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Glossary of Terms

A reference guide to common terms used in EEG, neuroscience, and the Metrics application.

Brain & Biosignals​

EEG (Electroencephalogram)​

Measurement of electrical activity produced by the brain. EEG captures voltage fluctuations from neurons firing in the brain, detected by electrodes placed on the scalp. Metrics visualizes EEG data in real-time from Muse headbands.

EMG (Electromyogram)​

Measurement of electrical activity produced by muscles. Muse headbands can detect facial muscle activity (such as jaw clenching or eye blinks) which appears as artifacts in the EEG signal.

Brainwaves​

Rhythmic patterns of electrical activity in the brain, categorized by frequency:

  • Delta (0.5-4 Hz): Deep sleep
  • Theta (4-8 Hz): Drowsiness, light sleep, meditation
  • Alpha (8-13 Hz): Relaxed, calm, eyes closed
  • Beta (13-30 Hz): Active thinking, focus, alertness
  • Gamma (30+ Hz): Higher cognitive functions, perception

Artifact​

Unwanted signals in EEG data caused by non-brain sources such as eye blinks, muscle movements, or electrical interference. Metrics provides signal filtering to help reduce artifacts.

PPG (Photoplethysmography)​

An optical technique used to detect blood volume changes. Muse S headbands include a PPG sensor that can measure heart rate.

Accelerometer​

A sensor that measures acceleration and orientation. Muse headbands include accelerometers to detect head movement.

Gyroscope​

A sensor that measures rotational motion. Combined with accelerometer data, it provides detailed head movement tracking.

Streaming & Integration​

LSL (Lab Streaming Layer)​

A research-focused EEG and marker streaming system that provides high-resolution timestamps in addition to high-frequency EEG streaming. LSL is widely used in neuroscience research for synchronizing multiple data streams. Metrics can stream data via LSL to applications like MATLAB, Python, and Unity.

OSC (Open Sound Control)​

A protocol for networking sound synthesizers, computers, and other multimedia devices. Originally designed for music applications, OSC is now used broadly for real-time data communication. Metrics can stream EEG data via OSC to creative applications, game engines, and more.

Webhook​

An HTTP callback that sends data to a specified URL when events occur. Metrics can stream data to webhooks for cloud integration and custom applications.

API (Application Programming Interface)​

A set of protocols that allows different software applications to communicate. The Metrics API enables developers to programmatically access EEG data and control the application.

Data & Recording​

Sample Rate​

The number of data points captured per second, measured in Hertz (Hz). Muse headbands sample EEG at 256 Hz, meaning 256 measurements per second per channel.

Channel​

A single electrode or sensor input. Muse headbands have 4 EEG channels (TP9, AF7, AF8, TP10) corresponding to electrode positions on the scalp.

Timestamp​

A marker indicating when a data point was recorded. Metrics provides millisecond-precision timestamps for accurate data analysis and synchronization.

CSV (Comma-Separated Values)​

A simple file format for storing tabular data. Metrics can export recorded sessions as CSV files for analysis in spreadsheet applications or data science tools.

Session​

A continuous period of EEG recording. In Metrics, a session begins when you start recording and ends when you stop.

Hardware​

Muse Headband​

A consumer EEG headband manufactured by Interaxon. Metrics supports Muse 2 and Muse S models for real-time EEG streaming and visualization.

Electrode​

A conductive pad that detects electrical signals from the scalp. Muse headbands use dry electrodes that don't require gel or paste.

Bluetooth Low Energy (BLE)​

A wireless communication protocol used by Muse headbands to connect to computers and mobile devices. Metrics connects to Muse via BLE.

Concepts​

BCI (Brain-Computer Interface)​

Technology that enables direct communication between the brain and external devices. EEG-based BCIs interpret brain signals to control computers, prosthetics, or other systems.

Neurofeedback​

A technique that provides real-time feedback about brain activity, allowing users to learn to self-regulate their brainwaves. Metrics visualization can be used for basic neurofeedback applications.

Telepathic Software​

Software that is capable of interpreting and responding to a user's state of mind, as detected through biosensors like EEG. Petal Technology develops telepathic software tools.

Telepathic User​

A person who communicates with software using their mind via brain-computer interface technology.

See Also​