Spiral ganglion neuron (SGN) (SGN)

Spiral ganglion neurons (SGNs) are the primary afferent neurons of the auditory system, located within the Rosenthal canal of the cochlea (StatPearls). They are essential for hearing, acting as the critical link that transmits electrical signals from the sensory hair cells in the organ of Corti to the cochlear nucleus in the brainstem (PubMed). SGNs are primarily bipolar neurons, categorized into Type I neurons, which are myelinated and represent approximately 95% of the population, and Type II neurons, which are unmyelinated (Wikipedia). Degeneration of these neurons is a primary cause of permanent sensorineural hearing loss and auditory neuropathy, often resulting from aging, noise trauma, or exposure to ototoxic drugs such as cisplatin or aminoglycoside antibiotics (NIH). While SGNs are a cell population rather than a single molecular receptor, they are the focus of therapeutic interventions using neurotrophic factors (e.g., BDNF, NT-3) and gene therapies aimed at preserving neural connectivity (PubMed). Their survival and density are also critical determinants for the success of cochlear implants, which must directly stimulate the remaining SGN population to restore auditory function (Journal of Neuroscience).

Neuroprotection and synaptogenesis through activation of TrkB and TrkC receptor signaling pathways, modulation of glutamatergic signaling, and prevention of apoptosis in response to cochlear insult (PubMed; StatPearls).