Hironori Koyama

The tonotopic organization of the bullfrog amphibian papilla, an auditory organ lacking a basilar membrane

SummaryIntracellular dye-injection studies have revealed tonotopic organization of the bullfrog (Rana catesbeiana) amphibian papilla, an auditory organ lacking a basilar membrane or its equivalent. The best excitatory frequency (BEF) for auditory stimuli was identified in each of twenty-nine VIIIth-nerve afferent axons that subsequently were traced to their peripheral terminations at the sensory surface. Among those axons, the five with BEFs greater than 550 Hz all terminated in the caudalmost region of the papilla, the ten with the BEFs greater than 300 Hz and less than or equal to 550 Hz all terminated in the central region of the papilla, and the fourteen with BEFs equal to or less than 300 Hz all terminated in the rostralmost region of the papilla (Fig. 4). The tectorium is very much larger and presumably more massive under the low-frequency region of the papilla than it is under the high-frequency region (Fig. 1). Higher-frequency axons tended to innervate few (one to four) receptor cells, and low-frequency axons tended to innervate many (six or more). Higher-frequency axons often terminated in large claw-like structures that engulfed the basal portions of individual hair cells and in this way were morphologically similar to type I terminals in the inner ears of higher vertebrates.

Acute seismic sensitivity in the bullfrog ear

Single axons in the auditory/vestibular nerve of the American bullfrog exhibit by far the most exquisite sensitivity to substrate-borne vibration yet reported for a quadruped vertebrate. Earlier dye-injection studies revealed that these axons, which are relatively insensitive to airborne sound, originate at the saccular and lagenar maculae of the bullfrog inner ear. The more sensitive axons exhibited clear responses to vibratory sinusoids with peak accelerations as low as 0.005 cm/s2.

Mapping functionally identified auditory afferents from their peripheral origins to their central terminations

An afferent tiber in the Vlll th cramal nerve of a terrestrial vertebrate exhibits exquisitely sensitive and selective response to one of the following stimuli to the ear. hnear acceleration or tilt with respect to the gravitational vector; angular acceleration ; air-borne sound; and m some lower vertebrates at least, substrate-borne vlbranon 1,16. Among afferents responding to a given mode (e.g. angular acceleration), the stimulus response properties vary markedly from fiber to fiber. The degrees of freedom include the regularity of the response spike tram, the axis intercept 0.e. either the threshold level for response to weak stimuli or the zero-input firing rate), the constant of propomonahty (gain) between stimulus and response at higher stimulus levels, the degree of adaptation to sustained stlmuh, and the dynamics of adaptation :3.6,l~. Fibers exhlNting auditory or vibratory responses have frequency-dependent sensitlwties (tuning) and non-hneanties (two-tone suppression, difference tone stimulation, and the hke), with additional associated degrees of freedom, e.g. the sharpness of tuning (Q); frequency of greatest sensmvlty (center frequency); presence or absence of non-hnearitles z& Large-scale morphological dlstinctmns generally are presumed to account for the major stimulus-response divisions: e.g. presence of semicIrcular canals for sensitivity to angular acceleration; presence of otocomal membranes for sensitivity to hnear acceleratmn; t~lt or wbratmn; and presence of intimate connection to the sound-conducting apparatus of the middle ear for sensmvlty to air-borne sound. The morphological variations that account for the degrees of freedom within the major divisions, on the other hand, are not known. Candidates include morphological variations known to exist among the receptor cells (hair cells) 16, morphological variations known to exist among the acellular, gelatmoub structures (tectorml membranes, otoconial membranes, cupulae) lying over the

The Role of Toe-gap Force for the Evaluation of Falling Risk on the Elderly

This paper was proposed a toe-gap force measurement to estimate the lower limb muscular power. In the proposed method, the clipping toe-gap force is measured between the great toe and the digitus secundus. The toe-gap force in this situation, is muscles of the lower limb, which are supposed to have roles in the effort against falling. This study was used three experiments to determine whether or not the use of the toe-gap force measurement was useful from a practical viewpoint. First, the aging change in toe-gap force was examined by using the developed measuring device for 361 people included the elderly with physical weakness. Second, to examine the relation between the toe-gap force and falling, we were examined falling experience in a year for 82 healthy volunteers. Third, to examine the relation between muscular power and the toe-gap force, the results of the toe-gap force were compared to the result of the 10 m walking time for 153 healthy volunteers. We found following results: 1. the toe-gap force reflected the lower limb muscular power decrease rapidly from 65 years old. 2. The non-faller group demonstrated the factor of 1.3 greater toe-gap force compared with the faller group. The subjects who have less toe-gap force have experienced many falls. 3. the measured toe-gap force is closely related negative correlation to walking ability. This implies that the lower limb muscular power is reflected on the toe-gap force measurement. It is thus concluded that, the proposed method can be a practically useful method for evaluating quantitatively the lower limb muscular power of the elderly against fall.

