Neural engineering (also known as neuroengineering) is a discipline within biomedical engineering that uses engineering techniques to understand, repair, replace, or enhance neural systems. Neural engineers are uniquely qualified to solve design problems at the interface of living neural tissue and non-living constructs.
Overview The field of neural engineering draws on the fields of computational neuroscience, experimental neuroscience, neurology, electrical engineering, and signal processing of living neural tissue, and encompasses elements of robotics, cybernetics, computer engineering, neural tissue engineering, materials science, and nanotechnology. Prominent goals in the field include restoration and augmentation of human function via direct interactions between the nervous system and artificial devices, with an emphasis on quantitative methodology and engineering practices. Other prominent goals include better neuro imaging capabilities and the interpretation of neural abnormalities through quantitative data.
Much current research is focused on understanding the coding and processing of information in the sensory and motor systems, quantifying how this processing is altered in a pathological state, and how it can be manipulated through interactions with artificial devices, including brain–computer interfaces and neuroprosthetics. There is also research is into neuromorphic encoding, which can restore normal sensory inputs for amputees through sending electrical impulses to the brain through a transcutaneous nerve stimulation machine. Also, in order to better understand muscle intent, neuroengineers use myographic decoding through pattern recognition via electromyography. Other research concentrates more on investigation by experimentation, including the use of neural implants connected with external technology. Neurohydrodynamics is a division of neural engineering that focuses on hydrodynamics of the neurological system.
History
Thousands of years ago, traditional Egyptian and Roman medicine used artificial neuromodulation methods to repair and enhance neural systems. They used the electrical properties of animals for therapeutic purposes. According to an interpretation of frescoes in the tomb of the architect Ti at Saqqara, Egyptians used the electricity-generating Nile catfish (Synodontis batensoda and Malapterurus electricus) to stimulate tissue electrically. The first documented use of electrical stimulation for pain relief dates back to 46 AD, in the Roman Empire, when Scribonius Largus used the electric properties of torpedo fish to relieve headaches.
The first use of electrocutical apparatus for medical treatment was recorded in Middlesex Hospital of London in 1767.Steavenson William Edward (1892). "Medical electricity". Philadelphia: P. Blakiston, Son & Company. pp. 86. Retrieved 2025-08-24 from https://archive.org/details/medicalelectric00steagoog/page/n107/mode/1up The origins of what is now called neural engineering begin with 18th-century Italian physician, physicist, and biologist Luigi Galvani. Galvani, along with pioneers such as 19th-century physiologist Emil du Bois-Reymond, discovered that electrical signals in nerves and muscles control movement, thus marking the first understanding of the brain's electrical nature. In 1800, Alessandro Volta reported to the Royal Society that he heard an unpleasant boiling sound while applying 50 volts to his head. This was the first experiment on electrical stimulation of the human auditory system. In 1924, German physiologist and psychiatrist Hans Berger (1873–1941) discovered the brain's electrical activity (called brain waves) and, in particular, the alpha wave rhythm. This led to the invention of human electroencephalography.
From the early 1900s through the 1940s, the field saw an decrease in respectability because the claims of those in the field were not supported by either plausible mechanisms or results. However, in 1956, the field experienced a resurgence when transistors were created, for the first time making possible electrical stimulation from inside the body, as opposed to all the past methods which required external stimulation, the latter being far less accurate and having much more intense effects. The use of micro-electronics led to decades of innovations in the field that would define what neural engineering is now. The cochlear implant, cardiac pacemaker, sacral nerve stimulators, intraspinal stimulator, and spinal cord epidural stimulator all came about during this time, which propelled neural engineering to the forefront of medicine by the 1990s.
As neural engineering is a relatively new field, information and research into it is comparatively limited, although this is changing rapidly. The first journals specifically devoted to neural engineering, The Journal of Neural Engineering and The Journal of NeuroEngineering and Rehabilitation both began publication in 2004. International conferences on neural engineering have been held by the Institute of Electrical and Electronics Engineers (IEEE) each year since 2003. At the initial conference in 2003, one of the defining talks was given by Carol Lucas, the biomedical program director of the National Science Foundation at the time. Her talk provided an overview and gave insights into the future of neural engineering and neuroscience initiatives. She covered over 200 papers spanning an array of topics, including neural informatics, behavioral dynamics, and brain imaging. This was the fundamental base work for future research regarding neural engineering. Specialization in this new field is taking place. For example, in 2024 a new branch of the field was identified, introducing the notion of mother-fetus neurocognitive mode.
