Glossary

Action Potential: The change in electrical potential associated with the passage of an impulse along the membrane of an electrically active cell like muscle cells and neurons.

Anterior and Rostral:

• Anterior: Nearer the face or front of the body

• Rostral: An anatomical term meaning toward the forehead in the brain, toward the neck in the spinal cord

Asynchronous BCI: brain computer interfaces (BCIs) that only take control commands from the patient when the patient wants to control the BCI

(definition is debatable)

Auditory cortex: Region of the cortex of the brain associated with sound processing; part of the temporal lobe

Autonomic nervous system: The division of the nervous system mostly responsible for non-conscious bodily functions like breathing, heartbeats, and digestion in addition to your body’s relaxation and excitement processes.

Axon: Structure that extends away from the neuron’s body, responsible for carrying information - or nerve impulses - to other neighboring neurons (Luo, 2016); unlike dendrites, which are short and are receivers for neural impulses, axons instead are the long outlets for neural impulses.

Band-Stop Filter: A filter used to remove a specific frequency bands from data, while allowing others to pass with minimal loss.

Brainstem Connects the brain to the spinal cord and is also responsible for controlling certain homeostatic functions such as pain modulation, heart rate, breathing, body temperature, wake and sleep cycles, digestion, sneezing, coughing, vomiting, and swallowing.

Brain waves: Captured using electrodes on the scalp, brain waves are repetitive and oscillatory patterns of neural activity occurring at different frequency bands, based on the current cognitive task. The ranges of their frequencies vary from project to project but are usually similar. Their inconsistency in application and interpretation is worthy of further skepticism.

• Delta: (~0.5 - 4 Hz) Associated with deep sleeps and loss of awareness.

• Theta: (~4 - 8 Hz) Associated with meditation, dreams, and reduced conscious awareness.

• Alpha: (~8 - 13 Hz) Associated with conscious but relaxed mental state.

• Beta: (~13 - 32 Hz) Associated with conscious but engaged mental state.

• Gamma: (~32 - 100 Hz) Associated with high levels of conscious presence, such as for tasks that require multiple cognitive mechanisms.

NOTE: There are also sub-bands of these five and other brain wave bands not listed here.

Broca’s area: Area in the left frontal lobe associated with speech production. (an easy way to remember this is that the Spanish word “Boca” means “Mouth”)

Cerebellum: Brain structure associated with posture control, balance, and movements coordination.

Cerebrum: Major superficial (surface) structure of the brain commonly divided into four superficial lobes: Frontal, Occipital, Parietal, Temporal.

Cochlea: organ responsible for transducing (converting) mechanical energy (sound waves) into electrical impulses to be transmitted along the auditory nerve to the thalamus and then to the auditory cortex of the brain’s temporal lobe.

Cochlear Implant: Electronic device implanted within the cochlea of patients with deafness or impaired hearing which restores some extent of their ability to hear on that side of their head.

Cognitive Enhancement: The use of technological devices to enhance cognitive performance, such as attention, reasoning, and decision-making processes.

Connectome: a map of the connections in a human brain.

Connexon: An ion channel that allows current to flow from a presynaptic membrane to a postsynaptic membrane in electric synapses.

Computerized Tomography: Advanced x-ray imaging procedure that takes a series of scans of one’s body, allowing for a final three-dimensional image when all scans are combined.

Central Nervous System (CNS): Comprised of the brain, cranial nerves, and spinal cord.

Cylindrical or helical nerve cuff: Commonly used in neuroprosthetic applications, these electrodes are designed to be wrapped around a nerve of interest and typically electrically stimulate the nerve from the outside to restore lost functions or reduce pain. These cuffs typically consist of a tube wrapped around the nerve or a spiral shaped device with electrodes embedded in its surface.

Deep Brain Stimulation (DBS): An invasive technology in which electrodes are planted within the brain to stimulate subcortical brain structures

Dendrites: Structure that extends from the neuron’s body and receives information from neighboring neurons.

Dorsal: An anatomical term meaning toward the superior (top) of the brain, toward the back in the spinal cord

Dorsolateral Prefrontal Cortex: Involved in higher-order executive functions such as complex reasoning, working memory, planning, behavioral inhibition, and emotional regulation. (Genomics, Circuits, and Pathways in Clinical Neuropsychiatry

2016, Pages 345-364)

Electrodes: Any material used to collect or deliver electrical signals from or to a target of interest; in the case of neurotechnology, these detect electrical changes in neural activity or stimulate the nervous system to restore function or reduce pain.

Electrocorticography (ECoG) - a semi-invasive electrode array placed on brain tissue without penetration which can be used for recording or stimulation

Electroencephalography (surface): Functional imaging tool that, when placed on one’s scalp, is typically used to record changes in the electrical activity of populations of the brain’s neurons by recording electrical signals that pass through the skull, dura, and muscles of the head.

Electromyography: Technology used for recording electrical activity of the muscles

FINE electrodes: Flat Interface Nerve Electrodes (FINEs) are designed to be placed around the nerve with the aim to move the neurons and deeper fascicles closer to the electrode by flattening the nerve to improve access to the innermost neurons for stimulation (Leventhal & Durand, 2003)

Frontal lobe: Major frontal structure of the cerebrum, managing goal-directed behaviors via high cognitive functions, as well as motor functions and communication.

