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Astrocytes

dshanin's picture

 Neural and Behavioral Sciences Senior Seminar

Bryn Mawr College, Spring 2010

Astrocytes

Astrocytes are a type of glial cell.  Glial cells had always been thought to provide physical structure and little else to the neuronal networks of the central nervous system.  However, as with many topics in neuroscience, a great deal of more recent research has shed light on the complex and sometimes surprising functions of the astrocyte.  The astrocyte has been found to posses many abilities that were previously thought to be exclusive to neurons including neurotransmitter release and inter-cell signalling.  I would like to spend some time discussing some of the more recent findings as well as their implications in terms of many neurologic disorders whose physical cause may lay within the astrocyte (and thus remain poorly understood).  Beyond the astrocyte itself I want to focus on what exactly makes this research so important, especially considering it challenges one of the oldest rules of neuroscience, the neuron doctrine.  So please take check out the readings (which were emailed to you) but also try to think about astrocytes' place within the realm of neuroscience.    

Background readings:

Araque, A. (2008). Astrocytes process synaptic information. Neuron Glia Biology, 4(1), 3-10.

Giaume, C., Koulakoff, A., Roux, L., Holcman, D., & Rouach, N. (2010). Astroglial networks: a step further in neuroglial and gliovascular interactions. Nature Reviews Neuroscience, 11, 87-99.

Keyser, J., Mostert, J., & Koch, M. (2008). Dysfunctional astrocytes as key players in the pathogenesis of central nervous system disorders. Journal of the Neurological Sciences, 267, 3-16

Some relevant thoughts from last week:

the culture of science demands that emotions must be hidden and the jargon must be cutting-edge, which necessarily prevents the vast majority of the public from  understanding ... VGopinath

The inclusion of subjectivity and personal experience, which initially captivated me and was my favorite part of her account, is now essentially an academic turn-off of sorts ... sberman

nothing could fully be explained without the use of metaphors because everything we show or support comes from a subjective viewpoint that must be modified towards a broader audience ... All scientists do this in fact all people do this. What is communication without metaphor, really? ... Isn’t every word a metaphor for some intangible meaning? Don’t attack expression just be open to a different meaning in unexpected contexts ... mrobbins

Some diagnoses already rely (at least to some extent) on self-report data; patients  must report feeling upset, lethargic, or even suicidal for an extended period of time in order for physicians to diagnose them with depression ... kenglander

the subjectivity we tried so hard to keep separate has become the very topic to be investigated ... maybe emotion should not be kept so strictly distinct from science ... I imagine that as repulsive as we find the integration of emotion into science, we find the incorporation of religion about a hundred times worse ... Is it possible that science is an inevitable part of religion, or even more jarringly, that religion is an inevitable outcome of science? ... David F

neurobiological observations might over time lead to the conclusion that there is in all people an irreducible, non-categorizable, non-calibrateable, distinctive individuality/subjectivity.  Might experience with that residual distinctive subjectivity, unique to each individual, be related to/the origin of, what in religious discourse is referred to as the "soul" or "spirit"? ... Paul

William James, heralded as "the father of American psychology", was obsessed with the study of emotions and fluctuations in mood. He had personal experience confronting "serious psychological difficulties" and this personal experience inspired him to study how his (and others, later on) own spirituality and consciousness related to physiology and neuroscience ... meroberts

if the theory is impossible to test it is not science, a scientific theory may not be provable across all possible circumstances, but is must be possible to disprove ... Jeremy Posner

Comments

Sasha's picture

astrocytes

I found Dan's presentation on astrocytes to be very interesting even if it was perhaps more of a lecture topic rather than discussion topic. Astrocytes seem to be the new "hit" in neuroscience research and as research continues we will start to learn more and more them. Just because astrocytes are not taught or discussed in classes now doesn't mean that they are not relevant in our pursuit of understanding the brain. When my father was in school they didn't teach about what DNA was because no one really knew at the time. The amazing thing about science and research is that it is constantly changing. Things that we think of as secondary or perhaps not important, may one day be proven to be an essential component of how we develop and behave. I'm glad Dan enlightened us on the current research of astrocytes and who knows, maybe when our children are in college they will be shocked that we didn't know about astrocytes and that it wasn't taught in every intro bio or neuroscience class. We'll see what happens...

dshanin's picture

Science as religion

 

