The auditory system is a fascinating sensory organ that overall, converts sound signals to electrical signals of the nervous system. Initially, sound energy is converted to mechanical energy via amplification processes in the middle ear, followed by transduction of mechanical movements of the oval window into electrochemical signals in the cochlear hair cells, and finally, neural signals travel to the central auditory system, via the auditory division of the 8th cranial nerve. The majority of people above 60 years have some form of age-related hearing loss, also known as presbycusis. However, the biological mechanisms of presbycusis are complex and not yet fully delineated. In the present article, we highlight ion channels and transport proteins, which are integral for the proper functioning of the auditory system, facilitating the diffusion of various ions across auditory structures for signal transduction and processing. Like most other physiological systems, hearing abilities decline with age, hence, it is imperative to fully understand inner ear aging changes, so ion channel functions should be further investigated in the aging cochlea. In this review article, we discuss key various ion channels in the auditory system and how their functions change with age. Understanding the roles of ion channels in auditory processing could enhance the development of potential biotherapies for age-related hearing loss.

The human entorhinal region consists of a number of areas; however, there is no generally accepted nomenclature for these cytoarchitectonic fields, and the designation of its constituent layers or strata is a matter of controversy. Here, we consider a hitherto neglected adjacent field, the preamygdaloid claustrocortex. Its medial subfield has a small common border with the rostromedial entorhinal region (width maximal 2 mm). Both fields are cytoarchitectonically rather similar. The rostromedial oral entorhinal field lacks ascending terminal islands. Its unusually small pre-alpha cells are arranged in a thin band or small clusters consisting of pyramidal, triangular, or polymorphic cells. The conspicuous chromophilic pre-beta cell clusters are composed of a variety of cell types, including groups of ‘immature’ spindle-shaped or bipolar nerve cells. Furthermore, a rare sulcus within the entorhinal region (central sulcus of the entorhinal region: observed in 4% of the 450 brains examined) is associated with an unusual lamination of the entorhinal layers in its wall and floor. Both the specific shape and arrangement of neurones in the claustrocortical-rostral entorhinal border region and the unusual lamination within the rare central entorhinal sulcus are regarded as reflecting neurodevelopmental disturbances characteristic of schizophrenic brains. In contrast, our observations in a large sample of serially sectioned brains from controls, schizophrenics, and patients suffering from neuropsychiatric diseases other than schizophrenia do not support this assumption.

No abstract

The slow accumulation of inflammatory biomarker levels in the body—also known as inflammaging—has been linked to a myriad of age-related diseases. Some of these include neurodegenerative conditions such as Parkinson’s disease, obesity, type II diabetes, cardiovascular disease, and many others. Though a direct correlation has not been established, research connecting age-related hearing loss (ARHL)—the number one communication disorder and one of the most prevalent neurodegenerative diseases of our aged population—and inflammaging has gained interest. Research, thus far, has found that inflammatory markers, such as IL-6 and white blood cells, are associated with ARHL in humans and animals. Moreover, studies investigating ion channels and mitochondrial involvement have shown promising relationships between their functions and inflammaging in the cochlea. In this review, we summarize key findings in inflammaging within the auditory system, the involvement of ion channels and mitochondrial functions, and lastly discuss potential treatment options focusing on controlling inflammation as we age.

No abstract