Fundamentals The core principles of neuroengineering revolve around understanding the interplay among neurons, neural networks, and the functions of the nervous system to create measurable models that facilitate the creation of devices capable of interpreting and controlling signals to generate meaningful responses. The primary focus of progress in this field lies in constructing theoretical models that mimic entire biological systems or their functional components found in nature.Eliasmith, C.; Anderson, C. H. (2003). Neural Engineering: Computation, Representation, and Dynamics in Neurobiological Systems. MIT Press. The central objective of this technological advancement phase is the integration of machinery with the nervous system, enabling the monitoring and modulation of neural activity..
Neuroscience One of the main goals of neural engineering is to understand how the nervous system works. Messages that the body uses to influence thoughts, senses, and movements are directed by nerve impulses transmitted across brain tissue and to the rest of the body. Neurons are the basic functional units of the nervous system; they are highly specialized cells that are capable of sending these signals that operate high and low-level functions needed for survival and quality of life. Neurons have special electro-chemical properties that allow them to process information and then transmit that information to other cells.
Neuronal activity is dependent upon neural membrane potential and the changes that occur along and across it. A constant voltage, known as the membrane potential, is normally maintained by certain concentrations of specific ions across neuronal membranes. Disruptions or variations in this voltage create an imbalance, or polarization, across the membrane. Depolarization of the membrane past its threshold potential generates an action potential, which is the main source of signal transmission, known as neurotransmission of the nervous system. An action potential results in a cascade of ion flux down and across an axonal membrane, creating an effective voltage spike train or "electrical signal" which can transmit further electrical changes in other cells. Signals can be generated by electrical, chemical, magnetic, optical, and other forms of stimuli that influence the flow of charges, and thus voltage levels, across neural membranes.
Presynaptic and postsynaptic neuronal activities produce oscillations that have a dual function in brain networks: neuronal oscillations are influenced by spiking inputs, and, in turn, they affect the timing of spike outputs. Thus, neurons are both generators and recipients of electromagnetic fields. This fact means that neurons interact with other neurons' oscillations and, therefore, they may change their oscillations by interacting with other electromagnetic fields. Artificial impact of electric current and magnetic fields may alter brain activity.
Engineering The second main goal of neural engineering is to develop technological tools that can be used to understand and interact with complex neural systems. Methods of studying and generating chemical, electrical, magnetic, and optical signals, responsible for extracellular field potentials and synaptic transmission in neural tissue, aid researchers in the modulation of neural system activity. To understand the properties of neural system activity, engineers use signal processing techniques and computational modeling. To process these signals, neural engineers must translate the voltages across neural membranes into corresponding information, a process known as neural decoding. The corresponding field of neural coding studies how the brain encodes thoughts, inputs, and outputs in the form of central pattern generators (CPGs), movement vectors, the cerebellar internal model, and somatotopic maps to understand movement and sensory phenomena. Decoding of these signals in the realm of neuroscience is the process by which neurons understand the voltages that have been transmitted to them. Transformations involve the mechanisms that signals of a certain form get interpreted and then translated into another form. Engineers look to mathematically model these transformations.
There is a variety of methods being used to record neuronal signals, typically voltage or calcium concentration. Invasive methods can be intracellular or extracellular. Extracellular methods involve single-unit recordings, extracellular field potentials, and amperometry; more recently, multielectrode arrays have been used to record and mimic signals. Intracellular methods include electrode-based methods and optical methods. The electrode-based methods include sharp micro-electrode recording, the patch clamp technique, and some variations of these methods at the nano scale. Optical methods include optogenetic stimulation, which can activate or inhibit a neuron, and optical recording, typically calcium or voltage imaging, which monitors the changes in membrane voltage.Guo, L. (2022). Principles of electrical neural interfacing: A quantitative approach to cellular recording and stimulation. Springer.
The nervous system can be monitored and affected externally and non-invasively, the basis of the field of neuromodulation, as seen below.
Scope
Neuromechanics