Brain Mapping: What You See in a Report

A brain map — more precisely, a quantitative EEG topographic map — is a visual representation of electrical activity measured across the scalp, presented as a color-coded head diagram. Each map corresponds to a specific metric (such as absolute power in the alpha band) and shows how that metric varies across electrode sites. The scalp is depicted from above, with the nose at the top, and values between electrode locations are interpolated to create a smooth, continuous surface.

Color scales on brain maps encode the magnitude of the measured variable. In z-score maps, the color represents how far a value deviates from the normative mean. A common convention uses cool colors (blue, green) for values near or below the norm and warm colors (yellow, orange, red) for values above the norm. The specific scale varies by software and database, so the legend accompanying each map must be read carefully. A bright red spot does not inherently mean something is wrong — it means that the value at that location is statistically elevated relative to the reference population.

Band power maps are among the most commonly reviewed. A delta power map shows the spatial distribution of slow-wave (0.5–4 Hz) activity; an alpha power map shows the 8–12 Hz distribution; and so on for each band. Clinicians and practitioners review these maps to identify patterns — for example, excessive frontal theta might appear in someone reporting concentration difficulties, while asymmetric alpha in posterior regions might be noted in a client describing mood instability. However, these are correlational observations, not diagnoses.

Beyond single-band power maps, brain mapping reports often include coherence maps, which show how strongly two brain regions are communicating within a given frequency band, and asymmetry maps, which compare left-hemisphere values to their right-hemisphere counterparts. Phase maps show timing relationships between sites. Together, these metrics build a multidimensional picture of cortical function that extends well beyond what a raw EEG waveform alone can convey.

It is essential to approach brain maps as data summaries, not diagnostic images. A brain map does not show disease, injury, or pathology the way an MRI shows a lesion. It shows statistical patterns of electrical activity. How those patterns relate to symptoms, history, and clinical context is the domain of the interpreting clinician. EEG Paradox Solutions generates and structures these maps with precision and transparency, but the clinical meaning is always left to licensed professionals.