Purchase this article with an account.
Hope Shi, Carl Sabottke, Dan Butts, Karen Carleton, Joshua H Singer; Physiological Characterization of Retinal Ganglion Cell Types in Tilapia mariae. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3250.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
African cichlids are models of vertebrate photopigment evolution. Although color vision in these fish has been studied genetically (O’Quin et al., 2010) and behaviorally (Smith et al., 2011), little is known about their retinal function. Therefore, we used multielectrode array (MEA) recording to examine responses of the retinal ganglion cells (RGCs) of the cichlid Tilapia mariae to light stimulation.
Fish were euthanized and retinas were dissected under dim red light. Prior to recording, the isolated retina was dark-adapted for at least 30 minutes. Light responses from RGCs from the peripheral retina were recorded in vitro using a 60-channel, perforated MEA (Multichannel Systems) mounted on the video port of an inverted microscope. The retina was perfused continuously with Ames’ medium (Sigma) diluted to 260 mOsm. Light stimuli were generated using the Matlab psychophysics toolbox (Mathworks) and delivered by a digital projector (Hewlett Packard) through the objective. Stimuli comprised 3-stage square-wave, random-checkerboard, and random-binary whole-field flash paradigms delivered as white, short (450nm), medium (514nm), and long (625 nm) wavelengths. Temporal response profiles were characterized using spike-triggered averages (STA), generalized linear models, and nonlinear modeling techniques. All recordings were performed between 10 am and 5 pm, under photopic conditions, at room temperature.
All RGCs responded to each of the 3 wavelengths. Of the recorded cells, 24% were ON-type, 68% were transient OFF-type, and 8% were sustained OFF-type. The temporal profiles of their receptive fields typically were biphasic, with a larger lobe peaking near 50 milliseconds, a second peak of opposite sign near 100 ms, and zero-crossing time near 75 ms. An example of spatial receptive field and a temporal STA of an OFF RGC is shown in Figure 1.
The tilapia retina contains RGC types similar to those of mammalian retinas observed under similar conditions. The temporal properties of these RGCs resembles those of the primate (Chichilnisky and Kalmar, 2002) and of the mouse (Wang et al., 2011) retinas. Cichlids’ trichromatic cone vision and the hardy nature of their retinas make them a wonderful model for future color vision research.
This PDF is available to Subscribers Only