Firstly I want to thank everybody for their patience during the astrocyte class. I can say without any doubt it was the most difficult presentation I have ever given and I appreciate the participation even though it did not generate the same level of debate as some of our other topics. This lack of strong debate (especially when our class is so clearly capable of it) got me thinking. The topics that have evoked the most discussion are those that weigh a scientific perspective against a less-science-y popular opinion (The stroke article being a good example). Yet this topic produced a far more opinionated response from Paul, who generally keeps his own feeling hidden. It is an interesting point in our education where we can state with confidence what science is and is not but do not yet have the foundation necessary to engage in a debate between two highly scientific approaches. We clearly have no trouble identifying the border of science and other methodologies of understanding our world such as religion or personal experience-based philosophy but we were struck silent when trying to weigh the virtues of neuronal vs. astrocyte research. While I have no doubt the approachability of non-science topics adds to the discussion I think there is more to it. We have truly become acolytes of science, ready to defend our ideology from all who attempt to weaponize science and use its seeming objectivity to influence the un-learned masses. It is interesting (and certainly supports the notion of science as religion) that we can so ravenously defend science but leave the intra-scientific debates about what science should be (rather than what it is not) to the “church elders”, the journal editors and well-published professors.             

LMcCormick's picture

Astrocytes and the scientific process

            I’m not entirely sure why we are treating the study of astrocytes differently from any other scientific research topic.  It is a given that there is going to be uncertainty, inaccurate results at times, and likely excitement about these false claims.  However, this does not make the research any less important. Megan wrote, “So is it even worth it to reduce astrocyte functioning to be understood by laypeople if we'll have to redefine them and explain new theories about astrocytes over and over again?”  Of course it is.  This is the essence of science; it is constantly restructured and molded as we make new discoveries, but that doesn’t mean we should ignore contemporary theories because they may be discredited in the future.

            On the other hand, the more that I learn about the process of sifting through data as well as the politics of publishing papers, the more skeptical I become about the objectivity of the entire research process.  I was recently working in a lab in which one of the scientists had data that potentially disproved an article published in a prominent journal.  He tried to publish a “rebuttal” article in the same paper, and he was extremely discouraged by the politics of the process.  The journal made it extremely difficult for him to publish this data (including allowing the original authors to read his rebuttal and write a lengthy response).  It makes sense that a scientific journal may not be interested in publishing a rebuttal article, as this might make their readers more skeptical of the validity of their articles in the future.  Ideally, however, science should be a constant back and forth dialogue.  This example demonstrates the importance of considering the influence of scientific journals in shaping the information that we are exposed to as well.  This may be particularly relevant because – unlike articles in the NYT that cater to the general public – articles published in scientific journals will influence what scientists chose to research in the future.

            As a side note, I’m not sure why the discovery of communication between astrocytes via gap junctions might indicate that astrocytes play a critical role in cognition.  Many cells communicate in this manner (such as epithelial cells in the intestines) but we wouldn’t presume that this system of cells produce cognition.

 

Claire Ceriani's picture

Astrocytes in the Classroom

I know I learned a little about astrocytes in a previous class, but they were a sidenote, and I'd completely forgotten the word until we did these readings.  Even though we don't know a great deal about them (at least, compared to neurons), I was actually surprised by how much researchers do know about them, given that they're an uncommon topic in the classroom.  I think for an intro level biology or psychology class, a small metion of them is appropriate, but I think any more advanced neuroscience class should spend a little more time on them.  We may not understand every detail of them, but they're clearly more complex than we might assume.  I think it's worth mentioning what we do know about them and discussing why they might be a valuable course of research.  Many students thinking about going into neurological research may not be aware of the current research being done on astrocytes.  Some people might be intrigued by the idea of researching something for which there is comparatively little information.  If it turns out that astrocytes are key to treating or curing a particular condition, it will have been worth mentioning them in the college lecture that inspired a particular student to investigate them.  Given that there are already suspected links between astrocytes and certain conditions, they may be a good horse to bet on.

Paul Grobstein's picture

Astrocytes as a case study in science as shared subjectivity

Astrocytes, as per our Monday evening conversation and below, are clearly more interesting to some people, less so to others.  For the record, I'm still in the less interested camp.  That's not to say I don't think astrocyes do significant things but rather that astrocyes have been around/investigated for a long time and I'm not persuaded by the current claims that there is an impending breakthrough in our understanding of them or their relation to neurons.  What interested me a lot though was the conversation, Monday and below (and excerpted here), about what researchers do and why, and how that gets translated both into courses and into public awareness. 

