Strict Independence of Parallel and Poly-synaptic Axon-Target Matching during Visual Reflex Circuit Assembly

Publication date: 12 December 2017
Source:Cell Reports, Volume 21, Issue 11
Author(s): Tania A. Seabrook, Onkar S. Dhande, Nao Ishiko, Victoria P. Wooley, Phong L. Nguyen, Andrew D. Huberman
The use of sensory information to drive specific behaviors relies on circuits spanning long distances that wire up through a range of axon-target recognition events. Mechanisms assembling poly-synaptic circuits and the extent to which parallel pathways can "cross-wire" to compensate for loss of one another remain unclear and are crucial to our understanding of brain development and models of regeneration. In the visual system, specific retinal ganglion cells (RGCs) project to designated midbrain targets connected to downstream circuits driving visuomotor reflexes. Here, we deleted RGCs connecting to pupillary light reflex (PLR) midbrain targets and discovered that axon-target matching is tightly regulated. RGC axons of the eye-reflex pathway avoided vacated PLR targets. Moreover, downstream PLR circuitry is maintained; hindbrain and peripheral components retained their proper connectivity and function. These findings point to a model in which poly-synaptic circuit development reflects independent, highly stringent wiring of each parallel pathway and downstream station.

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Teaser

Seabrook et al. found using conditional genetic deletion of specific retinal ganglion cell types that retinal innervation of the pretectum is highly regulated and that downstream circuit connections are maintained following removal of peripheral sensory drive.


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