Tongue movement state evaluation device, food evaluation method, and food evaluation device

Abstract

To provide a tongue movement state evaluation device capable of evaluating a tongue movement state during mastication, and a food evaluation method and a food evaluation device capable of evaluating the ease of mastication of food.SOLUTION: A tongue movement state evaluation device includes at least a suprahyoid muscle group myoelectric sensor 11 and either a masseter myoelectric sensor 12 or a temporalis myoelectric sensor 13. Information processing means 20 performs muscle synergy analysis using time-series biological signals obtained from the suprahyoid muscle group myoelectric sensor 11 and the masseter myoelectric sensor 12 or temporalis myoelectric sensor 13 during mastication, extracts three or more muscle synergies during mastication, excludes a mouth-opening muscle synergy associated with jaw-opening motion during mastication and a mouth-closing muscle synergy associated with jaw-closing motion during mastication, identifies a tongue movement muscle synergy associated with tongue movement during mastication from among the multiple muscle synergies, and evaluates the tongue movement state on the basis of the activity level (time pattern) of the identified tongue movement muscle synergy.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a tongue movement state evaluation device that evaluates the tongue movement state during mastication, a food evaluation method that uses synergy identified by the tongue movement state evaluation device, and a food evaluation device that evaluates the ease of mastication of food. [Background technology]

[0002] During the chewing phase of eating and swallowing, coordination between the mandible and tongue is important for bolus formation. Various methods for measuring mandibular movement have been proposed, and measurement is easy. However, there are no adequate techniques for evaluating intraoral tongue movement during mastication (bolus formation) other than videofluoroscopic swallowing, which involves invasive procedures such as radiation exposure. Therefore, there are no sufficiently developed non-invasive and safe techniques for assessing food from a biological perspective, such as detecting declines in tongue function or masticatory function (bolus formation ability), detecting the presence or absence of disease or dysfunction, or assessing ease of mastication (ease of bolus formation). Patent Document 1 proposes a method for evaluating eating and swallowing function that does not pose risks such as radiation exposure, can be performed at the bedside or in home medical care, and can improve the evaluation of eating and swallowing function by determining which parts move and how they move during eating and swallowing with a small number of swallowing attempts, and at which stage of eating and swallowing which muscles move in coordination with what level of activity, timing, and time. In Patent Document 1, muscle synergies are evaluated using nonnegative matrix factorization (NMF). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-142087 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 evaluates the swallowing function from the start to the end of swallowing, and does not evaluate the state of tongue movement during mastication.

[0005] The present invention aims to provide a tongue movement state evaluation device capable of evaluating the tongue movement state during mastication, and a food evaluation method and food evaluation device capable of evaluating the ease of mastication of food. [Means for solving the problem]

