The research objective of this proposal is to investigate stimulus-evoked intrinsic optical signals (IOSs) associated with photoreceptor and post-photoreceptor neural responses in the complex retinal neural network. This project will start with investigating fast IOSs in frog retinal slices. A retinal slice preparation exposes a cross-section of the retinal layers, and thus allow simultaneous recording of fast IOSs from the photoreceptors and post-photoreceptor neurons, with feasibility of concurrent electrophysiological recording of targeted retinal cells. This phase will test two hypotheses: 1) Fast IOSs correlated with early photoreceptor activities to light stimulation occurs immediately after the stimulus delivery; while fast IOSs associated with second- and third-order post-photoreceptor neurons may have a time delay relative to the stimulus. 2) Fast IOSs can be used to image oscillatory and spike neural activities generated by post-photoreceptor neurons. The second phase of this project is to explore simultaneous optical coherence tomography (OCT) imaging of photoreceptors and post-photoreceptor responses in the intact eye. In order to achieve this objective, an acousto-optic deflector (AOD) based optical coherence tomography (OCT) is proposed for pursuing vibration- and inertia-free optical dissection of retinal neural activities.
