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Rene C. Renteria, Nikolay P. Akimov; Immaturity Of Contrast Thresholds And Temporal Frequency Responses At Eye Opening In Mouse Retinal Ganglion Cells. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4561.
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When a mouse’s eyes open, vision is immature and matures over the following weeks. We previously showed that the distribution of retinal ganglion cell (RGC) contrast thresholds at postnatal day (P)16 is similar to the adult (P30+) and that firing properties are immature. Here, we find two immaturities at eye opening (P13-14): 1) in contrast threshold of RGCs and 2) in the temporal frequency response of RGCs.
A multi-electrode array was used to record spiking responses to visual stimuli from RGCs of C57Bl6 mouse retinas at P13, P14, P16, and P30-P39. A square of light that covered the array was presented. The intensity of the square was varied sinusoidally at 18 contrasts ranging from 2.4% to 92% and presented at 3.75 and 1 Hz. Next, 10 temporal frequencies ranging from 0.75 Hz to 12.5 Hz were presented at 50% contrast.
RGC contrast thresholds were higher at P13 and P14 than at P16 or P30+. Peak frequencies of the RGCs’ frequency response curves were lower at P13 and P14 than at the older ages. At P16 and P30, many RGCs not only had peak responses at higher frequencies but also had broader bandwidths. The slow frequency response at eye opening did not appear to account for the poor contrast thresholds of the RGCs: Contrast thresholds tested using 1 Hz stimuli, while significantly lower than at 3.75 Hz, were still significantly worse at P13 and P14 than for P16 RGCs tested at either frequency.
Contrast thresholds were immature and poor at eye opening, even when tested using a stimulus frequency much slower than that used for P16 or P30+. The temporal frequency response of RGCs was immature at eye opening, having a narrower bandwidth and a lower peak frequency. For these parameters, nearly all maturation occurred by P16. Thus, RGCs have profound response immaturities at eye opening, and maturation happens quickly, over the ensuing few days.
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