Audio-visualization of spiking activity in a model of two interconnected cortical areas Time-lapse movies showing depth-wise (left panel) and radial (right panel) histograms of spiking activity in a model of two interconnected cortical areas. The audio track provides an aural representation of spiking activity, with a frequency mapping to depth (lower frequencies at higher depths) and an amplitude proportional to the number of spikes. The left audio channel provides information on activity in area X, and the right channel on activity in area Y. In movies showing each region separately, the left audio channel is for INH neurons and the right channel for EXC neurons. Best listened with headphones. Temporal resolution is 1 ms, depth resolution is 20 µm, and radial resolution is 5 µm. Before stimulus onset at timecode t = 6000 ms, we observe spontaneous activity only, which is very sparse as can be heard. On stimulus arrival we see and hear a strong response in area X that propagates depth-wise through internal connections (notice progression to lower audio frequencies) and also propagates to area Y through long-range connections (notice progression from left to right ear). The induced activity in area Y propagates again depth-wise through internal connections and then bounces back to area X through long-range connections, closing the feed-forward/feedback loop. This kind of audio-visualization serves to generate intuition on the propagation dynamics of neuronal activity within and across interconnected cortical microcircuits.

This work was supported by funding to the Blue Brain Project, a research center of the École polytechnique fédérale de Lausanne (EPFL), from the Swiss government's ETH Board of the Swiss Federal Institutes of Technology.