Everyone and their mom makes one of these Best of The Year lists or something related, so here is my version. Join me in looking back at what I consider some of the highlights from 2012 in neuroscience. As always I will present a numbered list. This is not supposed to be a ranking; I just like lists.
1. The Great Debate
The Great Brain Mapping Debate (Brain Brawl): Tony Movshon versus Sebastian Seung (link)
This was just fantastic. I highly recommend watching the video of this great debate. I had a wonderful time watching this live from my hotel room when I was in Chicago for grad school interviews. You can read some of the articles about this here, here, and here.
2. Optogenetic activation of an engram!?
Optogenetic stimulation of a hippocampal engram activates fear memory recall Xu Liu, Steve Ramirez, Petti T. Pang, Corey B. Puryear, Arvind Govindarajan, Karl Deisseroth & Susumu Tonegawa ; Nature 2012 (link)
Generation of a Synthetic Memory Trace Aleena R. Garner, David C. Rowland, Sang Youl Hwang, Karsten Baumgaertel, Bryan L. Roth, Cliff Kentros, Mark Mayford ; Science 2012 (link)
Ok that is certainly a bold description, but I think it is fairly appropriate for both. When these two papers came out I was extremely excited. I think what these papers accomplish represents a pretty big milestone for neuroscience. Of course I favor the Tonegawa manuscript because I have a known weakness for a certain scientific method. You can read about the two papers and how a similar accomplishment was shown in a previous SFN poster in 2009 here (I recommend reading the comments as well).
3. Zebrafish in the matrix (sort of.. ok not really.. but it’s so cool)
Brain-wide neuronal dynamics during motor adaptation in zebrafish Misha B. Ahrens, Jennifer M. Li, Michael B. Orger, Drew N. Robson, Alexander F. Schier, Florian Engert & Ruben Portugues ; Nature 2012 (link)
My list is dangerously close to becoming a highlight reel from the Nature Action Potential blog and you can certainly read an interesting commentary about this paper from them here. But let me just say I think this might be my favorite paper of the year. What really made this paper special for me was watching the first supplementary movie showing real time motor adaptation as they switch the gain for neural activity controlling the perceived motion. Seeing and hearing the neurons fire while the fish tries to “swim against the current” in order to stay still is really awesome.
4. PV+ neurons and their effect on visual cortex
Activation of specific interneurons improves V1 feature selectivity and visual perception Seung-Hee Lee, Alex C. Kwan, Siyu Zhang, Victoria Phoumthipphavong, John G. Flannery, Sotiris C. Masmanidis, Hiroki Taniguchi, Z. Josh Huang, Feng Zhang, Edward S. Boyden, Karl Deisseroth & Yang Dan ; Nature 2012 (link)
Division and subtraction by distinct cortical inhibitory networks in vivo Nathan R. Wilson, Caroline A. Runyan, Forea L. Wang & Mriganka Sur ; Nature 2012 (link)
even though it didn’t make the 2012 cut these should be considered along with..
Parvalbumin-Expressing Interneurons Linearly Transform Cortical Responses to Visual Stimuli Bassam V. Atallah, William Bruns, Matteo Carandini, and Massimo Scanziani ; Neuron 2011 (link)
How specific subtypes of interneurons are involved in neural function is a question that is going to be asked for a long time. The battle to classify neurons into subtypes is itself an ongoing process (popular 2004 Markram review here). I constantly wonder if the subtypes we can target in optogenetics right now are even all that relevant or specific enough. It seems to be a case of the tail wagging the dog with so many papers looking at specific roles of what has become the holy trinity of genetically targetable subsets: PV+, SOM, and VIP interneurons. But I should save a discussion on neural subtypes for another time. Let me tell you what I liked about these papers. I enjoyed them because they are a perfect example of multiple papers asking almost the exact same questions, using almost the exact same methods getting published at almost the exact same time (sometimes this happens in different journals as you can see above for the engram papers or sometimes in the same journal with a nice little editorial to compare the two). When this happens it creates a wonderful opportunity for comparison. It is especially great when the papers come up with drastically different conclusions! I find it to be a sobering reminder that we are all doing science and sometimes just because results are published in Nature or Science it doesn’t mean the findings are ready to be engraved in stone. Of course there are interesting methodological differences between these three papers – awake verses anesthetized for example; however they still come up with fundamentally different results that anesthesia alone might not explain. So I think it is fun to question whether the differences are due to preparations and methods or our lack of understanding on another level. Only time will tell.
