Key Terms & Definitions
A comprehensive glossary of scientific and technical terms used across this project — from neuroscience and electromagnetic biology to satellite engineering.
44 terms
Adaptive Coding and Modulation
Technique used in satellite communications that dynamically adjusts modulation scheme and forward error correction code rate based on real-time link quality, maximizing throughput under varying atmospheric conditions.
See in context →Attitude Determination and Control System
Satellite subsystem responsible for determining and controlling the spacecraft orientation using star trackers, reaction wheels, and magnetorquers.
See in context →Adaptive Deep Brain Stimulation
Next-generation DBS that uses real-time biomarkers (e.g., beta-band oscillatory power) to modulate stimulation intensity dynamically, reducing stimulation time by ~50% while maintaining clinical outcomes.
See in context →Absorbed Power Density
Metric replacing SAR for frequencies above 6 GHz in the ICNIRP 2020 guidelines, measured in W/m². Better accounts for the shallow penetration depth of millimeter-wave radiation where energy is absorbed in the skin surface.
See in context →Brain-Computer Interface
A system that records neural signals from the brain and translates them into commands for external devices such as computers, robotic arms, or communication systems.
See in context →Brain-Spine Interface
A wireless system linking cortical recording electrodes to a spinal cord stimulator, enabling paralyzed individuals to control leg movements via thought (Lorach et al., 2023).
See in context →Deep Brain Stimulation
Neurosurgical procedure involving implantation of electrodes deep in the brain (STN, GPi, VIM) to deliver high-frequency electrical pulses (~130 Hz) for Parkinson’s disease, essential tremor, and dystonia. FDA-approved since 1997.
See in context →Electrocorticography
Recording of electrical activity from electrodes placed directly on the cortical surface (subdural or epidural). Provides 50–100× better signal quality than scalp EEG without penetrating brain tissue. Used in speech BCIs and epilepsy monitoring.
See in context →Electroencephalography
Non-invasive recording of brain electrical activity from scalp electrodes. Measures collective neuronal activity with ~1–2 cm spatial resolution and millisecond temporal resolution. Basis for most non-invasive BCIs.
See in context →Epidural Electrical Stimulation
Targeted electrical stimulation applied to the spinal cord surface via epidural electrodes. Used to reactivate spinal locomotor circuits and restore walking in paralyzed individuals.
See in context →Effective Isotropic Radiated Power
The total equivalent power that a transmitter would need to radiate equally in all directions to produce the same signal strength as the actual antenna in its focused direction. EIRP = Transmit Power × Antenna Gain. Starlink max: 66.89 dBW (~4.9 MW equivalent).
See in context →Extremely Low Frequency
Electromagnetic radiation in the 3–30 Hz range. Includes the frequencies of power lines (50/60 Hz) and some brain rhythms. Classified as Group 2B ("possibly carcinogenic") by IARC in 2002.
See in context →Electromyography
Recording of electrical activity produced by skeletal muscles. Used to measure motor evoked potentials (MEPs) during TMS experiments.
See in context →Forward Error Correction
Coding technique that adds redundancy to transmitted data, enabling the receiver to detect and correct errors without retransmission. Critical for satellite links operating near the noise floor. Modern systems use LDPC or turbo codes.
See in context →Functional Electrical Stimulation
Application of electrical currents directly to motor nerves or muscles through surface or implanted electrodes to produce functional movements in paralyzed limbs.
See in context →Functional Near-Infrared Spectroscopy
Non-invasive neuroimaging technique measuring hemodynamic responses through the skull using near-infrared light (700–900 nm). Slower than EEG (~5–8 s response) but provides better spatial resolution. Used in hybrid BCI systems.
See in context →Free-Space Path Loss
The attenuation of radio energy between transmitter and receiver in free space: FSPL(dB) = 20·log₁₀(4πd/λ). At 12 GHz and 550 km, FSPL ≈ 173 dB, meaning only 1 in 10¹⁷ units of energy arrives.
See in context →Transcranial Focused Ultrasound
Non-invasive neuromodulation using focused acoustic waves (250 kHz – 1 MHz) through the skull to stimulate deep brain structures with ~1 mm precision. Mechanisms include radiation force and mechanosensitive ion channel activation.
See in context →Geostationary Earth Orbit
Circular orbit at ~35,786 km altitude where satellites orbit at the same rate as Earth’s rotation, appearing stationary. Used for broadcast and weather satellites. Path loss at 20 GHz: ~210 dB.
See in context →Gallium Nitride
Semiconductor material used in high-power, high-frequency amplifiers on satellites. GaN SSPAs deliver 100–500 W of RF output with higher efficiency than traditional TWTAs.
See in context →High-Definition tDCS
Advanced form of tDCS using arrays of small electrodes (~1 cm²) instead of standard large pads (25–35 cm²), providing improved spatial focality for targeting specific cortical regions.
See in context →International Agency for Research on Cancer
WHO agency that evaluates carcinogenic risks. Classified RF electromagnetic fields as Group 2B ("possibly carcinogenic") in 2011 and ELF magnetic fields as Group 2B in 2002.
