Figure 5: An excitotoxic cascade is initiated by the dopaminergic expression of the human LRRK2-G2019S transgene (DA → G2019S). In young, 1-day-old DA → G2019S flies, the eyes show much greater contrast sensitivity than the controls. At 3 days, the visual sensitivity measured by a flash electroretinogram (fERG) is indistinguishable from control flies. At 10 days, the DA → G2019S flies are more sensitive to energy demands than controls. Energy demand is increased by either treatment with flashing light or knockdown of potassium channels. By 21 days, the DA → G2019S eyes show evidence of apoptosis (anticleaved-caspase-3 staining). Old flies, 28 days, show little photoreceptor response, extensive vacuoles, and deformed mitochondria, showing loss of both function and structure. Data and exact genotypes in [15, 49].