OHBM 2016 Symposia on Brain Connectivity

BY THOMAS YEO

Symposia have always been a major highlight of the OHBM annual meeting for me. Talks in a symposium are shorter than keynotes but often feature similarly senior speakers. As such, these talks provide high-level insights that expand my horizons beyond my own research focus. This year, there were so many excellent proposals that the Program Committee decided to go with three parallel tracks each afternoon, similar to the morning workshops (now called morning symposia). I suspect many meeting attendees, like me, will find an embarrassment of riches. Given my interests in brain networks and connectivity, I found this year’s program especially exciting, with at least seven different symposia directly related to this topic.

The brain networks and connectivity bonanza kicks off on Monday afternoon, with Aaron Kucyi and Jessica Cohen highlighting links between dynamic functional connectivity and subjects’ behavior and experience. Given recent interests in dynamic functional connectivity (see Hutchison et al., 2013 for review), a major open question is whether dynamic connectivity fluctuations are behaviorally meaningful or are just epiphenomena. The Monday symposium promises to shed light on this important issue. ​

Since the demonstrations by Power et al. (2012), Satterthwaite et al. (2012) and Van Dijk et al. (2012) that even relatively small motion can lead to spurious functional connectivity, the field has been extremely concerned about motion bias in many studies involving patients, as well as young and old participants, who tend to move more than control groups. Since then, studies have shown that motion can also affect diffusion and structural MR morphometric measurements. On Tuesday morning, the symposium by Anastasia Yendiki, Cameron Craddock, Joelle Sarlls and Dylan Tisdall will present the newest updates on this topic, as well as novel methods to deal with such motion.

Fellow connoisseurs of connectivity research will also have to consider a parallel “Skeptical Connectivity” session in which Tom Nichols, Moo Chung, and Victor Solo introduce new connectivity analysis techniques. Tom Nichols will present a clever multi-network extension of the stochastic block model that includes covariates to account for connectivity differences between subjects due to nuisance factors (e.g., motion or age). Since the first talk in the motion session will be about diffusion MRI (which is of less research interest to me), I might pop into the “Skeptical Connectivity” session for Tom’s talk and run back to the motion session. For undecided OHBM participants, I suspect the “Skeptical Connectivity” session might be of particular interests to methods developers, while the parallel session on motion might cater to a wider audience. 

Since Karl Friston introduced the concepts of functional and effective connectivity more than 20 years ago and despite advances such as dynamic causal modeling, many in the field remains skeptical about effective connectivity and causality measures. On Wednesday morning, Bin He, Karl Friston, Guido Nolte and Sheraz Khan will review state of the art functional/effective connectivity and causality mapping approaches. Perhaps they will be able to convert the remaining skeptics in the field! 

Invasive and non-invasive brain stimulations have proven therapeutically effective in certain mental disorders. Because the effects of focal brain stimulation will propagate through anatomical connections to affect multiple brain networks, connectivity and network approaches are especially potent for analyzing, understanding and predicting the effects of brain stimulation. On Tuesday afternoon, Andrew Zalesky will host a symposium that discusses network modulation by non-invasive brain stimulation, cognitive training, or brain injury and disease, while Wednesday afternoon will see Michael Fox leading a session on the use of functional connectivity to guide invasive (e.g., DBS) and noninvasive (e.g., TMS) brain stimulation.

Hierarchical control is thought to involve the frontoparietal control network (e.g., Vincent et al., 2007; Cole et al., 2013) modulating the processing of other brain regions. However, there is relatively little work on examining executive function from the perspective of brain connectivity. Therefore to top off the week, on Thursday morning, Marie Banich, Lucina Uddin, Bruce Morton and Nathan Spreng will examine the relationship between executive function and brain connectivity from the perspective of both resting-state and task-based functional connectivity. 

Perhaps the biggest dilemma for me is that in previous years, the single track symposium format allowed me to skip sessions I am least interested in, giving me time to meet with distant collaborators. The many exciting choices for me this year will force me to make some difficult decisions! The parallel symposia format at OHBM 2016 has definitely imposed on me the enviable problem of the paradox of choices! ​