Purpose:
To validate the feasibility of imaging retinal flicker response using fast intrinsic optical signals (IOSs); and to characterize the relationship between fast IOSs and electrophysiological changes in the retina activated high frequency flicker stimuli.
Methods:
Near infrared (NIR) flood-illumination microscope and customer-designed line-scan confocal imager were employed to investigate transmitted and reflected light IOSs in isolated frog retinas. Both imaging systems provided ~µm and ms spatiotemporal resolution. Dynamic differential imaging was used to separate fast IOSs from slow optical changes. Simultaneous ERG measurements were conducted to compare optical and electrophysiological responses in the retina activated by variable frequency (0.5-10 Hz) flicker stimuli.
Results:
High-speed (1000 Hz) dynamic differential imaging disclosed rapid IOS immediately after the onset of the stimulus. Both fast IOSs and simultaneous electrophysiological responses could follow high frequency flicker stimuli up to at least 6 Hz.
Conclusions:
The feasibility of IOS imaging of retinal flicker response was demonstrated. Dynamic differential imaging indicated that rapid IOSs occurred immediately after the onset of the stimulus, and could track high frequency flicker stimuli up to at least 6 Hz. It is well known that different retinal neurons, such as cone and rod systems, have different critical fusion frequency (CFF). We anticipate that further development of dynamic differential imaging of fast IOSs correlated with retinal flicker stimuli may provide selective evaluation of different retinal neurons.
Keywords: retina • electrophysiology: non-clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)