[0006] The tongue movement state evaluation device of the present invention described in claim 1 is a tongue movement state evaluation device that evaluates the tongue movement state during mastication, and includes at least a suprahyoid muscle myoelectric sensor 11 that detects biosignals of the suprahyoid muscles involved in opening, occlusion, and tongue movement, a masseter muscle myoelectric sensor 12 that detects biosignals of the masseter muscle involved in closing the mouth (including occlusion), or a temporalis muscle myoelectric sensor 13 that detects biosignals of the temporalis muscle, and an information processing means 20 detects the suprahyoid muscle myoelectric sensor 11, the masseter muscle myoelectric sensor 12, or the temporalis muscle myoelectric sensor 13 during mastication. The method is characterized in that muscle synergy analysis is performed using time-series biosignals from the temporalis muscle electromyography sensor 13, three or more muscle synergies during mastication are extracted, and by excluding the jaw opening muscle synergy associated with the action of opening the lower jaw during mastication and the jaw closing muscle synergy associated with the action of closing the lower jaw during mastication, a tongue motor muscle synergy associated with the tongue movement during mastication is identified from the multiple muscle synergies, and the tongue movement state is evaluated based on the activity (time pattern) of the identified tongue motor muscle synergy. The present invention as set forth in claim 2 is characterized in that in the tongue movement state evaluation device as set forth in claim 1, the muscle synergies during the three chewing movements are extracted by the muscle synergy analysis, and the jaw opening muscle synergies and the jaw closing muscle synergies are excluded, thereby identifying the tongue motor muscle synergies. The present invention as set forth in claim 3 is characterized in that, in the tongue movement state evaluation device as set forth in claim 1, the four muscle synergies during mastication are extracted by the muscle synergy analysis, and the tongue motor muscle synergies are identified by excluding the jaw opening muscle synergies, the jaw closing muscle synergies, and the masticatory muscle synergies associated with the clenching movement (bite movement) during mastication. The food evaluation method of the present invention described in claim 4 is characterized in that it evaluates the characteristics of food bolus formation using the jaw opening muscle synergy, the jaw closing muscle synergy, and the tongue motor muscle synergy identified by the tongue movement state evaluation device described in any one of claims 1 to 3. The food evaluation method according to claim 5 of the present invention is characterized in that, in the tongue movement state evaluation device according to claim 4, the feature of the food at the time of bolus formation is ease of mastication. The food evaluation device of the present invention as set forth in claim 6 is a food evaluation device for evaluating the ease of mastication of food, and includes at least a suprahyoid muscle electromyogram sensor 11 for detecting biosignals of the suprahyoid muscles involved in opening, occlusion, and tongue movement, and a masseter muscle electromyogram sensor 12 for detecting biosignals of the masseter muscle involved in closing the mouth (including occlusion), or a temporalis muscle electromyogram sensor 13 for detecting biosignals of the temporalis muscle, and an information processing means 20 calculates the information during mastication from the suprahyoid muscle electromyogram sensor 11, the masseter muscle electromyogram sensor 12, or the temporalis muscle electromyogram sensor 13. a muscle synergy analysis using the time-series biosignals of the above-mentioned, extracting three to five muscle synergies during mastication, and excluding jaw opening muscle synergies associated with the action of opening the lower jaw during mastication and jaw closing muscle synergies associated with the action of closing the lower jaw during mastication, thereby identifying tongue motor muscle synergies associated with the tongue movement during mastication from the plurality of muscle synergies, and evaluating the ease of mastication of the food using the jaw opening muscle synergy, the jaw closing muscle synergy, and the tongue motor muscle synergy. [Effects of the Invention]

[0007] According to the present invention, tongue motor muscle synergies associated with tongue movement during mastication are identified from biological signals including mandibular movement, and the tongue movement state is evaluated based on the activity of the tongue motor muscle synergies, thereby enabling quantitative evaluation of the tongue movement state during mastication. Furthermore, according to the present invention, tongue motor muscle synergies associated with tongue movement during mastication can be identified from biosignals including mandibular movement, and the tongue movement state can be evaluated based on the activity of the tongue motor muscle synergies, thereby enabling evaluation of the characteristics of food bolus formation. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing the configuration of a tongue movement state evaluation device according to an embodiment of the present invention. [Figure 2] Muscle synergy analysis [Figure 3] Diagram showing where to wear the EMG sensor [Figure 4] Figure showing the sEMG signal during measurement and the associated changes in the trajectory of the mandible and the magnitude of tongue movement due to optical flow. [Figure 5] Diagram showing three muscle synergies based on synergy analysis [Figure 6] Diagram showing four muscle synergies based on synergy analysis [Figure 7] Graph of muscle synergy during mastication of dried squid [Figure 8] Muscle synergy graph when chewing a cookie [Figure 9] Muscle synergy graph when chewing sweet potato [Figure 10] Muscle synergy graph when chewing meatballs [Figure 11] Graph of muscle synergy during peanut chewing [Figure 12] Graph showing tongue movement during chewing for different foods DETAILED DESCRIPTION OF THE INVENTION

[0009] The tongue movement state evaluation device according to the first embodiment of the present invention includes at least an electromyographic sensor for suprahyoid muscles that detects biosignals of the suprahyoid muscles involved in opening, occlusion, and tongue movement, and an electromyographic sensor for masseter muscles that detects biosignals of the masseter muscles that are involved in closing the mouth (including occlusion) or an electromyographic sensor for temporalis muscles that detects biosignals of the temporalis muscles. The information processing means performs muscle synergy analysis using time-series biosignals from the electromyographic sensor for suprahyoid muscles and the electromyographic sensor for masseter muscles or the electromyographic sensor for temporalis muscles during mastication to extract three or more muscle synergies during mastication and excludes jaw opening muscle synergies associated with the jaw opening movement during mastication and jaw closing muscle synergies associated with the jaw closing movement during mastication, thereby identifying tongue motor muscle synergies associated with tongue movement during mastication from among the multiple muscle synergies, and evaluates the tongue movement state based on the activity (time pattern) of the identified tongue motor muscle synergy. According to this embodiment, tongue motor muscle synergies associated with tongue movement during mastication are identified from biological signals including mandibular movement, and the tongue movement state is evaluated based on the activity of the tongue motor muscle synergies, thereby enabling quantitative evaluation of the tongue movement state during mastication.

