Abstract
An animal’s motion through the environment can induce large and frequent fluctuations in light intensity on the retina. These fluctuations pose a major challenge to neural circuits tasked with encoding visual information, as they can cause cells to adapt and lose sensitivity. Here, we report that sensitization, a short-term plasticity mechanism, solves this difficult computational problem by maintaining neuronal sensitivity in the face of these fluctuations. The numerically dominant output pathway in the macaque monkey retina, the midget (parvocellular-projecting) pathway, undergoes sensitization under specific conditions, including simulated eye movements. Sensitization is present in the excitatory synaptic inputs from midget bipolar cells and is mediated by presynaptic disinhibition from a wide-field mechanism extending >0.5 mm along the retinal surface. Direct physiological recordings and a computational model indicate that sensitization in the midget pathway supports accurate sensory encoding and prevents a loss of responsiveness during dynamic visual processing.
Highlights
An animal’s motion through the environment can induce large and frequent fluctuations in light intensity on the retina
A computational model based on synaptic input recordings further indicated that this increase in sensitivity greatly enhanced the fidelity of encoding natural scenes
–0.5 0 0.5 Negative contrast recordings—the adapting stimulus evoked a leftward shift in the contrast-response curve relative to the unadapted control (Fig. 7b). These results indicated that contrast sensitization was present in the excitatory synaptic input from midget bipolar cells to midget ganglion cells
Summary
An animal’s motion through the environment can induce large and frequent fluctuations in light intensity on the retina. Given that neural sensitization was only recently discovered, relatively little is known about its roles in neural information processing To address this issue, we recorded from five types of output neurons in the macaque monkey retina—broad thorny (koniocellular-projecting), On and Off parasol (magnocellular-projecting), and On and Off midget (parvocellular-projecting) ganglion cells. We recorded from five types of output neurons in the macaque monkey retina—broad thorny (koniocellular-projecting), On and Off parasol (magnocellular-projecting), and On and Off midget (parvocellular-projecting) ganglion cells These cells have well described roles in visual processing and no known functional counterparts. The lack of an adapting counterpart to midget cells indicated that sensitizing circuits performed a distinct role in primate retina relative to that observed in other vertebrate neural systems[10,11,12,16]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
