Neural Prostheses


A neural prosthesis is a device that aims to restore or replace the functions of the nervous system that are lost to disease or injury. Examples include devices to improve hearing, vision, motor and cognitive functions. Neural prostheses artificially stimulate the nervous system to convey sensory information, activate paralysed muscles or modulate the excitability of neural circuits to improve conditions such as chronic pain, epilepsy or tremor. Some neuroprostheses also record activity from the nervous system, which can be useful for patients who have difficulty moving or communicating. These devices can decipher the intention of the user or detect ongoing brain events such as seizures by recording neural signals directly from the brain. Emerging neuroprostheses aim to ‘close the loop’ using recorded neural activity to control stimulation delivered elsewhere in the nervous system with the goal of improving function.

Key Concepts

  • Neural prostheses aim to replace lost function or control activity within the nervous system following injury or disease.
  • Sensory neural prostheses transduce external events (e.g. sound, light) into artificial stimulation delivered to the nervous system.
  • Motor neural prostheses aim to restore functional movement to weak or paralysed muscles.
  • Neuromodulatory devices utilise electrical stimulation to modulate the excitability of neural circuits to improve symptoms of neurological diseases such as pain, tremor and the occurrence of seizures.
  • Recording neuroprostheses aim to detect the user's intention or brain state in order to enable communication or control of external devices.
  • Closed‐loop neuroprostheses utilise neural recording to control functional or symptom‐relieving stimulation.
  • Methods are emerging for optical and magnetic stimulation of the nervous system to supplement the electrical stimulation techniques currently in use.

Keywords: brain–computer interface; deep brain stimulation; functional electrical stimulation; intraspinal microstimulation; cochlear implant; retinal prosthesis; neuromodulation; ultrasound

Figure 1. Cochlear implant. An external microphone and speech processor relay sound information to an external transmitter, which transmits it to the internal receiver. Here, it is converted to a stimulation pattern that is delivered to the cochlea via the implanted electrode array. Inset images detail the electrode array with multiple contacts ascending the spiral anatomy of the cochlea to activate the auditory nerves sensitive to different wavelengths of sound. Figure Copyright MRC Cognition and Brain Sciences Unit, used by kind permission.
Figure 2. Visual prostheses. An example visual prosthesis system and its implantation. The Argus II (Second Sight Medical Products) consists of (a) a camera mounted on glasses and a video processing unit (VPU). The implanted components (b) include the electrode array and a coil for wireless communication and stimulation. In this design, the retinal stimulation is delivered through a 6 × 10 electrode array (c), visualised with optical coherence tomography in (d). Reproduced with permission from Humayun et al. () © Elsevier.
Figure 3. Signals used for brain–computer interfaces. High‐frequency brain signals are recorded from micro‐electrodes that penetrate the cortex of the brain to resolve the timing of individual neuron action potentials. Moderate frequency signals representing the activity of many thousands of neurons are recorded with electrocortigraphic (ECoG) electrodes on the brain surface. Low‐frequency activity representing the average activity of hundreds of thousands of neurons is recorded from electroencephalography (EEG) electrodes on the surface of the scalp. These signals are then processed to extract information about the intent of the user and control a brain–computer interface, such as the movement of a robotic arm, control of a computer cursor or for written communication.
Figure 4. Brain‐controlled FES system. Electrodes implanted on the surface of the brain (electrocorticography – ECoG) or penetrating within the cortex of the brain record neural activity that can be translated into stimulation of muscles to enable functional movements after paralysis. Reproduced from Scott SH () © Nature Publishing Group.
Figure 5. Approaches to spinal stimulation. Intraspinal microstimulation (ISMS) utilises electrodes placed within the spinal cord to activate specific neural circuits within the gray matter or area of spinal cord cell bodies. Epidural stimulation utilises electrodes placed on the dorsal surface of the spinal cord, above the dura or protective covering of the spinal cord. In most cases, stimulation is delivered below a site of injury to restore functional activity to the areas disconnected from descending brain input after injury. Epidural stimulation preferentially targets sensory fibres near the dorsal surface of the cord, whereas penetrating stimulation can reach the motor neuron cell bodies in the ventral horn. Reproduced with permission from Mondello SE, Kasten MR, Horner PJ and Moritz CT () Creative Commons Attribution License.


