#OHBM2016 IN REVIEW

BY CYRIL PERNET

​During the annual OHBM meeting in Geneva I had fun making word clouds from the twitter feed of the hashtag #OHBM2016. Attendants could see the word clouds in between every presentation, and I think it made the welcome screen look pretty cool (you can find them on the @OHBM_members channel and on the OHBM facebook page). In case you thought some information was missing, that is simply because it was either not that frequently discussed on Twitter or http://www.wordclouds.com/ did not show it (not all words appear depending on design and size). There was no censoring, and you can blame me if something was not to your liking.

Using google tools I fetched #OHBM2016 for a given day and then ran a macro in notepad++. The macro removes the following names: RT, #OHBM2016, https://t.co/ (and versions of that) and then splits sentences into a long vector of words from which I generated the clouds. If I noticed (visually) redundancy, I merged the words: for instance 50 Poldrack and 100 @russpoldrack woud give 150 @russpoldrack. For this last word cloud, I fetched #OHBM2016 from Sunday 26 June to Friday 1st July, and ran the macro. Again I merged redundancy and I added back @ and http, while removing non informative words. This made a nicer cloud with twitter handles and links. To check what was discussed and by who, I crossed the top tweets with post on personal accounts.

The exciting stuff
The most discussed lectures were those of Tim Behrens and Fernando Lopes da Silva, closely followed by the talk from Gael Varoquaux. The main topics that engaged attendees were connectivity analyses, machine learning, power analyses, BIDS and yes, Brexit.

Connectivity analyses
Thomas Yeo aptly summarized the current state of connectivity analyses on the OHBM blog so no need to talk more about it.

Machine learning
Machine learning is increasingly used in neuroimaging applications these days and Gael Varoquaux had lots of comments about his talk: 'Cross-validation to assess decoder performance: the good, the bad, and the ugly'. In this talk he shows that leave one out strategies are biased and that N-folds cross validation, providing we keep the data structure, works much better.

Power analyses
I am really glad that use of power analyses is now at the forefront of neuroimagers’ discussions. During Sunday’s reproducibility workshop I discussed and presented two of the main tools used to carry out power analyses on full maps: fMRIpower and neuropower. These tools were then presented by Jeanette Mumford (creator of fMRIpower) and Joke Durnez (creator of neuropower) in the Open Science SIG room.

BIDS
Another favorite topic of mine: data sharing. BIDS, or to give it its full name - Brain Imaging Data Structure - is driven by Chris Gorgolewski, and describes how to structure and store your data in an easily shareable way. It provides advice on how to name files and how to create simple metadata text files (tsv and json). Using BIDS doesn’t require programming knowledge, and does substantially improve data sharing, by allowing machines to read data easily.

The controversies
A paper from Anders Eklund et al. about failure to control the family-wise error rate (FWER) using cluster size was recently published in PNAS and elicited many comments, not just online but also from the floor. The paper suggests that cluster size correction may significantly inflate false-positives, addresses the extremely important issue of controlling FWER, and is a must read along with the comment from Glass Brain awardee Karl Friston and Guillaume Flandin.
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From our community, gender imbalance and diversity was frequently discussed and added to the #GenderAvenger hashtag. It was often commented that committee members and awardees were predominantly white males from wealthy countries. The Organization is well aware of this and has actively sought to reflect the geographic diversity of our membership as well as to balance the number of male and female session and keynote speakers. Council takes this feedback, of the need to do more, seriously and is actively at work to further address these issues, and push for all aspects of OHBM to become as diverse as the members it represents.
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Top 5 twitter users
During the conference, the OHBM and OHBM_SciNews accounts retweeted posts from or with twitter users mentioned. Thanks to the top 5: @kirstie_j, @NKriegeskorte, @pierre_vanmedge, @ChrisFiloG, @ten_photos.

Note: A version of this post previously appeared on Cyril Pernet's personal blog: 
​http://neurostatscyrilpernet.blogspot.co.uk/2016/07/what-happened-during-ohbm2016.html

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