BioelectricaAlterspan Labs
SIW
Sara Imari Walker
Portrait: Christopher Michel, CC BY-SA 4.0 · Wikimedia Commons
Person

Sara Imari Walker

Sara Imari Walker co-authored three held works that apply information theory to living systems. One presents a software library for information measures12. Another argues for information measures as experimental tools in biophysics45. A third maps functional connectivity in non-neural tissue67. Levin cites Walker's work on information and goal-directedness3.

Country
United States
Field
astrobiologist, theoretical physicist, physicist
In the library
3 works, named in 7 passages elsewhere
Facts from
Wikidata · Wikipedia · ORCID
18501875190019251950197520002025Moore DG, Valentini G, Walker SI, Levin…, 20181Moore DG, Valentini G, Walker SI, Levin…, 20182Levin M, 20193McMillen P, Walker SI, Levin M, 20224McMillen P, Walker SI, Levin M, 20225Blackiston D, Dromiack H, Grasso C…, 20256Blackiston D, Dromiack H, Grasso C…, 20257Levin M, 20198
01

A shared analysis toolkit

In the 2018 Inform paper, Walker is one of four authors. The authors say that writing separate software for each information measure is slow for users, and that one library for many measures is a better answer1. The framework offers optimized versions of less common measures, among them effective information, information flow, evidence for integration and partial information decomposition2. The aim is to let researchers study collective behavior across fields without hunting for a new library for each measure.

02

Information as an experimental tool

The 2022 paper, with McMillen and Levin, argues that information theory can supplement one-pathway-at-a-time experiments. The authors state that mutual information between two factors is useful even when the mechanism linking them is unknown4. Their own example is amputation of a developing frog limb, where the undamaged limb stained with a voltage-sensitive dye at a matching position. For causal questions they name transfer entropy as the best current statistical tool, and they warn that delayed mutual information alone can mix up correlation and causation5.

03

Networks in aneural tissue

The 2025 paper, with Blackiston, Levin and others, uses functional connectivity networks built from statistical dependencies between signals in different parts of a system. The authors note that neuroscience uses these networks widely, and here they apply them to calcium signals in organoids without neurons6. After puncture, edge time series showed more highly correlated edges early in the post-puncture period7. Levin's 2019 essay cites Walker and colleagues for defining a self through information and goal-directedness, and cites Walker and Davies on life-as-it-could-be38.

SourcesEach quotation was checked word for word against the passage it opens.
  1. One solution is to develop and make use of general-purpose software frameworks which can be applied across domainsMoore DG, Valentini G, Walker SI, Levin M, 2018 · Inform: Efficient Information-Theoretic Analysis of Collective Behaviors · open at passage 4
  2. Optimized implementations of less common concepts such as effective information, information flow, evidence for integration and partial information decomposition.Moore DG, Valentini G, Walker SI, Levin M, 2018 · Inform: Efficient Information-Theoretic Analysis of Collective Behaviors · open at passage 12
  3. argue for a definition based on information and goal-directedness (Walker et al., 2016) from a developmental biology perspectiveLevin M, 2019 · The Computational Boundary of a "Self": Developmental Bioelectricity Drives… · open at passage 9
  4. establishing mutual information between two factors can be very important even without knowing the mechanistic interaction between the two factorsMcMillen P, Walker SI, Levin M, 2022 · Information Theory as an Experimental Tool for Integrating Disparate… · open at passage 12
  5. In information theory, the best current tool for inferring statistical causation is called transfer entropy (TE)McMillen P, Walker SI, Levin M, 2022 · Information Theory as an Experimental Tool for Integrating Disparate… · open at passage 20
  6. FC networks are weighted, undirected networks generated based on instantaneous statistical correlations, or statistical dependencies, between activity in different areas of a system.Blackiston D, Dromiack H, Grasso C, Varley TF, Moore DG…, 2025 · Revealing non-trivial information structures in aneural biological tissues via… · open at passage 4
  7. Edge time series of post- puncture networks were seen to have more highly correlated edges at the beginning of the post-puncture observation periodBlackiston D, Dromiack H, Grasso C, Varley TF, Moore DG…, 2025 · Revealing non-trivial information structures in aneural biological tissues via… · open at passage 16
  8. Future empirical work will reveal whether Scale Free Cognition is a useful way to organize what we know about the mechanisms and algorithms of life and life-as-it-could be (Langton, 1995; Walker and Davies, 2013).Levin M, 2019 · The Computational Boundary of a "Self": Developmental Bioelectricity Drives… · open at passage 73
In the library3 works
Inform: Efficient Information-Theoretic Analysis of Collective BehaviorsMoore DG, Valentini G, Walker SI…
2018
Inform: Efficient Information-Theoretic Analysis of Collective Behaviors
Moore DG, Valentini G, Walker…
2018 · read
Information Theory as an Experimental Tool for Integrating Disparate Biophysical Signaling ModulesMcMillen P, Walker SI, Levin M
2022
Information Theory as an Experimental Tool for Integrating Disparate…
McMillen P, Walker SI, Levin M
2022 · read
Revealing non-trivial information structures in aneural biological tissues via functional connectivityBlackiston D, Dromiack H, Grasso…
2025
Revealing non-trivial information structures in aneural biological tissues via…
Blackiston D, Dromiack H…
2025 · read
Quoted inArticles that quote this person's work