Not quite another Piece of the Puzzle - Yet

But there soon will be one. And an existing piece has received a bit of a polish.

Two comments by Prof Italiano over at Theosophical Ruminations:

Dear Zoe, You mentioned the study by Cohen-Kettenis on 5 Alpha Reductase 2 deficiency and 17 Beta HSD 3 deficiency. I might add that this study was in the infamous ASB journal and Cohen-Kettenis seems to be adversely influenced by some of those people. For instance, she noted that some individuals develop a male gender identity and some develop a female gender identity in each of the two conditions and that this is independent of the severity of the mutation. She cites the noted endocrinologist Jean D. Wilson and his research on this. She then goes on to attribute the difference in the gender outcomes which are independent of the severity of the mutation to social factors, while completely OMITTING that Dr. Wilson suggested that the difference in gender identity outcomes which are independent of the severity of the mutation, are the result of variations in the compensation of alternative enzymatic pathways.

Peggy Cohen-Ketternis's work is quoted at BiGender and the Brain - and the rest of that article strongly points to a biological cause for the difference in gender outcomes. I wasn't aware of Dr Wilson's commentary, but the rest of the evidence, and Prof Ecker's later work, pointed very much in that direction.

The next comment is interesting, because it promises yet more evidence. Probably just confirming what we think we know, but if we're lucky, will point us in new directions instead.

You see, that's what I'm trying to do. Not push any particular line. I go where the evidence takes me, and where it's taking me is for a strict biological causation. Science though advances very slowly by accretion of evidence confirming what we think we know: the really exciting stuff is when we get to say "hmmm... that's odd", when evidence doesn't fit our neat theories. Now I don't think we will, but who knows, we might be lucky. I'd be astonished at this point if we were though, things look pretty clear and consistent.

Dear Zoe and Jason, You should note that there are more studies. I just gave a few examples. For instance, Talaya McCright-Gill has just published her undergraduate thesis where she investigated transsexuals and have found that the transsexuals respond in accord with their gender identity and brain sex and not according to their genital anatomy on a verbal memory task in the amygdala which is the seat of human emotional memory. Numerous studies by Larry Cahill (UC Irvine) have demonstrated that men and women differ in the response of the amygdala as demonstrated by functional Magnetic Resonance Imaging.
The transsexuals brains typed according to the sex they think they are and none of them were treated with hormones. It should be noted that the BSTc connects the hypothalamus to the amygdala.
Another study which will be out is another one by Eillen Luders group (with Arthur Toga). They have found in untreated transsexuals cortical thickness which corresponds to the brain sex and gender identity with which the transsexuals believe that they are and in discordance with the genital anatomy. Their group (number is 24) have not been treated with hormones either.

Here's Talaya McRight-Gill's description of her thesis:

Thesis title: "Brain Processing of Emotional Information in Transgender Individuals"
Mentors: Julie Dumas, Psychiatry, and Larry Rudiger, Psychology
Major: Psychology and Sociology
Background: My home is Brooklyn, NY. I am currently applying for Teach for America, and hope to teach after graduation. I love basketball and my favorite player is Shaquille O'Neal.

When I began the thesis process in January of this year (2008) I had no idea what I wanted to do it on, but I lucked out and my topic sort of just fell into my lap. I have been working for the Clinical Neuroscience Research Unit since my freshman year and during my time there they have conducted various clinical trials exploring memory functioning with the use of functional Magnetic Resonance Imaging (fMRI). So, when it was time to begin my senior thesis it was only natural that it involves memory and the use of fMRI. While discussing my thesis ideas with my boss and mentor we decided to incorporate transgender individuals into my thesis. After some research and much thought we finally came up with a topic.

For my senior thesis I am conducting a brain imaging study to examine the emotional memory and related brain activation in transgender individuals in order to learn more about the relationship between gender, hormones and the sexually dimorphic pattern of brain activation observed for remembering emotional information. We are looking to see if transgender individuals have brain lateralization in congruence with their gender identity rather than their biological sex.

Since my thesis involves the use of human participants I have had to apply for IRB approval which is something that many students writing a thesis will not have to do. The IRB process was very intense for me. I had to fill out an extensive application that required me to clearly define the reasons for the study, how we were going to implement the study, the criteria we would use to include and exclude participants, as well as background information that supported my hypothesis. I also had to explain the precautions we had taken to ensure participant safety. Finally I had to write a consent form clearly explaining the study and the possible benefits and risks for participants. After I completed the application, the IRB board had to discuss my work and then they sent me questions which required that I resubmit my proposal with the revisions and answers to their questions before I could receive approval from the IRB. It took me a total of about two months to complete the application, wait for it to be viewed and submit the revisions which also had to be reviewed, before I was able to get IRB approval and start recruiting.

I am currently still recruiting for my thesis and I have scanned 4 participants in the MRI machine to date. As for the writing part of the thesis I have completed two sections thus far, the abstract and methods sections. I would suggest that you break your thesis down into sections and write them separately bit by bit as you go along throughout the year. By doing this it should make the task of writing such a long paper less daunting. At least it has for me.

Science is a very human occupation, you see. No matter what she finds, I wish her well - and she has my personal thanks. My thanks to Professor Italiano as well. I'm just an amateur, a systematiser, someone who takes others' work and shows how different pieces of knowledge from different disciplines lead to a coherent picture. I put the pieces of the puzzle together, but I rely on others to do the real work of discovering them, teasing out Nature's secrets from the raw stuff of the Universe.