High-speed line-scan confocal imaging of stimulus-evoked intrinsic optical signals in the retina.

A rapid line-scan confocal imager was developed for functional imaging of the retina. In this imager, an acousto-optic deflector was employed to produce mechanical vibration- and inertia-free light scanning, and a high-speed (68,000 Hz) linear CCD camera was used to achieve subcellular and submillisecond spatiotemporal resolution imaging. Two imaging modalities, i.e., frame-by-frame and line-by-line recording, were validated for the reflected light detection of intrinsic optical signals (IOSs) in visible light stimulus activated frog retinas. Experimental results indicated that fast IOSs were tightly correlated with retinal stimuli and could track visible light flicker stimulus frequency up to at least 2 Hz.