This paradigm was designed by Seymour Benzer and presented in his paper “Behavioral Mutants of Drosophila Isolated by Countercurrent Distribution” from 1967 (Benzer, 1967). The main goal of this paradigm is to fraction a population of flies according to their geotactic or phototactic responses. In Benzer’s own words, “The method described here for fractioning populations is analogous to countercurrent distribution, an eminently effective method of separating molecules from a mixture by their partition between two solvent phases. Using, instead, the relative preference of an organism for two behavioral alternatives, one obtains rapid, simultaneous measurements of many subjects” (Benzer, 1967).

The simplicity of the apparatus promoted a rapid implementation in many laboratories, becoming today one of the most widely used paradigms.

Figure 1. a) Description of the protocol by S. Benzer, taken from (Benzer, 1967). b) Picture of our own apparatus while it is used for phototaxis experiments.


Benzer, S. (1967). Behavioral Mutants of Drosophila Isolated by Countercurrent Distribution. Proc Natl Acad Sci U S A, 58(3), 1112–9.

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