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Minds of small things  ·  Article

Multi-stimulus integration and behavioral priority

Multi-stimulus integration is the combining of several signals into one behavioral outcome. Inoue and colleagues state that animals are thought to integrate multiple signals and show appropriate behaviors afterwards.1 They asked whether planarians prioritize different stimuli and whether the order of predominance is absolute.1 Other authors pose the same problem for bacterial protein complexes and molecular networks.56

Earliest held
2015, Inoue T, Hoshino H, Yamashita…
Most discussed in
Planarian shows decision-making behavior in…, 2015
In the library
11 passages in 4 works
Rewritten
2026-10-11
18501875190019251950197520002025Inoue T, Hoshino H, Yamashita T…, 20151Inoue T, Hoshino H, Yamashita T…, 20152Inoue T, Hoshino H, Yamashita T…, 20153Inoue T, Hoshino H, Yamashita T…, 20154Lyon P, 20155Timsit Y, Grégoire SP, 20216Timsit Y, Grégoire SP, 20217Rosciglione C, 20268
01

The planarian combinatory assay

Inoue, Hoshino, Yamashita, Shimoyama and Agata (2015) built an integrative assay that presents two distinct stimuli, light and a chemoattractant, in one chamber.1 The chamber was divided into five zones so that behavior could be measured quantitatively.2 A planarian placed in the center zone moved randomly, and the heat map of time spent per zone showed no tendency, as in their earlier control data.2 When each stimulus was tested alone, planarians moved away from a 400-lux light source.1

02

Signal strength and outcome

The authors report that they manipulated the outcome of integration by changing signal strength.3 They compared time spent in the darkest zone and in the chemoattractant-source zone.3 Planarians given 800 lux of light and chemoattractant together seemed to move randomly, like unstimulated controls, and time in those zones did not differ significantly.3 Trajectories told a different story. Each control moved extensively, while each exposed planarian moved toward the chemoattractant or toward the dark region.4 Average zone time alone therefore hid individual choices.4

03

Integration at other scales

Lyon (2015) lists candidate information-processing structures in bacteria. One is the stressosome of B. subtilis, a large protein complex that integrates multiple signals into a single outcome, activation of σB.5 Timsit and Grégoire (2021) call the central mechanistic question how molecular networks integrate multiple signals and decide, and they locate the answer in modular organisation and combinatory interaction of modules.6 They cite a dual-sensor histidine kinase that integrates light and phosphorylation signals.7 Rosciglione (2026) defines plant behaviour operationally, including a change in physiological priority that depends on environmental information.8

SourcesEach quotation was checked word for word against the passage it opens.
  1. It is thought that animals integrate multiple signals, and show appropriate behaviors after integrating their responses.Inoue T, Hoshino H, Yamashita T, Shimoyama S, Agata K, 2015 · Planarian shows decision-making behavior in response to multiple stimuli by… · open at passage 28
  2. The 60 × 10 × 3 mm assay chamber was divided into five zones to enable quantitative measurement of the planarian behaviors.Inoue T, Hoshino H, Yamashita T, Shimoyama S, Agata K, 2015 · Planarian shows decision-making behavior in response to multiple stimuli by… · open at passage 28
  3. this graph clearly indicates that we successfully manipulated the outcome of the integration process by changing the signal strength.Inoue T, Hoshino H, Yamashita T, Shimoyama S, Agata K, 2015 · Planarian shows decision-making behavior in response to multiple stimuli by… · open at passage 29
  4. each control planarian moved extensively in the assay chamber, whereas each planarian exposed to 800 lux of light and chemoattractant moved toward the chemoattractant or moved toward the dark regionInoue T, Hoshino H, Yamashita T, Shimoyama S, Agata K, 2015 · Planarian shows decision-making behavior in response to multiple stimuli by… · open at passage 29
  5. a large (multimillion dalton) protein complex associated with the general stress response that integrates multiple signals into a single outcome (σB activation)Lyon P, 2015 · The cognitive cell: bacterial behavior reconsidered · open at passage 97
  6. the central question is, how do molecular or brain networks integrate multiple signals and take appropriate decisions?Timsit Y, Grégoire SP, 2021 · Towards the Idea of Molecular Brains · open at passage 84
  7. A recent dynamic crystallographic study on a dual-sensor histidine kinase has deciphered the allosteric mechanisms underlying the integration of its perception of light and phosphorylation signals.Timsit Y, Grégoire SP, 2021 · Towards the Idea of Molecular Brains · open at passage 91
  8. a measurable change in state, growth, movement, chemical release or physiological priority that depends on environmental information and alters the plant’s subsequent interaction with its environmentRosciglione C, 2026 · Plant Behaviour, Adaptive Plasticity and Evolution: Reassessing the Debate on… · open at passage 8
Linked ideas
The planarian assay is a case of choosing between competing stimuli, and the question of how choice arises without neurons is the same.
In the planarian assay, changing signal strength changed which behavior won, so intensity governs priority.
Bacterial receptor clusters are one candidate site where multiple chemical signals are combined into a single motor output.
Basal cognitionrelated to
Integration of several signals into an appropriate behavior is offered as a basic cognitive capacity of simple organisms.
Plant responses to light and gravity are the cases where Rosciglione sees behaviour as redistribution of growth under several environmental cues.
Orientation treated as forced response sits against the planarian result that stimulus strength shifts which behavior predominates.
Both concern the planarian brain and its behavior. The passage says planarians have a simple brain and ask whether it integrates multiple signals. It says nothing about memory or regeneration.
Where it is discussedPassages matching integrate multiple signals, prioritize different stimuli, combinatory assay, order of predominance of behaviors
2015Planarian shows decision-making behavior in response to multiple stimuli by… · Inoue T, Hoshino H, Yamashita T…6
2021Towards the Idea of Molecular Brains · Timsit Y, Grégoire SP3
2026Plant Behaviour, Adaptive Plasticity and Evolution: Reassessing the Debate on… · Rosciglione C1
2015The cognitive cell: bacterial behavior reconsidered · Lyon P1