This glossary of neuroscience, neural engineering, and neurotechnology terms was compiled from multiple sources, including curriculum units authored by participants in the Center for Neurotechnology’s Research Experience for Teachers program. 

A

Action potential: The nervous system’s communication method is via action potentials, which are electrochemical changes that originate in neurons, are propagated down their axons, and elicit a corresponding response in the adjacent neurons.

Artificial neural networks (ANN): Artificial neural networks are made of code written to train the network for optimal performance. ANNs trains themselves to recognize the most important neural spikes and what the spikes mean – which spikes match which movements! This is a type of artificial intelligence.

Atypical: Not representative of a type or group; unusual or uncommon.

Assistive device: Any device that helps someone do something that they might not otherwise be able to do well or at all.

Auditory: Sensory information obtained through your auditory system (e.g., outer/middle/inner ear, cochlear nucleus, auditory cortex in brain).

Axon: The part of a neuron that takes information away from the cell body.

B

Bioethics: A specialization within the field of ethics that is concerned with the societal issues surrounding biomedical research, new scientific techniques, and new biomedical technologies, devices, and treatments. Bioethicists consider the ethical, legal, and social implications of research, treatments, and technologies. The study of bioethics includes three main principles: respect for persons, maximizing benefits/minimizing harm, and justice.

Biosignal: A signal generated by the human body that can be measured. Bioelectrical signals are electrical signals produced by the nervous system (e.g., EMG, EEG, ECoG) or organ systems (e.g., ECG/EKG, GSR).

Brain: An organ contained in the skull that functions as the body’s command center. The brain, along with the spinal cord, is part of the central nervous system. It controls movement, functions, sensations, memory, and thoughts. The brain can be thought of similarly to an electric circuit, where sensory neurons receive input, the brain processes this, and motor neurons instigate a response.

Brain-Computer Interface (BCI): A communication pathway linking neural signals from the brain with an external device. The neural signals are decoded by a computer using an algorithm that translates the signals into a motor output (action), such as controlling a neuroprosthetic hand or steering a wheelchair. BCIs may operate using either EEG or ECoG recordings or single unit activity from neurons. Also called a Brain-Machine Interface or a Brain-Control Interface.

Brain stem: The brain stem connects the brain to the spinal cord and is responsible for the control of breathing, heart rate, and blood pressure. The brain stem contains structures including the medulla, pons, tectum, reticular formation, and tegmentum.

C

Cerebellum: The part of the brain that helps with movement, balance, and posture.

Cerebral cortex: The outside layer that covers the cerebrum of the brain. Also referred to as “gray matter”.

Cerebral hemispheres: The two halves of the brain, as divided down the middle. Each cerebral hemisphere is divided into four lobes by sulci (fissures) and gyri (bumps) that can be seen on the surface of the brain.

Central Nervous System: The portion of the nervous system that contains the brain and spinal cord.

Circuit: A closed-loop pathway through which an electrical current travels from its source (e.g., batteries). A simple circuit consists of a power source, wires, and resistors. Inputs (e.g., sensors) and outputs (e.g., motors, LEDs, speakers) may be added to a circuit.

Closed control loop: A closed loop sensorimotor device receives signals from the nervous system and provides feedback to the body. With a Brain-Computer Interface, a closed loop is achieved by providing sensory feedback to the user of the device, such as visual feedback (seeing the position and movement of the device) or tactile feedback (feeling the position and movement of the device).

Cochlear implant: An electronic device manufactured for people (most often children) with significant hearing loss known as sensorineural hearing loss. A cochlear implant bypasses damaged hair cells in a part of the inner ear known as the cochlea. It consists of an implanted (internal) receiver and electrodes, external microphone, speech processor, and transmitter.

Cognitive: The brain’s role in thinking or learning.

Constraint: A limitation to an engineered design (e.g., cost, time, materials, etc.).

D

Deficit: A deficiency or impairment.

Degree of a node: Within a network, the number of edges connecting to a node.

Demo: A demonstration of something, such as a technology, for others to see.

Dendrite: The part of a neuron that brings information to the cell body.

Decoding Intended Movement: The BCI reads brain activity (signal acquisition) and decodes the neural patterns to understand what movement the individual is wanting.

Disability: Human variation is normal, therefore there are differences in the ways that people move, sense, and think. Disabilities are the restrictions created by society that impact people with impairments, such as infrastructure (i.e., lack of wheelchair ramps; movies without closed captioning), beliefs, or biases.

Disruption/Disturbance: Events that cause a change to a system.

