This is a 2D cross-section reading of the same brain volume the 3D version renders: a lattice of pixels sampled inside a brain-shaped envelope for the currently selected imaging plane. In Structural mode a scan line sweeps across the slice — exactly how an MRI or CT scanner builds a cross-sectional image line by line, using tissue-dependent signal (grey vs white matter) rather than a single flat X-ray. In Functional mode the same slice shows a simulated BOLD (Blood-Oxygen-Level-Dependent) signal: cortical "activation" regions oscillate with a task/rest paradigm, and only pixels whose signal crosses your threshold are lit — the same statistical-thresholding step real fMRI analysis pipelines (SPM, FSL) apply before drawing an activation map.
BOLD(p,t) = S0 + A·G(p)·max(0, sin(2·pi·f·t))
G(p) = exp(-|p - c|^2 / (2·sigma^2))
- Scan mode — Structural sweeps a scan line across static tissue (MRI/CT-style); Functional overlays a time-varying activity signal (fMRI/PET-style) instead.
- Axial / Sagittal / Coronal — the three standard imaging planes; changing the plane changes which 2D cross-section of the brain volume is shown and which direction the scan line sweeps.
- Scan speed — how fast the scan line sweeps across the slice (lines per second).
- Activity threshold — the ΔBOLD cutoff below which a pixel is treated as noise and hidden, matching statistical thresholding of a real activation map.
- Task paradigm freq — how often the simulated task/rest block repeats, driving the oscillation of each activation center's signal.
Real-world relevance: this two-mode split mirrors how neuroimaging actually works — structural scans (MRI, CT) map anatomy, while functional scans (fMRI, PET, EEG/MEG) map the brain activity layered on top of that anatomy, and clinicians/researchers routinely combine both. This 2D companion reads as a single scanner cross-section, the way a radiologist actually flips through slices on screen.