Hormones & Psychology: Oxytocin (Part 1)

I find it crucial to discuss the endocrine system (hormonal system) and its role in behavior. I am quite disappointed that it is not a mandatory subject covered when doing a major in Psychology. It is well known that the nervous system works with the endocrine system to elicit different behaviors. Where some are found to be typical of either gender (influenced greatly by the hormone levels), other behaviors are triggered by experience and the processes of cognition in the brain. The endocrine system is also concerned with the never-ending nature-nurture debate as some hormone secretions depend on your genetic make-up (i.e. predisposition) and others depend on more direct environmental factors and past learning. [We know both genetic factors and environmental are responsible for behavior, therefore we should now focus on to what extent.] In that matter, as the nervous system elicits fast responses depending on the external stimuli, the endocrine system concerns itself with more bureaucratic (i.e. slow cascades of responses) with a few exceptions of course.

What is important to know about the connection between the nervous system and the endocrine system is that they communicate through the hypothalamus (a structure deeper in the brain that is not called a gland but that does secrete many hormones as well).When the hypothalamus secretes a hormone to release in the body or to trigger a cascade of other hormones in the body, this hormone has to pass by the gate called the pituitary gland in order to end up in the blood stream. Substances in the brain are highly controlled and separated from other substances in the rest of the body by the brain-blood barrier (a preventive measure in order to protect the brain from harmful substances). However, you might have guessed that drugs do end up fooling this barrier in order to elicit their effects on the brain. By now, I probably suffocated you with biology… In any case, I would like to discuss, now all that being said, about the hormone oxytocin and its role in behavior.

I haven’t yet done or found a good literature review on the subject of oxytocin. However, I would use a great book published recently on that matter (see its source below). Basically, oxytocin is made by the hypothalamus and secreted by the pituitary gland in the blood stream. Also, when I first learned about oxytocin, I was very intrigued that this hormone is one of the few exceptions that generate a positive feedback on its control center: the hypothalamus. In other words, upon secretion of oxytocin, high levels of this hormone will trigger even more release of that hormone. This being in contrast with most hormones that have a negative feedback on the brain, meaning that a high level of those hormones will trigger the brain to release less precursors (being hormones that will transform in another hormone) or other releasing hormones (hormones that trigger the release of another hormone). One of the major roles of oxytocin is of course during labor when you can understand the importance of a positive feedback as the contractions are getting stronger and more frequent. The second major role is the one of triggering the release of milk once the baby is born (mammary growth, milk production and release being controlled by the other hormones such as progesterone and prolactin). Here is a nice picture of the process of milk release by the mammary glands which is also called the oxytocin reflex or milk ejection reflex.

These bodily reactions are, as you noticed, automatic behaviors that any mother will go through and have no control over. However, some new research found that oxytocin has an important role in more complex behaviors. I would resume on this in a later post…
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BOOK SOURCE:

Neave, N. (2008). Hormones and Behaviour: A Psychological Approach. Cambridge, New York: Cambridge University Press.

I recommend you read Chapter 1 of this book since it is one of the best written summaries about the nervous system that I have read. It is concise, straightforward and covers the basic you need to know to get around in articles about the brain. Believe me I am quite annoyed with revisions and introductions on that matter and it is the first time I’ve read this part without being bored to death or pulling my hairs out.

It is time!

I modified a program in Java (I took from a website) that is designed to test your reflexes when reacting to a visual stimulus. Depending on the speed it takes you to click on the colored square, a message will appear with your reaction time and some information and statistics on factors that can change your ability to respond like the average individual. Feel free to try it many times at different speeds to learn more about drugs, the average reaction times and how mental disorders are correlated with different responses. Do not take your results too seriously as your internet speed, mental state and the color of your hair[1] can all affect the outcome.

I could not put the script directly on the blog, so here is a link:

Test Your Reflexes!

[1] This is another one of my attempts at humor :)
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Literature Review of Reaction Times
http://biology.clemson.edu/bpc/bp/Lab/110/reaction.htm

Other articles:
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VC9-4GCX1RV-3&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=1149f1f591bff0a0c56a182392f03b8e

Books:

Drug Abuse Handbook

By Steven B. Karch

Edition: 2, illustrated

Published by CRC Press, 2007

ISBN 0849316901, 9780849316906

1267 pages

http://books.google.ca/books?id=F0mUte90ATUC&pg=PA219&lpg=PA219&dq=simple+reaction+time+visual+stimulus+drug&source=bl&ots=f4Mtv4zxGz&sig=LrKQ-hB0kDaoDFDfXPp68W97V7s&hl=en&sa=X&oi=book_result&resnum=9&ct=result#PPA229,M1

Brainbows in Microscopic Pictures

“Brainbow” transgenic mouse hippocampus (40x)
by Dr. Tamily Weissman

Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, United States

“Brainbow” mouse brain stem with auditory pathway axons (40x)
by Dr. Jean Livet

Institut de la Vision, INSERM U592 and UPMC, Paris, France

Most microscopic pictures of cells, insects and small organisms can be scientifically interesting, even from time to time reasonably appealing. However, when I came across these microscopic pictures of neurons, I wondered if someone dropped gallons of paint on some poor mice’s brains…or if some artist “photoshoped” these pictures. I soon realized that these pictures meant much more than eye candy to my visual pathways. Curiosity derived me here:

Approximately a year ago, a very glowing new discovery was made by Osamu Shimomura (Marine Biological Laboratory (MBL) Woods Hole, MA, USA), Martin Chalfie (Columbia University, New York, NY, USA) and Roger Y. Tsien (University of California, San Diego, CA, USA; Howard Hughes Medical Institute) who share this year’s Chemistry Nobel Prize: the discovery and use of the Green Fluorescent Protein (GFP).

The GFP was first found in the jellyfish Aequorea, which is responsible for the green fluorescent color this animal has.

(from http://www.plantsci.cam.ac.uk/Haseloff/imaging/GFP/GFPbackgrnd.html)

Thus, if we join the gene of this protein with any gene of the protein of interest, then the GFP can be used as a tracer for this protein since it is fluorescent. Furthermore, a new technique developed at Harvard University last year by the team of Jeff W. Lichtman and Joshua R. Sanes now permits neuroscientists to add many different variants of this GFP’s gene in the desired neurons’ genetic configuration and basically observe the turning on and off of the proteins as they color these cells at random in different hues. The older technique allowed for the mapping of only a few neurons at the time which limited research in the area. Thus, besides making the most amazing pictures of neurons, this new technique of making brainbows is a major breakthrough in neuroscience research.

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For more amazing microscopic pictures, take the time to look at: http://www.nikonsmallworld.com/gallery.php

For more information on the Chemistry Nobel Prizes, please visit: http://nobelprize.org/nobel_prizes/chemistry/laureates/2008/index.html

For more on this new technique, take a look at: http://www.conncoll.edu/ccacad/zimmer/GFP-ww/GFP-1.htm