Functional changes in Tg XXXX -1 @entity35 retinal responses: differences between ON and OFF pathway transmission to the superior colliculus.

@entity227 @entity18857 @entity3264 @entity41812 @entity10880 @entity6391 @entity164 @entity5995 @entity35 @entity20256 @entity528
The morphological consequences of @entity5995 @entity528 are well documented. Much less is known about changes in visual function during degeneration and whether central @entity227 directly reflect changes in retinal ganglion cell (RGC) function. To address this, we compared changes in visual function of RGCs and cells in the superior colliculus (SC) in transgenic (Tg) @entity41812 -1 @entity35 , a model of @entity6391 ( @entity6391 ), and @entity164 ( @entity164 ) @entity35 at postnatal days 35-50 (P35-50) and P300. RGCs were classified on the basis of their responses to light: onset (ON), offset (OFF), or both (ON-OFF). The distribution of ON, OFF, and ON-OFF RGCs is similar between @entity164 and P35 Tg @entity41812 -1 @entity35 . By P300, many Tg @entity41812 -1 RGCs are nonresponsive (NR). At this age, there is a sharp decline in ON and ON-OFF RGCs, and the majority that remain are OFF RGCs. Spontaneous rhythmic activity was observed in many RGCs at P300, but only in OFF or NR RGCs. In the SC, @entity164 and P50 Tg @entity41812 -1 responses are similar. At P300, Tg @entity41812 -1 ON SC responses declined but OFF responses increased. We examined postsynaptic @entity3264 receptor expression located on the bipolar cells (BC), where the ON and OFF pathways arise. At @entity20256 , metabotropic @entity3264 receptor 6 ( @entity10880 ) expression is lower than in @entity164 , consistent with a decrease in ON RGC responses. @entity18857 expression, an ionotropic @entity3264 receptor associated with OFF BCs, appears similar to that in @entity164 . The loss of ON responses in Tg @entity41812 -1 RGCs and in the SC is conserved and related to reduced @entity10880 signaling.