Dynamic: Constant change.

E

Edge: Lines that connect the nodes within a network; the relationships between the nodes.

Electroencephalography (EEG): A technique for recording electrical activity of the brain obtained from electrodes placed on the scalp. EEG is a non-invasive way to record brain signals.

Electroencephalography (EEG): Non-invasive method used to take recordings from the brain using an electrode array placed on the scalp, with the benefit that no surgery is needed.

Electrocorticography (ECoG): A technique for recording the electrical activity of the brain obtained from electrodes placed on the surface of the brain. ECoG is an invasive way to record signals from the brain, requiring surgery to access the brain’s surface.

Electrocorticography (ECoG): A semi-invasive methods used to take recording of biosignals by using an electrical array (delicate microplate) placed on the brain’s surface.

Electrode: A conductor in which electricity enters or leaves an object. In neuroscience, electrodes are used to detect biosignals produced by the body. Electrodes are used in EEG, EMG, ECoG, and signal units to record the electrical activity within neurons.They may be laid on the surface of the skin, onto the surface of the brain under the skull, or inserted directly into brain tissue or the spinal cord. Some electrodes are being engineered to also be able to provide electrical stimulation, light (optigenetic) stimulation, and/or deliver small amounts of pharmaceutical drugs. These kinds of electrodes are made from metals, glass, glassy carbon, and other materials that do not react when surgically implanted in an animal’s body. Some are made to be flexible so that they can move with the spinal cord.

Electromyography (EMG): A technique for recording the electrical activity of skeletal muscles obtained from electrodes placed on the skin. EMG is a non-invasive way to record motor neuron activity.

Electrophysiology: The study of the electrical properties of the cell.

End-user: A person or group of people who are the likely users or consumers of a new technology. Engineers need to consider end-users needs, wants, preferences, and desires when designing new products or devices.

Engineering: A discipline that applies math and science to design and build products (devices, structures, tools, machines, etc.) to solve an authentic problem.

Engineering design process: A dynamic and creative process in which engineers identify authentic human problems, ideate possible solutions, and then develop, test, and optimize prototypes–in consideration of design criteria and constraints.

Enhancement: Something that causes an increase in quality or function. Human enhancement is making purposeful changes to the human body in order to increase its physical or mental capabilities, such as supplements, drugs, implants, or other technologies.

Equilibrium: The condition of a system in which competing influences are balanced.

Ethics: A system of moral principles. Rules or standards that govern thinking, decision making, and behavior, in particular for how humans think and act in regards to others.

F-G-H

Feedback: The process the output of a system is used to make changes in the operation of the system.

Foramina: Holes in the skull that allow the passage of nerves and blood vessels.

Frontal lobe: One of the four lobes of the brain. Concerned with reasoning, planning, parts of speech and movement (motor cortex), emotions, and problem-solving.

Glia: Cells that surround neurons (nerve cells), providing support and protection for the neurons.

Hypothalamus: A structure of the brain located below the thalamus. It is responsible for regulating many bodily functions such as body temperature, hunger, thirst, and biological rhythms.

I

Impairment: A state of something being impaired, damaged, or functioning in an atypical way. This includes physical or mental conditions that causes a limitation or difference in the way a person moves, senses, or thinks. Impairments can be can be physical, sensory, intellectual, or psychological. They can be temporary, long-term, or permanent.

Implant: A medical device manufactured to replace or enhance a structure in the body. For example, a cochlear implant used to restore hearing, a retinal implant used to restore vision, or an electrode array implanted in the brain to stimulate a damaged area.

Input: A component of an electrical circuit that provides information into the system (e.g., photoreceptor, microphone, proximity sensory, force sensor, temperature sensor, etc.). In the human nervous system, this is analogous to the role of a sensory neuron, which carries information from the body’s sensory receptors (eyes, nose, ears, tongue, skin, muscles, joints) to the central nervous system.

Interneurons: Neurons in the brain that communicate between the sensory and motor neurons.

Intraaparenchymal: Directly records neurons with incredible precision with electrodes that are surgically inserted into brain tissue. Invasive, requires surgery.

J-K-L-M

Light-emitting diode (LED): A small light source often used in building circuits. LEDs come in different colors and can be programmed using a microcontroller to change in intensity and blink.

Microelectrodes: Very small electrodes used for either recording neural signals or for electrical stimulation (i.e., electrical stimulation of the brain or spinal cord).

Motor neuron: A neuron that carries information from the central nervous system to muscles, sending a message for the muscle to activate and initiate movement.

