Hope Shi will be delivering a seminar, Die Fledermaus: Regarding Retinal Light Adaptation, Chicks Are Mice with Wings on December 12th at 1:00pm in the John A. Moran Eye Center auditorium.
Through adaptation, animals can function visually under an enormous range of light intensities. Adaptation to changes in light intensity takes place early, in the retina. One role of adaptation is to regulate the spatiotemporal tuning of retinal outputs via ganglion cells. We used the optokinetic response to characterize contrast sensitivity (CS) in the chick retina as a function of spatial frequency and temporal frequency at different mean light intensities. We previously found that adaptation caused a shift in tuning preference of CS from light to dark.
Recently, we explored mechanisms that modulate spatiotemporal CS under different adaptational conditions. We injected agents affecting dopamine (DA) and nitric oxide
(NO) actions and gap junction coupling into the eyes (vitreous bodies) of dark- or light-adapted chicks. We demonstrated that cell-cell coupling and NO, as well as DA, are adaptation-sensitive modulators of spatiotemporal visual processing in the retina.
Optokinetic CS is a rapid and noninvasive method for assessing retinal function, which can be manipulated rapidly, conditionally and reversibly by intravitreal injection of specific pharmacological agents. The chick’s large eyes, and the similarities of control of light adaptation in chick and other species (e. g., mouse), make the chick a powerful new model for retinal research.