[0010] In the second embodiment of the present invention, the tongue movement state evaluation device according to the first embodiment extracts three muscle synergies during mastication by muscle synergy analysis, and specifies tongue motor muscle synergies by excluding jaw opening muscle synergies and jaw closing muscle synergies. According to this embodiment, tongue motor muscle synergies can be easily specified, and the tongue movement state during mastication can be quantitatively evaluated.

[0011] The third embodiment of the present invention is a tongue movement state evaluation device according to the first embodiment, which extracts four muscle synergies during mastication by muscle synergy analysis, and specifies tongue motor muscle synergies by excluding jaw opening muscle synergies, jaw closing muscle synergies, and masticatory muscle synergies associated with clenching (biting) during mastication. According to this embodiment, tongue motor muscle synergies can be easily specified, and the tongue movement state during mastication can be quantitatively evaluated.

[0012] The food evaluation method according to the fourth embodiment of the present invention evaluates the characteristics of food at the time of bolus formation by using jaw opening muscle synergies, jaw closing muscle synergies, and tongue motor muscle synergies identified by the tongue movement state evaluation device according to any one of the first to third embodiments. According to this embodiment, the characteristics of food at the time of bolus formation can be evaluated.

[0013] The fifth embodiment of the present invention is a food evaluation method according to the fourth embodiment, in which the characteristics of a food when a food bolus is formed are determined as ease of mastication. According to this embodiment, the differences between foods with different ease of mastication can be evaluated from tongue motor muscle synergy.

[0014] A food evaluation device according to a sixth embodiment of the present invention includes at least an electromyographic sensor for the suprahyoid muscles that detects biosignals of the suprahyoid muscles involved in opening, occlusion, and tongue movement, and an electromyographic sensor for the masseter muscles that detects biosignals of the masseter muscles that are involved in closing the mouth (including occlusion) or an electromyographic sensor for the temporalis muscles that detects biosignals of the temporalis muscles. An information processing means performs muscle synergy analysis using time-series biosignals from the electromyographic sensor for the suprahyoid muscles and the electromyographic sensor for the masseter muscles or the electromyographic sensor for the temporalis muscles during mastication to extract three to five muscle synergies during mastication and excludes jaw opening muscle synergies associated with the opening movement of the lower jaw during mastication and jaw closing muscle synergies associated with the closing movement of the lower jaw during mastication to identify tongue motor muscle synergies associated with tongue movement during mastication from the multiple muscle synergies, and evaluates the ease of mastication of foods using the jaw opening muscle synergies, jaw closing muscle synergies, and tongue motor muscle synergies. According to this embodiment, tongue motor muscle synergies associated with tongue movement during mastication are identified from biosignals including mandibular movement, and the tongue movement state is evaluated based on the activity (time pattern) of the tongue motor muscle synergies, thereby enabling evaluation of the characteristics of food bolus formation. [Example]

[0015] An embodiment of the tongue movement state evaluation device of the present invention will be described below. FIG. 1 is a diagram showing the configuration of a tongue movement state evaluation device according to one embodiment of the present invention. The tongue movement state evaluation device in this embodiment has an electromyography sensor 10 that detects biosignals during mastication, information processing means 20 that analyzes the tongue movement state during mastication and the ease of mastication of food using the biosignals from the electromyography sensor 10, and output means 30 that outputs the evaluation results analyzed by the information processing means 20. The electromyography sensor 10 detects surface electromyography (sEMG) signals of multiple muscles. In the present invention, ease of mastication means the ease of bolus formation. Generally, ease of mastication can mean whether or not something is easy to chew, but in the present invention, the ease of mastication is used as the ease of bolus formation, i.e., the ease of bolus formation, because it can be seen that the greater the amount of tongue movement, the more tongue movement was required to form the bolus, and the smaller the amount of tongue movement, the less tongue movement was required to form the bolus. By observing the change in tongue movement from mastication to swallowing, it is also possible to make an evaluation such as, for example, that the amount of tongue movement is large at first and that almost no tongue movement is required immediately before swallowing.

