1fast–track
adjective \ˈfas(t)-ˌtrak\
Definition of FAST-TRACK
1 : of, relating to, or moving along a fast
track <fast–trackexecutives>
2 : of, relating to, or being a construction
procedure in which work on a building begins before designs are completed.
In the brain development PBS linked article (http://www.pbs.org/wnet/brain/episode1/index.html),
they mention that neural tube development occurs at about the rate of 250,000
neurons/minute. That translates to 360,000,000/day. Recalling last weeks
material, that neural tube is completed in 11 days. Hmmm, that's 15,000,000/hr;
or 360,000,000/day; which translates to a staggering 11 day total of
3,960,000,000 cells or 3.96x108. That's fast tracking.
Certainly reinforces prenatal nutritional requirements and the complications
that may result if deficient.
The article this week on "Babies, Bonds and Brains" has
parallel considerations. First, the above numbers reflect 11 days of neural
development; from there, brain development continues and the final numbers must
be staggering. This week's article suggests the number of connections
(synapses) between these nerve cells increases by about 20x during an infant’s
first several months are 2x that in a 2 year old. That's a lot of neurons and
their supporting glial mates, without whom neurons just barely function. As
mentioned, as we develop, the neural landscapers (glial cells) are always at
hand "pruning" away the circuits and synapses that are in disuse and
create new neural pathways in response to new or increased stimuli.
Sort of like the living bridges of the Meghalaya (http://youtu.be/5jrmm7gjZGE)
- except one can appreciate how fast the human brain can build its
"new bridges". Experiences (stress, lovelessness, affection, love,
nurturing,) are the dynamic forces changing both the neuronal circuitry and the
"living bridges". The far reaching effects of lack of nurture and
attachment I find are amazing. From depressed immune systems to what seems like
PTSD in the extreme abuse/neglect situations, leave me shaking my head in
wondering how it all works. It seems we’re clearly built to love and be loved,
with all the breadth and depth that word encompasses.
In another lifetime, I was a DEA agent. During one
undercover investigation, I walked up to the street entrance apt and met my
connection, a young couple. They were sitting on the front steps, just
finishing shooting up with heroin (it was a very hot Chicago summer evening). I went inside and found their 9 month old
lying in a bassinette; feces were coming out both leg openings of the diaper in
such large quantities, I guessed the baby hadn't been changed for two day. A
bottle of formula was propped up on the edge at the baby’s mouth. The scale of
neglect was so huge and so extensive; it was difficult for me to maintain focus
on what I was there for. It has been the only time in my life I became so
enraged, I wanted to shoot someone. I've never forgotten that little tyke and
wondered if it ever had any chance at all at a life. The case was handed over
to someone else and I have no recollection of the outcomes. Perhaps child
protective services were finally notified, as I detailed the conditions of the
baby in my report.
To close this section, I’d like any reader to reflect on a
couple of aspects of the neuroanatomist Santiago
Ramón y Cajal, 1852 – 1934. (http://bit.ly/11fsULe).
Using just simple microscopes he painstakingly hand – mapped neurons and their
circuits of the brain. Below, I've provided two examples of his work; one of a single neuron and one showing the
synaptic and branching of active neural circuits. Note the complex routing, connections and
networks. Imagine the glial cells nudging more connections in really active
neurons, even calling for new neurons to keep up with the traffic. In a small
way, perhaps it will foster an appreciation for the complexity and wonder of
our brains. Not to mention, how a guy with a microscope and a pen, started figuring
out for us how these things work.
A single neuron
Neuronal Networks
Here's the Promised Tidbits
Well, they're sorta big ones! More satisfying :-}
Here's the Promised Tidbits
Well, they're sorta big ones! More satisfying :-}
After reading the materials concerning gender, it seemed that at times, the concepts of gender identity and the conformation of gender roles were somewhat/sometimes conflated. I want to make it crystal clear that gender identity is the gender that one perceives her/his self and is not something that is shaped through the early developmental years. Gender identity is established in utero and complete at birth. But it is also clear that once gender identity is established, the expression of that identity is shaped by culture, parenting, etc. I'm reminded of the transwoman in Saudia Arabia who walked through a shopping mall in a full burka. She was arrested because her gait was not consistent with a cis-gendered female. She was not well treated.
A group of Dutch researchers studied the brains of transgendered
male → females and found a certain critical area of the brain (BSTc) that controls gender identity was the same as in cis-gendered females. This
part of the brain is formed in response to prenatal hormone secretion as
up/downregulated by gene expression. There are two particular times in prenatal
development that these hormones play a crucial role in gender identity. One is
occurs about at the 4 – 6 week period and the last closer to the end of the
third trimester (sorry cites not available). The result is that gender identity
is formed in utero and is nothing the individual “decides”. I found it
interesting that the one female → male transgender (does there have to be a
label?) had the BSTc of a normal male.
