Brain Machine-Interfaces for Sensory Systems

  • Takashi Fujikado


A brain–machine interface (BMI) is a system that provides direct communication between the brain and an external device. It is designed to assist or repair human cognitive or sensory-motor functions. BMI research has studied sensory systems with a focus on the use of neuro-prosthetic devices to restore impaired hearing or vision.

Because of cortical plasticity, signals from implanted prostheses can be processed by the brain after rehabilitation.

The most widely used neuro-prosthetic devices are cochlear implants. A cochlear implant is activated by sound waves, and signals generated from it are filtered and decomposed into an envelope and a temporal structure, which are then converted into electrical energy. The electrical energy then stimulates the auditory nerve. Speech perception scores typically continue to improve during the first 3–12 months of implant use, suggesting that plastic changes occur in the brain to use sparse inputs better.

In retinal prosthesis, a camera takes an image, and a computer processes and transmits it wirelessly to the implant. The implant maps the image across an array of electrodes, and it stimulates neurons in the retina and sends neural signals to the visual cortex. The recipients then perceive a monochromatic pattern of dots.

Several approaches exist in rental prosthesis; epiretinal prosthesis in which electrode array is inserted under the retina, subretinal prosthesis in which electrode array is fixed on the retina, suprachoroidal prosthesis in which electrode array is inserted in the suprachoroidal space or in the sclera pocket.

Currently, the best decimal visual acuity achieved by retinal prosthesis is 0.037 by subretinal prosthesis. Even though the visual acuity is still poor, patients with implants can read large letters. To achieve an improvement of the quality of life for blind patients implanted with a retinal prosthesis, not only an improvement of surgical procedures and engineering advancement but also a development of effective rehabilitation are necessary.


Brain-machine interface Cochlear implant Retinal prosthesis Visual prosthesis 


  1. Brelen, M.E., Vince, V., Gerard, B., et al.: Measurement of evoked potentials after electrical stimulation of the human optic nerve. Invest. Ophthalmol. Vis. Sci. 51, 5351–5355 (2010)CrossRefGoogle Scholar
  2. Brindley, G., Rushton, D.: Implanted stimulators of the visual cortex as visual prosthetic devices. Trans. Am. Acad. Ophthalmol. Otolaryngol. 78, 741–745 (1974)Google Scholar
  3. da Cruz, L., Coley, B.F., Dorn, J., et al.: The Argus II epiretinal prosthesis system allows letter and word reading and long-term function in patients with profound vision loss. Br. J. Ophthalmol. 97, 632–636 (2013)CrossRefGoogle Scholar
  4. Dobelle, W.H.: Artificial vision for the blind by connecting a television camera to the visual cortex. ASAIO J. 46(1), 3–9 (2000)CrossRefGoogle Scholar
  5. Dobelle, W.H., Mladejovsky, M.G.: Phosphenes produced by electrical stimulation of human occipital cortex: and their application to the development of a prosthesis for the blind. J. Physiol. 243(2), 553–576 (1974)CrossRefGoogle Scholar
  6. Fujikado, T., Morimoto, T., Kanda, H.: Evaluation of phosphenes elicited by extraocular stimulation in normals and by suprachoroidal-transretinal stimulation in patients with retinitis pigmentosa. Graefes Arch. Clin. Exp. Ophthalmol. 245, 1411–1419 (2007)CrossRefGoogle Scholar
  7. Fujikado, T., Kamei, M., Sakaguchi, H., et al.: Testing of semi-chronically implanted retinal prosthesis by suprachoroidal-transretinal stimulation in patients with retinitis pigmentosa. Invest. Ophthalmol. Vis. Sci. 52, 4726–4733 (2011)CrossRefGoogle Scholar
  8. Helms, J., Mueller, J., Schon, F., et al.: Evaluation of performance with the COMBI 40 cochlear implant in adults: a multicentric clinical study. ORL J. Oto-Rhino-Laryngol. Relat. Spec. 59, 23–35 (1997)CrossRefGoogle Scholar
  9. Humayun, M.S., de Juan, E.J., Dagnelie, G., et al.: Visual perception elicited by electrical stimulation of retina in blind humans. Arch. Ophthalmol. 114(1), 40–46 (1996)CrossRefGoogle Scholar
  10. Humayun, M.S., Dorn, J.D., da Cruz, L., et al.: Interim results from the international trial of Second Sight’s visual prosthesis. Ophthalmology 119(4), 779–788 (2012)CrossRefGoogle Scholar
  11. Maynard, E.M., Nordhausen, C.T., Normann, R.A.: The Utah intracortical electrode array: a recording structure for potential brain–computer interfaces. Electroencephalogr. Clin. Neurophysiol. 102(3), 228–239 (1997)CrossRefGoogle Scholar
  12. Morimoto, T., Kanda, H., Kondo, M., et al.: Transcorneal electrical stimulation promotes survival of photoreceptors and improves retinal function in rhodopsin P347L transgenic rabbits. Invest. Ophthalmol. Vis. Sci. 28(53), 4254–4261 (2012)CrossRefGoogle Scholar
  13. Niparko, J.K., Tobey, E.A., ThaI, D.J., et al.: Spoken language development in children following cochlear implantation. J. Am. Med. Assoc. 303, 1498–1506 (2010)CrossRefGoogle Scholar
  14. Rubinstein, J.T.: How cochlear implants encode speech. Curr. Opin. Otolaryngol. Head Neck Surg. 12, 444–448 (2004)CrossRefGoogle Scholar
  15. Schatz, A., Röck, T., Naycheva, L., et al.: Transcorneal electrical stimulation for patients with retinitis pigmentosa: a prospective, randomized, sham-controlled exploratory study. Invest. Ophthalmol. Vis. Sci. 52(7), 4485–4496 (2011)CrossRefGoogle Scholar
  16. Schmidt, E.M., Bak, M.J., Hambrecht, F.T., et al.: Feasibility of a visual prosthesis for the blind based on intracortical microstimulation of the visual cortex. Brain 119(Pt. 2), 507–522 (1996)CrossRefGoogle Scholar
  17. Stingl, K., Bartz-Schmidt, K.U., Besch, D., et al.: Artificial vision with wirelessly powered subretinal electronic implant alpha-IMS. Proceed. R. Soc. Biol. Sci. 280(1757), 20130077 (2013)CrossRefGoogle Scholar
  18. Veraart, C., Raftopoulos, C., Mortimer, J.T., et al.: Visual sensations produced by optic nerve stimulation using an implanted self-sizing spiral cuff electrode. Brain Res. 813(1), 181–186 (1998)CrossRefGoogle Scholar
  19. Villalobos, J., Nayagam, D.A., Allen, P.J., et al.: A wide-field suprachoroidalretinal prosthesis is stable and well tolerated following chronic implantation. Invest. Ophthalmol. Vis. Sci. 54, 3751–3762 (2013)CrossRefGoogle Scholar
  20. Wilson, B.S., Dorman, M.F., Woldorff, M.G., et al.: Cochlear implants matching the prosthesis to the brain and facilitating desired plastic changes in brain function. In: Schollellbor, J., Ganviczallli, M., Donielsell, N. (eds.) Progress in Brain Research, Elsevier, Amsterdam,vol. 194, pp. 117–129 (2011)Google Scholar
  21. Zrenner, E.: Will retinal implants restore vision? Science 295(5557), 1022–1025 (2002)CrossRefGoogle Scholar

Copyright information

© Springer Japan 2016

Authors and Affiliations

  1. 1.Graduate School of MedicineOsaka UniversitySuitaJapan

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