Postural instability occurs in some patients, and could be caused by a wide range of disorders, including neurological diseases, vestibular, visual and/or somatosensory dysfunctions, and musculoskeletal impairments. Problems in postural balance are commonly evaluated by posturography. Posturography is based on the principle of measuring changes in the center of pressure (COP), which represents the center point of the entire pressure exerted by the foot-ground contact surface on the force plate.

　Graphical representations called stabilograms and statokinesigrams are commonly obtained by measurement of the body sway using posturography. Stabilograms depict the time series of the COP displacement in either the anteroposterior or mediolateral direction, while statokinesigrams show the bidimensional COP trajectory on the ground extracted by the COP plot. Parameters derived from the COP trajectories to assess the patients' capabilities and performance to keep their balance include the sway path (cm), sway area (cm²), RMS (root mean square), and the Romberg quotient. A 0.2-Hz postural sway is a characteristic finding in unilateral vestibular disorders. Patients with anterior cerebellar lesions manifest a characteristic increase in sway activity in higher power spectra frequency bands, with a typical peak between 2 and 4Hz. Higher values of the Romberg quotient for variables of the sway path and area are seen in patients with vestibular or proprioceptive dysfunction. Posturography could assist in the differential diagnosis of balance disorders, and is a useful tool to evaluate the degree of postural imbalance and the effects of therapeutic interventions.

　Although the usefulness of posturography for the differential diagnosis of some diseases presenting with dizziness and balance disorders remains limited, several recent technological developments may offer the promise for improved diagnostic precision.

　The Video Head Impulse Test (vHIT) is an excellent technique for evaluating the function of the vertical semicircular canals, in addition to that of the lateral semicircular canals.

　vHIT to evaluate the function of the lateral semicircular canals involves the use of a single method (the neck is rotated on around the yaw plane), and there is little difference in result by the difference of the model the results are scarcely affected by differences in the model used. However, testing of the vertical semicircular canals by vHIT is more difficult, and the test method differs depending on the vHIT model used.

　There are two EyeSeeCam (ESC) methods used to determine the functioning of the vertical semicircular canals. One is to rotate in the pitch direction in head while watch the mark in the front of subject after 45 degrees made it rotate on yaw plane In the first, the head is abruptly rotated around the yaw axis up to 45 degrees in the pitch direction while the subject watches the mark in front of him. In the other, is head rotating on the head is rotated in the stimulation reception plane of each vertical semicircular canal while watch the mark in the front of subject the subject is asked to fix his/gaze on a mark in front of him. In generally, the examiner chooses the method that is easier to use. In Japan, ICS impulse (ICS) is also used for vHIT, besides ESC.

　Testing of the vertical semicircular canal function test by ICS is done by a single method to rotate in the pitch direction in head after 45 degrees made it rotate on yaw plane: the head is rotated around the pitch axis after it is rotated 45 degrees around the yaw plane.

　The results of testing of the vertical semicircular canal function could vary according to the device model used, and the method was unified so that we thought it would be desirable to unify the method of stimulation.

　As a preliminary step to unify the stimulation methods, we examined the effect of the difference between the two types of vertical semicircular canal stimulation methods by ESC.

　Subjects were healthy subjects without dysequilibrium. Using ESC, on the same day, the examiner examined the lateral semicircular canal function test and the vertical semicircular canal of two kinds. We compare with an obtained gains of the Vertical canal of two kinds. There were no differences in the results of testing of the vertical semicircular canal function between the two stimulation methods in the test of either the vertical or horizontal semicircular.

　In the elderly, falls can result in serious injuries, such as bone fracture, and also in loss of mobility and independence. Thus, with the aging of society, falls incur increasing costs impose a great cost burden on the public health system. In this short review, we introduce two related cases in experimental studies that are strongly correlated with falls: the first is the poorness of anticipatory postural adjustments (APAs) and the other is deficits of working memory in gait. There are two major aspects to postural control: compensatory postural reaction via sensory feedback mechanisms, and APAs via feed-forward mechanisms. The cerebellum has been suggested as being the brain region principally responsible for these postural control mechanisms. The first part of this review focuses on the deficiencies of APAs in a mouse model of spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease (MJD). Memory function deficits, often encountered in patients with Alzheimer's disease (AD), are believed as being among the important causes of increased tripping in elderly patients. The second part of this review focuses on the impairments of memory-guided limb movements while stepping over an obstacle in triple-transgenic (3 xTg) mice generated as a model of AD.