This interactive visualization charts valence values derived from alpha and beta EEG frequencies recorded at the F3 and F4 electrode sites. Users can toggle between the four frequency-channel combinations via buttons, with the colored line representing the selected signal and a zoom feature for closer inspection. The example loads data from separate CSV files for each frequency band and uses D3.js version 4 to render the line chart as an SVG with animated transitions. The underlying code also demonstrates importing modules from local ES6 files and loading D3 via UNPKG.