Research
The peripheral auditory system is a marvel of engineering, able to detect vibrations that occur at the molecular level, while also capable of detecting motion ten orders of magnitude greater without damaging the sensory cells.
Aside from this incredible dynamic range, the auditory system operates across 4 orders of magnitude in frequency. In accomplishing these amazing feats, a single set of sensory hair cells are used. These cells must survive for an entire lifespan.
Damage to these cells results in permanent hearing loss. Damage can occur from noise exposure, from toxic compounds, from genetic disorders and simply from normal wear and tear that accrues with aging.
The Ricci lab is interested in unraveling the molecular mechanisms of audition and in so doing identifying sites of intervention for the protection, preservation and restoration of hearing. To do this we use multiple novel technologies to explore the initial stages of the hearing process.
Our Goal
Identify the biophysical and molecular mechanisms most relevant to how sound information is processed and conveyed to the brain.
Develop technologies and therapies that will prevent, repair or replace damage to the inner ear that would result in hearing loss.
Four Areas of Research
Likely the most primitive sense used by all cells at some level. The inner ear has specialized this sense to operate at molecular dimensions across more than 4 orders of magnitude in frequency. The hair bundle of the sensory cell is the site of mechanotransduction. Here an unidentified ion channel responds to force exerted when the the hair bundle is deflected. The sensitivity in time and force are unmatched by any known mechanosensitive process. The dynamic range of hair cell mechanotransduction is dictated by an adaptation process.
Ongoing Projects
Each fiber innervating a hair cell makes one synaptic contact and this contact is responsible for conveying information about the frequency, intensity and timing of the hair cell response (1). These synapses and afferent fibers vary in their sensitivity and dynamic range (2) despite the only input being from a single hair cell with a uniform receptor potential. These synapses are also unique in being able to operate at high rates for extended periods of time without fatigue (3).
Ongoing Projects
Our five senses, sight, smell, taste, touch, and hearing are critical to our ability to interface with our environment, and we are using at least one of them every moment of every day. Recent in vivo approaches are elucidating multicellular signal processing at peripheral sensory organs in response to natural stimulation. Unfortunately, the auditory periphery (cochlea) is the one exception where technical hurdles have limited progress. Technical problems include: (i) the deep location within the temporal bone makes access difficult, (ii) the fluid-filled bony structure prevents imaging cellular activity, and (iii) existing surgical approaches for in vivo studies cause hearing loss. For these reasons, current in vivo approaches at the auditory periphery lack either cellular resolution or population information. We are developing an in vivo method for monitoring functional activity of multiple cochlear cells. Our method provides new opportunities for addressing important physiological and pathophysiological questions about how cochlear cells respond dynamically to sound stimuli and transfer information to the central nervous system.
