An information-theoretic analysis of the ON/OFF pathway split in the Drosophila visual system

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Many animals exhibit sensory systems that split into multiple parallel pathways at an early processing stage. For example, the visual system of the fruit fly Drosophila melanogaster is split into separate ON and OFF pathways to facilitate the detection of increments and decrements in light intensity, respectively. Although previous studies have considered the computational features of similar ON/OFF pathway architectures, they have invariably focused on sensory systems that utilize a digital code consisting of action potentials. In contrast, the Drosophila visual system consists largely of cells that fire graded potentials and therefore rely on an analog rather than digital code. In this study I have sought to address the hypothesis that an analog ON/OFF pathway architecture of the sort exemplified by the Drosophila visual system is advantageous for the efficient coding of sensory stimuli. By evaluating the information-theoretic properties of an analog model sensory system consisting of parallel ON/ON or ON/OFF pathways, I demonstrate that the latter configuration requires a lower average signal amplitude to convey the same amount of information about a given stimulus. Furthermore, I show that empirical estimates of the information capacity of the split ON/OFF pathway in flies are consistent with the predictions of my rudimentary model. These results suggest that pathway splitting has similarly beneficial implications for sensory systems based on analog codes as for systems based on digital codes.


Type of resource text
Date created June 6, 2018


Author Zimmerman, David M.
Degree granting institution Stanford University, Department of Physics
Primary advisor Clandinin, Thomas R.
Advisor Burchat, Patricia R.


Subject Drosophila
Subject visual system
Subject pathway splitting
Subject efficient coding
Subject information theory
Genre Thesis

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Zimmerman, David M. (2018). An information-theoretic analysis of the ON/OFF pathway split in the Drosophila visual system. Stanford Digital Repository. Available at:


Undergraduate Theses, Department of Physics

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