance (SR) jig is shown in Figure 6. The jig shown in Figure 6(a) is used to present white noise vibration to the tip of the tongue, and in order to present the noise vibration efficiently, it has a depression that can be touched over a wide area of ​​the tongue tip. In addition, as shown in Figures 6(b) and 6(c), a small protrusion that can be felt with the tip of the tongue is attached to the center of the jig, which serves as a reference point for aligning the protrusion with the center of the tongue tip.

[0028] Sensitivity test fixture An overview of the sensitivity inspection jig is shown in Figure 7. Figure 7(a) is a diagram showing the shape of the sensitivity inspection jig, and Figure 7(B) is a diagram showing the jig in use. The sensitivity test jig presents sine wave vibrations to the dorsum of the tongue. Considering safety and hygiene in the oral cavity, it is necessary to be able to present vibrations to the dorsum of the tongue without inserting the actuator 14 into the oral cavity. For this reason, the jig was designed so that the actuator 14 was fixed outside the oral cavity and the entire jig was vibrated to present vibrations to the dorsum of the tongue, as shown in Figure 7(b).

[0029] method An overview of the experimental environment is shown in Figure 8. Figure 8(a) shows the measurement environment, and Figure 8(b) shows the presentation position of the noise vibration. In this experiment, the white noise vibration was presented at the tip of the tongue, and the tactile threshold for sine wave vibration at the dorsum of the tongue (30 mm from the tip of the tongue) was measured. To present the vibration to the tip of the tongue, an actuator (SR actuator) 14 that applies white noise as vibration and an SR jig were used. To present the vibration to the dorsum of the tongue, an actuator 14 that applies sine wave vibration and a sensitivity test jig were used. In addition, a dental mouth opener (bite block, Premium Plus Japan Co., Ltd.) was used to prevent the teeth from touching the jig, and headphones were worn to block the driving sound of the actuator 14 by playing white noise, so that the vibration could not be determined from the driving sound. First, the tactile threshold of the tongue tip for white noise vibration (subject's specific threshold σ th Next, the tactile threshold of the dorsum of the tongue for sine wave vibration is measured. At this time, white noise vibration is presented to the tip of the tongue and sine wave vibration is presented to the dorsum of the tongue at the same time. The vibration intensity of the white noise vibration is ασ th The five conditions are (α = 0, 0.4, 0.6, 0.8, 1.0), and the tactile threshold of the tongue dorsum is measured at each vibration intensity in random order. th is no noise vibration, 1.0σ th is the vibration intensity when the tactile threshold of the tongue tip for white noise vibration is 100% (i.e., the intrinsic threshold σ th This means that the vibration intensity is The vibration frequency of the sine wave applied to the dorsum of the tongue was set to 100 Hz, taking into account the response frequency characteristics of the tactile receptors.Five young people (23.5±1.5 years old) participated in this experiment.

[0030] result The experimental results are shown in Figure 9. 9(a) shows the sensation threshold (the minimum amplitude A of the sine wave vibration that can be perceived) of the dorsum of the tongue when noise vibration is applied. th ), Figure 9(b) shows the case without noise vibration (0σ th ) when A th The sensory threshold is normalized to be 1. In both Figures 9(a) and 9(b), the smaller the vertical axis value, the better the tactile sensitivity, and the larger the value, the worse the sensory function. The horizontal axis represents the intensity of the presented white noise vibration. As shown in Figure 9(a) and (b), 1.0σ th Under the condition, the white noise vibration applied to the tongue tip was higher than the tactile threshold (specific threshold σ th ) and means the vibration intensity at the boundary between whether or not noise vibration can be perceived. Therefore, some subjects were able to perceive white noise vibration at the tip of the tongue, making it difficult to distinguish between white noise vibration and sine wave vibration, and therefore, accurate measurement of the tactile threshold at the dorsum of the tongue was not possible. On the other hand, 0.8σ th At this vibration intensity, the tactile sensitivity of the dorsum of the tongue was significantly improved. In this way, the wearer's specific threshold σ th Using ασ th By applying a vibration intensity of (for example, α=0, 0.4, 0.6, 0.8, 1.0), it is possible to find the vibration intensity conditions that will produce the SR effect, and by adjusting the specific threshold to the vibration intensity found, the noise vibration generating means 10 can generate noise vibrations that will produce the SR effect.