Functional imaging: The use of neuroscientific tools to study changes in brain functionality when engaging in specific tasks.

Functional MRI: Functional imaging tool that shows which brain areas are involved during specific cognitive tasks. This technique uses changes in blood flow as an indication of localized neural activity.

Functional Near Infrared Spectroscopy: Non-invasive functional imaging tool that measures brain activity as a function of changes in hemoglobin in blood moving through the brain using infrared light (similar to a pulse oximeter)

Gap Junction: an electric synapse

Glial cells: Cells found in the central nervous system responsible for the protection and support of neurons and management of the neuronal extracellular matrix (surrounding environment).

Gyri: Bumps found on the brain surface contribute to its wrinkled appearance.

Human Connectome Project: Project that aims to provide a “virtual” map of the anatomy, functions, and connections found within the brain.

Hyperpolarization: a membrane potential that is negative and thus a store of potential energy

Lateral: An anatomical orientation term meaning away from midline (longitudinal fissure)

LIFE electrodes: Longitudinal Intrafascicular Electrodes (LIFEs) are electrodes designed to be inserted along the length of a nerve rather than through them radially. They may also be inserted radially and sewn into the nerve so that their electrodes are still aligned along the length of the nerve.

Limbic System: Collection of internal brain structures involved in emotion and memory processing.

Magnetoencephalography (MEG): Functional imaging tool that shows which brain areas are involved during specific cognitive tasks. This technique detects the emergence of magnetic fields when electrical impulses are produced by the brain.

Magnetic Resonance Imaging (MRI): Imaging tool that provides pictures on the anatomy and structure of the brain using three-dimensional nuclear magnetic resonance imaging.

Medial: An anatomical orientation term meaning toward the midline (longitudinal fissure in brain)

Microelectrode Arrays (MEAs): A grid of tiny electrodes implanted into neural tissue designed to offer a high degree of specificity in recording or stimulating neurons.

Microwire Arrays: An electrode array composed of multiple flexible wires to which can record or stimulate neurons. Their flexibility allows them to be implanted deep into brain tissue in nonlinear arrangements, allowing for more control of their positioning in neural tissues.

Mind-Body Problem: Philosophical problem that seeks for an answer to what is the relationship between one’s physical body and the presence of non-observable mental states, such as consciousness.

Motor Areas: Including M1 and M2, these regions are involved in planning and executing motor actions

Motor Imagery (MI): The mental visualization of one’s body part moving; this imagery also occurs when one actually performs the physical action and so this imaginary component can also be used to control assistive technologies for patients with physical disabilities of many kinds.

Motor-cortical Homunculus: A schematic map of the anatomical subdivisions of the motor cortex where each part is linked to a specific body part.

Motor Neuroprosthetics: Devices that can translate the user’s conscious intention to move a prosthetic limb into machine-readable signals, so that such a limb can be controlled accordingly.

Mu Rhythms: Neural oscillations (8-12 Hz) that can be observed in the motor cortex and triggered during motor imagery tasks.

Mysticism: Altered state of consciousness where one believes in contact with a religious or spiritual entity.

Neuroma: Painful inflammation of a sensory nerve, colloquially called a “pinched” nerve; in absence of relocation of the nerve, this is a typical result of limb amputation when the nerve is severed.

Neuromodulation: Therapeutic intervention that aims at ameliorating patients’ conditions by delivering external drugs or electrical impulses or other stimuli to modulate the activity of any part of the nervous system.

Neurons: Populations of cells involved in the transmission of information via electrical impulses giving rise to cognitive processing.

Neural Synchronization: Populations of neurons firing together in a similar pattern; synchronization of behavior from large groups of neurons.

Neural Desynchronization: Populations of neurons suddenly not firing together in similar patterns; large groups of neurons suddenly not behaving in a synchronized way.

Neuroplasticity: The ability of the brain to adjust and reorganize its neural connections as a result of previous experiences or environmental changes.

Neurostimulation: Neuroscientific method that generates electrical impulses over localized nervous system areas to either disrupt or increase neural activity.

Neurotechnology: A technology that records, stimulations, or works with the brain to influence how researchers understand the brain and consciousness, supplement, engage or monitor the nervous system, or allow a user to influence the functioning of a machine from brain function.

Negative-Going Potential: A signal which is characterized by a negative magnitude; a potential that peaks in the negative rather than positive.

Noise: Unwanted activity (electrical or otherwise) that distorts biosignals.

Non-invasive Neurotechnologies: Technological solutions that interface with one’s nervous system (brain, spinal cord, peripheral nerves, etc.) using non-invasive tools, such as EEG.

Non-penetrating Interfaces: As opposed to penetrating interfaces, non-penetrating ones sit on the cortex or nerve surface and enable the control of neuroprosthetics with minimal damage of nervous tissue.

Notch Filter: A Band-Stop filter that removes power line noise (typically between 50-60 Hz).