I think there is an interesting relation between this conversation and some threads that have been running through all our conversations, beginning with Exploring the brain's role in experiencing and running through the discussion of reactions to Jill Bolte Taylor.   If indeed all understanding (scientific and otherwise) is brain construction,  and so there are only "subjectivities" and "shared subjectivities," then, as Alison put it in her introductory posting, "How does the brain decide what is important"?  Or, expanding a bit: how do brains, individually and collectively, decide what is important?  are we comfortable with how it is done or do we want to change it, to create a new shared subjectivity?

"researchers are able to ascribe all sorts of potential incredible breakthroughs ... those who are involved in that research are happy to have the publicity" ... a good thing or a bad thing?

"As scientists, we know that the field is constantly changing and that scientists often make new discoveries that contradict contemporary theories ... But to the public, this back-and-forth can discredit science" ... do we know that?  do we make it clear? 

"Who, or what decides what we should learn about from TV, newspapers, or a 200 level biology class?  In the case of Neurobiology and Behavior, it is Paul who directly decides. But ultimately, he makes his decision with consideration of the amount of attention being given to astrocytes in the scientific community, and whether this amount of attention is enough to carve a place for astrocytes in his course."  ... is that how the decisions get made?  should it be? 

While some people legitimately can and should work on astrocytes, maybe its at least as important that others be doing research on what motivates particular constructions in particular brains and how these interact to yield shared subjectivities?  With an understanding that the business of science is as much to open new possibilities as it is to account for the current state of "reality"? 

 

 

rdanfort's picture

 I remember some astrocyte

 I remember some astrocyte stuff as long ago as AP Psychology in high school - it was sparse, but we did learn it.  Maybe I've been lucky, but I at least got some exposure to basic and relevant concepts - myelination, immune respose beyond the BBB, etc.  I think the focus was on oligodendrocyte/schwann cell activity as it pertained to MS.  Still, I can completely believe it when people say that they've never been taught much about astrocytes or barely heard of them.

We more or less talked about this in class, but the omission is somewhat reasonable - all the dramatic things that are presently known to happen in the nervous system have been investigated in terms of neuronal signalling.  As Dan said, it's a lot easier to look at.  It's also a far more effective medium for high-speed signals than the gap junction-mediated changes to expression and vescicle deployment discussed w/r/t astrocyte networks.  I was personally a little confused as to why this form of transmission was not measurable electronically - movement of Ca2+ ions will produce a current - but am assuming that the ion flow is slower than in an action potential and, compared to the neuronal activity happening all around the brain, somewhat dampened.  

Personally, I think that microglia are very interesting - I know that there are genetic and functional connections between immune cell lines and neural cell lines, and microglia have this weird role that compensates for the isolation of the CNS from the immune system proper.  This appears to have a lot of consequences for neuroregeneration and response to brain injury, which are an emerging field of research and probably does belong in entry-level courses.

vpina's picture

I myself have a personal

I myself have a personal issue with the fact that astrocytes have not been proven to be important enough to study for an extensive period of time. Professor Grobstein is right in saying that there is a line where you must say this an irrelevant point in the grand skim of things. Personally I do think it is something that should at least be mentioned at some point before med school because if the goal is to spark interest for figuring out something that we do not entirely know everything about than that interest starts well before med school. 

I realized in a later after the class that I was exposed to the knowledge of astrocytes in high school and if I were more into bio than I am into psychology than maybe I would have thought more of it. The point is I was exposed to it at an early age and it is that little exposure that can be the difference between someone finding a cure to cancer sooner than later.     

Bo-Rin Kim's picture

I found the astrocyte

I found the astrocyte readings/discussion interesting because they added another dimension of complexity to the nervous system that I was not really aware of before. Most of my studies have focused on the neuron doctrine, and these readings on astrocytes helped me to see that there is so much more in the nervous system to be discovered. It is true that we have done really well in terms of explaining cognitive and behavioral phenomena just with the neuron and its networks. However, I don't think that is reason to discard astrocytes as being useless and not worth researching. It may be true that astrocytes may be receiving so much attention because they are the new frontier of neuroscience that young scientists are trying to become famous for, but aren't there other great discoveries that were made because some young scientist wanted to make a name for themselves? It may be true that scientists will later find that astrocytes are not a significant contributer to the function of the nervous system, but I think it is important to at least research them and learn about them until this conclusion is reached...because as of now, it seems like they do (or at least contribute to) some pretty important stuff.

