Function Of Sensory Organs Research Articles

COMPASS: Computations for Orientation and Motion Perception in Altered Sensorimotor States.

Reliable perception of self-motion and orientation requires the central nervous system (CNS) to adapt to changing environments, stimuli, and sensory organ function. The proposed computations required of neural systems for this adaptation process remain conceptual, limiting our understanding and ability to quantitatively predict adaptation and mitigate any resulting impairment prior to completing adaptation. Here, we have implemented a computational model of the internal calculations involved in the orientation perception system’s adaptation to changes in the magnitude of gravity. In summary, we propose that the CNS considers parallel, alternative hypotheses of the parameter of interest (in this case, the CNS’s internal estimate of the magnitude of gravity) and uses the associated sensory conflict signals (i.e., difference between sensory measurements and the expectation of them) to sequentially update the posterior probability of each hypothesis using Bayes rule. Over time, an updated central estimate of the internal magnitude of gravity emerges from the posterior probability distribution, which is then used to process sensory information and produce perceptions of self-motion and orientation. We have implemented these hypotheses in a computational model and performed various simulations to demonstrate quantitative model predictions of adaptation of the orientation perception system to changes in the magnitude of gravity, similar to those experienced by astronauts during space exploration missions. These model predictions serve as quantitative hypotheses to inspire future experimental assessments.

The microRNA-183/96/182 Cluster is Essential for Stereociliary Bundle Formation and Function of Cochlear Sensory Hair Cells

The microRNA (miR)-183/96/182 cluster plays important roles in the development and functions of sensory organs, including the inner ear. Point-mutations in the seed sequence of miR-96 result in non-syndromic hearing loss in both mice and humans. However, the lack of a functionally null mutant has hampered the evaluation of the cluster’s physiological functions. Here we have characterized a loss-of-function mutant mouse model (miR-183CGT/GT), in which the miR-183/96/182 cluster gene is inactivated by a gene-trap (GT) construct. The homozygous mutant mice show profound congenital hearing loss with severe defects in cochlear hair cell (HC) maturation, alignment, hair bundle formation and the checkboard-like pattern of the cochlear sensory epithelia. The stereociliary bundles retain an immature appearance throughout the cochlea at postnatal day (P) 3 and degenerate soon after. The organ of Corti of mutant newborn mice has no functional mechanoelectrical transduction. Several predicted target genes of the miR-183/96/182 cluster that are known to play important roles in HC development and function, including Clic5, Rdx, Ezr, Rac1, Myo1c, Pvrl3 and Sox2, are upregulated in the cochlea. These results suggest that the miR-183/96/182 cluster is essential for stereociliary bundle formation, morphogenesis and function of the cochlear HCs.

Self-reported cataracts in older adults in Ghana: sociodemographic and health related factors.

BackgroundChanges in function of sensory organs with increasing age have significant impact on health and wellbeing of older persons. This paper describes cataract, a chronic eye condition, self-reported among older adults in Ghana and the need for improving access to eye care services.MethodsThis work was based on the World Health Organization’s multi-country Study on global AGEing and adult health (SAGE), conducted in six countries including Ghana. SAGE Wave 1 in Ghana was conducted in 2007–2008 in a nationally representative sample of 4278 older adults, ≥ 50 years. Data were obtained on sociodemographic and health factors related to self-reported cataracts in older persons in Ghana. Data were analysed using descriptive measures (frequencies and proportions), chi-square test for associations in categorical outcome measures, and logistic regression for predictors of cataracts with SPSS version 21.ResultsOverall prevalence of self-reported cataracts among 4278 older adults in Ghana was 5.4%. Prevalence was proportionately higher for women (5.9%) than men (4.7%). Reported cataracts increased with age, among urban residents, in older adults living without partners and among those with the worse life satisfaction index. Older adults in lower income groups, poorly educated or living alone had difficulty seeking vision care services. Prevalence was 8.4% among persons with diabetes, 10.4% among hypertensives and 11.4% in persons with previous history of stroke. Among older persons who had ever used alcohol or tobacco, prevalence rates of reported cataracts were 5.7% and 4.9%, respectively. Logistic regression analysis indicated that increasing age, lower income status and self-reported hypertension were significantly associated with cataract among older adults in Ghana.ConclusionsCataract is prevalent in older people in Ghana with approximately 1 in 20 people aged 50 years or older reporting a previous diagnosis of cataract. As cataract surgery is restorative, a public health approach on behavioural modification, well structured national outreach eye care services (for rural residents), inclusion of basic eye health services at sub-district levels, increased family support and national health insurance for older persons is indicated.

Therapeutic Cooling

Stretch reflexes contribute to joint stiffness, but the effects of therapeutic cooling on these reflexes are unknown. Therapeutic cooling is frequently used in knee rehabilitation, for instance, after rupture of the anterior cruciate ligament. Cooling a joint can affect nerve conduction velocity and the function of sensory organs. Such changes in neuromuscular coupling could reduce knee stability and increase the risk of knee injury. The aim of the present study was to evaluate whether there are negative effects of knee cooling on the hamstring short and medium latency reflex responses or on the anterior tibia trajectory after mechanically induced tibia translation. In 15 healthy volunteers, the latency and size of short latency and medium latency reflex responses of hamstring muscles were assessed before and after 20 min of cold therapy of the knee joint as applied in rehabilitation. Reflex responses were evoked by a mechanically induced posterior-anterior tibia translation during standing. Reflexes were recorded by surface electromyography. The distance of anterior tibia motion and its velocity were assessed by potentiometric position transducer. Local cold therapy of the knee did not alter the latency or the size of short or medium latency responses. Also, the extent and the velocity of tibia translation were unchanged after knee cooling. Cold therapy does not seem to adversely influence the spinal reflexes of the hamstrings induced by anterior tibia translation. As neuromuscular coupling was not significantly affected, the cold therapy, as performed in the present study, is not likely to increase the risk of knee injury.