Alilain WJ, Li X, Horn KP, et al. (2008) Light‐induced rescue of breathing after spinal cord injury. Journal of Neuroscience 28: 11862–11870.

Angeli CA, Edgerton VR, Gerasimenko YP and Harkema SJ (2014) Altering spinal cord excitability enables voluntary movements after chronic complete paralysis in humans. Brain 137 (Pt 5): 1394–1409.

Anikeeva P, Andalman AS, Witten I, et al. (2012) Optetrode: a multichannel readout for optogenetic control in freely moving mice. Nature Neuroscience 15: 163–170.

Berger TW, Hampson RE, Song D, et al. (2011) A cortical neural prosthesis for restoring and enhancing memory. Journal of Neural Engineering 8: 046017.

Brindley GS and Lewin WS (1968) The sensations produced by electrical stimulation of the visual cortex. Journal of Physiology 196: 479–493.

Collinger JL, Wodlinger B, Downey JE, et al. (2013) High‐performance neuroprosthetic control by an individual with tetraplegia. Lancet 381: 557–564.

Creasey GH, Grill JH, Korsten M, et al. (2001) An implantable neuroprosthesis for restoring bladder and bowel control to patients with spinal cord injuries: a multicenter trial. Archives of Physical Medicine and Rehabilitation 82: 1512–1519.

DiMarco AF (2009) Phrenic nerve stimulation in patients with spinal cord injury. Respiratory Physiology & Neurobiology 169: 200–209.

DiMarco AF, Kowalski KE, Geertman RT and Hromyak DR (2009) Lower thoracic spinal cord stimulation to restore cough in patients with spinal cord injury: results of a National Institutes of Health‐sponsored clinical trial. Part I: methodology and effectiveness of expiratory muscle activation. Archives of Physical Medicine and Rehabilitation 90: 717–725.

Dobelle WH and Mladejovsky MG (1974) Phosphenes produced by electrical stimulation of human occipital cortex, and their application to the development of a prosthesis for the blind. Journal of Physiology 243: 553–576.

Ethier C, Oby ER, Bauman MJ and Miller LE (2012) Restoration of grasp following paralysis through brain‐controlled stimulation of muscles. Nature 485: 368–371.

Fang ZP and Mortimer JT (1991) A method to effect physiological recruitment order in electrically activated muscle. IEEE Transactions on Biomedical Engineering 38: 175–179.

Feiereisen P, Duchateau J and Hainaut K (1997) Motor unit recruitment order during voluntary and electrically induced contractions in the tibialis anterior. Experimental Brain Research 114: 117–123.

Fetz EE (1969) Operant conditioning of cortical unit activity. Science 163: 955–958.

Fridley J, Thomas JG, Navarro JC and Yoshor D (2012) Brain stimulation for the treatment of epilepsy. Neurosurgical Focus 32: E13.

Gstoettner WK, Helbig S, Maier N, et al. (2006) Ipsilateral electric acoustic stimulation of the auditory system: results of long‐term hearing preservation. Audiology & Neuro‐Otology 11 (Suppl 1): 49–56.

Han X, Qian X, Stern P, Chuong AS and Boyden ES (2009) Informational lesions: optical perturbation of spike timing and neural synchrony via microbial opsin gene fusions. Frontiers in Molecular Neuroscience 2: 12.

Harkema S, Gerasimenko Y, Hodes J, et al. (2011) Effect of epidural stimulation of the lumbosacral spinal cord on voluntary movement, standing, and assisted stepping after motor complete paraplegia: a case study. Lancet 377: 1938–1947.

Hochberg LR, Bacher D, Jarosiewicz B, et al. (2012) Reach and grasp by people with tetraplegia using a neurally controlled robotic arm. Nature 485: 372–375.

Hochberg LR, Serruya MD, Friehs GM, et al. (2006) Neuronal ensemble control of prosthetic devices by a human with tetraplegia. Nature 442: 164–171.