Myelin: A lipid (fatty) substance that surrounds the axons of neurons, providing insulation and increasing the rate at which action potentials pass along the length of the axon. Myelin is made up of a particular type of glial cells.

N

Negative feedback: A change in one direction causes an additional change in the opposite direction. This reduces the disturbance to a system.

Network: An interconnected or interrelated chain, group or system. Often thought of as a system of interconnected components. Examples of complex networks (and their nodes and edges) include: neural networks (neurons and synaptic connections), biochemical networks (molecules and chemical reactions), internet networks (computers and satellites/routers/Ethernet cables), cellular networks (phones and cellular towers), and social networks (people and their friendships).

Neural engineering: An engineering discipline that uses concepts from math and science to connect to and interact with the nervous system. Neural engineering is based on the loop between the sensory information that is received by the brain, information that the central nervous system (CNS) sends out, and computers/machines that receive input and produce outputs that feed back into the CNS.

Neural plasticity (neuroplasticity): Also known as brain plasticity. The ability of the brain to modify its neural connections, form new neural connections, or re-wire itself throughout an individual’s lifetime. This happens through learning and memorization and due to the immense neural connections–the neural network–between cells in the human brain. Neuroplasticity occurs during brain development when the brain processes sensory information from infancy through adulthood. Neuroplasticity also occurs as an adaptive mechanism; for example, in the case of brain injury, the brain may compensate for lost functions or amplify remaining functions.

Neural spikes: Large action potentials generated by the nervous system.

Neuroanatomy: The structure of the nervous system.

Neuroethics: The study of philosophical issues related to neurotechnologies; a sub-specialty within the study of bioethics. Neuroethics combines an understanding of neuroscience, philosophy, and the legal system. Neuroethical issues can arise during the design of a neurologically-focused device, drug, or therapy, all the way to the impacts it has once used with patients. Neuroethics deals with complex philosophical issues, such as identity, security, privacy, autonomy, fairness, and justice. Questions include the ethics of the methodology of research studies, accessibility of devices, legality of rights and patents, and delineating the line between human/animal consciousness, volition, and computer/machine influence.

Neurological disorder: A disorder of the nervous system.

Neuroprosthetic: An engineered device that interfaces with the nervous system to support abilities lost due to damage or disease or to enhance existing body function.

Neurotransmitter: Chemicals that are released from a neuron at the axon terminal. Molecules of neurotransmitter then cross a small gap (the synaptic gap) where they may attach to the next neuron at a specialized site called a receptor.

Nervous system: Consists of the central nervous system (brain and spinal cord) and peripheral nervous system (all nerves throughout the body not part of the brain or spinal cord).

Neuron: A specialized cell within the nervous system that transmits information. It is characterized by the axon and dendrite. Also called a nerve cell.

Neuroscience: The scientific study of the brain and nervous system.

Node: The members of a network. A point of intersection; a connection point (such as within a network).

O

Occipital lobe: One of the four lobes of the brain. Concerned with vision.

Optical stimulation (optigenetics): A technique used by neuroscientists that uses both light and genetic manipulation to control neurons. Neurons are genetically manipulated to be light-sensitive, thus enabling light to cause neurons to fire.

Output: A component of an electrical circuit that communicates information out of the system and makes something happen (e.g., motor, speaker, LED, etc.). In the human nervous system, this is analogous to the role of a motor neuron, which carries information from the central nervous system to muscles, sending a message for the muscle to activate and initiate movement.

P

Parietal lobe: One of the four lobes of the brain. Concerned with perception of stimuli such as touch, pressure, temperature, and pain.

Peripheral nerves: Nerves located outside of the brain and spinal cord. Peripheral nerves connect the parts of the body with the spinal cord.

Peripheral nervous system: The portion of the nervous system that contains the nerves of the body.

Population: A specific group of people, distinguishable based on specific characteristics (e.g., gender, age, income level, ability).

Positive feedback: A change in one direction causes a change in the same direction. This tends to increase the disturbance in a system.

Poster: A scientific poster provides a particular format for communicating a research study. Generally, scientific posters are presented during a poster session at a conference or scientific meeting. A scientific poster includes information about the research study such as title, authors, background, research question/hypothesis, methods, findings, discussion, and acknowledgements.

Productive uncertainty: Making advances in scientific research requires that scientists feel comfortable with pushing on the boundaries of their knowledge and living with a feeling of uncertainty. It is okay to not know everything and to have some level of productivity based around this uncertainty. This can lead to deeper meaning and discovery.

