Qualitatively Distinct Signaling in Cells: The Informational Landscape of Amplitude and Frequency Encoding

TL;DR

This paper compares amplitude and frequency encoding in cellular signaling, revealing that frequency encoding offers broader and more reliable information transmission across stimulus ranges, with potential biological implications.

Contribution

It demonstrates that amplitude and frequency encoding have distinct information transmission capabilities, highlighting the advantages of frequency encoding for broad stimulus discrimination.

Findings

Frequency encoding transmits information reliably over wider stimulus ranges.

Amplitude encoding is optimal for limited stimulus strengths.

Cells may combine both strategies to expand discrimination span.

Abstract

Cells continuously sense their surroundings to detect modifications and generate responses. Very often changes in extracellular concentrations initiate signaling cascades that eventually result in changes in gene expression. Increasing stimulus strengths can be encoded in increasing concentration amplitudes or increasing activation frequencies of intermediaries of the pathway. In this paper we show that the different way in which amplitude and frequency encoding map environmental changes endow cells with qualitatively different information transmission capabilities. While amplitude encoding is optimal for a limited range of stimuli strengths, frequency encoding can transmit information with equal reliability over much broader ranges. The qualitative difference between the two strategies stems from the scale invariant discriminating power of the first transducing step in frequency codification. The apparently redundant combination of both strategies in some cell types may then serve the purpose of expanding the span over which stimulus strengths can be reliably discriminated. In this paper we discuss a possible example of this mechanism in yeast.