[0016] Generally, the masticatory phase (during chewing) is said to consist of two phases: the opening phase, in which the mandible opens, and the closing phase, in which the mandible closes. The closing phase includes the occlusion phase, in which the chewing action is performed. The biosignals (sEMG signals) detected during the chewing phase include muscle signals related to mouth opening, mouth closing (including occlusion), and tongue movement. To detect muscle signals related to opening, closing (including occlusion), and tongue movement, sEMG signals from the suprahyoid muscles, infrahyoid muscles, temporalis muscle, buccinator muscle, and masseter muscle can be used, but it is difficult to detect only muscle signals related to tongue movement, and therefore it is effective to use at least a suprahyoid muscle electromyogram sensor 11 that detects biosignals of the suprahyoid muscles involved in opening, closing, and tongue movement, and a masseter muscle electromyogram sensor 12 that detects biosignals of the masseter muscle involved in closing (including occlusion), or a temporalis muscle electromyogram sensor 13 that detects biosignals of the temporalis muscle, as the myoelectric sensor 10. That is, in the tongue movement condition evaluation device of this embodiment, it is effective to use the suprahyoid muscle electromyogram sensor 11 and the masseter muscle electromyogram sensor 12, or the suprahyoid muscle electromyogram sensor 11 and the temporalis muscle electromyogram sensor 13.

[0017] The information processing means 20 performs muscle synergy analysis using time-series biosignals from the electromyography sensor 11 for the suprahyoid muscles and the electromyography sensor 12 for the masseter muscle or the electromyography sensor 13 for the temporalis muscle during mastication, extracts three or more muscle synergies during mastication, and excludes jaw opening muscle synergies associated with the action of opening the lower jaw during mastication and jaw closing muscle synergies associated with the action of closing the lower jaw during mastication, thereby identifying tongue motor muscle synergies associated with tongue movement during mastication from among the multiple muscle synergies, and evaluates the tongue movement state based on the activity (time pattern) of the identified tongue motor muscle synergy.

[0018] The biosignal receiving unit 21 receives time-series biosignals from the myoelectric sensor 11 for the suprahyoid muscles, the myoelectric sensor 12 for the masseter muscles, or the myoelectric sensor 13 for the temporalis muscles during chewing, and the received time-series biosignals are stored in the memory unit 22.

[0019] The muscle synergy analysis unit 23 performs muscle synergy analysis using the time-series biological signals stored in the storage unit 22. In the muscle synergy analysis, the number of muscle synergies to be extracted by dimensionality reduction is set in advance. The muscle synergies extracted by the muscle synergy analysis unit 23 are stored in the storage unit 22.

[0020] The tongue motor muscle synergy identifying unit 24 identifies tongue motor muscle synergies associated with tongue movement during mastication from among multiple muscle synergies. For example, if the muscle synergy analyzing unit 23 extracts three muscle synergies during mastication, the tongue motor muscle synergies are identified by excluding jaw opening muscle synergies and jaw closing muscle synergies. Alternatively, if the muscle synergy analyzing unit 23 extracts four muscle synergies during mastication, the tongue motor muscle synergies are identified by excluding jaw opening muscle synergies, jaw closing muscle synergies, and masticatory muscle synergies associated with clenching movements during mastication. The memory unit 22 stores whether each muscle synergy is a jaw opening muscle synergy, a jaw closing muscle synergy, a masticatory muscle synergy, or a tongue motor muscle synergy.

[0021] The tongue movement state evaluation unit 25 evaluates the tongue movement state based on the activity (time pattern) of the tongue motor muscle synergy identified by the tongue motor muscle synergy identification unit 24. For example, the tongue movement amount can be calculated by integrating the activity (time pattern) of the tongue motor muscle synergy, and the tongue movement state during mastication can be quantitatively evaluated. The muscle activity during mastication evaluated by the tongue movement state evaluation unit 25 is output by the output means 30.

[0022] The food feature evaluation unit 26 evaluates the features of food at the time of bolus formation using jaw opening muscle synergies, jaw closing muscle synergies, masticatory muscle synergies, and tongue motor muscle synergies. Note that the food feature evaluation unit 26 can also evaluate the features of food at the time of bolus formation using only tongue motor muscle synergies. The features of food at the time of bolus formation include, for example, ease of mastication.