[0031] (Verification 2: Verification of the stochastic resonance (SR) effect caused by noise vibrations on the submandibular region of a living body) Stochastic Resonance (SR) Evoked by Noise Vibration from the Submandibular Region of a Living Body In this experiment, we simulate an actual eating situation and verify whether the tactile sensitivity of the dorsum of the tongue can be improved by applying noise vibration indirectly from the submandibular region, rather than by applying noise vibration to the tip of the tongue.

[0032] method An overview of the experimental environment is shown in Figure 10. In this experiment, the white noise vibration was presented to the anterior belly of the digastric muscle, one of the suprahyoid muscles, and the tactile threshold for sine wave vibration applied to the dorsum of the tongue (15 mm from the tip of the tongue) was measured. An SR actuator was used to present vibration to the anterior belly of the digastric muscle, and a sensitivity test actuator and sensitivity test jig were used to present vibration to the dorsum of the tongue. The vibration intensity of the white noise vibration was ασth (α=0, 0.4, 0.6, 0.8, 1.0, 1.2), the sine wave presented to the dorsum of the tongue was 100 [Hz], and other tactile threshold measurements and the experimental environment were carried out in the same manner as in the above experiment, and the results were also tested in the same manner as in the above experiment. Nine young people (23.3±1.3 years old) participated in this experiment.

[0033] result The experimental results are shown in Figure 11. (a) shows the sensation threshold (the minimum amplitude A of the sine wave vibration that can be perceived) of the dorsum of the tongue when noise vibration is applied. th ), Figure 11(b) shows the case without noise vibration (0σ th ) when A th The sensory threshold is normalized to be 1. In both Figure 11(a) and (b), the tactile threshold decreased under all conditions, especially at vibration intensity of 0.4σ. th The highest effect is seen at 0σ th It was shown that the tactile threshold was approximately 21% lower compared to the control group.

[0034] Consideration The change in tactile sensitivity of the dorsum of the tongue due to indirect application of noise vibration shown in Figure 11 is significantly different from the result when noise vibration is applied to the tongue shown in Figure 9. When noise vibration is applied, the change in tactile sensitivity of the dorsum of the tongue is significantly different from the result when noise vibration is applied (0 σ th ) the tactile threshold was lower in all conditions compared to the 0.4σ condition. th This was the case when a vibration intensity of .

[0035] Fig. 12 is an image diagram showing the attachment position of the sensitivity improvement device in Verification 3 and Verification 4. In Verification 3 and Verification 4, the stochastic resonance (SR) effect caused by noise vibration to the submandibular region of a living body was verified. As shown in Figure 12, in Verifications 3 and 4, an indirect method was adopted in which two piezoelectric actuators were placed in a V-shape under the submandibular region (corresponding to the suprahyoid muscles) to apply noise vibrations from the distal part so as not to interfere with eating and swallowing. The noise vibration was white noise with a low-pass filter of 350 Hz. The intensity of the noise vibration was set at the specific threshold σ, which allows the submandibular area to perceive the presence or absence of vibration. th is calculated for each subject using the up-down method, and then the characteristic threshold σ th Using this as a standard, we varied the intensity of the applied noise vibration to verify whether SR was expressed and the degree of its effect. The subjects were five young healthy individuals (22.2 ± 0.8 years old). The intensity of the noise vibration was measured at a sensory threshold of σ th 0 times (0σ th ,no noise vibration),0.6 times (0.6σ th ), 0.8 times (0.8σ th ), 1.0 times (1.0σ th The tongue sensory sensitivity was measured using static and dynamic tests.

[0036] (Verification 3: Static inspection (touch test) to verify the stochastic resonance (SR) effect) method In the static test, a touch test was performed using a SW tester to quantify the change in perceptual sensitivity due to SR when the tongue was stationary. The test point was 10 mm from the tip of the tongue, and records at each noise vibration intensity were measured using the up-down method. FIG. 13 is an explanatory diagram showing a static inspection method in Verification 3. As shown in Figure 13, the tactile threshold of the tongue was measured using filaments with four different hardness levels.