The concept of a “tripartite synapse” really caught my attention because it indicated that there is a whole other system that we were previously not taking into consideration when thinking of neural function. While we do know so much about nervous system, there is also so much that we do not know and phenomena that we cannot explain. Despite the complexity of this tripartite synapse, the idea of a more complicated synapse also offers hope of finding the answers to the questions that we still have related to cognitive/behavioral function. While astrocytes cannot account for everything we do not know, they may hold the answer to some of mysteries of how the brain works.
 

 

Jeremy Posner's picture

Projecting onto Astrocytes

 While I don’t disagree with Paul’s point about the politics of academia and the current popularity of astrocytes as a research topic may be in large part the result of a push by researchers in the field to increase the visibility of their own work I think I’d say that even if we never discover how to treat HIV/AIDS through astrocyte research or identify key previously unknown components of cognition the same way there is enough known currently about the significant role of astrocytes in the function of the nervous system that it is worth including at least briefly in classes intended to provide an overview of the overall structure and function of the nervous system.  Obviously each class is designed to accomplish a particular goal, to impart a certain set of ideas, and astrocytes aren’t necessarily going to have to be a part of every lesson plan, but the more in-depth look at astrocytes I received in classes taught by Andrea Morris at Haverford really was quite valuable and very interesting. 

I do think that a couple of the possible reasons I posited for the current popularity of astrocyte research to your question, Peter, were really just the answer you provided in more optimistic terms.  Even with the influence of especially talented or vocal astrocyte researchers I do think that a part of the popularity of astrocyte research currently, and part of the reason why any particular area becomes a hot topic in a scientific field is the degree to which the extent of the influence of astrocytes upon the function of the nervous system is unknown.  Astrocytes are something of a blank canvas right now and researchers are able to ascribe all sorts of potential incredible breakthroughs to them (again things like significance in HIV/AIDS treatment).  Because it seems possible that the established understanding of the function of astrocytes was wrong we are allowed to hope that it may have been so wrong that there is tremendous potential in astrocyte research, and those who are involved in that research are happy to have the publicity.    

meroberts's picture

Peter?

Who's Peter and what was his question?

I do agree with you, Jeremy, and with most of the rest of the class that astrocytes are receiving attention now from professionals because their function has seemed rather ambiguous up until this point. The only problem then comes from the gap between what scientists know and what the general public knows. The question is (and we mentioned this in class and in the forum already) how do we inform the general public about astrocytes when the people researching astrocytes can't pinpoint their exact functioning? It could be true that astrocytes fulfill a broad range of functions. This would make the most sense to me because it fits with my own understanding of the brain and it's plasticity.

For those of you who haven't taken Paul's Neurobiology and Behavior class, I will say that reducibility seems to be the name of the game. As mentioned in senior seminar, Paul describes neurons as "boxes" in Neurobiology and Behavior. Now, if neurons- which until recently were thought to be the end-all, be-all of nervous system functioning- can be reduced to "boxes" to facilitate discussion with people who may not be well-versed in neuroscience jargon, how would we reduce astrocytes and explain their ambiguous role in nervous system functioning so that it could be understood by laypeople? We talked about this in class and I don't mean to beat a dead horse, but I feel like laypeople wouldn't care to try to understand what astrocytes are because not enough is concretely known about them. And, as Allie said, information is constantly subject to change. So is it even worth it to reduce astrocyte functioning to be understood by laypeople if we'll have to redefine them and explain new theories about astrocytes over and over again?

kenglander's picture

I agree with Megan about the

I agree with Megan about the difficulty and potential irrelevance of defining astrocytes. However, I think it is a worthwhile exercise to try to define astrocytes or glial networks in general. Even if we only say that astrocytes simply support and facilitate neuronal firing, we have at least acknowledged that they exist within the brain. Obviously this definition can be revised as we continue to learn more about their role in the brain (after all, we continue to reshape the definitions and descriptions of other anatomical organs and pathways-- i.e. from phrenology to the more contemporary understanding of the brain and temperament). I don't know how many people would listen to/care about an explanation of the role of astrocytes in the brain, but I don't think that's a good enough reason to exclude information from the general public. The moment we decide that astrocytes are not worth any attention from the general public is the same moment that science becomes more exclusive and monolithic in nature thus precluding a more transparent and accessible relationship between the laboratory and the rest of the world.

aliss's picture

During our discussion of

During our discussion of astrocytes, I found myself at a loss to explain their importance.  We know that neurons do the work of the brain; scientists have been studying neurons for at least 100 years and in that time have made many discoveries about their function.  In my first psychology class, we learned the process of signal propagation and transduction down the neuron, a process that I remembered learning even in my high school biology class.  It had always been a given in my mind that neurons were the cells of the brain.  Of course, I had also learned about astrocytes, the supporting cells in the brain that processed neurotransmitters, produced the myelin sheath, and provided structural support for the neurons.  However, until these readings and our discussion, it never occurred to me that astrocytes might have their own processing networks, simply because I had never been told. 