[0023] In this way, the tongue movement state evaluation device in this embodiment can quantitatively evaluate the tongue movement state during mastication by identifying tongue motor muscle synergies associated with tongue movement during mastication from biological signals including mandibular movement and evaluating the tongue movement state based on the activity level of the tongue motor muscle synergies. Furthermore, the jaw opening muscle synergy, jaw closing muscle synergy, and tongue motor muscle synergy identified by the tongue movement state evaluation device in this embodiment can be used to evaluate the characteristics of food during bolus formation, and quantitatively evaluate the characteristics of food during bolus formation. Furthermore, the tongue movement state evaluating device in this embodiment can also be used as a food evaluation device by including the food feature evaluation unit 26. The food evaluation device in this embodiment has at least an electromyographic sensor 11 for the suprahyoid muscles and an electromyographic sensor 12 for the masseter muscle or an electromyographic sensor 13 for the temporalis muscle. The information processing means 20 performs muscle synergy analysis using time-series biosignals from the electromyographic sensor 11 for the suprahyoid muscles and the electromyographic sensor 12 for the masseter muscle or the electromyographic sensor 13 for the temporalis muscle during mastication to extract three to five muscle synergies during mastication and excludes jaw opening muscle synergies associated with the opening movement of the lower jaw during mastication and jaw closing muscle synergies associated with the closing movement of the lower jaw during mastication to identify tongue motor muscle synergies associated with tongue movement during mastication from the multiple muscle synergies, and evaluates the ease of mastication of foods using the jaw opening muscle synergies, jaw closing muscle synergies, and tongue motor muscle synergies. The food evaluation device of this embodiment identifies tongue motor muscle synergies associated with tongue movement during mastication from biological signals including mandibular movement, and evaluates the tongue movement state based on the activity level of the tongue motor muscle synergies, thereby enabling quantitative evaluation of the characteristics of food bolus formation.

[0024] Figure 2 shows muscle synergy analysis. In this embodiment, sEMG signals are measured from the multi-channel electrodes of the myoelectric sensor 10, and a signal separation technique called muscle synergy analysis is used. The concept of muscle synergy was introduced to elucidate the motor control system. Humans have multiple muscles and joints that operate to achieve a desired movement, and there are countless combinations of muscle output and joint angles. The concept of muscle synergy is based on the idea that each muscle is not controlled individually, but rather that each muscle module that works in coordination is controlled by control commands at a lower level than the number of muscles. For example, patterned movements such as walking and standing are composed of pre-defined muscle modules, and these movements are suitable for muscle synergy analysis. Furthermore, swallowing is a patterned movement composed of simple voluntary movements and reflex movements, and muscle synergy analysis allows the multiple movements that make up swallowing to be extracted as muscle synergies from sEMG signals. In this way, muscle synergy is the idea that multiple muscles move in an organized manner in response to a single command from the brain, and is evaluated by separating the observed signal into a spatial pattern, which is a weight matrix, and a temporal pattern, which is a basis signal, using non-negative matrix factorization.Muscle synergy analysis subdivides the numerous signals related to mastication into synergies, each of which has its own physiological meaning.

[0025] Figure 2 shows signal analysis for extracting muscle synergies during mastication from sEMG signals. Muscle synergies consist of spatial patterns that represent the relative activity ratio of each muscle and temporal patterns that represent the time-varying activity of each muscle. In muscle synergy analysis, it is assumed that muscle activity M is composed of the relative activity ratio of each muscle (hereafter referred to as spatial pattern W) and the time-varying activity (hereafter referred to as temporal pattern C). Then, muscle contraction is considered positive, M, W, and C are all treated as non-negative matrices, and non-negative matrix factorization (NMF), a dimensionality reduction technique, is used to decompose the muscle activity matrix M, which is a non-negative matrix, into non-negative matrices W and C.

[0026] Verification 1 In the analysis, three types of synergies related to each chewing cycle were extracted: opening, closing, and tongue movement. For the opening and closing synergy, we focused on the activity level in each phase defined by the mandibular movement trajectory. We evaluated the degree of agreement between the period in which the extracted synergy was active and the period during the opening and closing phases. Therefore, the evaluation axis was area quantity, and the synergy with the highest value when the integral value of the synergy in the period during each phase was calculated can be defined as the synergy corresponding to that phase. For the tongue synergy, we calculated the correlation coefficient with the change in the magnitude of tongue movement calculated by optical flow to evaluate the similarity between the synergy and the tongue movement trajectory.

