The Cochlear Nuclei:
The Diagram above shows the major neuronal types in the cochlear and cochlear nuclei, it was created using information I have gathered for The List, it shows the start of the auditory pathway that conveys sound information from the sensory hair cells in the cochlear to higher brain areas.
I have tried to show all the known connections between different cell types and whether they are inhibitory, excitatory, or the one known example where the synapses can be both inhibitory, or excitatory, depending on the context (Golding, 1996). It is worth noting that this only shows identified connections between neuronal types, other connections and even other cell types are likely to exist, but are less well documented. I have also tried to show the targets of neurons that project from the cochlear nuclei to higher brain areas.
It was tempting to hypothesise unverified connections, possibly using dashed lines. For example, type II Spiral Ganglion Neurons (SGNs) have been shown to drive medial olivocochlear (MOC) neurons via a connection in the cochlear nuclei (Froud, 2015). As T-stellate cells in the posterior ventral cochlear nucleus project to MOC neurons, it seems likely that type II SGNs drive activity in T-stellate cells, however I haven't found any evidence for this connection in the literature, only that type II SGNs project to granule cell regions of the cochlear nuclei (Berglund, 1994) and this paper is not open access.
Versions of these connectivity maps appear in many scientific publications and web resources, especially for well-studied areas like the retina. But are often simplified to only show specific cell types with specific function, or specific pathways. I would rather that each neuron was displayed and it's information available for anyone to be able to decide which ones are important.
Furthermore, I believe that this information should be freely available and modifiable, therefore I have created this diagram using Inkscape (freely available design software), and kept it simple by using simple shapes and colours to show the connectivity. The inkscape (svg) file and the PNG image file will be freely available to download under a creative commons share-alike licence, i.e. modifications and redistribution are allowed, so long as they are shared freely online, or in a classroom.
Finally, I would like to welcome feedback, modifications, ideas, collaboration etc. You can contact me via the form here.