Occipital lobe: Major posterior structure of the cerebrum responsible for the emergence of conscious visual experience.

Optically Pumped Magnetometers: This technology allows the measurement of very weak magnetic fields, making it way more precise and sensitive than conventional MEG systems (Tierney et al., 2019).

Organ of Corti: Structure found in the ear responsible for the translation of sound vibrations through hair cells in the cochlea into meaningful neural signals in the auditory nerve.

Paddle Electrodes: A flat device with arrays of electrodes, typically used in spinal cord stimulation

panopticon - all-seeing Orwellian state of surveillance

Parietal lobe: Major posterior structure of the cerebrum associated with the complex processing of sensory stimuli.

Penetrating Interfaces: As opposed to non-penetrating interfaces, penetrating ones are more invasive. These are often placed inside a region of interest, such into the motor cortex or through a nerve, to interface with neuroprosthetics.

Peripheral nerve interfaces: Any device used to record or stimulate a peripheral nerve to create a link between the nerve and an external device; these can often also be applied to cranial nerves.

Population Coding: "Population coding: Information is encoded in the brain by groups of electrically active cells and can be used to determine an average vector which correlates with actual motions for what is called population vector coding." (Springer, 2018)

Posterior and Caudal:

- Posterior: Towards the back

- An anatomical term meaning toward the back of the brain, toward the feet in the spinal cord

Posterior Parietal Cortex: understood to play an important role in sensory integration and focus (Neuroscientifically Challenged, 2017)

Peripheral Nervous System (PNS): Collection of all the nerves outside the Central Nervous System (CNS). The PNS facilitates communication between the CNS and many other parts of the body, including your muscles, sense of touch, sense of temperature, and sense of muscle position (proprioception).

Prefrontal cortex: The most frontal and superior part of the brain involved in complex cognitive functions, such as decision-making.

Premotor Cortex (M2): Understood to be involved in movement planning, spacial and sensory guidance of movement, mirroring the actions of others, and motor imagery. (Neuroscience. 2nd edition, Dale Purves et al., 2001)

Primary auditory cortex: Region of the cortex of the brain most associated with sound processing; part of the temporal lobe

Primary Motor Cortex (M1): region of the brain responsible for executing motor tasks and sending motor commands to the spinal cord.

Primary Visual Cortex: Also known as V1, this occipital cortical region is the first step towards conscious visual experience (e.g. edge detection).

Proprioception: The humans’ natural ability to sense the position of their body in space; perceived by neurons innervating the muscles that respond to them stretching and relaxing.

Reductive Physicalists: A theory that argues that scientific research will be able to explain away both physical and mental properties.

Regenerative Peripheral Nerve Interfaces (RPNIs): Novel surgical procedure that aims at alleviating neuroma’s symptoms and facilitating neuroprosthetic control by using muscle and skin tissue taken from the patient to give a residual nerve something to grow into.

Sensory transduction: In sensory neurons, sensory transduction refers to the translation process of sensory signals into electrical impulses.

Signal to Noise Ratios (SnRs): A measure that indicates the quantity of actual signal against undesired background noise.

Population vector encoding: Computational mechanism observed at the population level by which the firing of each individual neuron reveals the function of the whole population (e.g. neurons within the same population will all fire for the same stimulus feature).

Steady-State Visually Evoked Potentials (SSVEPs): Periodic brain activity resulting from the presentation of visual stimuli that flick at a constant frequency.

Soma: Also known as the cell-body, the Soma contains the cell nucleus responsible for fundamental chemical processes that provide energy to the neuron.

Somatic Nervous System: The part of the PNS responsible for carrying voluntary motor information from/to the CNS to/from muscles and sensory information to the CNS.

Somatosensory Cortex: Part of the cortex responsible for processing all sensory information, such as touch and pain.

Somatosensory System: System responsible for the emergence of conscious somatosensory experiences.

Spatial Resolution: a measure of size of the area being sampled. High spatial resolution means that data can be sampled from small areas with high specificity.

Structural imaging: Method that allows the anatomical visualization and inspection of the brain.

Sulci: Grooves found on the brain surface contribute to its wrinkled appearance.

synaptic cleft: A small space between two neurons where communication occurs.

Synaptic Bouton: terminating end of an axonal branch responsible for creating, packaging, and releasing neurotransmitter into the synaptic cleft.

Temporal Lobe: Major lateral structure of the cerebrum associated with the encoding of memory and sound.

Temporal resolution: a measure of how long it takes to collect and make use of data from a system. Higher resolution means the data is usable faster

Thalamus: Internal structure of the brain responsible for many functions, including the transmission of motor and sensory signals to the cortex; it also regulates sleep. ( StatPearls Publishing; 2021)

Time Series: Data graphed in successive order over some period of time.

Targeted Muscle Reinnervation (TMR): Surgical intervention that involves implanting residual nerves from amputations into other muscles of the body to prevent further nerve injury and pain. Often used for controlling prosthetic limbs.

Ventral: An anatomical orientation term meaning toward the inferior (bottom, toward the neck), toward the chest in the spinal cord

Wernicke's area: Area in the left temporal lobe associated with speech comprehension.