Here’s the research results:
Volume 1, Number 1, July - September 1997
A Sex Difference in the Human Brain and its Relation
to Transsexuality
Citation:
Zhou J.-N, Hofman M.A, Gooren L.J, Swaab D.F (1997) A Sex Difference in the
Human Brain and its Relation to Transsexuality. IJT 1,1, http://www.symposion.com/ijt/ijtc0106.htm
Transsexuals
have the strong feeling, often from childhood onwards, of having been born
the wrong sex. The possible psychogenic or biological etiology of
transsexuality has been the subject of debate for many years [1,2]. Here we
show that the volume of the central subdivision of the bed nucleus of the
stria terminalis (BSTc), a brain area that is essential for sexual behavior
[3,4], is larger in men than in women. A female-sized BSTc was found in
male-to-female transsexuals. The size of the BSTc was not influenced by sex
hormones in adulthood and was independent of sexual orientation. Our study is
the first to show a female brain structure in genetically male transsexuals
and supports the hypothesis that gender identity develops as a result of an
interaction between the developing brain and sex hormones [5,6].
Investigation
of genetics, gonads, genitalia or hormone level of transsexuals has not, so
far, produced any results that explain their status [1,2]. In experimental
animals, however, the same gonadal hormones that prenatally determine the
morphology of the genitalia also influence the morphology and function of the
brain in experimental animals in a sexually dimorphic fashion [6,7]. This led
to the hypothesis that sexual differentiation of the brain in transsexuals
might not have followed the line of sexual differentiation of the body as a
whole. In the past few years, several anatomical differences in relation to
sex and sexual orientation have been observed in the human hypothalamus (see
[6] for a review), but so far no neuroanatomical investigations have been
made in relation to the expression of cross-gender identity (transsexuality).
|
We
have studied the hypothalamus of six male-to-female transsexuals (T1-T6);
this material that was collected over the last eleven years. We searched for
a brain structure that was sexually dimorphic, but not influenced by sexual
orientation, as male-to-female transsexuals may be "oriented" to
either sex with respect to sexual behavior. Our earlier observations showed
that the paraventricular nucleus (
The
localization of the BST is shown in figure 1. The central part of the BST
(BSTc) is characterized by its somatostatin cells and vasoactive intestinal
polypeptide (
The
BSTc volume in heterosexual men (2.49±0.16 mm3) was 44% larger
than in heterosexual women (1.73±0.13 mm3) (P<0.005) (Fig. 3).
The volume of the BSTc of heterosexual and homosexual men was found not to
differ in any statistically significant way (2.81±0.20 mm3)
(P=0.26). The BSTc was 62% larger in homosexual men than in heterosexual
women (P<0.005). AIDS did not seem to influence the size of the BSTc: the
BSTc size of two heterosexual AIDS-infected women and three heterosexual
AIDS-infected men remained well within the range of the corresponding
reference group (Fig. 3). The AIDS-infected heterosexuals were therefore
included in the corresponding reference group for statistical purposes. A
small volume of the BSTc (1.30±0.23 mm3) was found in the
male-to-female transsexuals (Fig. 3). Its size was only 52% of that found in
the reference males (P<0.005) and 46% of the BSTc of homosexual males
(P<0.005). Although the mean BSTc volume in the transsexuals was even
smaller than that in the female group, the difference did not reach
statistical significance (P=0.13). The volume of the BSTc was not related to
age in any of the reference groups studied (P>0.15), indicating that the
observed small size of the BSTc in transsexuals was not due to the fact that
they were, on average, 10 to 13 years older than the hetero- and homosexual
men.
The
BST plays an essential role in masculine sexual behavior and in the
regulation of gonadotrophin release, as shown by studies in the rat [3,4,21].
There has been no direct evidence that the BST has such a role in human
sexual behavior but our demonstration of a sexually dimorphic pattern in the
size of the human BSTc, which is in agreement with the previously described
sex difference in a more caudal part of the BST (BNST-dspm) [19], indicates
that this nucleus may also be involved in human sexual or reproductive
functions. It has been proposed that neurochemical sex differences in the rat
BST may be due to effects of sex hormones on the brain during development and
in adulthood [22,23]. Our data from humans however, indicate that BSTc volume
is not affected by varying sex hormone levels in adulthood. The BSTc volume
of a 46-year-old woman who had suffered for at least 1 year from a tumour of
the adrenal cortex that produced very high blood levels of androstenedione
and testosterone, was within the range of that of other women (Fig. 3: S1).
Furthermore, two postmenopausal women (aged over 70 years) showed a completely
normal female-sized BSTc (Fig. 3: M1, M2). As all the transsexuals had been
treated with estrogens, the reduced size of the BSTc could possibly have been
due to the presence of high levels of estrogen in the blood. Evidence against
this comes from the fact that transsexual T2 and T3 both showed a small,
female-like BSTc (Fig. 3), although T2 stopped taking estrogen about 15
months before death, since her prolactin levels were too high and T3 stopped
hormone treatment since a sarcoma was found about three months before death;
also a 31-year-old man who suffered from a feminizing adrenal tumour which
induced high blood levels of estrogen, nevertheless had a very large BSTc
(Fig. 3: S2).
