Richard G. Petty, MD

Neurogenesis 101

Posted by on March 23, 2006 · Leave a Comment 

The great Spanish histologist and Nobel Prize winner in Physiology or Medicine, Santiago Ramón y Cajal, was probably the first modern scientist to say that neurons in the adult brain did not divide.  In other words, humans are born with a finite number of brain cells and an individual cannot develop/grow/replicate new cells over the course of their adult lives. This is an axiom that underlies some parts of the stem-cell debate.

There is emerging research that seems to refute this notion.  I have written a long article for my friends over at Psychiatric Resource Forum discussing the research indicating that humans may have the ability to produce new neurons in key regions of the brain throughout life, a process called neurogenesis.  I also discuss what this means for field of psychiatry.

The concept of neurogenesis also engenders hope for the fields of personal and spiritual development.  I will discuss these at a later date.  I just wanted to link to this article because it provides (along with the links) a good primer on neurogenesis that will be helpful as I write new posts.

Technorati tags: , ,

Filed under Brain, Creativity, Mental Illnesses, Neurogenesis, Personal Growth, Psychiatry, Science · Tagged with

Love, Sex and Cupid’s Chemicals?

Posted by on February 14, 2006 · Leave a Comment 

Well, once again some of my colleagues would like to reduce everything about love to a series of chemical reactions in the brain. The BBC recently reported a study from Pavia in Italy that actually came out at the end of last year in the Journal Psychoneuroendocrinology. The Italian researchers measured the levels of a group of hormones known as neurotrophins that stimulate the brain to produce new connections or, under certain circumstances, new cells. This research contributes to a chemical scheme that says that there are three stages of love, and that they run something like this:

1. Lust: This is supposed to be driven by the sex hormones testosterone and estrogen and happens together with rises in the nerve growth factor (NGF). So the idea is that we learn to enjoy lust. I don’t think that we needed millions of dollars of research to tell us that!

2. Attraction: This is the phase when we are supposed to be thinking of nothing else but the new significant other, and even reduce our need for food and sleep. The NGF is still lurking around here, but now there are supposed to be other chemicals coming into the picture: Serotonin, that makes us feel good; Dopamine, that is involved with emotion and the important facility of salience: deciding what is important in the environment; and norepinephrine, that cranks up our metabolism and also gets involved in the formation of memories and behavioral responses.

3. Attachment: This is supposed to be what happens after the initial stage of attraction, if a relationship is going to last. This is said to be mediated by the hormones vasopressin, which is involved in memory and fluid balance, and oxytocin, that is produced during childbirth and during breast feeding, and is thought to be involved in cementing a bond between mother and child. Oxytocin is also released during sexual orgasm, so it has been thought that oxytocin is the reason why having a lot of sex brings a couple closer.

Well, that all sounds good. But can it really explain the vast panoply of behaviors and emotions that are going on today all over the world?
The answer is, of course, a resounding “NO.”
I admire and respect this type of research work. It is difficult and takes enormous patience and persistence. But we know that this research is in its infancy.
To try and “explain” human love and human sexual experience on the basis of half a dozen chemicals is about the same of looking at a street map of New York and pretending that you can then understand the experience of living in Brooklyn. Yet some people have looked at some of this research and said that we should expect to fall out of lust after a year or two and instead be content with coexistence and cuddles. Whichever way you look at that interpretation, it is dead wrong. The more so, because I have seen people suggest that these chemical discoveries present a ready made license for seeking new partners who will stimulate their testosterone, NGF or whatever.
The Italian studies had the virtue of being done in human beings, but a lot of the studies have been done in animals. There is one species that has been studied hundreds of times: The Prairie Vole. This tiny creature has many attributes important to the research scientist. But very few that are applicable to human beings.
Let me give a concise Valentine’s Day summary about love, sex and chemicals:

1. Yes, there is a chemical contribution to many of our experiences, but it is a contributor, and not the explanation for them

2. We have huge amounts of data to prove that our emotional and psychological reactions cannot be reduced to chemicals alone. There is a human mystery that is way beyond such reductionist notions

3. These chemical studies will eventually need to include not just our subjective experiences, but also the role of other individuals: our relationships

4. None of the studies is yet ready to deal with the subtle systems that pervade our world. Let me ask you a question: Have you ever had an intimate partner who drained your energy and another who flooded it with positive energy? That’s pretty good evidence!

5. Have you ever felt that you had a soul connection to your partner? If you have, you know that it cannot be reduced to chemicals. It affects every part of your being.

Happy Valentine’s Day!

Addendum:  CNN has just published a similar article:  please click here to read it.

Technorati tags: , , 

Filed under Brain, Neurogenesis, Relationships · Tagged with

« Previous Page

logo logo logo logo logo logo