See in context →Intracortical Microstimulation
Delivery of small electrical currents through microelectrodes implanted in the cortex to evoke specific neural responses, such as tactile sensations in BCI applications (Flesher et al., 2021).
See in context →International Commission on Non-Ionizing Radiation Protection
Independent scientific organization providing guidelines for limiting exposure to non-ionizing radiation. ICNIRP 2020 guidelines set SAR limits at 2 W/kg (10g average) and introduced APD for >6 GHz.
See in context →Inter-Satellite Link
Communication link between satellites in a constellation, typically using laser (optical) terminals at 1,550 nm wavelength. Starlink uses ISLs for satellite-to-satellite data relay, reducing ground station dependency.
See in context →Low Earth Orbit
Orbital altitude between 200–2,000 km. Starlink operates at ~550 km. LEO offers low latency (~25 ms round-trip) but requires large constellations for continuous coverage. Satellites travel at ~7.5 km/s.
See in context →Long-Term Potentiation / Depression
Persistent strengthening (LTP) or weakening (LTD) of synaptic connections, considered the cellular basis of learning and memory. NMDA receptor-dependent LTP/LTD mechanisms underlie the after-effects of tDCS.
See in context →Motor Evoked Potential
Electrical response (typically 0.1–5 mV) recorded in a target muscle following TMS of the motor cortex. MEP amplitude and latency assess corticospinal tract integrity. First demonstrated by Barker et al. (1985).
See in context →Medium Earth Orbit
Orbital altitude between 2,000–35,786 km. GPS operates at ~20,200 km in 6 orbital planes. MEO balances coverage area and signal strength but with higher latency (~135 ms) than LEO.
See in context →Navigated TMS
TMS combined with real-time MRI-based neuronavigation, enabling precise mapping of cortical functions (motor, language areas) with millimeter accuracy. Used in presurgical planning for brain tumor resections.
See in context →On-Board Computer
The main processing unit on a satellite, handling command/data management, attitude determination, and payload scheduling. Typically radiation-hardened (e.g., RAD750, LEON4).
See in context →P300 Event-Related Potential
A positive voltage deflection occurring ~300 ms after a rare target stimulus, detectable via EEG. Forms the basis of the P300 speller BCI paradigm, allowing character selection at 5–10 characters per minute.
See in context →Power Flux Density
Power per unit area at a given distance from a transmitter, measured in W/m². Satellite PFD at Earth’s surface is regulated by ITU. Starlink limit: −146 dBW/m² per 4 kHz.
See in context →Repetitive Transcranial Magnetic Stimulation
TMS delivered in trains of pulses at specific frequencies. High-frequency (≥5 Hz) increases cortical excitability; low-frequency (≤1 Hz) decreases it. FDA-approved for depression, OCD, smoking cessation, and migraine.
See in context →Specific Absorption Rate
Rate of RF energy absorption in tissue: SAR = σ|E|²/ρ (W/kg). FCC limit: 1.6 W/kg (1g average); ICNIRP limit: 2.0 W/kg (10g average). Harm threshold: 4 W/kg whole-body. Basis for all RF safety regulations.
See in context →Steady-State Visual Evoked Potential
Brain response to flickering visual stimuli at a specific frequency, detectable via EEG. The fastest non-invasive BCI paradigm, enabling 40+ commands per minute by identifying the attended flickering target.
See in context →Solid-State Power Amplifier
RF power amplifier using semiconductor devices (typically GaN or GaAs) rather than vacuum tubes. State-of-art satellite SSPAs deliver 100–500 W of RF output.
See in context →Stent-Electrode Array (Synchron)
An endovascular BCI implanted via the jugular vein into the superior sagittal sinus. Uses a self-expanding stent with 16 electrodes to record cortical local field potentials without craniotomy.
See in context →Transcranial Alternating Current Stimulation
Non-invasive brain stimulation delivering sinusoidal alternating currents (0.5–2 mA, 0.5–100 Hz) to entrain endogenous brain oscillations at specific frequencies (alpha, theta, gamma).
See in context →Theta-Burst Stimulation
Rapid TMS protocol delivering 600 pulses in ~3 minutes (vs. ~37 minutes for standard rTMS). Produces long-lasting changes in cortical excitability. cTBS decreases, iTBS increases excitability.
See in context →Transcranial Direct Current Stimulation
Non-invasive neuromodulation applying weak DC current (1–2 mA) through scalp electrodes. Produces electric fields of 0.3–0.8 V/m at the cortex. After-effects persist 60–90 minutes via NMDA-dependent plasticity.
See in context →Transcranial Magnetic Stimulation
Non-invasive brain stimulation using a rapidly changing magnetic field (1.5–3 T) to induce electric currents in the cortex via electromagnetic induction. First demonstrated by Barker et al. in 1985.
See in context →Telemetry, Tracking & Command
Satellite subsystem for communication with ground stations. Handles health monitoring, command reception, and orbit determination. Typically uses S-band (2 GHz).
See in context →Utah Microelectrode Array
4×4 mm silicon chip with 96 penetrating microelectrodes (each 1–1.5 mm long, 400 µm pitch) for intracortical recording. Made by Blackrock Neurotech. Core of the BrainGate BCI system since 2004.
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