Physical limits of gradient sensing by cell collectives
In plain words
Single cells can be poor at sensing a weak chemical gradient, but clusters of cells sometimes follow gradients better than any single member. How much a group can gain, and what limits it, is unsettled.
Precise statement
For a cluster of $N$ cells of size a, coupled by gap junctions or mechanical contacts, in a shallow gradient g = |grad c|/c, find the minimum error in estimated gradient direction as a function of $N$, intercellular communication noise and cluster geometry. Answer: the scaling of the error with N, including the crossover from N^-1/2 averaging to saturation set by communication noise, compared with experiments on cell clusters.
What would settle it
Measurements of chemotactic accuracy versus cluster size with controlled coupling strength, compared with the predicted crossover.
Status in the literature
Theory since 2016 predicts saturation at large N from communication noise; quantitative experimental tests remain few.