Circuit Neuroscience Highlights from FENS 2018
Thousands of scientists descended upon Berlin several weeks ago to attend Europe’s largest neuroscience conference. The Federation of European Neuroscience Societies (i.e., “FENS”) Forum is a 5-day, biennial meeting boasting a full schedule of brainy presentations, exhibits, and social events. This year FENS was attended by over 7,300 of Europe’s best and brightest brain explorers and I was lucky enough to be among them! In collaboration with Inscopix, I canvassed the meeting in search of the latest trends and findings in circuit neuroscience. I was also excited to find several posters relevant to those performing in vivo calcium imaging. Here’s a recap of my FENS highlights:
The conference center for FENS 2018. Image by Stina Börchers (@stina.biologista).
New from Team Inscopix
The Inscopix booth, manned by their energetic European team, was bustling all week! Drs. Diane Damez-Werno, Fabrizio Sitzia, and Jonathan Zapata caught up with their community members and showed off Inscopix’s new technological advancements. Among them was the Inscopix commutator, which allows for unrestricted movement during calcium imaging experiments. To showcase the tech, the booth displayed a commutator suspended over a rotating platform attached to a model of a mouse equipped with nVista 3.0. The new active motorized commutator compensates for animal movements to eliminate cable entanglement – allowing for in vivo recordings with minimal supervision. See my video of the commutator in action here.
There was also excitement surrounding Inscopix’s new Data Processing Software. The completely revamped software package is more intuitive and streamlined to aid in the transition from data collection to analysis. And the new software is INCREDIBLY fast! As someone with years of calcium imaging experience, I was astounded by the 10x processing speed in this update. Well done Inscopix! To learn more about the Data Processing Software go here.
Advances in In Vivo Imaging Tools & Tech
One consideration with 1-photon imaging is the removal of “background”, or signal arising from neuropil or out of focus cells (1–3). A promising new tool to address this issue is “comCaST” or “Compartmentalized Calcium Sensor Toolbox”, spearheaded by Abhinav Grama in David Cox’s Lab at Harvard. comCaST localizes calcium sensors to the nucleus or axon terminals by fusing them to histone or synaptophysin, respectively. The result for histone-fused GCaMP is nuclear-constrained expression and calcium signals devoid of neuropil contamination – and it has already been tested in vivo! This is undoubtedly a giant leap in the right direction for epifluorescent calcium imaging.
A new era of monitoring and manipulating neuronal circuits is officially upon us – systems and sensors are now available to allow for both simultaneously! Dr. Diane Damez-Werno presented Inscopix’s nVoke system for simultaneous calcium recordings paired with optogenetic manipulation. The nVoke system has a 455 nm GCaMP excitation (i.e., “EX-LED”) paired with a 590 nm LED for optogenetic stimulation of red-light sensitive opsins (i.e., “OG-LED”). Both ex vivo and in vivo experiments show minimal crosstalk between the 455 nm EX-LED and red-shifted opsins such as, Chrimson (4), NpHR (5), and JAWS (6). To view these controls and other applications of the nVoke system, read the newest peer-reviewed publication (7) from the Inscopix Team here!
I love rats and I was thrilled to find that Europe loves rats too. While walking the poster session aisles, I was struck by the large proportion of circuit neuroscience being conducted in rats in European laboratories, contrasting to the heavily mouse-focused research programs within the United States. Of course not all tools are suited for both rats and mice, and until recently, calcium imaging with miniaturized microscopes was one of them. However, Inscopix rolled out its nVista Rat Application Module a year ago and it’s clear that Europe is ready to put these modifications to good use. One poster I visited used Inscopix tech to record activity in the rat prefrontal cortex and then using their recordings, reconstructed the field of view in 3D. By doing so, recorded neurons could be anatomically identified which leads to the possibility of later being able to investigate cell characteristics with immunohistochemistry. Leading the development of this novel method was Philip Anner, Georg Dorffnner, and Thomas Klausberger from the Medical University of Vienna.
Another trend that I loved was exploring motivation and circuit function in complex behavioral environments. In a naturalistic setting, cues that guide motivated behavior— such as seeking reward and avoiding punishment— often occur simultaneously. Yet how competitive stimulus interactions (i.e., when both positive and negative cues occur at the same time) are encoded within the brain is still understudied (8). One poster caught my eye by Laurie Hamel in Rutsuko Ito’s Lab at the University of Toronto. In their studies, they interrogated the role of projections from the medial prefrontal cortex (mPFC) to the nucleus accumbens (NAc) core is operant responding to discriminative appetitive, aversive, and competitive stimuli using DREADD technology. I won’t spoil the results but I’m excited to see paradigms like this on the rise!