A five-minute journey through the layers of mouse somatosensory cortex (whisker area). Green fluorescence light up a small (3-5%) genetic subset of neurons, blue highlights the microtubule cores of all axons and dendrites, and red lights up the synapses. The inset image with roving magenta rectangle at upper left navigates the journey. Each red synapse comprises approximately 100,000 protein switches. There are more than six million synapses in the tissue volume rendered here, and at least one hundred billi