What is a .loc file?

A .loc file is a file type that stores detailed information about the location of sensors. These files are essential for correctly mapping EEG data in three-dimensional space, ensuring that electrical signals are accurately linked to specific areas of the brain. 

Key Features of a .loc File: 

• Sensor Positions: The .loc file includes the exact coordinates and labels of the sensors placed on the scalp. Each sensor’s position is described in the standard coordinate system 10-20, commonly used in EEG studies.
• Sensor Labels: Each sensor has a unique label (e.g., Fp1, Fp2, C3, C4) that indicates its location on the head. 

How are .loc Files Used in EEG Analysis?

• Visualization: When analyzing EEG data, .loc files are used in software tools to visualize where each sensor is placed on the head. This allows researchers to see the origin of the recorded signals.
• Spatial Analysis: The exact placement of sensors is critical for spatial analyses, such as source localization (determining where in the brain a signal originates) or creating topographical maps (visual representations of brain activity across the scalp).