FEATURES OF STATOKINETIC STABILITY OF YOUNG GYMNASTS

The aim of the research is an assessment of statokinetic stability of young gymnasts in the annual training cycle by means of conventional stabilographic tests supplemented by vestibular response stimulation. Materials and methods. The research brought together young athletes aged 8-9 years engaged in gymnastics during the early stages of involvement. We used the «Stabilan 01-2» stabilographic hardware-software complex (ZAO OKB «Rhythm», Russia) for the assessment of a statokinetic function. Results. We have provided the analysis of stabilographic indicators of statokinetic stability of young gymnasts in the annual training cycle, as well as children who do not participate in sport. We have revealed statistically significant differences in statokinetic stability between the representatives of the examined contingent and statistically significant positive dynamics in the annual cycle in young athletes. We have demonstrated that application of tests stimulating vestibular response along with conventional approaches for assessing statokinetic resistance results in getting better resistance indicators of gymnasts compared to non-athletes. Conclusion. The research revealed that younger athletes have a higher level of maintaining body balance, especially in conditions of vestibular response stimulation compared to non-athletes. Consequently, it is necessary to complement conventional stabilographic tests with disturbing factors, for example vestibular response stimulation or local fatigue of the muscles of lower extremities.

Design and Application of a Novel Virtual Reality Navigational Technology (VRNChair)

This paper presents a novel virtual reality navigation (VRN) input device, called the VRNChair, offering an intuitive and natural way to interact with virtual reality (VR) environments. Traditionally, VR navigation tests are performed using stationary input devices such as keyboards or joysticks. However, in case of immersive VR environment experiments, such as our recent VRN assessment, the user may feel kinetosis (motion sickness) as a result of the disagreement between vestibular response and the optical flow. In addition, experience in using a joystick or any of the existing computer input devices may cause a bias in the accuracy of participant performance in VR environment experiments. Therefore, we have designed a VR navigational environment that is operated using a wheelchair (VRNChair). The VRNChair translates the movement of a manual wheelchair to feed any VR environment. We evaluated the VRNChair by testing on 34 young individuals in two groups performing the same navigational task with either the VRNChair or a joystick; also one older individual (55 years) performed the same experiment with both a joystick and the VRNChair. The results indicate that the VRNChair does not change the accuracy of the performance; thus removing the plausible bias of having experience using a joystick. More importantly, it significantly reduces the effect of kinetosis. While we developed VRNChair for our spatial cognition study, its application can be in many other studies involving neuroscience, neurorehabilitation, physiotherapy, and/or simply the gaming industry.

An Update on the Genetics of Usher Syndrome

Usher syndrome (USH) is an autosomal recessive disease characterized by hearing loss, retinitis pigmentosa (RP), and, in some cases, vestibular dysfunction. It is clinically and genetically heterogeneous and is the most common cause underlying deafness and blindness of genetic origin. Clinically, USH is divided into three types. Usher type I (USH1) is the most severe form and is characterized by severe to profound congenital deafness, vestibular areflexia, and prepubertal onset of progressive RP. Type II (USH2) displays moderate to severe hearing loss, absence of vestibular dysfunction, and later onset of retinal degeneration. Type III (USH3) shows progressive postlingual hearing loss, variable onset of RP, and variable vestibular response. To date, five USH1 genes have been identified:MYO7A(USH1B),CDH23(USH1D),PCDH15(USH1F),USH1C(USH1C), andUSH1G(USH1G). Three genes are involved in USH2, namely,USH2A(USH2A),GPR98(USH2C), andDFNB31(USH2D). USH3 is rare except in certain populations, and the gene responsible for this type isUSH3A.

Effects of galvanic mastoid stimulation in seated human subjects

The vestibular responses evoked by transmastoid galvanic stimulation (GS) in the rectified soleus electromyogram (EMG) in freely standing human subjects disappear when seated. However, a GS-induced facilitation of the soleus monosynaptic (H and tendon jerk) reflex has been described in few experiments in subjects lying prone or seated. This study addresses the issue of whether this reflex facilitation while seated is of vestibulospinal origin. GS-induced responses in the soleus (modulation of the rectified ongoing EMG and of the monosynaptic reflexes) were compared in the same normal subjects while freely standing and sitting with back and head support. The polarity-dependent biphasic responses in the free-standing position were replaced by a non-polarity-dependent twofold facilitation while seated. The effects of GS were hardly detectable in the rectified ongoing voluntary EMG activity, weak for the H reflex, but large and constant for the tendon jerk. They were subject to habituation. Anesthesia of the skin beneath the GS electrodes markedly reduced the reflex facilitation, while a similar, although weaker, facilitation of the tendon jerk was observed when GS was replaced with purely cutaneous stimulation, a tap to the tendon of the sternomastoid muscle, or an auditory click. The stimulation polarity independence of the GS-induced reflex facilitation argues strongly against a vestibular response. However, the vestibular afferent volley, insufficient to produce a vestibular reflex response while seated, could summate with the GS-induced tactile or proprioceptive volley to produce a startle-like response responsible for the reflex facilitation.