[0027] Figure 3 shows where the EMG sensor is attached. In this verification, a four-channel small electrode was attached to the anterior neck as well as the masticatory muscles, so six electrodes were used to measure a total of 24 channels of myoelectric potential. Numbers "1" and "2" shown in Figure 3 indicate the attachment positions of the electromyographic sensor 11 for the suprahyoid muscles, number "5" shown in Figure 3 indicates the attachment position of the electromyographic sensor 12 for the masseter muscles, and number "6" shown in Figure 3 indicates the attachment position of the electromyographic sensor 13 for the temporalis muscles. The myoelectric sensors 10 were also attached at positions corresponding to the buccinator, masseter, and temporalis muscles. The masticatory muscles (muscles of mastication) comprise four muscles: the masseter, temporalis, medial pterygoid, and lateral pterygoid. The masticatory muscles are located deep within the head and are stronger than the facial muscles. They attach to the sides and base of the skull and the mandible. The masseter is the most superficial of the masticatory muscles and can be seen on the surface of the body when the teeth are closed. Measuring the sEMG signals of the masseter and temporalis muscles can provide detailed information about the strength and pattern of chewing movements and mandibular movement. The buccinator muscles move food within the mouth, hold food in place, and assist in chewing by moving and mixing food. We believe that simultaneously measuring the sEMG signals of these muscles can provide comprehensive information about symptoms and functions related to oral movements and mastication.

[0028] Tongue movement measurement using an ultrasound diagnostic device Tongue movement during chewing is recorded using an ultrasound diagnostic device, and the tongue movement is analyzed from the obtained images, allowing for a comparative evaluation of the sEMG signals and the time series of extracted synergies. Tongue movement extraction using optical flow To quantitatively evaluate tongue movement, optical flow was used to track corresponding points in the video and express the changes as vectors. By representing the movement of each peak cell as a vector, it is possible to capture and analyze the subtle movements of the tongue during chewing with high resolution, allowing for quantitative evaluation of tongue movement patterns, speed, direction, etc. Furthermore, the magnitude of tongue movement can be quantitatively evaluated by calculating the sum of the magnitudes of all detected vectors. Measurement of mandibular movement using a motion capture device Motion capture can capture complex movement patterns with high precision and acquire data in real time, allowing for comprehensive evaluation by simultaneously observing not only mandibular movement during chewing, but also the subtle movements of the associated muscles and head.

[0029] FIG. 4 shows the sEMG signal during measurement, the associated trajectory of the mandible, and the change in the magnitude of tongue movement (i.e., tongue movement amount) due to optical flow. Figures 4(a) to (f) show the sEMG signals from six locations, each representing one channel. Figure 4(a) shows the sEMG signal from the mylohyoid muscle, Figure 4(b) shows the sEMG signal from the geniohyoid muscle, Figure 4(c) shows the sEMG signal from the infrahyoid muscles, Figure 4(d) shows the sEMG signal from the buccinator muscle, Figure 4(e) shows the sEMG signal from the masseter muscle, and Figure 4(f) shows the sEMG signal from the temporalis muscle. Figures 4(g) to (i) show the trajectory of mandibular movement measured by a motion capture device, with Figure 4(g) being the x (horizontal) component, Figure 4(h) being the y (vertical) component, and Figure 4(i) being the z (front-to-back) component. Figure 4(j) shows the time-series values ​​(amount of tongue movement) obtained by analyzing image data acquired by an ultrasound diagnostic device using optical flow. Note that Figure 4 shows the results of one experiment on one subject.

