This example plots time-series measurements of arousal and valence from an EEG dataset (channel F4) as an animated, interactive line chart. The visualization displays one of three data segments at a time, with buttons to switch between arousal and valence signals, or to cycle through the segments. The chart uses a gradient stroke from blue to red to encode the signal amplitude, while individual samples appear as small yellow dot markers on click. The code uses the D3.js library, specifically `d3.csv` for data loading, `d3.scale.linear` for axes, and `d3.svg.line` for the path geometry.