Model Systems

Mouse dorsal lateral geniculate nucleus (dLGN) : The dLGN is the primary link between the retina and visual cortex. The functional architecture of the dLGN recapitulates retinal organization in that functionally distinct maps of visual space are stacked on top of one another. Unlike the retina, the output of these maps is regulated by the convergence of inputs from other parts of the brain (visual cortex, reticular nucleus, brain stem, and others). The dLGN also differs from the retina in that its organization is heavily dependent on developmental patterns of neural activity. Because the dLGN combines the stereotyped functional organization of the retina with the plasticity and feedback modulation characteristic of cerebral circuitry, the dLGN is an ideal system for studying how neural activity shapes neural circuits.

Synaptic glomeruli are glial encapsulated bundles of synapses that are characteristic of the feed-forward synaptic connectivity of the mouse dLGN. The circuitry within glomeruli varies between different channels of visual information. Be belive the organization of these structures, which retinal ganglion cells innervate them and how local interneurons transmit inhibition, to be key to feature detection and enhancement in the dLGN.

Mouse retina: The functional architecture of the retina is simple and stereotyped in that it consists of a stack of 2D maps of visual spaces. However, the mouse retina consists of approximately 100 types of neurons, each forming its own 2D mosaic across the retina. The patterns of synaptic connectivity between these mosaics are the first stage of the diversification of visual responses. We attempt to identify the strategies by which retinal neurons organize their synaptic connections and relate these strategies to specific visual computations and behaviors.

EM reconstruction of exciatatory and inhibitory inputs onto a retinal amacrine cell

Human retina: Access to live human retinas from surgical enucleations is giving us direct access to the retinal circuitry underlying human vision. In collaboration with Daniel Kerschensteiner’s lab, we are investigating the electrophysiology and circuit connectivity of human retinal ganglion cells.

Anole visual system: Anoles are diurnal lizards whose hunting, social interactions, and navigation are all highly visual. They have a cone-dominated retina with both a temporal fovea for binocular vision and a central fovea for high-acuity vision. As amniotes, they possess a dLGN connecting their retina to their visual cortex. Anoles have also demonstrated a greater capacity for regeneration after optic nerve damage than mice.