[0030] Figure 5 shows three muscle synergies based on synergy analysis. In the graph showing muscle synergies, the vertical axis represents muscle activity and the horizontal axis represents time. The pink bar in Figure 5(b) indicates the mouth-opening movement, and the green bar in Figure 5(c) indicates the mouth-closing movement. The mouth-opening and mouth-closing movements were determined from the movement trajectory of the mandible measured by a motion capture device. As shown in Figures 5(b) and 5(c), jaw opening and closing movements show regular muscle activity, which indicates jaw opening and closing muscle synergy. In this way, when muscle synergies during three masticatory movements are extracted by muscle synergy analysis, two muscle synergies corresponding to jaw-opening and jaw-closing muscle synergies can be distinguished from the regularity of muscle activity. In Figure 5(a), the black waveform indicates muscle synergy, and the red waveform indicates the magnitude of tongue movement during mastication recorded using an ultrasound diagnostic device. As shown in Fig. 5(a), a high correlation is observed between the black and red waveforms. In the data shown in Fig. 5(a), a statistically significant difference was observed in the correlation coefficients of muscle synergies. Therefore, it was verified that the muscle synergy shown in Figure 5(a) is a tongue motor muscle synergy.

[0031] Figure 6 shows four muscle synergies based on synergy analysis. In the graph showing muscle synergies, the vertical axis represents muscle activity and the horizontal axis represents time. The pink bar in Figure 6(b) indicates the mouth-opening movement, the green bar in Figure 6(c) indicates the mouth-closing movement, and the yellow bar in Figure 6(d) indicates the bite movement. The mouth-opening movement, mouth-closing movement, and bite movement were determined from the movement trajectory of the mandible measured by a motion capture device. As shown in Figures 6(b), 6(c), and 6(d), jaw opening, jaw closing, and jaw clenching movements show regular muscle activity, which indicates jaw opening, jaw closing, and jaw clenching synergies, respectively. In this way, when the four muscle synergies during mastication are extracted by muscle synergy analysis, three muscle synergies corresponding to jaw opening, jaw closing, and masseter synergies can be distinguished from the regularity of muscle activity. In Figure 6(a), the black waveform indicates muscle synergy, and the red waveform indicates the magnitude of tongue movement during mastication recorded using an ultrasound diagnostic device. As shown in Fig. 6(a), a high correlation is observed between the black and red waveforms. In the data shown in Fig. 6(a), a statistically significant difference was observed in the correlation coefficients of muscle synergies. Therefore, it was verified that the muscle synergy shown in Figure 6(a) is a tongue motor muscle synergy.

[0032] Verification 2 Tongue movement state evaluation can lead to an individualized evaluation of mastication ease. In order to prevent swallowing disorders, it is important to adjust the mastication ease of meals, and mastication ease can be evaluated from three perspectives: food, food bolus, and human tongue movement. According to this embodiment, mastication ease can be evaluated from human tongue movement rather than from the physical properties of food or food bolus.

[0033] Figures 7 to 11 show three muscle synergies with different foods. Figure 7 shows muscle synergies during mastication of dried squid, Figure 8 shows muscle synergies during mastication of cookies, Figure 9 shows muscle synergies during mastication of sweet potatoes, Figure 10 shows muscle synergies during mastication of meatballs, and Figure 11 shows muscle synergies during mastication of peanuts. In each figure, (a) shows tongue motor muscle synergies, (b) shows jaw opening muscle synergies, and (c) shows jaw closing muscle synergies. Figures 7 to 11 were performed on the same subject. As shown in Figures 7 to 11, there are large differences in the temporal changes in muscle activity depending on the food. The activity of tongue motor muscle synergies can be used to evaluate the characteristics of food bolus formation. Furthermore, by adding jaw opening and closing muscle synergies to tongue motor muscle synergies, the characteristics of food bolus formation, especially the ease of mastication, can be evaluated. In this way, the extraction of the three synergies can be applied to assessing the masticatory function of individuals as well as the ease of mastication of individual foods.

[0034] Fig. 12 shows graphs of tongue movement during mastication for different foods, where Fig. 12(a) shows tongue movement in the first half of jaw-closing muscle synergy, Fig. 12(b) shows tongue movement in the second half of jaw-closing muscle synergy, and Fig. 12(c) shows tongue movement in the entire jaw-closing muscle synergy. Three subjects were tested. As shown in Figure 12, it can be seen that each food has its own distinctive difference in muscle activity. The volume and fragility of the food likely influenced the activity of the "cookies," which resulted in high tongue and mouth-closing activity. "Sweet potato" is easy to chew because it is in a paste form, and both tongue movement and mouth-closing movement are extremely weak. The "meatball" is loose and difficult to hold together, and its jaw-closing movement is more active than that of the "sweet potato." "Peanuts" are hard and difficult to clump together, and are highly active in both tongue and mouth movements. In this way, the jaw opening muscle synergy, jaw closing muscle synergy, and tongue motor muscle synergy can be used to evaluate the characteristics of food bolus formation, and the differences in ease of mastication between foods can be evaluated from the tongue motor muscle synergy.

