They found that the OSEs of the receptors particularly matched characteristic features of species-specific acoustic communication signals used by grasshoppers to attract mating partners.
"Hence, instead of maximizing the average information gained about natural stimuli, the receptors appear to maximize the information gained about specific, but less often occurring aspects of the stimuli," concluded the researchers. "This result suggests that an organism may seek to distribute its sensory resources according to the behavioral relevance of the natural important stimuli, rather than according to purely statistical principles.
"For instance, if a few important stimuli within the natural environment need to be encoded with high precision, a large part of a system's coding capacity could be designated to encode these stimuli. Consequently, it may well be that even small subensembles strongly influence the coding strategy of sensory neurons. In this case, the optimal stimulus ensemble will not match the ensemble of all natural stimuli encountered by the particular species."
The researchers also concluded that "We therefore suggest that the coding strategy of sensory neurons is not matched to the statistics of natural stimuli per se, but rather to a weighted ensemble of natural stimuli, where the different behavioral relevance of stimuli determines their relative weight in the ensemble."
Machens, Herz, and their colleagues also concluded that their analytical technique could yield broader insight into the evolution of sensory circuitry.
"Our approach presents a systematic way to uncover potential mismatches between the statistical properties of the natural environment and the coding strategy of sensory neurons. In turn, these discrepancies might improve our understanding of the evolutionary design of the specific sensory system," they wrote.