Abstract
Purpose: :
Our goal was to investigate the light induced Ca dynamics of morphologically identified subclasses of ipRGCs.
Methods: :
We created a recombinant Pseudorabies virus (PRV) based, retrograde, transsynaptic tracer expressing a genetically encoded Ca-sensor. This, Activity-sensor PRV (As-PRV) was injected into the anterior chamber of the right eye of adult mice. 3.5-5 days after the injections the contralateral retina was isolated and stimulated with light. Ca-imaging was performed from labeled ganglion cells with the help of 2-photon microscopy. After live-imaging, the retinas were fixed and stained with different antibodies for further analysis via confocal microscopy.
Results: :
As-PRV infects highly specifically the pupillary reflex pathway including the Edinger-Westphal and Olivary pretectal nuclei as well as other connected regions like the Intergeniculate leaflet or Suprachiasmatic nucleus. In the contralateral retina As-PRV labeled mainly ipRGCs at early times of retinal infection. Light stimulation of the retina resulted in large Ca changes in a well defined morphological class of ipRGCs while another class of ipRGCs had much smaller or undetectable Ca response. Morphological analysis of the recorded cells showed, that the cells with large Ca response were stratifying in the OFF sublamina while the other class stratified in the ON sublamina.
Conclusions: :
Our results indicate that different morphological classes of ipRGCs have remarkably different Ca responses during light activation. These ipRGC subclasses might activate different brain regions or different subtypes of neurons in ipRGC target regions.
Keywords: retinal connections, networks, circuitry • calcium