Aphasia

 Neural and Behavioral Sciences Senior Seminar

Bryn Mawr College, Spring 2010

Aphasia

Aphasia is a language disorder caused by brain damage, and may appear suddenly (as the result of a stroke or trauma) or gradually (as in Alzheimer's or primary progressive aphasia).  The most common forms are typically classified as either fluent (Wernicke's aphasia) or nonfluent (Broca's aphasia), with fluent affecting a person's ability to understand speech and put words together meaningfully, and nonfluent affecting a person's ability to articulate and express words verbally.  Studies of sufferers has led to a better understanding of how and where the brain processes language, but has also opened up some questions about how language use may be integrated with other skills within the brain.  Attempts to "reteach" spoken language to aphasics has given us greater insight into neuroplasticity and the integration of the left and right hemispheres.

Background readings:

• Unravelling Bolero, Seeley (2007)
• Preservation of Singing in Broca's Aphasia,Yamadori (1977)
• Evidence for Plasticity..., Schlaug (2009)
• Words Come Easier After a Singalong, NewScientist.com (2006)
• Do Bilingual Persons...?,ScienceDaily.com (2009)

Videos:

• Broca's Aphasia
• Wernicke's Aphasia
• Music Therapy and Aphasia

Some continuing conversation from  last week:

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 ... there is tremendous potential in astrocyte research, and those who are involved in that research are happy to have the publicity ... Jeremy Posner

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 ... Bo-Rin Kim

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 ... VGopinath

an emerging field of research and probably does belong in entry-level courses ... rdanfort

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 ... vpina

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 ... David F

The only problem then comes from the gap between what scientists know and what the general public knows. The question is  ... how do we inform the general public about astrocytes when the people researching astrocytes can't pinpoint their exact functioning? ... meroberts

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. ... aliss

An interesting issue sparked by our astrocyte discussion is that there is only so much science that can be communicated from scientists to others ... 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? .... 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 ... sberman

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 ...  science should be a constant back and forth dialogue .... demonstrates the importance of considering the influence of scientific journals in shaping the information that we are exposed to as well ... 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 ... lmccormick

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 ... dshanin

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? ... 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"?  .... Paul

Discussion summary (Bobby)

Claire opened with the Seeley paper, which delineates an attempt to connect the progression of a woman’s degenerative aphasia to changes in her painting style and subject material.  The paper’s major contention was that the artist’s move towards transmodal expression and visual realism indicated that her lost brain tissue and speaking ability were concurrent with functional gains in polysensory integration of stimuli.  Some note was made of the ambiguity of the patient’s diagnosis and difficulty in connecting paintings to discrete brain phenomena, although David pointed out that the nature of a case study is such that causative assertions cannot be made anyway.  Some discussion regarded the appropriateness of the term, “gain of function,” applied to brain damage.  A brain “unlocked” by trauma is a prevalent cultural myth, but can it be justified?  One prominent example in favor was the gain in tactile and auditory ability by the blind, among similar examples for other sense deficits.  I asked if “becoming more visual” were a proper hypothesis for the artist, as it seemed to conflate a loss of expression with sensory loss in order to appeal to this notion.  It was also asked- why is this woman painting houses if this is her way of speaking?  Respondents noted the lack of clear connection between observed increases in grey matter in particular regions and painting behavior, given the other pronounced changes in behavior and thinking that would come with aphasia.  Perhaps the artist changed as she spent less time talking, and more time looking at leaves.  Conceptualization of the “usefulness” of the article was difficult.  Perhaps it helped us to understand the jargon and concepts used by psychologists to attempt to analyze difficult subjects such as “creativity,” or perhaps it was just an interesting read.

The next paper addressed retention of singing abilities in some aphasia patients, and attempts to re-learn speech through singing-oriented therapy.  Few were surprised by the singing/speaking differentiation, although it was very difficult to pin down exactly what about the rhythm and cadence of song was not found in speech.  As in our recent talks on stroke and EMDR, watching the video had a striking impact on our understanding of the process.  The man presenting his success in re-learning speech was intelligible, but lacked what Paul called the “fluent” quality of speech, making him difficult to listen to.  It was still a fairly impressive accomplishment, and the noted development of the right hemisphere in response to therapy was interesting.  We were fairly curious about the integration of hand-tapping into the therapy program, and disappointed in the lack of control or justification for this protocol.  On the notion of language “centers” and multiple “centers”, people were not fundamentally opposed but had some questions.  It turns out that senses adapt quickly, as demonstrated by temporary blindness experiments, and Paul wanted to know “who decides” how/if/why changes occur in this fashion.  David talked about the importance of input upstream of a disabled region in promoting new connections, and I suggested that some process (potentially our own higher cognition) notices that something is seriously wrong (I’m blind!) and that this initiates adaptation.  Paul noted that words were once thought to be stored in Broca’s area, but that violence has since been done to that exclusive model and that word “templates” may be diffuse, degenerate, or otherwise difficult to pin down.  Billingual-raised and acquired-language brain differences were invoked to illustrate features that separate “word” from “concept” in such an investigation.  We still could not find a clear distinction between language and singing, but realized that singing in a group does carry a measure of correction from auditory feedback.  On that note, the study’s use of folk songs with predictable rhyme and tone schemes was thought to be highly relevant to its success, and it was agreed that atonal or unpredictable music would be far more difficult for aphasia sufferers to reproduce.  Paul noted the use of a relatively new form of brain imaging, Diffusion Tensor Imaging, and suggested these would in general yield  future new insights into the long connections that make up white matter and how they relate to these associative functions.