[0035] Although the explanation using Fig. 5 shows a case where three muscle synergies are extracted, and the explanation using Fig. 6 shows a case where four muscle synergies are extracted, it is also possible to identify tongue motor muscle synergies associated with tongue movement during mastication by extracting five or more muscle synergies and excluding muscle synergies for identifiable movements and muscle synergies extracted as noise components from the multiple muscle synergies. [Industrial Applicability]

[0036] According to the present invention, the state of tongue movement during mastication can be evaluated, and the characteristics of food bolus formation can be evaluated. [Explanation of symbols]

[0037] 10 EMG sensor 11. Suprahyoid muscle electromyography sensor 12 Masseter muscle electromyography sensor 13 Temporal muscle electromyography sensor 20 Information Processing Means 21 Biological signal receiving unit 22 Memory section 23 Muscle Synergy Analysis Department 24 Tongue motor muscle synergy specific area 25 Tongue movement status evaluation unit 26 Food Characterization Department 30 Output Method

Claims

1. A tongue movement state evaluation device for evaluating a tongue movement state during mastication, comprising: The device has at least a suprahyoid muscle electromyogram sensor for detecting biosignals of the suprahyoid muscles involved in mouth opening, occlusion, and tongue movement, and a masseter muscle electromyogram sensor for detecting biosignals of the masseter muscle involved in mouth closing (including occlusion) or a temporalis muscle electromyogram sensor for detecting biosignals of the temporalis muscle, In the information processing means, performing a muscle synergy analysis using time-series biosignals from the suprahyoid muscle electromyogram sensor and the masseter muscle electromyogram sensor or the temporalis muscle electromyogram sensor during the mastication, and extracting three or more muscle synergies during the mastication; identifying tongue motor muscle synergies associated with tongue movement during mastication from the plurality of muscle synergies by excluding jaw opening muscle synergies associated with jaw opening movements during mastication and jaw closing muscle synergies associated with jaw closing movements during mastication; The tongue motor state is evaluated based on the activity (time pattern) of the identified tongue motor muscle synergy. A tongue movement status evaluation device characterized by:

2. extracting the muscle synergies during the three mastications by the muscle synergy analysis; Identifying the tongue motor muscle synergies by excluding the jaw opening muscle synergies and the jaw closing muscle synergies.

2. The tongue movement state evaluation device according to claim 1.

3. extracting the muscle synergies during the four mastications by the muscle synergy analysis; The tongue motor muscle synergy is identified by excluding the jaw opening muscle synergy, the jaw closing muscle synergy, and the masticatory muscle synergy associated with the clenching movement (occlusion movement) during mastication.

2. The tongue movement state evaluation device according to claim 1.

4. The tongue movement state evaluation device according to any one of claims 1 to 3 uses the jaw opening muscle synergy, the jaw closing muscle synergy, and the tongue motor muscle synergy to evaluate the characteristics of food bolus formation. A food evaluation method characterized by:

5. The characteristic of the food when the food bolus is formed is defined as ease of chewing. The food evaluation method according to claim 4 .

6. A food evaluation device for evaluating the ease of chewing of food, The device has at least a suprahyoid muscle electromyogram sensor for detecting biosignals of the suprahyoid muscles involved in mouth opening, occlusion, and tongue movement, and a masseter muscle electromyogram sensor for detecting biosignals of the masseter muscle involved in mouth closing (including occlusion) or a temporalis muscle electromyogram sensor for detecting biosignals of the temporalis muscle, In the information processing means, performing a muscle synergy analysis using time-series biosignals from the suprahyoid muscle electromyogram sensor and the masseter muscle electromyogram sensor or the temporalis muscle electromyogram sensor during mastication, and extracting three to five muscle synergies during mastication; identifying tongue motor muscle synergies associated with tongue movement during mastication from the plurality of muscle synergies by excluding jaw opening muscle synergies associated with jaw opening movements during mastication and jaw closing muscle synergies associated with jaw closing movements during mastication; The ease of chewing of the food is evaluated using the jaw opening muscle synergy, the jaw closing muscle synergy, and the tongue motor muscle synergy. A food evaluation device characterized by:

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