Study of Touch Display in Surrounding Environmental Information Acquisition System for Deaf-blind Persons

Surrounding environmental information on the approach of the person etc. is transmitted to deaf-blind person by the interpreter and caregiver. However, when the interpreter and caregiver leave the side, the deaf-blind person comes not to be able to understand surrounding environmental information and feels insecurity. It is considered that the uneasiness can be reduced by presenting the distance and direction of the others from the deaf-blind person. To reduce this uneasiness, the surrounding environmental information acquisition system is developed in the study. This system is assuming use at home, since deaf-blind person spends a lot of time at home. The system is useful to understand the distance and direction of the others when the interpreter and caregiver are away from the side of deaf-blind person. The information are the direction and the distance from deaf-blind person to the others. The system can present the horizontal directions and the three distances, less than 1m, 1m to 2m, and 2m or more. Deaf-blind person can obtain the information via vibration of solenoid built in the touch display. In this paper, the appropriate shape of display and arrangement of presentation devices in the acquisition system for surrounding environment information for use were examined.

Research of Operation Method of Accessibility Equipment for Severely Handicapped Based on Voluntary Eye Blink

Serious disabled persons with motor disabilities such as amyotrophic lateral sclerosis and progressive speech impairment necessitates the use of an assistive communication aid. However, the disabled also need accessibility equipment to use the aids. This paper describes the research of the input method for the operation of the accessibility equipment, which is used by the serious disabled. The input method is based on electro-oculo-gram (EOG) that is controlled by the disabled. EOG is a technique for recording eye movements and eye blinks through electrodes placed around the eye. If the disabled can create several patterns of EOG waveforms, multiinput method is realized using these differences. We previously reported the technique to identify voluntary eye blink appeared on the EOG. Because voluntary eye blink is simple operation, we investigate the possibilities of utilization of consecutive blinks and gaze. 1) We examined the influences of the consecutive voluntary eye blinks by changing the blink intervals. We revealed that the blinks in interval at 95% when incorporating upward gaze and forward gaze. The results suggest that the incorporation of upward gaze and forward gaze has possibilities of realization of multi-input method.

Evaluation of Lower Limb Function of Age Change by Using Principal Component Estimation

Falling is one of the most common and serious problems because advancing age has been associated with muscle weakness, reduced cutaneous sensation and deterioration of walking ability. We have investigated relation between the fall and lower limb function by development of evolution methods for lower limb function using principal component analysis so far. This paper focuses on change of the value of the evaluation of lower limb function, such as value of walking ability, value of muscle strength of lower limb and value of flexibility of ankle. The subjects were 16 healthy young volunteers (mean ± S.D: 19.9 ± 0.6 years) and 10 healthy aged volunteers (mean ± S.D: 80.6 ± 6.1 years)) living in a special elderly nursing home. All subjects completed the informed consent procedures, and agreed to participate in this study. Measurement items related to lower limb function were selected from the items which we have ever used. Selected measurement items of function of lower are distance of extroversion of the toe, angle of flexion of the toe, maximum width of step, knee elevation, moving distance of greater trochanter, walking balance, toe-gap force and rotation range of ankle joint. The young group demonstrated the factor of 1.6 greater the assessment score of walking ability compared with the aged group. The young group demonstrated the factor of 1.4 greater the assessment score of muscle strength of lower limb compared with the aged group. The young group demonstrated the factor of 1.2 greater the assessment score of flexibility of ankle compared with the aged group. Parameters with significant differences between the elderly group and young group were selected and summarized by principal component analysis into lower ability assessment indices including walking ability and flexibility of ankle. The results suggested that it was possible to assess the lower limb function of aged and young numerically and to advise on their foot function.

Periodical measurement and evaluation of the ambulatory ability of aged under taking the medical foot care for one year

Many countries are gradually forming the aging society. Social concern is increasing in preventing fall of aged. Since 80% or more of hip fracture of aged were caused by falls, fall is one of the most serious problem in aged. The improvement in aged people’s walking ability is important for QOL, and fall prevention. In order to evaluate the improvement of the walking ability after medical foot care, the rotation range of ankle joint, the knee elevation, the walking balance, and the moving distance of greater trochanter were investigated during the walk. The subjects were 10 healthy volunteers (age range 73–96 years old, mean 80.3±6.0 years old, 3 males and 7 females) living in a special elderly nursing home. The coordinates of markers attached to the subject’s greater trochanter, knee joint, ankle, turberosity of fifth metatarsal bone, and heel were measured using digital camcorder during the walk. The data was analyzed statistically. As a result of performing medical foot care for one year, the rotation range of ankle joint, the knee elevation, and the walking balance during the walk were improved, also the moving of greater trochanter became stabilized. Because the medical foot care, which removes the interference from thickening of the nail, improved the rotation range of ankle joint, the knee elevation, the walking balance and the moving of greater trochanter, it seems that it is effective to improve the walking ability of the aged. It is suggested that the medical foot care of the aged has possibility to prevent the fall.