Humayun MS, Dorn JD, da Cruz L, et al. (2012) Interim results from the international trial of Second Sight's visual prosthesis. Ophthalmology 119: 779–788.

Johnson LA, Wander JD, Sarma D, et al. (2013) Direct electrical stimulation of the somatosensory cortex in humans using electrocorticography electrodes: a qualitative and quantitative report. Journal of Neural Engineering 10: 036021.

Kobetic R, Triolo RJ and Marsolais EB (1997) Muscle selection and walking performance of multichannel FES systems for ambulation in paraplegia. IEEE Transactions on Rehabilitation Engineering 5: 23–29.

Leuthardt E, Schalk G, Wolpaw J, Ojemann J and Moran D (2004) A brain‐computer interface using electrocorticographic signals in humans. Journal of Neural Engineering 1: 63–71.

Lorach H, Marre O, Sahel JA, Benosman R and Picaud S (2013) Neural stimulation for visual rehabilitation: advances and challenges. Journal of Physiology, Paris 107: 421–431.

Mehic E, Xu JM, Caler CJ, et al. (2014) Increased Anatomical Specificity of Neuromodulation via Modulated Focused Ultrasound. PLoS One 9: e86939.

Mondello SE, Kasten MR, Horner PJ and Moritz CT (2014) Therapeutic intraspinal stimulation to generate activity and promote long‐term recovery. Frontiers in Neuroscience 8: 21.

Moritz CT, Lucas TH, Perlmutter SI and Fetz EE (2007) Forelimb movements and muscle responses evoked by microstimulation of cervical spinal cord in sedated monkeys. Journal of Neurophysiology 97: 110–120.

Moritz CT, Perlmutter SI and Fetz EE (2008) Direct control of paralysed muscles by cortical neurons. Nature 456: 639–642.

Mushahwar VK, Gillard DM, Gauthier MJ and Prochazka A (2002) Intraspinal micro stimulation generates locomotor‐like and feedback‐controlled movements. IEEE Transactions on Neural Systems and Rehabilitation Engineering 10: 68–81.

Mushahwar VK and Horch KW (1998) Selective activation and graded recruitment of functional muscle groups through spinal cord stimulation. Annals of the New York Academy of Sciences 860: 531–535.

Nishimura Y, Perlmutter SI and Fetz EE (2013) Restoration of upper limb movement via artificial corticospinal and musculospinal connections in a monkey with spinal cord injury. Frontiers in Neural Circuits 7: 57.

O'Doherty JE, Lebedev MA, Ifft PJ, et al. (2011) Active tactile exploration using a brain‐machine‐brain interface. Nature 479: 228–231.

Peckham PH, Kilgore KL, Keith MW, et al. (2002) An advanced neuroprosthesis for restoration of hand and upper arm control using an implantable controller. Journal of Hand Surgery. American Volume 27: 265–276.

Pohlmeyer EA, Oby ER, Perreault EJ, et al. (2009) Toward the restoration of hand use to a paralyzed monkey: brain‐controlled functional electrical stimulation of forearm muscles. PLoS One 4: e5924.

Prasad A, Xue QS, Sankar V, et al. (2012) Comprehensive characterization and failure modes of tungsten microwire arrays in chronic neural implants. Journal of Neural Engineering 9: 056015.

Prochazka A, Mushahwar VK and McCreery DB (2001) Neural prostheses. Journal of Physiology 533: 99–109.

Putzke JD, Wharen RE Jr Wszolek ZK, et al. (2003) Thalamic deep brain stimulation for tremor‐predominant Parkinson's disease. Parkinsonism & Related Disorders 10: 81–88.

Ramirez S, Liu X, Lin PA, et al. (2013) Creating a false memory in the hippocampus. Science 341: 387–391.

Rouse AG, Williams JJ, Wheeler JJ and Moran DW (2013) Cortical adaptation to a chronic micro‐electrocorticographic brain computer interface. Journal of Neuroscience 33: 1326–1330.

Ryan DB, Frye GE, Townsend G, et al. (2011) Predictive spelling with a P300‐based brain‐computer interface: Increasing the rate of communication. International Journal of Human Computer Interaction 27: 69–84.

