NeuroAnalyzer Glossary

The glossary defines terms and conventions specific to NeuroAnalyzer.

Channel

A single vector of values recorded over time. Each channel has a label (e.g. “Fp1”), a type (e.g. “eeg” or “eog”), and a unit (e.g. “μV”). All available channel types are listed in the NeuroAnalyzer.channel_types variable.

Data

The raw neurophysiological recording, stored as one of the following:

  • a vector (e.g. a single channel)
  • a matrix (e.g. channels × channels or channels × epochs)
  • a 3D array (channels × time points × epochs)

Available NeuroAnalyzer data types are:

  • eeg - electroencephalography (EEG)
  • ecog - electrocorticography (ECoG)
  • seeg - stereoelectroencephalography (SEEG)
  • ieeg - intracranial electroencephalography (iEEG)
  • csd - current source density (CSD)
  • meg - magnetoencephalography (MEG)
  • nirs - near-infrared spectroscopy (NIRS)
  • sensors - various body sensors
  • eda - electrodermal activity (EDA)
  • mep - motor evoked potentials (MEP)
  • erp - event-related potential (ERP)
  • erf - event-related field (ERF)
  • tpt - two-point pinch test (TPT)

All available channel types are listed in the NeuroAnalyzer.data_types variable.

Epoch

A segment of recorded data, defined either by event markers (e.g. stimuli or experimental events) or fixed time intervals.

Every recording imported into NeuroAnalyzer contains at least one epoch.

Label

The name assigned to a channel, e.g. “Fp1” for EEG or “S1_D1 OD” for NIRS.

Locs

The positions of electrodes or sensors used to record neurophysiological data (e.g. EEG electrodes or NIRS optodes). Positions are defined separately in 2D and 3D space using three coordinate systems:

  • Cartesian (X, Y, Z)
  • Planar (radius, theta)
  • Spherical (radius, theta, phi)

NeuroAnalyzer uses the RAS (Right-Anterior-Superior) coordinate system:

Axis Positive direction Negative direction
X Right Left
Y Anterior (front) Posterior (rear)
Z Superior (top) Inferior (bottom)

Marker

An event recorded simultaneously with the neurophysiological data, such as a button press or stimulus onset. Each marker has four attributes:

  • id - event identifier (e.g. “S01”)
  • onset - time of the event in samples
  • duration - length of the event in samples
  • description - a text label (e.g. “stim”)

Mutator

A function that modifies its input object in place rather than returning a modified copy. Mutator functions are identified by a ! suffix in their name, e.g. delete_channel!() or add_locs!().

NEURO object

The fundamental data structure in NeuroAnalyzer. Each object contains:

  • a header with recording, subject, and experiment metadata
  • time points and epoch time points
  • recording data
  • channel locations
  • event markers
  • processing history

A new NEURO object is created by importing a neurophysiological recording (e.g. EEG or MEG).

Pick

A named selection of channel locations. For example, a [:left, :frontal] pick resolves to channels ["Fp1", "F3", "F7"].

Signal channel

A channel containing recorded neurophysiological data. Examples include:

  • EEG: channels labelled "Fp1", "C3", etc., including reference (e.g. "A1") and oculogram (e.g. "EOG1") channels
  • MEG: magnetometer ("meg") and gradiometer ("grad") type channels