Figure 4.

The ipRGCs can approximately track gradual changes in light intensity. A, The response of an ipRGC to a 10 h light stimulus designed to simulate gradual light intensity changes over the course of the day. In this stimulus, the intensity was slowly ramped up from 8.1–12.8 log quanta cm⁻² s⁻¹ over 2.5 h, held constant at 12.8 log quanta cm⁻² s⁻¹ for 5 h, and slowly ramped back down to 8.1 log quanta cm⁻² s⁻¹ over 2.5 h. This response was recorded in normal Ames' medium to allow rod/cone input. B, The averaged spike histogram of all ipRGCs subjected to this ramp stimulus (n = 3), with a bin size of 5 min. All cells were superfused with normal Ames' medium.