Schlaepfer TE, Bewernick BH, Kayser S, Mädler B and Coenen VA (2013) Rapid effects of deep brain stimulation for treatment-resistant major depression. Biol Psychiatry 73: 1204–1212.

Scott SH (2008) Cortical‐based neuroprosthetics: when less may be more. Nature Neuroscience 11: 1245–1246.

Shain W, Spataro L, Dilgen J, et al. (2003) Controlling cellular reactive responses around neural prosthetic devices using peripheral and local intervention strategies. IEEE Transactions on Neural Systems and Rehabilitation Engineering 11: 186–188.

Shepherd RK, Shivdasani MN, Nayagam DA, Williams CE and Blamey PJ (2013) Visual prostheses for the blind. Trends in Biotechnology 31: 562–571.

Thomson EE, Carra R and Nicolelis MA (2013) Perceiving invisible light through a somatosensory cortical prosthesis. Nature Communications 4: 1482.

Torab K, Davis TS, Warren DJ, et al. (2011) Multiple factors may influence the performance of a visual prosthesis based on intracortical microstimulation: nonhuman primate behavioural experimentation. Journal of Neural Engineering 8: 035001.

Tufail Y, Yoshihiro A, Pati S, Li MM and Tyler WJ (2011) Ultrasonic neuromodulation by brain stimulation with transcranial ultrasound. Nature Protocols 6: 1453–1470.

Wang W, Collinger JL, Degenhart AD, et al. (2013) An electrocorticographic brain interface in an individual with tetraplegia. PLoS One 8: e55344.

Whittingstall K and Logothetis NK (2009) Frequency‐band coupling in surface EEG reflects spiking activity in monkey visual cortex. Neuron 64: 281–289.

Widge A, Daugherty DD and Moritz CT (2014) Affective brain‐computer interfaces as enabling technology for responsive psychiatric stimulation. Journal of Brain–Computer Interfaces 1: 126–136.

Widge AS and Moritz CT (2014) Pre‐frontal control of closed‐loop limbic neurostimulation by rodents using a brain‐computer interface. Journal of Neural Engineering 11: 024001.

Wilson BS and Dorman MF (2008) Cochlear implants: current designs and future possibilities. Journal of Rehabilitation Research and Development 45: 695–730.

Zhang F, Gradinaru V, Adamantidis AR, et al. (2010) Optogenetic interrogation of neural circuits: technology for probing mammalian brain structures. Nature Protocols 5: 439–456.

Zimmermann JB and Jackson A (2014) Closed‐loop control of spinal cord stimulation to restore hand function after paralysis. Frontiers in Neuroscience 8: 87.

Further Reading

Andersen RA, Burdick JW, Musallam S, Pesaran B and Cham JG (2004) Cognitive neural prosthetics. Trends in Cognitive Science 8: 486–493.

Daly JJ and Wolpaw JR (2008) Brain‐computer interfaces in neurological rehabilitation. Lancet Neurology 7: 1032–1043.

Homer ML, Nurmikko AV, Donoghue JP and Hochberg LR (2013) Sensors and decoding for intracortical brain computer interfaces. Annual Review of Biomedical Engineering 15: 383–405.

Jackson A and Zimmermann JB (2012) Neural interfaces for the brain and spinal cord–restoring motor function. Nature Reviews. Neurology 8: 690–699.

Nicolelis MA (2003) Brain‐machine interfaces to restore motor function and probe neural circuits. Nature Reviews. Neuroscience 4: 417–422.

Rao RPN (2013) Brain‐Computer Interfacing: an introduction. New York, NY: Cambridge University Press.

Shih JJ, Krusienski DJ and Wolpaw JR (2012) Brain‐computer interfaces in medicine. Mayo Clinic Proceedings 87: 268–279.

Thompson DM, Koppes AN, Hardy JG and Schmidt CE (2014) Electrical stimuli in the central nervous system microenvironment. Annual Review of Biomedical Engineering 16: 397–430.

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Kasten, Michael R, Ievins, Aiva M, and Moritz, Chet T(Jan 2015) Neural Prostheses. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0024011]