By Peter Midford and George Gkoutos
We held a one-day behavior ontologies workshop on Sunday, February 24, immediately prior to this
year’s RCN summit. Our goals were to bring ontology developers and behavioral biologists together
to review the NBO (NeuroBehavior Ontology) as well as discuss its use and interoperability with other
ontologies. We started the day with a series of short talks: George Gkoutos and Robert Hoehndorf
explaining the development and initial applications of the NBO, followed by six speakers who
volunteered to discuss related topics.
Beorn Brembs presented a data workflow that captured Drosophila movements in the course of
a ‘choice’ experiment. The flow went from raw video to depositing data in figshare, via R, and finished
by showing the role of NBO annotations in the final deposit. Melissa Haendel raised several issues
related to capturing behavior observations using ontologies: What does behavior inhere in? How to
relate observations across species? How do measurements and observations relate to phenotypes
or conditions? David Osumi-Sutherland discussed the application of behavior terms in annotations
within the Virtual Fly Brain (http://www.virtualflybrain.org). Janna Hastings discussed two new
ontologies for Emotions (https://code.google.com/p/emotion-ontology/) and Mental Functioning
(https://code.google.com/p/mental-functioning-ontology/) and both their relationships to the NBO and
their application to mental disease. Christine Wall introduced an ontology of processes involved in
mammalian feeding, which looked like a good candidate for inclusion in NBO and raised important
questions of representation of sequential behavior events and behaviors existing on a continuum.
Finally, Allan Kalueff introduced a community developed catalog of zebrafish behavior.
We followed this with a morning breakout session with groups selected by areas of taxonomic focus:
arthropods, non-mammalian vertebrates, non-human mammals, and humans. When the breakout
groups reported out, there were some common concerns about taxon specificity of terms, both in text
definitions and in their placement in the hierarchy – the later potentially leading to incorrect inferences
for taxa not considered during development of the ontology. There were questions about behaviors,
social and otherwise, involving more than one organism, and the role of abnormal and ‘clinic’ behavior
phenotypes. Finally one group looked at several previous efforts to construct behavior ontologies (e.g.,
the ABO constructed at a series of workshops, and David Shotton’s SABO project).
After lunch, we proposed and discussed topics for a new set of breakouts, and settled on Application
to Behavioral Ecology, Representing Affective Behavior, and a group reviewing the behavior process
branch, with NBO developers George Gkoutos and Robert Hoehndorf soliciting suggestions for high
priority changes.
The Behavioral Ecology session brought a group of behavioral ecologists together with Chris Mungall
to discuss the ABO ontology and how it might be integrated with the NBO. Anne Clark and Sue
Margulis discussed how the ABO had been used in the development of the Ethosearch tool, an online
collection of text ethograms indexed with terms from the ABO. They had also written, and offered
to contribute a collection of text definitions they had developed during the Ethosearch effort. The
consensus was that the ontologies were fairly compatible and that it would be desirable to graft portions
of the NBO in the ABO. The group also agreed that the learning and cognition sections of the NBO
should be a priority area for review as both structure and definitions suffered from species specificity.
The review group wound up focussing on terms for voluntary and involuntary movement, an issue that
came up in the invertebrate morning breakout as well. There was discussion of reflexes, of which the
NBO has a large number, many of which are human or mammal specific, but of significant clinical
interest.
The report-out from the affective behavior group generated a lively discussion that started by
addressing the conflation between observable behavior (e.g., smiling) and an inferred diagnosis
(emotional happiness). Although this distinction between observable behavior and inferred emotion
(which might belong in the emotion-ontology) is straightforward, other behavior terms (‘agoraphobic
behavior’) conflate behavior and diagnosis. There was also discussion of fear-related terms in general
and whether these might be too human-centric and what the scope of the NBO was; in particular
would the NBO apply to plants or even paramecia, which have been the subject of multiple ethograms
in the past 15 years. The consensus appeared to be that NBO should apply to animals with nervous
systems, that other types of behavior ought to be welcome additions to the Biological Process branch
of the Gene Ontology. There was also discussion of terms of the form ‘behavioral control of x’ where
x was a process, such as defecation or lacrimation, was meaningfully different from the underlying
physiological process.
The discussion of affective terms provided a nice transition to Barry Smith’s presentation ‘On the
Future of the NeuroBehavior Ontology and Its Relation to the Mental Functioning Ontology.’ After
reviewing the partitioning of domains of biological knowledge by various OBO ontologies, Barry
made the case that the portion of Biological Process that applied to whole organisms needed to be
split between the NBO for observable behavior and the complementary Mental Functioning Ontology
(MFO). The MFO will cover terms related to mental states and processes, for example sensory
perception. Perception is not an observable behavior, though there are behaviors associated with
perception (e.g., head turning, flehman response). He recommended that NBO retain the prefix NBO,
but be considered the (narrow) Behavior Ontology. He also recommended that the feeding ontology
developed by the FEED project be incorporated into NBO, that merging the ABO ontology should
be explored, perhaps scoping behavioral terms taxonomically (e.g, with ‘occurs-in-taxon’) when
appropriate, and to create a separate version of the NBO that marks the human-specific terms. He also
thought we shouldn’t be spending a lot of time discussing what is and isn’t behavior.
We finished the day with a discussion of next steps and deciding what are the best routes for providing
feedback to the NBO developers. In regard to feedback routes, we looked at several options: the OBO-
behavior list, the tracker associated with the NBO repository on google-code, as well as the notes
mechanism within the NCBO Bioportal and Ontobee. We decided that the OBO-behavior list and the
google tracker were adequate at this time. George also said he would add some new committers to
facilitate additions from the FEED ontology, the ABO, as well as terms from the community-developed
list of zebrafish terms in collaboration with ZFIN (this has been done).
We discussed next steps, in terms of ontology work, publications and funding. There was interest
in proposing a behavior ontology focussed RCN to fund workshops. There is interest in among the
behavioral ecology attendees in proposing two followups, the first being a hackathon for ontology
developers (perhaps 3 days) to clear up the ontology issues in the NBO (such as the relation between
the process and phenotype branches) which could be followed up by a workshop for a review from
the perspective of behavioral biology, perhaps in the space between ISBE and ABS in summer 2014.
There is sense that prior to seeking major funding, we should generate more publications, and that the
data and use cases are there to demonstrate the value of behavior ontologies, as several presentations
during the day had already demonstrated. One suggestion was to look at disease terms in the NBO
and look for clusters of behavior phenotypes associated with those terms. Given the importance of
behavior in model organism communities, the group expected that both the NIH and EU funding
agencies would be interested in supporting further work with the NBO.
We broke up shortly before 6 PM, though the behavior thread continued throughout the RCN summit. The application of ontologies to behavior still lags behind the use of anatomy ontologies, but combining the opportunities to benefit from the experiences with anatomical ontologies and the enthusiasm expressed at the workshop, there is reason to be optimistic about the future development and application of behavior ontologies.