Conjoined Twins and Split Brain Patients

Conjoined twins are identical twins[1] joined in utero. An extremely rare phenomenon, the occurrence is estimated to range from 1 in 49,000 births to 1 in 189,000 births, with a somewhat higher incidence in Southwest Asia and Africa.[2] Approximately half are stillborn, and an additional one-third die within 24 hours. Most live births are female, with a ratio of 3:1.[2][3]

Two contradicting theories exist to explain the origins of conjoined twins. The more generally accepted theory is fission, in which the fertilized egg splits partially.[4] The other theory, no longer believed to be the basis of conjoined twinning,[4] is fusion, in which a fertilized egg completely separates, but stem cells (which search for similar cells) find similar stem cells on the other twin and fuse the twins together. Conjoined twins share a single common chorion, placenta, and amniotic sac, although these characteristics are not exclusive to conjoined twins, as there are some monozygotic but non-conjoined twins who also share these structures in utero.[5]

Chang and Eng Bunker (1811–1874), Thai brothers born in Siam, now Thailand, traveled widely for many years and were labeled as The Siamese Twins. Chang and Eng were joined at the torso by a band of flesh, cartilage, and their fused livers. In modern times, they could have been easily separated.[6] Due to the brothers’ fame and the rarity of the condition, the term “Siamese twins” came to be used as a synonym for conjoined twins.

As often is the case in science, the study of unique phenomenon can provide a wealth of knowledge and information about normal occurrences. This is true with regard to case studies of both split brain patients and conjoined twins. The unique experiences of these patients have contributed a great deal to our understanding of how the brain functions in a range of both normal and extraordinary circumstances.

Split brain patients are people who have had surgery to cut the corpus callosum, which you may recall, is the main pathway connecting the two halves of the cortex. Often this procedure was done to alleviate symptoms of epilepsy. These patients acted normal enough so that for the first few years after such surgeries were performed, physicians reported that there were no consequences of the procedure. Over the years, however, careful behavioral studies revealed that these patients appeared to have two minds at work in one body. One mind, mediated by the left hemisphere, could talk and respond to questions, while the other mind, in the right hemisphere, could only communicate by gestures and action. Remarkably, the left brain seemed to be unaware that another mind controlled half of the body.

In the case of dicephalic parapagus conjoined twins, (twins who share a body but have separate brains) it is clear that there are two minds because there are two separate brains and each of them can communicate. In craniopagus conjoined twins, there are two separate bodies but a shared brain or portions of brain.

The range of behavior, from relatively normal to unique, of split brain patients and conjoined twins raises questions about what it means to be a “person.” For this week’s Discussion, you compare and contrast split brain patients and conjoined twins, and explore what “personhood” means in light of what these patients can teach us about the brain and its functions.

With these thoughts in mind:

Explain how split-brain patients demonstrate the organization of the brain. Then, describe two similarities and two differences between split brain patients and conjoined twins. Finally, define “personhood” in your own words as it relates to split brain patients or conjoined twins and use the current literature to support your definition.

APA format

Plagiarism free

ADDITIONAL INSTRUCTIONS FOR THE CLASS

Discussion Questions (DQ)

Initial responses to the DQ should address all components of the questions asked, include a minimum of one scholarly source, and be at least 250 words.
Successful responses are substantive (i.e., add something new to the discussion, engage others in the discussion, well-developed idea) and include at least one scholarly source.
One or two sentence responses, simple statements of agreement or “good post,” and responses that are off-topic will not count as substantive. Substantive responses should be at least 150 words.
I encourage you to incorporate the readings from the week (as applicable) into your responses.

Weekly Participation

Your initial responses to the mandatory DQ do not count toward participation and are graded separately.
In addition to the DQ responses, you must post at least one reply to peers (or me) on three separate days, for a total of three replies.
Participation posts do not require a scholarly source/citation (unless you cite someone else’s work).
Part of your weekly participation includes viewing the weekly announcement and attesting to watching it in the comments. These announcements are made to ensure you understand everything that is due during the week.

APA Format and Writing Quality

Familiarize yourself with APA format and practice using it correctly. It is used for most writing assignments for your degree. Visit the Writing Center in the Student Success Center, under the Resources tab in LoudCloud for APA paper templates, citation examples, tips, etc. Points will be deducted for poor use of APA format or absence of APA format (if required).
Cite all sources of information! When in doubt, cite the source. Paraphrasing also requires a citation.
I highly recommend using the APA Publication Manual, 6th edition.

Use of Direct Quotes

I discourage overutilization of direct quotes in DQs and assignments at the Masters’ level and deduct points accordingly.
As Masters’ level students, it is important that you be able to critically analyze and interpret information from journal articles and other resources. Simply restating someone else’s words does not demonstrate an understanding of the content or critical analysis of the content.
It is best to paraphrase content and cite your source.

LopesWrite Policy

For assignments that need to be submitted to LopesWrite, please be sure you have received your report and Similarity Index (SI) percentage BEFORE you do a “final submit” to me.
Once you have received your report, please review it. This report will show you grammatical, punctuation, and spelling errors that can easily be fixed. Take the extra few minutes to review instead of getting counted off for these mistakes.
Review your similarities. Did you forget to cite something? Did you not paraphrase well enough? Is your paper made up of someone else’s thoughts more than your own?
Visit the Writing Center in the Student Success Center, under the Resources tab in LoudCloud for tips on improving your paper and SI score.

Late Policy

The university’s policy on late assignments is 10% penalty PER DAY LATE. This also applies to late DQ replies.
Please communicate with me if you anticipate having to submit an assignment late. I am happy to be flexible, with advance notice. We may be able to work out an extension based on extenuating circumstances.
If you do not communicate with me before submitting an assignment late, the GCU late policy will be in effect.
I do not accept assignments that are two or more weeks late unless we have worked out an extension.
As per policy, no assignments are accepted after the last day of class. Any assignment submitted after midnight on the last day of class will not be accepted for grading.

Communication

Communication is so very important. There are multiple ways to communicate with me:
Questions to Instructor Forum: This is a great place to ask course content or assignment questions. If you have a question, there is a good chance one of your peers does as well. This is a public forum for the class.
Individual Forum: This is a private forum to ask me questions or send me messages. This will be checked at least once every 24 hours.