June 15, 2012

The Public Understanding of Neuroscience: My Work

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While looking at my blog statistics, I realized that one of the more popular posts here is Neuroscience At All Levels.  This is likely because of its broad overview and accessibility to the public.  I am a fan of Neuroscience "outreach" and there have been some interesting posts on the matter of how scientists should be doing more of it. scicurious (part II), one of Nature's blogs, and there are others circulating.

The basic story from what I can see:  One side says that scientists should be telling the public about their research in an attempt to help them understand what's going on in their world!  The opposite side: we don't have time! (Please excuse the brevity and feel free to add more arguments in the comments.)  While I think both sides have valid points, I fall in the middle, luckily!  Yes, I am a graduate student and do research and my postings here have been going downhill lately, because I've been busy with research.  I also don't have the added enormous pressure, as of yet, to publish in order to save my career and do not have to worry about grant writing or giving talks at conferences.

So, onward with the Outreach!  What I'm doing is trying to understand the relationship between the hippocampus, anxiety, and behavior.  My story follows...


  While this blog is pretty much dedicated to the hippocampus, I'll give a brief description of the "sea horse" in the brain.


The hippocampus is a structure in the meaty (middle) portion of the brain that is involved with aspects of memory and anxiety.  There are debates on this and sub-debates on the debates ad infinitum, but this is the more popular view.



While I originally wanted to look at the hippocampus and memory, I soon found my way to studying stress and anxiety.  Within the hippocampus, there's a small region known as the dentate gyrus.  The place is remarkable in the sense that it generates NEW neurons all throughout life and also "fires" or communicates with surrounding areas quite selectively.

 It was thought that, once a person was born or soon there after, neurons stopped being born and you were stuck with what you got.  Not so is the case.  So, now the question is: what are these new neurons doing (see here for the latest and greatest chatter on what they might be doing)?  Are they participating in the aforementioned functions of the hippocampus; are they just there for show; are they deleterious to the connectivity and stability within the hippocampus?  The thought now is that they DO function in a helpful way.  How? In what aspects of memory and anxiety (stress!) do they participate?  That's questionable and that's the game of science -- to find out.

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Currently, I'm looking at how these new neurons contribute to anxiety.  'Anxiety' is a word that only humans can express.  I study anxiety in the mouse and rat.  How?  Well, we look at certain behaviors that are suggestive of anxiety, especially when we put the rodent in a situation that is known to produce anxiety.  Many of the tasks that we give rodents have been applied in some way to humans (in which there's self-report of anxiety), so we are pretty sure they're sound tasks.  These tasks include having them crawl along an open beam that is elevated off the ground, exposing them to bright lights in a new environment, letting them not know if something that is harmful is still harmful to them, and other situations that are just threatening to their well-being.  Think in humans: human walking across an open beam that is 3 stories tall, putting them in an unknown environment with bright lights for unknown reasons, or placing them in a room with a threat of getting shocked.  These will surely generate a sense of angst in most everyone.

The behaviors mainly associated with anxiety are risk assessment behaviors - behaviors done to gain more information about the threat or the situation:

Stretch Attend behavior is when the animal's hind legs are stationary but the animal stretches its body out to investigate and gather more information about the surroundings.   In humans you can think about a person peeking around a corner towards an alley to make sure the criminal is gone...  you're staying behind the wall but stretching your body out to expose yourself just enough to gather more information (to see if the criminal is still there).

Rearing behavior is a bit more straight forward.  The rodent (or human) will stretch their body upward in an attempt to gain more information on the situation, say if they are unsure if something threatening looms in the distance.  Rodents do this more frequently (because they don't stand upright normally) to gain visual information but also to gain olfactory (smell) information.

Flat-Back Approach is when the rodent stretches its body out while it's walking, usually because they're unsure of their next step or want to try to minimize their movement but still investigate and stay low to the ground.  In humans, this would be equivalent to someone slowly walking, cautiously, down an alley because they are unsure if it's safe, say if they are walking in a 'bad neighborhood'.


Freezing behavior is also a measure of anxiety but is classically associated more with fear.  In fear, this is easy.  You see a huge gorilla right in front of you and you freeze out of fright.  This is the same with a rodent; they hear or see something that petrifies them, like a cat staring at them, so they freeze.  This is a natural response.  In anxiety, this is a bit trickier.  You could be freezing to gather more information (and time) in order to assess if something that may be harmful is actually harmful.  In rodents, as with humans, you can see this behavior when the subject is slowly moving their head to scan the environment but for all purposes their body is frozen.  Also, if they aren't sure if the threat is really a threat, they may freeze and passively assess the situation and think of what their next move should be at that time.


Those are just some behaviors that are indicative of anxiety.  Behaviors are a curious beast and very interesting to observe in other people!

You may be thinking, "Well, yea, so?  Mice and rats can exhibit these behaviors but it does not necessarily mean they're anxious".  One must remember that, when the rodent is in a negative (aversive) situation, like being tested in a previously shocked environment, and they display these behaviors, we can safely conclude that they are experiencing some sort of anxiety (or, more properly, anxiety-like symptoms).  It all comes down to where you see these being displayed.

So, to bring it back together, I'm seeing if these new neurons generated in the hippocampus (read: dentate gyrus) play some unique role in anxiety by observing some of the behaviors mentioned.



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