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Title: Physical limits of gradient sensing by cell collectives
Plain: 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: 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.
Settled by: Measurements of chemotactic accuracy versus cluster size with controlled coupling strength, compared with the predicted crossover.
Kind: well-posed
Answer type: value
References: (empty)
Literature status: partially-resolved
Status note: Theory since 2016 predicts saturation at large N from communication noise; quantitative experimental tests remain few.
Posed since: (empty)