Bio

Riccardo Marrocchio received his BSc in Physics from the Sapienza University of Rome and his MSc in Physics from the University of Rome Tor Vergata. During his master, he had the opportunity to study and develop analytical and computational techniques to build mathematical models of complex biological systems, in particular of neuronal networks and the hearing system. He then joined the Institute of Sound and Vibration Research as a Ph.D. researcher at the University of Southampton. During his Ph.D., he worked on the development of a model of active cochlear micromechanics. After his PhD he continued at the University of Southampton joining the DigiTwin project as a Research Fellow, to work on the generalization of the biological feedback system of the cochlea to the design of control systems. To pursue his interests in hearing research, he joined Dr. Ó Maoiléidigh Lab, where he is working on stochastic fluctuations in hair bundles.

Honors & Awards

  • FGSA Award for Excellence in Graduate Research, American Physical Society (2021)

Boards, Advisory Committees, Professional Organizations

  • Member, Association for Research in Otolaryngology (2021 - Present)
  • Member, UK Acoustic Network (2020 - Present)
  • Member, American Physical Society (2020 - Present)

Professional Education

  • PhD, University of Southampton, Engineering and Physical Sciences (2022)
  • MSc, University of Rome Tor Vergata, Physics (2018)
  • BS, Sapienza University of Rome, Physics (2014)

Stanford Advisors

Contact

  • Academic
    rickmarr@stanford.edu
    University - Scholar Department: OHNS/Otolaryngology/Head & Neck Surgery Position: Postdoctoral Scholar

Additional Info

All Publications

  • Links regulate deflection fluctuations in the sensory cells of hearing. Physical review. E Marrocchio, R., Ó Maoiléidigh, D. 2025; 111 (3-1): 034403

    Abstract

    In our ears, inner-hair-cell hair bundles (IHBs) convert sound-induced forces into electrical signals, which are ultimately transmitted to the brain. An IHB comprises filamentous stereocilia emanating from the inner-hair-cell apex. Stereocilium deflections promote ion-channel opening and closing, causing receptor currents. This process is limited by fluctuations in the deflections, which compete with the sound signal, limiting the threshold of hearing. Stereocilia are viscoelastic structures and are coupled by fluid and viscoelastic links. The stiffness and damping of the system's components constrain stereocilium deflections, but increasing damping increases thermal deflection fluctuations. Competition between the constraining forces and thermal forces determines the deflection fluctuations. To better understand the deflection fluctuations, we build a mathematical model that relates the IHB's mechanical properties to deflection fluctuations. We find that the coherency of neighboring stereocilium deflections is less than 0.75 at frequencies corresponding to the physiological range of sound frequencies. The coherency for pairs of stereocilia decreases exponentially with the distance between them and is approximately zero between stereocilia at the center and edge of the IHB. We determine how the deflection fluctuations depend on the stiffness and damping of the links. In the absence of stiff links between stereocilia, neighboring stereocilia are weakly or negatively correlated in the physiological frequency range. We show how the sign of the coherency between stereocilium pairs is determined by the eigendecomposition of the deflection power spectral density matrix. Increasing the number of stereocilia in the IHB decreases the coherency between stereocilium pairs. The model also predicts that the threshold of hearing corresponds to IHB stereocilium deflections owing to sound of < 1.5 nm and that links of physiological stiffness decrease the threshold of hearing by at least 10dB. Predictions of the mathematical model are experimentally testable using recently developed techniques.

    View details for DOI 10.1103/PhysRevE.111.034403

    View details for PubMedID 40247582

  • Links regulate deflection fluctuations in the sensory cells of hearing Physical Review E Marrocchio, R., Ó Maoiléidigh, D. 2025; 111: 034403

    View details for DOI 10.1103/PhysRevE.111.034403

  • Forms of Longitudinal Coupling in the Organ of Corti Elliott, S., Marrocchio, R., Grosh, K. edited by Dong, W., Epp, B. AMER INST PHYSICS. 2024

    View details for DOI 10.1063/5.0189306

    View details for Web of Science ID 001226934800017

  • The coherency of motion of two stereocilia depends on the viscoelastic properties of their link 15th International Mechanics of Hearing Workshop Marrocchio, R., Ó Maoiléidigh, D. Zenodo. 2024

    View details for DOI 10.5281/zenodo.12613263

  • Wave motion in the longitudinally coupled cochlea Marrocchio, R., Grosh, K., Elliott, S. edited by Dong, W., Epp, B. AMER INST PHYSICS. 2024

    View details for DOI 10.1063/5.0197126

    View details for Web of Science ID 001226934800063

  • Inferring Excitatory and Inhibitory Connections in Neuronal Networks ENTROPY Ghirga, S., Chiodo, L., Marrocchio, R., Orlandi, J. G., Loppini, A. 2021; 23 (9)

    Abstract

    The comprehension of neuronal network functioning, from most basic mechanisms of signal transmission to complex patterns of memory and decision making, is at the basis of the modern research in experimental and computational neurophysiology. While mechanistic knowledge of neurons and synapses structure increased, the study of functional and effective networks is more complex, involving emergent phenomena, nonlinear responses, collective waves, correlation and causal interactions. Refined data analysis may help in inferring functional/effective interactions and connectivity from neuronal activity. The Transfer Entropy (TE) technique is, among other things, well suited to predict structural interactions between neurons, and to infer both effective and structural connectivity in small- and large-scale networks. To efficiently disentangle the excitatory and inhibitory neural activities, in the article we present a revised version of TE, split in two contributions and characterized by a suited delay time. The method is tested on in silico small neuronal networks, built to simulate the calcium activity as measured via calcium imaging in two-dimensional neuronal cultures. The inhibitory connections are well characterized, still preserving a high accuracy for excitatory connections prediction. The method could be applied to study effective and structural interactions in systems of excitable cells, both in physiological and in pathological conditions.

    View details for DOI 10.3390/e23091185

    View details for Web of Science ID 000699548000001

    View details for PubMedID 34573810

    View details for PubMedCentralID PMC8465838

  • Waves in the cochlea and in acoustic rainbow sensors WAVE MOTION Marrocchio, R., Karlos, A., Elliott, S. 2021; 106

    View details for DOI 10.1016/j.wavemoti.2021.102808

    View details for Web of Science ID 000685646900001

https://orcid.org/0000-0001-5269-4620