Abstract: Midget and parasol ganglion cells serve distinct roles in the visual pathway of the retina, and together form a large proportion of its output. Other components of the visual scene are processed by non-midget, non-parasol ganglion cells which project primarily to the koniocellular layers of the lateral geniculate nucleus. The functional characteristics of many of these koniocellular pathway ganglion cells, or “wide-field” types in primate retina remain poorly understood. We investigated the density of synaptic inputs onto two types of wide-field ganglion cells, to see whether synaptic input density may play a role in shaping the possible functional differences between these two morphologically contrasting ganglion cell types. We also investigated the contributions of wide-field ganglion cells and their presynaptic partners (bipolar cells) to visual signals within the fovea – a region of the retina specialised for transmitting high acuity visual signals. Presumed bipolar cell inputs were found to be at approximately equal density in large sparse and broad thorny ganglion cells. Thus, any functional differences between these cell types are unlikely to arise from variation in synaptic densities. Further, in our study of wide-field ganglion cells within the fovea, it was found that at least eight types of wide-field ganglion cell types previously described in peripheral retina are also present within 1mm of the fovea, along with a subset of their presynaptic partners. Retinal pathways involving wide-field ganglion cells are therefore highly likely to contribute to foveal vision.

Recent Publications:

1. Organisation of koniocellular-projecting ganglion cells and diffuse bipolar cells in the primate fovea. Percival KA, Martin PR, Grünert U.
Eur J Neurosci. 2013 Jan 13. doi: 10.1111/ejn.12117. [Epub ahead of print]

2. Synaptic inputs to two types of koniocellular pathway ganglion cells in marmoset retina. Percival KA, Martin PR, Grünert U.
J Comp Neurol. 2011 Aug 1;519(11):2135-53. doi: 10.1002/cne.22586.