A Cubic Millimeter of Mouse Brain

My latest #neuro #visualization is an intuition pump to help us appreciate the intricate interconnectivity of cells in your #brain. We begin by peeling through the #MICrONS cubic millimeter of mouse visual cortex, where ~75,000 neurons are packed tightly. We then see the layered organization of the cerebral cortex, segmented by their inputs and outputs. While the inputs and outputs are designated to distinct layers, the brain is functionally organized by vertical ‘columns’ through all these layers. Each column is a modular, computational unit, that processes and responds to one specific type of information. We take a moment to appreciate the coordinated firing of a sample of functionally-matched neurons from within a cortical mini-column. We then zoom in from the level of the circuit to the level of the synapse, onto a layer 5 Pyramidal neuron at the heart of the microcolumn, the principal excitation unit of the brain. This unremarkable pyramidal neuron has over 11,000 input synapses. It’s job is to integrate these inputs, and change its own output firing rate in response. Each glowing point is at the location of a synapse. For the synapses known to come from specific cortical layers, I’ve color coded these synapses, and animated them to flicker with juxtaposed activity data from the same type of cells elsewhere in the volume. As the camera pans away, we appreciate the neuronal diversity inside this tissue - each of the neurons that pops in and out of view is a sample from the same volume that is confirmed to share a synapse with this pyramidal. Some cells hug it closely, some reach over to “high-five“ from a distance. Thanks to the Allen Institute for their commitment to #openscience and making these impressive datasets openly available. Find the original data here: