How a thought moves
Everything your brain does is built from three moves. A single cell fires. Connections between cells change with use. Groups of cells in different regions pass work to each other. This lab lets you drive each move on the same brain. Turn the brain around, then fly the camera in to a single cell and one of its connections.
What you are looking at
Regions. The whole brain, front of the head toward the eyes. Drag to turn it. Regions light up in order for the task you pick. The glowing markers inside the brain are deep structures you could not see from the surface.
Spike. The camera flies in to one neuron in the cortex. The branches on the left are dendrites, which collect input. The round cell body adds that input up. The long axon carries the spike to its terminals on the right. Colour shows the voltage across the membrane: warm means the cell is pushed up toward firing, cool means it has dipped below rest just after a spike.
Synapse. Zoom into one axon terminal where Cell A touches Cell B. The swollen end of A holds packets of chemical messenger. Across a narrow gap, a small bump on B carries the receptors that catch it. A stronger connection has a bigger terminal, more packets, and more receptors.
The controls
- Input strength sets how hard the input pushes the cell. Below the threshold mark the cell rises a little and settles back. Above it, the cell fires a full spike. Stronger input makes the spike start sooner, but it does not make the spike bigger.
- A and B fire together sets how often Cell B fires just after Cell A on each trial. Each trial where they fire together strengthens the connection, and each trial where they fire apart weakens it.
- Task picks seeing, remembering, or deciding, and replays which regions take up the work and in what order.
- Run and the time slider play or scrub the current level. On the synapse level, moving time forward applies your current setting from that point, and moving it back shows earlier trials.
What is exact and what is not
Faithful to the biology
- The spike's shape: rise, fall, a dip below rest, then reset.
- All-or-nothing firing. A spike either happens in full or not at all.
- A spike travels one way, because the stretch it just left is briefly unable to fire again.
- The direction of change at the synapse: firing together strengthens a connection and firing apart weakens it.
- The order of regions in each task matches the standard textbook account.
Simplified
- Time is slowed by about a thousand times. A real spike lasts around 2 ms.
- The trace is a fitted shape. It is not solved from ion-channel equations.
- The threshold is a single number, and the axon has no myelin.
- The synapse uses a fixed plus-or-minus step per trial. Real plasticity depends on precise timing, calcium, and receptor trafficking.
- Sizes are not to scale between levels. A real synapse is about a thousandth of a millimetre across.
- The region map is a teaching diagram, not a brain scan. The folds on the 3D brain are generated, not traced from a real one.
This is a learning tool. It is not a medical or diagnostic tool.
