Ichinose, T., Fyk-Kolodziej, B., & Cohn, J.
Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri 63110, and Departments of Anatomy and Cell Biology, and Ophthalmology, Wayne State University School of Medicine, Detroit, Michigan 48201.
In the visual system, diverse image processing starts with bipolar cells, which are the second-order neurons of the retina. Thirteen subtypes of bipolar cells have been identified, which are thought to encode different features of image signalling and to initiate distinct signal-processing streams. Although morphologically identified, the functional roles of each bipolar cell subtype in visual signal encoding are not fully understood. Here, we investigated how ON cone bipolar cells of the mouse retina encode diverse temporal image signalling. We recorded bipolar cell voltage changes in response to two different input functions: sinusoidal light and step light stimuli. Temporal tuning in ON cone bipolar cells was diverse and occurred in a subtype-dependent manner. Subtypes 5s and 8 exhibited low-pass filtering property in response to a sinusoidal light stimulus, and responded with sustained fashion to step-light stimulation. Conversely, subtypes 5f, 6, 7, and XBC exhibited band pass filtering property in response to sinusoidal light stimuli, and responded transiently to step-light stimuli. In particular, subtypes 7 and XBC were high-temporal tuning cells. We recorded responses in different ways to further examine the underlying mechanisms of temporal tuning. Current injection evoked low-pass filtering, whereas light responses in voltage-clamp mode produced band pass filtering in all ON bipolar cells. These findings suggest that cone photoreceptor inputs shape band pass filtering in bipolar cells, whereas intrinsic properties of bipolar cells shape low-pass filtering. Together, our results demonstrate that ON bipolar cells encode diverse temporal image signalling in a subtype-dependent manner to initiate temporal visual information-processing pathways.
… “Light stimulation. Light stimuli were generated using a CoolLED pE-2 system that was controlled with Clampex software. Either 500 or 360nm LED light was projected to the slice preparation through a 60 x objective lens.”…
Product Associated Features
pE-2: A repeatable, controllable modular system with 20 different LED peaks. Instant on/off and intensity (0-100%) control.
The Journal of Neuroscience
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