[0037] result The experimental results are shown in Figure 14. Figure 14(a) shows the tactile thresholds of five subjects according to noise vibration intensity. As shown in Figure 14(a), th For 0.6σ th , 0.8σ th , 1.0σ th In all cases, applying noise vibration intensity enabled the perception of smaller stimuli. FIG. 14(b) is a graph showing the change in tactile threshold due to noise vibration for each subject. In Fig. 14(b), the 0σth The tactile threshold at 1000 kJ / s and the tactile threshold at the lowest when noise vibration was applied are plotted. The further below the line indicating 1:1 on the vertical and horizontal axes, the greater the improvement in perceptual sensitivity. As shown in Figure 14(b), people with low perceptual sensitivity (A, B, D) showed large changes in tactile thresholds, while people with high perceptual sensitivity (C, E) showed small changes in tactile thresholds.

[0038] Consideration FIG. 15 is a diagram for explaining a consideration of the effect of Verification 3. Figure 15(a) is a graph showing the improvement in tactile sensitivity due to noise vibration for each subject, based on the results of Figure 14(b). The improvement shown in Fig. 15(a) is [minimum tactile threshold - 0σ th tactile threshold at 0σ th This is the value divided by the tactile threshold at As shown in Figure 15(a), the average of the five subjects was 0σ th This is an improvement of approximately 29% compared to the previous case. FIG. 15(b) is a graph showing the intensity of noise vibration that most improved tactile sensitivity. As shown in Figure 15(b), in Test 3, the characteristic threshold σ th The noise vibration intensity of 60% to 80% was found to be an appropriate intensity for improving the tactile sensitivity of the tongue.

[0039] (Verification 4: Verification of the stochastic resonance (SR) effect through dynamic testing (active touch testing)) method In the dynamic test, the sensory sensitivity of the tongue was evaluated using active touch. Active touch is a "combined sensation of superficial and deep sensation" that perceives the unevenness, shape, size, hardness, etc. of an object while moving the tongue, and is an important function in the formation of a bolus and its delivery to the pharynx. In Verification 4, in order to take active touch into account, several spherical jigs with different surface roughness were created and the tongue's ability to distinguish roughness was quantified.

[0040] 16 and 17 are explanatory diagrams showing the dynamic inspection method in Verification 4. As shown in Figure 16, the tactile threshold of the tongue was measured using seven types of spherical jigs. The spherical jig had an outer diameter of 27 mm, including the surface protrusions, and the spherical part was made of biocompatible resin, while the rod part was made of stainless steel. The surface roughness of the spherical jig was measured based on surface roughness (ISO 25178), with the number of summit point densities (Spd) per unit area being 5, 7.5, 10, 12.5, 15, 17.5, and 20 / cm. 2 Seven types of jigs (Fig. 1) were produced using a dental 3D printer to achieve the following. The larger the Spd value, the finer the surface irregularities.

[0041] As shown in Figure 17, in verification 4, one spherical jig was presented to the subject as a comparison target (correct value), and jigs that were perceived as having the same roughness as the correct value were divided into seven candidate groups (Spd = 5–20 particles / cm 2 ) were selected. The comparison was made between three types (Spd = 7.5, 12.5, 17.5 particles / cm 2 ), and the number of trials was three for each. The time limit was 45 seconds, and the subject was free to choose how to lick the comparison object and candidate group, the number of times, and the order in which they were licked. The order in which the comparison object and vibration intensity were presented was also random, and the correct answer rate was calculated for each noise vibration intensity. In all experiments, to suppress the interference of bias caused by the actuator's driving sound and visual information, the subjects wore eye masks and noise-canceling headphones, and white noise was played.