Here the discussion blends into our talks from the first half of the class: how can we expect the public to know anything about science that they have never been told?  And how can we expect people to quickly change their minds when new scientific data emerges?  As scientists, we know that the field is constantly changing and that scientists often make new discoveries that contradict contemporary theories; part of being a scientist is using the data that you have to determine the truth, even if it goes against what you already know.  But to the public, this back-and-forth can discredit science.  Yesterday, eggs were bad for you, but today, eggs are good for you.  Cell phones cause brain cancer.  Cell phones do not cause brain cancer.  At the same time, it would be both unethical and almost impossible to hold back all information until we were sure that it was 100% correct.  We know that neurons don't work without astrocytes, but it has not been deemed important enough to explain to the public.  Just as most laypeople know that bones are made up of calcium, but they don't know how the calcium gets to their bones, scientists have decided that astrocytes aren't basic enough for the public to need to know.  And frankly, if we don't know what astrocytes are doing, why would the public want to know about them?  Once they become important enough that we can make some definitive statements about what they do and what processes they effect, that information will surely be shared with the public.  And then refuted.

sberman's picture

Communicating information about astrocytes

An interesting issue sparked by our astrocyte discussion is that there is only so much science that can be communicated from scientists to others- this issue was evidenced by Paul asking us whether he should teach about astrocytes in his neurobiology and behavior class. Each and every day, there is an increasing amount of scientific facts/information/theories being discovered or clarified. It is impossible for all these to be conveyed not only to the general populace, but from one scientist to another. Who, or what decides what we should learn about from TV, newspapers, or a 200 level biology class? In the case of Neurobiology and Behavior, it is Paul who directly decides. But ultimately, he makes his decision with consideration of the amount of attention being given to astrocytes in the scientific community, and whether this amount of attention is enough to carve a place for astrocytes in his course.  So in essence, it is whether or not the person who disseminates the information chooses to listen to what the "loudest voice" in scientific research is saying. Do we trust the NY Times to make the decision as to what the population should learn about science? Or Scientific American? Or our professors?

In regards to communicating information about astrocytes and other scientific findings that may not directly apply to the general population immediately, I honestly think that most individuals probably will not be all that interested (as we discussed in class). But for those who are interested, I think that scientists should put some sort of information out there, in addition to what is published in medical journals (more understandable, less jargon heavy). It seems that with astrocytes, although they are "under the spotlight" in the academic/research worlds, that people not involved in science do not know much, if anything, about astrocytes. Why is this? Is it because we as scientists do not think that astrocytes will be interesting to a lay audience so we don't discuss them? Or is it because the public holds so strongly to the idea of the neuron as the core of the nervous system? I'm inclined to think it's the former, because it seems to me that if scientists could make a big splash and get publicity by claiming that astrocytes have an important role just like neurons, they would - but without an interested public, there would be no big splash.

EB Ver Hoeve's picture

Variation - what do we do with that?

 

It does seem to be the case that the current trend in scientific research is to view the best, closest thing to truth, answer in terms of the smallest possible mechanism. In my own research, I find myself looking to ion channels and neurotransmitters in order to explain animal behavior. Is this bad? Is this the BEST way to go about it? In my observations, it is hard to deny that existing molecular and cellular mechanisms play significant roles in the coordination, and therefore, explanation of animal behavior- especially in a relatively simplistic model organism such as the medicinal leech! But then, how far down in this reductionist mentality do we go before we cannot take it any further? For instance, there is ALWAYS variation. Nine times out of ten, when I put a specific drug on the leech ventral nerve cord it will decrease the leech swim bouts. However, there will be times when the drug will not produce the predicted effect, or worse, will not produce the effect to the predicted degree. What are we to make of this? Should we really continue to believe that if we had better tools that allowed us to go even smaller and even more exact that we would be able to accurately elucidate the reasons behind all animal behavioral variation? I guess one response to this could be: well, if we didn’t look for underlying molecular mechanisms, where would we continue to look? Another response to this question could be that since we have long dismissed the simplistic linear input to output mechanism of the brain, agreeing instead that the brain is capable of generating outputs without external inputs, doesn’t it only make sense that we would be looking for small mechanisms within the brain to explain behavior?

