Thesis, in brief.

So it’s been a while since I went on about science per se, and longer since I went on about my own field of speech neuroscience.

Part of this has been my working on my thesis. I’ve been sort of buried in data and discussion and haven’t had an easy time breaking it down in my head, into a simpler form. And my thesis is looking more like a journal article than a thesis, so I’ve got plenty of work ahead of me.

For those of you who don’t know what I’m doing, here goes. This is at once more general, but much more descriptive, than my previous update.

I’ve got two imaging studies to work with, both older studies that were finished before I joined my current lab. In one, participants were put in an fMRI scanner while they viewed a picture, a word, or heard a word spoken. In each case it was an object, like “bread”. Half the time they just perceived the word passively. The other half of the time, they spoke the word aloud after perceiving it.

In the second study, participants were in the scanner while they watched a video of someone speaking a sentence. In some cases they saw a still image of the person’s face while the audio track played; in some cases the video track played silently; and in some cases they saw both together. Also, in some trials they had to decide if the speaker was angry or happy, and in others if the speaker was asking a question or saying a statement.

There’s a couple places I’m going with this. Firstly, I’m looking at how the brain activation during the listening condition in experiment #1 and all three modalities (auditory, visual, audiovisual) in experiment #2. Here, I’m trying to see if and how much perception activity overlaps with production activity, and whether it stays constant when you go from words to complete sentences. This is motivated partly by that motor theory of speech perception I talked about a while ago.

After that, I’m going to look at whether frontal or motor regions in the brain are more active for auditory, visual, or audiovisual perception. Another group of researchers has the idea that when you see someone talking, the visual information is sent on to motor regions involved in speech production. The brain then matches the gestures you’ve seen and the sounds you’d expect to come from those gestures if you’d made them yourself to the auditory speech information coming in your ears. This is known as hypothesis-and-test. And it predicts that speech that contains visual information should activate frontal and motor regions more than speech you just hear. So I’m also looking at that.

Lastly, if neither of those are confirmed, I’m going to look at activation for each modality in experiment #2 and try to explain how the activity we see is actually heavily dependent on both the task at hand and on the modality being used. A lot of motor theories suggest that activity during speech perception should be very general – that is, it shouldn’t matter much what sort of listening you’re doing, or what you’re thinking about doing while you’re listening. They often seem to say that there are certain regions which are always involved in speech perception, and part of my thesis will suggest that this is not, in fact, the case. Our lab generally thinks that activity is very dependent on the specifics of what the participant is being asked to do.

So far, that looks to be true.

Brief updates, Christmas.

So, it’s been a couple weeks. I submitted my official thesis proposal just before the holidays, and had a good chat with my inestimable third committee member, who turned me on to some excellent papers. I’ve mostly spent the holidays catching up with old friends and spending time with my family, which has been nice. The next six months or so promise to be pretty busy, but also pretty science-y since I’ll be finishing my analyses, writing my thesis, and figuring out what I’m doing next year.

Christmas is an interesting time as an white, Christianishly-raised atheist in Canada. People assume, for example, that you’re Christian much more often during the season, in a way that can at times be reminiscent of this. It’s sort of what happens when someone talks to me about how they get so jealous when their SO flirts with someone else – a general assumption that you side with them because you aren’t visibly different. But you’re still very much a part of that culture, so Christmas feels like a fairly secular holiday to me, despite it being a religious holiday, just because it’s so normal for me to participate in it.

But the war on Christmas stuff doesn’t make it too far north of the border. Aside from a few poorly-informed people wearing “Keep the ‘Christ’ in Christmas” buttons and “You can say ‘Merry Christmas to me” t-shirts, we’re usually okay at recognizing that Canadian =/= Christian. The ‘Happy Holidays’ thing is pretty normal, especially since for many people the only significant thing between December 23rd and January 1st is a couple days off and a new secularized calendar year. Oh, and a lot of annoying music piped in over loudspeakers on the local high streets. I could do with less of that.

Sometimes, I wonder if I’m sort of parasitizing on the whole ‘sacredness’ of the Christmas holidays. Not doing much work, spending time with people, eating lots of food and lazing about… “It’s Christmas” is often a good enough excuse for behaviour that would get me in trouble otherwise, even on other holidays. I suppose I can thank Charles Dickens for that more than the Bible, though.

My science is working.

So, I submitted my first abstract in my new field yesterday. That was pretty exciting, especially as I found out about the conference, modified my thesis proposal into an abstract, and figured out how to present my as-then-unsystematized results. I have interesting results, which should even be publishable at some point.

I have a post on communication in my head, floating about. I’ve been noticing just how bad humanities/arts people and science people are at talking to one another. I think some of it is disciplinary, but a lot of it has to do with funding anxieties, misperceptions and misconceptions, and socio-political anxieties. I have a couple examples and am still thinking on how to present them, but this recent kerfuffle over the American Anthropological Association’s decision to remove the word “science” from their mission statement, along with some personal experiences, have got me thinking about how important it is. Science advocates like myself have more allies than we think, and if we could communicate better with people in the arts, we’d realize it.

Now that my thesis is working out, maybe I can get this bloody connectivity model working.

Proposal, learning.

So, between working feverishly on my thesis proposal and my exam, I’ve been a bit pre-occupied this week.

The proposal’s come along well. I think I’ll like it more when I’ve fleshed it out into a full thesis. There’s some sections that could be laid out in more detail, and I skipped over some good papers in order to make my main points in a decent amount of space.

Essentially I’m taking a conjunction of three speech production tasks, done at the word level; extracting that conjunction as a region-of-interest; and then using that functional ROI to look at three speech perception tasks, which involved viewing either auditory, audiovisual, or purely visual recordings of someone speaking a sentence. They’re mostly abstract, non-action sentences, though I still need to double-check them for that. My hypothesis right now is there will be motor activity during perception of higher-level speech, in the same regions as during production of simple, single nouns. If there is, I’m predicting there will be more activity during the audiovisual and visual tasks than the purely auditory ones.

I’ve been pretty influenced by two papers in particular, Skipper et al 2007 and Tremblay & Small 2010. When it comes time to my thesis though, I’m going to broaden my background and will probably end up referring to the dorsal-ventral path theory put forth in Hickok & Poeppel 2004.

In related news, I spent much of Thursday and all of Friday teaching myself how to run a structural vector autoregression connectivity analysis using 1dSVAR, a program written in R for use with AFNI. No one else in my lab knows how to use it, and there’s not much of a manual for it, so I’m pretty pleased with myself. I still need to figure out how to interpret my output, and to double-check my input, but I’m on my way to being able to do another type of fMRI analysis, which is pretty cool.