Sensory Systems

Sensory organs are ideally suited to detect environmental signals and have maximum sensitivity to various stimuli. Congenital hearing loss associated with dysfunction of hair cells, receptors that perceive sound, is the most common sensory deficit in humans, which in most cases is associated with genetic causes. The reason of the significant role of genetics lies in the complex structure of the auditory analyser, which contains various types of highly specialized cells and proteins that ensure the function of hair cells. Removal or replacement of even one nucleotide in the genes encoding these proteins can disrupt the function of the well-coordinated high-precision system of the inner ear. The purpose of this article is to acquaint readers with the molecular structure of the auditory analyser, the hereditary forms of hearing loss and the modern possibilities for diagnostics and prevention of hereditary hearing loss. The main problem of genetic causes is related to the fact that a child with congenital deafness is born from a pair of healthy parents whose pedigree is “not burdened”, but at the same time they are carriers of mutations in the genes responsible for hearing impairment. Such carriage can now be found out even before the birth of the child thanks to the use of next-generation sequencing (NGS) methods. Prevention of severe hereditary diseases is gradually being introduced into the practice of medical and genetic counselling of healthy couples when planning offspring, and the development of preimplantation diagnostics methods within the framework of in vitro fertilization (IVF) programs allows couples at risk of hereditary diseases to give birth to a healthy child.

Visual fields of mammals are characterized by a non-uniform visual acuity. They contain the best-vision zones of high resolution, whereas visual acuity is markedly lower in other parts of the visual field. To a large extent, the visual acuity depends on the concentration (a number per unit of area) of the retinal ganglion cells: the cell concentration is maximal in the best-vision zones. The best-vision zone

Central auditory disorders caused by age-related changes in peripheral hearing are often associated with age-related cerebrovascular accidents and cognitive impairment. The study compared the state of spatial and speech hearing in patients with chronic sensorineural hearing loss of the first degree and central auditory disorders, who had an acute cerebrovascular accident in their anamnesis and without it. Thirty elderly and senile patients were examined using a dichotic number test, a test of alternating binaural speech, a test of intelligibility of heterosyllabic words in silence and in noise, and the SHQ spatial hearing questionnaire. The speech test scores in the two groups of patients were close and did not differ significantly. The use of SHQ revealed significant differences in the examined groups. Correlations between SHQ and speech test scores were found; a strong relationship between speech and spatial hearing was found in the group with a history of acute cerebrovascular accident.

The paper presents the results of the initial testing of an express exercise complex for the development of motor coordination and postural control in children with auditory-speech impairments, aimed at their independent training with the support of their parents. The experimental group included 11 boys aged 4 to 7 years with sensorineural hearing loss of the 2nd and 3rd degree, two of whom used hearing aids. All children had difficulties in implementing coordinated movements and maintaining balance. To overcome them, an express training complex of 8 exercises was developed. Classes with children for 2 months were conducted by parents under the remote supervision of a physical rehabilitation specialist. Analysis of video materials obtained during the exercise before and after the training course showed positive changes in motor coordination and control over vertical posture in all children from the experimental group. The effectiveness of the complex was confirmed by reports prepared by parents who participated in the testing. They included additional information on the increase in communicative and speech activity in a significant part of children (73% in the group), as well as on the improvement of facial expressions. Positive results of testing, compactness of the complex and the possibility of its successful use in the format of independent work at home allow us to recommend it for use in the accompaniment and rehabilitation of children with hearing loss. Experimental assessment of the impact of the complex on motor coordination, balance and speech communication will be continued with an increase in the sample of hearing-impaired children, as well as preschoolers with other developmental disorders and manifestations of vestibular dysfunction.

It is known that the characteristics of spontaneous and evoked neuronal activity undergo changes over time. Typically, these changes are studied in acute and subacute experimental settings (e.g., pharmacological anesthesia, sleep-wake cycles). Long-term (weeks to months) recording of activity from identified neurons presents considerable methodological challenges. Consequently, questions regarding whether such changes occur, their nature, and their impact on the functional properties of neurons and neuronal populations require further investigation. To our knowledge, such studies at the level of olfactory bulb (OB) neurons–particularly in relation to the perception of ultra-low-concentration odorants–have not been conducted to date. The aim of this work was to perform a longitudinal study of the characteristics of spontaneous and evoked activity (triggered by presentation of sulcatone vapor at ultra-low concentration, ~1 × 10–15 g/cm³) in identified mitral/bundle (M/B) neurons of the OB. To achieve this, M/B neuron activity in the OB was periodically recorded (no more than once weekly) under xylazine-tiletamine-zolazepam anesthesia in 5 rats over at least 1 month (maximum: 121 days). Analysis showed that the characteristics of both spontaneous and odorant-evoked activity in M/B neurons remain stable over extended periods. This finding is significant for research aimed at developing biohybrid sensory system technologies for identifying target substances at ultra-low concentrations.

A digital infrared oculograph has been created to record eye movements. Miniature cameras with a frame rate of 500 Hz and a high spatial resolution of 1440 × 1080 px, located on spectacle frames, have been used. A technology for analyzing oculograms and algorithm for detecting the temporal characteristics of saccades and gaze fixations has been developed. The oculogram analysis algorithm has been matched with measurements of other physiological parameters. Discriminant analysis has been used for statistical processing and evaluation of the effectiveness of the developed algorithm. The technology has been tested based on a study of eye movements in 500 subjects. The duration and speed of eye movements have been measured in 16 experiments. Oculograms have been analyzed and sets corresponding to fixations and saccades have been obtained. An algorithm for automatic search for these parameters has been developed. The description of coordinates of the receiving matrices of video cameras and displays on which stimuli were presented has been matched for the spectacle-type oculograph. The algorithm for detecting the main temporal and spatial characteristics provides classification of saccades and gaze fixations (between saccades) when searching for a target by an operator in different conditions. Correction of coordinate systems is provided when the monitor and video camera reference points do not match, accounting for the offset and rotation of the video camera coordinate system relative to the monitor coordinate system is introduced. It is shown that the algorithm provides reliable results for subsequent analysis and interpretation of gaze movements with a recognition level of 0.97. The implemented algorithm is included in the Neurobureau hardware and software complex, which is in demand in management structures, in industry, transport, marketing and medicine, coordinated with other devices for physiological control of cognitive functions directly during the study, control and correction of operator actions when searching for a target.