Degrading vision with too much Ca²⁺

Figures & data

Figure 1. Retinal organization and ganglion cell (GC) signaling in wild-type (Ca_v1.4-WT) and Ca_v1.4-IT mice. Compared to WT channels, Ca_v1.4-IT channels activate at more negative voltages, causing greater Ca²⁺ influx within the physiological range of PR membrane voltages (dotted rectangle, top graph). In Ca_v1.4-WT retina (left), temporally precise and uniform PR responses to light rely on normal synapse structure and proper kinetics of channel activation and deactivation upon dark-light transitions (hypothetical numerical values for PR responses are shown). The result is a rapid and strong increase in GC firing in response to light stimuli (lower graph). In Ca_v1.4-IT retina, PR degeneration, disrupted PR synapses, and retraction of axons into the outer nuclear layer (arrows) leads to variable PR signaling. As a consequence, GCs respond to a light stimulus more sluggishly and less robustly compared to in Ca_v1.4-WT retina.