Our
results might also be explained if the female-sized BSTc in the transsexual
group was due to the lack of androgens, because they had all been
orchidectomized except for T4. We therefore studied two other men who had
been orchidectomized because of cancer of the prostate (one and three months
before death: S4 and S3, respectively), and found that their BSTc sizes were
at the high end of the normal male range. The BSTc size of the single
transsexual who had not been orchidectomized (T4) ranged in the middle of the
transsexual scores (Fig. 3). Not only were five of the transsexuals
orchidectomized, they all used the antiandrogen cyproterone acetate (CPA). A
CPA effect on the BSTc does not seem likely, because T6 had not taken CPA for
the past 10 years, and T3 took no CPA during the two years before death and
still had a female-sized BSTc.
In
summary, our observations suggest that the small size of the BSTc in
male-to-female transsexuals cannot be explained by differences in adult sex
hormone levels, but is established during development by an organizing action
of sex hormones, an idea supported by the fact that neonatal gonadectomy of
male rats and androgenization of the female rats indeed induced significant
changes in the number of neurons of the BST and suppressed its sexual
dimorphism [17,18].
Considered
together with information from animals, then our study supports the
hypothesis that gender identity alterations may develop as a result of an
altered interaction between the development of the brain and sex hormones
[5,6]. The direct action of genetic factors should also be considered on the
basis of animal experiments [24].
We
found no relationship between BSTc size and the sexual orientation of
transsexuals, that is, whether they were male-oriented (T1,T6),
female-oriented (T3,T2,T5), or both (T4). Furthermore, the size of the BSTc
of heterosexual men and homosexual men did not differ, which reinforced the
idea that the reduced BSTc size is independent of sexual orientation. In
addition, there was no difference in BSTc size between early-onset (T2,T5,T6)
and late-onset transsexuals (T1, T3), indicating that the decreased size is
related to the gender identity alteration per se rather than to the age at
which it becomes apparent. Interestingly, the very small BSTc in transsexuals
appears to be a very local brain difference. We failed to observe similar
changes in three other hypothalamic nuclei, namely,
We
thank Mr. B. Fisser, Mr. H. Stoffels, Mr. G. van der Meulen, and Ms. T.
Eikelboom and Ms. W.T.P. Verweij for their help, and Drs. R.M. Buijs, M.A.
Corner, E. Fliers, A. Walter and F.W. van Leeuwen for their comments. Brain
material was provided by the Netherlands Brain Bank (coordinator Dr. R.
Ravid). This study was supported by NWO.
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Correspondence
and requests for materials to:
J.-N. Zhou, M.A. Hofman and D.F. Swaab Graduate School Neurosciences Amsterdam Netherlands Institute for Brain Research Meibergdreef 33 1105 AZ Amsterdam ZO The Netherlands
L.J.G.
Gooren
Department of Endocrinology Free University Hospital 1007 MB Amsterdam The Netherlands Email: lgooren@inter.nl.net |
What research
is revealing regarding Transgenders
Transsexuals
have, often from childhood onward, the strong feeling of having been born the
wrong sex. Their desire to resemble the opposite sex is so strong that they are
even willing to undergo major surgery and hormone treatments to achieve this
end. This gender-identity problem has been proposed to develop as a result
of a disturbed interaction between the developing brain and sex hormones.
The search for structures that may be directly related to gender identity,
i.e., structures whose anatomy is “female” in genetically male transsexuals,
has so far led to our studies of the central nucleus of the bed nucleus of the
stria terminalis (BSTc). A female-sized nucleus was found in
male-to-female transsexuals. The size of the BSTc was not influenced
by sex hormones in adulthood and was independent of sexual orientation.
Similar results were obtained when the total number of somatostatin neurons was
determined in the BSTc. In the BSTc
of one female-to-male transsexual a male volume and somatostatin neuron number
was found; (Zhou et al., 1995b;
Kruijver et al., 2000).
Although the BSTc may be one of many structures involved in the phenomenon of
gender identity, these results do
support the hypothesis that gender identity develops as a result of an
interaction between the developing brain and sex hormones.
(Structural and Functional Sex Differences In
the Human Hypothalamus
Dick F. Swaab,*, 1 Wilson C. J. Chung,*, †
Frank P. M. Kruijver,* Michel A. Hofman,* and Tatjana A. Ishunina*, ‡ *Graduate
School Neurosciences Amsterdam, Netherlands Institute for Brain Research, Meibergdreef
33, 1105 AZ Amsterdam, The Netherlands; †Department of Psychology, University
of Massachusetts, Amherst, Massachusetts; and ‡Department of Histology And
Embryology, Kursk State Medical University, Kursk, Russia Received August
9, 2000; accepted March 1, 2001)
Footnote: I just watched:
The Fast and the Furriest
Season 5 Episode 20 (42:45)
Aired on 04/15/2013 TV-14 CC
Take the beginning and the end and wayla: Erikson's first stage trust vs mistrust taken into the adult world. Nice snapshot. :-}
I love how much information you put into your blogs! You really go above and beyond to really explain the information you have found interesting. The great part is that it really makes me just as interested, you put so much excitment and enthusiasm into your blogs; it makes others excited to recieve this information. At least it does for me so thank you! :)
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