Microanatomy — Visual Neuroscience

Cellsone drawn, more to follow

Neuron · cortexPyramidal cellComing soon
NeuronPurkinje cellComing soon
GliaAstrocyteComing soon
GliaOligodendrocyteComing soon
GliaMicrogliaComing soon

Neurotransmittersthe messengers, drawn

What crosses the synapse. Each is drawn as a skeletal formula: every corner and line-end a carbon, hydrogens on carbon left out, the other elements named. Most are small — an amino acid, or something made from one in a few steps — and the brain keeps a stock of them ready in vesicles, which is part of why it can release and clear them within milliseconds. Pick a transmitter to see it on its own — the monoamines first, since they are what so many familiar drugs act on — and open What it does under any of them.

Receptors and channelswhat the messengers land on

A neurotransmitter does nothing on its own: it has to bind to something. Here is what it binds to — the receptors for the molecules in the Neurotransmitters sheet — and alongside them the ion channels and transporters that shape its signal and end it, a hundred and fifty in all. Among them are only ten kinds of machine, drawn first, and the first thing to know about the receptors is that they come in two speeds. An receptor is a channel: the transmitter opens it within a millisecond, and it shuts when the transmitter leaves, or sooner, since many desensitise while it is still bound. A receptor has no pore; it works through a G protein and chemical messengers inside the cell, so it is slower to act and keeps acting for seconds or minutes after the transmitter has gone. Glutamate, GABA, acetylcholine, serotonin and ATP each have receptors of both kinds; dopamine, noradrenaline, histamine, the opioids and the neuropeptides work through metabotropic receptors alone. Most drugs that act on the brain act on one of the machines below. Pick a transmitter below to see only its receptors — the monoamines first, since they are what so many familiar drugs act on — and search inside it by name, drug or effect. Every word in a tile’s small capitals, and , , and here, opens a plain explanation on a hover or a tap. Each tile gives the name pharmacologists use with the plain name under it, what binds it and how tightly, the drugs people have heard of that act on it, what happens when it is bound, and under What the kind means the kind’s explanation again with a line of context.

Aboutwhat this is, and where it comes from

The atlas pages draw the brain a region at a time. This one goes down to the cell, and below that to the molecules that pass between cells and the receptors they land on. Each drawing is an original schematic built from code, with every structure a click target: pick one in the box and read what it does, colour them all to see how the cell is put together, or press Test yourself on the bar and find each one from memory. One cell is drawn so far: a large multipolar neuron, the commonest kind in the brain and spinal cord, with the axons that reach it, an astrocyte, two labelled synapses, and its own axon leaving under a myelin sheath. The cortex’s own cell, the pyramidal neuron, is next.

A schematic, not to scale: the organelles are drawn larger and far fewer than in a real cell, and the axon runs on well past the edge of the frame. Click any part of the drawing to find out what it is.

Pinch or scroll over the drawing to zoom, drag it to move about when it is larger than the view, and Reset view fits it again.

Each drawing is an original schematic generated from code rather than traced from a micrograph, so it owes nothing to any published plate. The descriptions are standard textbook anatomy and do not yet carry citations; the digital textbook is where each claim gets its paper. The molecules are drawn from their chemical structures by RDKit, an open-source toolkit, and coloured by the page.