Prosthesis: This allows the brain to develop as humans grow from infants to adults and to repair itself after injury. This happens largely because of the immense neural connections, the neural network, between cells in the human brain. Device manufactured to replace a missing or damaged body part, such as a hand or leg.

Prototype: A model of a design, typically an early version of a model. Prototypes can be “looks like” and “works like” models. A prototype is often iterated on through multiple testing and re-design phases.

Pugh Chart: A matrix tool used to facilitate a disciplined, team-based process for concept generation and selection.

Q-R-S

Sector: A portion that is different or distinct from other portions.

Sensor: An electrical component that detects changes in the environment and communicates information to other electrical components. Examples of sensors commonly used in electrical circuits include flex, temperature, light, color, tilt, and proximity sensors.

Sensorimotor: A term that describes motor (movement) and sensory functions of the body. Sensorimotor neural engineering is specifically involved with the parts of the brain that control movement and process sensory information related to movement. Neurological injury or disease can cause a person to lose sensorimotor function.

Sensorimotor neural engineering:  A field of study that aims to understand how to capitalize on the sensorimotor loop to design devices, treatments, and therapies to help people with neurological, sensory, and motor disorders. Neural engineering connects the nervous system and computers to restore and enhance normal human function. Sensorimotor neural engineering is focused on the loop between sensory information received by the brain, information that the central nervous system (CNS) sends out, and devices (computers, implants, prosthetics, etc.) that receive inputs and produce outputs that feed back into the CNS.

Sensoriomotor pathway: Sensory neurons are nerve cells that transmit a signal to the brain from a stimulus/input in the body (e.g., touch, smell, etc.). Motor neurons carry signals from the spinal cord to active muscle movement.

Sensory neuron: A neuron that carries information from the body’s sensory receptors (eyes, nose, ears, tongue, skin, muscles, joints) to the central nervous system.

Sensory substitution: Sensory substitution is when one sense is substituted with another. Usually this occurs through a non-invasive device which takes one input (which the body can no longer sense) and converts it to a different input (which the body can sense, process, and react to). This relies heavily on brain plasticity, the brain’s ability to repair and enhance existing neural pathways.

Sensory substitution device: A device which enables one sense to replace the use of another sense

Signal processing: The processing (decoding or translation) of biosignals that allows a brain-computer interface to make sense of the signal and control a computer or machine. For example, the user of the BCI actively thinks about a movement like moving a cursor to the right, rotating a wheelchair towards a window, or extending a neuroprosthetic arm forward. The BCI records and processes the signals that capture the user’s intent for movement.

Society: The people who live together in a community. Also known as the public.

Spinal cord:  A component of the central nervous system located within the backbone. The spinal cord connects the brain to the other parts of the body.

Stimuli/Stimulus: Something that evokes a functional reaction, for instance visual stimulus that evoke a response in the brain. Some examples of stimuli include visual, tactile, auditory, smell, and motor.

Subsystem: A subset of interrelated parts within a larger system.

Synapse: Chemical or electrical junctions that allow signals to pass from a neuron to another cell.

System: An assemblage of interrelated parts or conditions through which matter, energy, or information flow. A system is a network of sub-systems that contain inputs, outputs, and feedback mechanisms in order to control or regulate a specific outcome. Disturbances affect the outcome of the system.

T-U-V-W-X-Y-Z

Tactile: Sensory information obtained through your sense of touch (e.g., pressure, temperature, texture).

Technology: Equipment, machinery, devices, or computer programs that are developed through a knowledge of science and/or engineering.

Temporal lobe: One of the four lobes of the brain. Concerned with perception and recognition of auditory stimuli (hearing), and memory (hippocampus).

Thalamus: A structure of the brain that helps direct sensory and motor information to and from the spinal cord and cerebral cortex.

Therapeutic: Something that helps to heal, repair, or restore a disease or injury.

Transcranial magnetic stimulation: A non-invasive method of stimulating neurons in the brain in which a magnetic field passes through the skin of the scalp and the skull, inducing an electric current in the brain. The maximum  depth that magnetic stimulation reaches is 3-5 cm.

Transcranial ultrasound: A non-invasive technique in which sound waves travel through bone and soft tissues to the brain. Low-intensity pulsed ultrasound influences neural activity without heating or damaging the tissue.

Users: People who are users of brain-computer interfaces or other neurotechnologies. This tends to people people who have lost at least partial function of their closed-loop sensorimotor system due to spinal cord injury or disease of the nervous system.

Visual: Sensory information obtained through your visual system (e.g., eyes, visual cortex in brain).