And again I can’t shake the pesky problem of questioning how specific our subgroups are to begin with. Sorry to beat the dead horse but just keep in mind this question, what does it mean to target PV+ neurons in the first place? How arbitrary are our classifications? Papers such as this one certainly have to be considered when reading these papers.
Ok I tried my best to avoid the subtype classification conundrum… oh well. I promise I’ll try and touch on it again in more detail another time.
5. Primate Optogenetics continues to mature
Saccadic eye movements evoked by optogenetic activation of primate V1 Mehrdad Jazayeri, Zachary Lindbloom-Brown & Gregory D Horwitz ; Nature Neuroscience 2012 (link)
This paper was particularly important to me this year because it was very relevant to some of my own work (shameless plug here). I have several thoughts on this paper as well as the recent influx of primate optogenetic publications that came out this year. I’m going to save that rant for a later post. Below are the other papers that came out involving primate optogenetics. Again, I will write a whole post about these later because I have a pretty long winded rant about the Jazayeri et al. and Cavenaugh et al. papers in particular.
Optogenetically Induced Behavioral and Functional Network Changes in Primates Annelies Gerits, Reza Farivar, Bruce R. Rosen, Lawrence L. Wald, Edward S. Boyden, Wim Vanduffel ; Current Biology 2012 (link)
Optogenetic Inactivation Modifies Monkey Visuomotor Behavior James Cavanaugh, Ilya E. Monosov, Kerry McAlonan, Rebecca Berman, Mitchell K. Smith, Vania Cao, Kuan H. Wang, Edward S. Boyden and Robert H. Wurtz ; Neuron 2012 (link)
In Vivo Optogenetic Control of Striatal and Thalamic Neurons in Non-Human Primates Adriana Galvan, Xing Hu, Yoland Smith,Thomas Wichmann ; PLoS One 2012 (link)
6. Wait.. what makes a Place Cell?
Hippocampal Place Fields Emerge upon Single-Cell Manipulation of Excitability During Behavior Doyun Lee, Bei-Jung Lin, Albert K. Lee ; Science 2012 (link)
So this year also marked the beginning of my diving into the world of hippocampus literature.. just picture that scene where Alice falls down the rabbit hole. The world of place cells, grid cells, head direction cells, episode cells, and phase precession continues to blow my mind with every new paper I read. One of the small joys of playing catch-up in a new field of research literature is starting with the early stuff and moving in chronological order. It’s always great when you read an old paper and think, “Woah that’s amazing! ….but I wonder what would happen if they looked at _______” and then finding a paper a couple years later that asks and answers your exact question!
But back to this paper. Place cells and place fields are a staple of hippocampal literature and I think their discovery is one of the more amazing phenomena in neuroscience research. This paper from the Lee lab (had to have a shameless plug for my friends at the farm) is great because it takes the standard model of what makes a place cell a place cell and completely flips it upside down! In fact the implications and questions this paper raises kind of scares me! I mean.. I can barely wrap my head around what the paper might mean. If all it takes to make a pyramidal cell a “place cell” is to depolarize it a little… then what does that mean about the wiring of the neurons themselves? Do the anatomical connections not matter? Of course they matter, but I just love the questions this paper raises. Definitely an exciting step forward in our attempt to understand the brain.
So this post turned out much longer than I anticipated. I can promise if you think they will all be this long then you should definitely lower your expectations
but hopefully as (and if) I continue to do this blog, posts will improve and become more concise; because the last thing anyone needs is to waste all of their time reading my rants when there are so many papers to catch up on!
What papers did you enjoy this year? What were some of the neuroscience reports that you thought where most interesting? Please please please share at least one of them in the comments!