SfN2014: Day5 (Last Day!) – Smell Spaces, Emotional Posters and the Neuro of Touch
Today was the last day of the meeting. So I grabbed all of my belongings, checked out of the hotel, then headed to the conference (will all of my stuff in tow).
It was still bitterly cold, but at least it wasn’t raining since I was now carrying my purse, my poster, a bag of exhibitor goodies and my carry-on roller cart luggage. I was able to stick my poster in the newly acquired Leica bag (it had a zipper! so it helped secure it in place). So it was all pretty manageable. And I was also able to stick to my plan of walking and not taking the shuttles. Seriously, 10 minute walk = not a problem. Also grabbed a quick latte from Starbucks on the way because as I’ve stated before, the lines for coffee at the meeting are way too long.
And this pic was from the last day when the lines had died down considerably.
Smell Spaces
First talk the morning of the last day of SfN, I guess everyone was out partying at socials and exhibitor events…
It did start to fill up more as blurry-eyed neuroscientists stumbled their way into the room slowly. But they missed an interesting introduction from Dr. Noam Sobel, introducing this symposium on OdorSpace: Deciphering Stimulus Space in Olfaction, asking how we can meaningfully probe the neural coding of smell. He recommends a different approach, a different way of thinking about the sense of smell that borrows from the longer/better studied senses like sight and hearing. By better I don’t mean that the science is better, but there’s just more of it and more has been figured out. We still have a lot to figure out about how we smell the world around us. Dr. Sobel started off with a thought experiment, the knowledge argument. In this argument, you imagine Mary, a brilliant leading physiology of vision scientist. She knows all there is to know about the mechanics of color vision. But… Mary is colorblind, she’s never seen color. If we could fix this, and she was suddenly able to see color, with this new ability will she gain any new insight into color vision? This brings into question the idea of physicalism, that physical aspects of a subject is all we need to understand it. Or is subjective experience additive and importantly relevant to understanding a subject? If we study olfaction on the basis of neural signaling and molecular weight of molecules are we missing something? Interesting question for this group. Coming from industry, however, we’ve always been very keen on that subjective experience, which is why our (HCDi.net) work focuses on that experience.
Anyway, Sobel then went on to talk about an interesting study of a phenomenon they noticed in the lab when setting participants up after introducing them to the scientist and setup. Typically the experimenter would shake the participants hand and then leave the room. They noticed that once the experimenter left the room the participant would bring their hand (the one that was shaken) to their face and breathe in, unconsciously. Meaning they may not realize it, but much like dogs sniffing each others’ butts, we smell the hands of the people we meet. Why? We are constantly chemo-signaling in order to function in the world around us.
Can you measure the difference between one kind of smell and another? It is very obvious that we have very many different kinds of smells, all the way from the odor of violets and roses up to asafetida. But until you can measure their likenesses and differences you can have no science of odor.
– Alexander Graham Bell – 1914
So that’s kind of a side note, because the real meat of this symposium came in with a quote from Alexander Graham Bell (yes, the telephone guy). Bell challenged researchers to understand the subjective differences between the odors we smell. Olfaction exists in 3 worlds, of sorts: molecular world, neural world and perceptual world. As scientists we need to try to understand what are the rules of these different worlds and how does information change and transmit, transform from one world to the next? If we are met with a novel molecular structure, can we predict how it will be perceived? Sobel and his team did just this. Mining previous data from Dravnicks Atlas of Odor Characters where 150 experts gave 146 dimensions/descriptors of 160 odorants. And using PCA (principal component analysis) they used this data to help predict molecular to perceptual and vice versa. For the perceptual world they found that the best predictor was “pleasantness”. And for the molecular world, the best predictor was “physical” or chemical structure to predict perception, giving a very strong correlation between the two. This way they were able to develop predictive modeling to answer exactly the question that Bell posed. But what about the real world? In the real world, we do not sample one odor at a time. We are met with mixtures. If treated as a vector, this approach is very predictive. We can predict how similar smells are.
In the neural world, however, Sobel and group record from olfactory epithelial cells in the human nose as it is exposed to odor as seen in the setup above. And the interesting part is that even in the neural wold, the strongest predictor of specificity in the topography of the nasal epithelium is “pleasantness”! And even while learning and preferences may change, this representation “doesn’t change dramatically, not much”, as he answered in the Q&A portion.