Religion in science makes me feel very uncomfortable. I don’t really like it at all, in any form.  I agree that we may very well find that there exists a level of irreducible individuality in every human brain, but do we necessarily need to take that next step and declare a connection to spirituality and the soul? I think I can very easily accept irreducible individuality in the brain, but I am not sure that I can accept the need of people to put a SPECIAL label on it when there just doesn’t need to be that further explanation.

I enjoyed the astrocyte readings.  Whether or not we agree with the current directions of neuroscience research or the reasons for the current directions of neuroscience, I still think it is useful to at least know the rationale behind the current issues. And I think that, as the articles suggest, this new way of thinking about astrocytes may impact the way we not only understand certain diseases but also how we design drugs to combat those diseases.   

 

VGopinath's picture

Glial Revolution

 To respond to David's question about whether or not there is media attention concerning glia and if we have reason to give them a second glace, I believe the answer is yes.  A book released in 2009 describes a glial revolution on the horizon and causes for attention concerning glia.  The author, R. Douglas Fields, is a senior investigator at NIH and he believes that glia control much of the actions of neurons.  He mentions that Albert Einstein's brain is indistinguishable from the average brain except that there are twice as many glia as normal.  Also, astrocytes in the cortex increase in size and number as one climbs the evolutionary ladder, with humans having the largest number and biggest astrocytes.   

There have been many exciting developments that have made their way out of technical journals.  Another article in Scientific American describes a finding a few years ago at University College of London that oligodendrocyte precursor cells can fire electrical signals in response to electrical stimulation, which contradicted previous assumptions about the separate roles of neurons and glia.  

One of the articles we read in class explicitly mentioned diseases linked to astrocytes but there are many more- Down's syndrome is also characterized by an overproduction of glia and that's a commonality used to tie together Alzheimer's research with Down's syndrome research.  Interestingly, glia are also fascinating targets for spinal cord injury patients.  One researcher used the analogy of glia as "parents" of neurons- they help them to grow up and direct them but will step in later if there are problems.  They are thus a target to induce adult nerve cell regeneration.  Whether or not we include them in our undergraduate neuroscience classes, I believe the research in the field has adapted to incorporate the wealth of new information and the contradictions to old assumptions in the field.  A journal called Neuron Glia Biology was launched in early 2004 and another journal called GLIA, described as the journal that launched the field of glial research, was launched in 1988.   

Here's the link to the Scientific American review of R. Douglas Fields's book: http://www.scientificamerican.com/article.cfm?id=mind-reviews-the-other-brain

Another interesting article (again a book review): http://www.scientificamerican.com/article.cfm?id=the-root-of-thought-what

 

 

 

David F's picture

The study of astrocytes: astrology?

 One of the lessons I took away from tonight's discussion on astrocytes was the importance of remaining wary of factors other than those one studies. It can become easy for researchers to focus so narrowly on their topic of interest that other players recede into the background (e.g., a researcher who specializes in the hippocampus might sometimes exaggerate the importance of that structure). In one sense, this is helpful, in that it allows us to remain focused on a subject and explore it to its fullest extent without becoming distracted by other necessary but separate factors. However, this way of thinking may also obscure answers that lie outside of that topic. In the case of astrocytes, their array of abilities can be startling to neuro-scientists who might sometimes overlook their very existence. But as we discussed in class, the question then becomes: well, having acknowledged their existence, do we have any reason to be startled, to attribute some previously elusive answer to them?

In many ways, the answer to that question seems to be no. While the laymen are familiar with neurons (they know that they comprise the brain, allow us to think, etc.), few have probably even heard of glial cells. Relating this back to the discussion at the beginning of class, the reason for this seems relatively straightforward: the average person learns about terms that are reported by the press, the press reports scientific data that are interesting to people, that which is most interesting to people is often that which is most relevant to them, and astrocytes do not seem to have any relevance to who we are or what we care about. The second we find out that astrocytes play a role in curing a disease, or housing our deepest thoughts in a manner that does not require neurons, then people will know about them. But to entertain the alternative, do we have any reason to believe that neurons play a role in curing a disease or housing our deepest thoughts in a manner that does not require astrocytes?