[0042] result The experimental results are shown in Figure 18. Figure 18(a) shows the correct answer rate for five subjects according to the noise vibration intensity. As shown in Figure 18(a), when there is no noise vibration, 0σ th For 0.6σ th , 0.8σ th The accuracy rate improved by applying noise vibration intensity at . FIG. 18(b) is a graph showing the change in the correct answer rate due to noise vibration for each subject. In Fig. 18(b), the 0σ thThe tactile threshold and the accuracy rate when noise vibration was applied are plotted, and the higher the values ​​on the vertical and horizontal axes are plotted above the line indicating 1:1, the more improved the perceptual sensitivity is. As shown in Figure 18(b), the subjects with low perceptual sensitivity (A, B, D) showed large changes in the correct answer rate, while the subjects with high perceptual sensitivity (C, E) showed small changes in the correct answer rate.

[0043] Consideration FIG. 19 is a diagram for explaining a consideration of the effect of Verification 4. FIG. 19(a) is a graph showing the improvement in tactile sensitivity due to noise vibration for each subject, based on the results of FIG. 18(b). The improvement shown in Figure 19(a) is [maximum correct answer rate - 0σ th Correct answer rate at [0σ th This is the value divided by the [correct answer rate in the test]. As shown in Figure 19(a), the average of the three subjects with low perceptual sensitivity (A, B, and D) was 0σ th This is an improvement of approximately 67% compared to the previous case. FIG. 19(b) is a graph showing the intensity of noise vibration that most improved the rate of correct answers for three subjects (A, B, D) with low perceptual sensitivity. As shown in Figure 19(b), in Test 4, the characteristic threshold σ th The noise vibration intensity of 60% to 80% was found to be an appropriate intensity for improving the tactile sensitivity of the tongue.

[0044] From the above, it became clear that by determining the intrinsic threshold for each subject and adjusting the stimulation intensity based on that vibration intensity, the tactile sensitivity of the dorsum of the tongue, which is important for forming a bolus and sending it into the pharynx, can be significantly improved by applying noise vibration from the submandibular region. This finding suggests that, when imagining a mealtime scenario, it is possible to improve the sensory function of the oral cavity and pharynx safely and hygienically without placing an actuator inside the body. In addition to white noise vibration, colored noise vibration, pink noise vibration, Brownian noise vibration, blue noise vibration, purple noise vibration, or gray noise vibration can also be used as noise vibration. Furthermore, the vibration frequency band is not limited to 0 to 350 [Hz]. [Industrial Applicability]

[0045] This invention can improve the tactile sensitivity of the tongue by using the stochastic resonance (SR) phenomenon. [Explanation of symbols]

[0046] 10 Noise vibration generating means 11 Signal generation unit 12 D / A converter 13 Amplifier 14 Actuators 20 Threshold setting means 21 Memory means 22 Vibration intensity change means 23 Intrinsic threshold adjustment means 30 Attachment means 40 Input Methods

Claims

1. A sensitivity enhancement device that uses a phenomenon called stochastic resonance to improve the sensory function of the oral cavity or pharynx, An actuator that generates noise vibrations is provided, The noise vibration is applied to the skin of the head and neck or to the tongue of the living body. A sensitivity-enhancing device characterized by:

2. The noise vibration is applied to the skin below the jaw of the living body. The sensitivity enhancing device of claim 1 .

3. The noise vibration is applied from above the suprahyoid muscles of the living body. The sensitivity enhancing device of claim 1 .

4. a threshold setting means for setting a vibration intensity of the noise vibration; In the threshold setting means, Applying different vibration intensities to the wearer; The wearer is prompted to input a stimulus vibration intensity at which the wearer begins to feel the noise vibration and a stimulus vibration intensity at which the wearer no longer feels the noise vibration; The wearer's inherent threshold is set based on the input vibration intensity with stimulation and the vibration intensity without stimulation. The sensitivity enhancing device of claim 1 .

5. As the noise vibration, a white noise vibration was used in which the vibration intensity was the same at all vibration frequencies. The sensitivity enhancing device of claim 1 .

6. The vibration frequency band of the white noise vibration is set to a range of 350 Hz or less. The sensitivity enhancing device of claim 5 .

7. Increases tactile sensitivity in the tongue The sensitivity enhancing device of claim 1 .

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