And then using lessons learned from vision and auditory research, Sobel took the idea of “white” and “white noise” to investigate an idea he calls “olfactory white”. so if you have 2 mixtures of the “olfactory spectrum”, spanning all possible areas of smell with no components in common, you can’t tell the difference between them. But you will also find that there are areas beyond perception, infrasmell and ultrasmell. There could be odors that are SO pleasant or SO stinky that you don’t smell them at all, and an area that you can smell that is a “smellable space” on the spectrum.
Dr. Lisa Stowers then spoke about leveraging olfaction to study the innate behaviors of the mouse, how does the brain generate innate behaviors like nursing, fear, love and anger?
These behaviors are bound to emotions, love is positive, fear is negative, etc and these are neurally coded. Odors drive these behaviors as cues and can therefor be used to study the neural mechanisms of the behaviors, which is less noisy than trying to measure the behavior themselves. For example, it can be impossible to measure the neural activity of fighting bears, but you can measure the affects of the smell of one bear on another.
So Stowers and team use this as a model to study mouse fear to cats. The interesting thing is that the mice used in research are very far removed from nature, like 100s of generations removed from nature. But, these inbred, never seen a cat in 100s of generations mice react to the scent of a cat with stress hormones, avoidance, etc., indicating that the cat smell is a kairomone, or signal between species that help prey from predators. These cues also work for attraction, where these same kairomones (MUPs) like rage cues in male mice actually are attractive to female mice, depending on the time she’s at of her estrus cycle.
There were 2 more talks after this, but unfortunately I was pressed for time. The last talk was by my former colleague at Monell, Joel Mainland on digitizing olfaction and the receptor responses to help map odors and the odor space.
Emotional Posters
So I came across this meme today…
But I saw some great work in this last day’s poster sessions.
Karin Norimoto, of Kyoto University, did some interesting work on how self projections onto pictures effect how people encode those pictures using fMRI. People are more likely to remember pictures encoded in self than other. So basically, if you can see yourself in the image, you are more likely to remember it and is confirmed by fMRI showing activiation in self-related thalamic regions and memory related regions.
Ayumi Omura of Doshisha University presented work on the sex differences of pleasantness levels of pictures using fMRI to examine the level of activation. In both men and women, lower pleasantness was associated with lower activity in teh frontal lobe. Overall men had lower brain activity than women (haha) suggesting that there are sex differences in brain activiation for pleasantness of imagery.
Sarah Witkowski of the University of Texas presented her undergraduate research on the relationship between social media use, circadian rhythms and mood regulation in young adults. Particularly of interest to me as I’ve been blogging this meeting. Over the course of 10 days, she measured a group of students on their 24 hour circadian cycles. As sleep patterns have been found to effect cognitive performance and mood, as have certain behaviors like social media use, the purpose of this study was to find the relationship between circadian rhythms, mood and social media usage. She did find that social media use correlates with mood. Sleep also correlates with mood, particularly for the morning after bad sleep. Good sleeps results in less stress. And social media done before sleep did not appear to correlate to bad sleep. One caveat was that the social media use was measured by activity, and therefor did not account for people that did not actively participate in social media (lurkers that just read social media without comment/action). Some interesting work for sure as Sarah decides what to study in her grad program.
Neuro of Touch
This was my last talk of the meeting. The meeting would have to continue without me as I needed to catch my bus back to Philly before the meeting ended.
This was a special lecture by Dr. David Ginty on Sensory Neurons of Touch. Dr. Ginty started with saying that skin is one of the most important organs. Yes, skin is an organ in case you didn’t know. Mechanoreceptors in the skin respond to different stimuli via different cells/receptors specific to that stimulus. He spoke of low threshold mechanosensory neurons (LTMRs) and how he has used genetic work to trace their paths and projects as well as physical characteristics, particularly in the hairy skin of mice.
Using conditional knockout mice, he and his team is able to investigate the neuroscience of sensations like tickling on the skin. For example, the neural steps of feeling a bug crawl across your skin (yuck!). He showed a series of images of stained receptors that he described as “beautiful structures… beautiful is a technical term.” And they are.
I’d also like to note here that his lab uses Nair hair removal to remove the hair from the mouse skin and then measures the neuronal response to stroking the skin. It’s also interesting that hair itself extends touch beyond the skin as these receptors are very sensitive and so the movement of the hair will also stimulate the receptor.
In Conclusion
I really enjoyed the meeting over all. I’m exhausted and full of new knowledge. Armed with this experience I hopped the bus home, ready to share my experience with my team at HCD Research.
I hope to also write up a summary post to help other neuro-academics in industry on why SfN is such an important meeting to attend.
Till next time, back to Philly!
nerdoscientist.com 