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How does the brain work? Using real and fictional characters to setup a story framework, I write about the science of the human (and sometimes animal) mind. I am a journalist rather than a neuroscientist so my approach is exploratory.

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Father’s Instinct

topic Nurturing
region pituitary gland, hypothalamus
chemicals oxytocin, prolactin, testosterone, vasopressin

 

 

tiny bundles
white yellow orange red
chicks being fed

The newborn pigeon chicks are being fed by their grey and black father. A few weeks ago, they were two tiny white eggs.

“They hatched!” I send a text message to my boyfriend. We take delight in this incubation-hatching-fledgling drama taking place just outside our apartment. Despite advice on the internet tpigeonhat pigeon birth cycle can turn into a nuisance, our curiosity wins and we allow the budding pigeon family to stay in the twigs nest they have built near our fire-escape stairs.

After the hatching, the father sits on the chicks to protect them as they grow. Sometime I see him feeding them but mostly he is a stoic silent dad, acting under the influence of his instincts. At night, the mother takes over the job of nurturing. Both parents’ brains are releasing the prolactin hormone which is secreted by the pituitary gland via instructions from the hypothalamus. In the case of birds, this chemical is released when the bird sits on an egg. Prolactin causes the secretion of milk in both pigeon parents thus the father is able to feed the chicks during the daytime and the mother at night. There is a decrease in the father’s testosterone level at this time also which is why he is able to shift from copulation to nurturing.

 

In humans, women start to secrete prolactin as the child is about to be born and continue to secrete it during the breast-feeding phase. Males, however, do not release prolactin nor do they show a reduction in testosterone production when the female is involved in child care. That is, unlike bird fathers, the human male does not decrease his sex-drive while his wife is rearing a new child.

pituitary & hypothalmusIn addition to prolactin, a woman’s hypothalamus also causes the release of oxytocin (via the pituitary gland) for the production of milk. Oxytocin is a catalyst in inducing labor so a female mammal can give birth. It is possible that birds also secrete oxytocin but more research has been done on rats and humans than on birds. Rats are often used in experiments because they are mammals, have a body and brain that is very similar to humans, and are much cheaper and easier to use for experiments than humans.

Beyond milk creation and inducing labor, the oxytocin neurotransmitter has the powerful affect of elucidating emotional bonding which results in the maternal drives required for child care. I suppose if we ever had a child, my boyfriend would probably help raise the newborn but he would not be producing oxytocin at the level that I am producing and would not feel the same level of chemical imperatives for nurturing.

Even though the human male’s brain keeps itself isolated from the nurturing drama by not releasing prolactin or extra oxytocin, there are other “potential” chemical activities that occur. In male voles, a rodent similar to a mouse, a hormone called vasopressin induces paternal care by the males. This study, however, has not been correlated to humans.

I watch the progress of the birds on my fire-escape and connect with the “maternal” instincts of the father pigeon. I do not see the mother much because it is too dark when she shows up. Since I am not pregnant, nor do I have a newborn, I do not have prolactin circulating in my system nor do I have an unusually high level of oxytocin. Oxytocin, however, is being released in my body consistently because I am in a committed romantic relationship (this chemical is not just for mothers, it is also released in humans when any bonding activities occur). I do not know for sure if the oxytocin in my body makes me feel more sympathetic to the pigeon parents but I suspect that it does. Either way, I am enjoying this pigeon child-care ritual.


Leena Prasad has a writing portfolio at http://www.FishRidingABike.com. Links to earlier stories in her monthly column can be found at http://www.WhoseBrainIsIt.com.

Dr. Nicola Wolfe is a neuroscience consultant for this column. She earned her Ph.D. in Clinical Psychopharmacology from Harvard University and has taught neuroscience courses for over 20 years at various universities.

References:

1. Bridges, Robert. Neurobiology of the Parental Brain. Academic Press 2008.

2. Numan, Michael; Insel, Thomas R. The Neurobiology of Parental Behavior. Spring 2011.

3. http://www.pleasebekind.com/pigeon.html

Harold’s Elephants

 

topic joy
organ limbic system
chemicals dopamine, endorphin, oxytocin, serotonin, cortisol

The envelope has been lying on his desk for two days. Harold is unable to open it. There is too much at stake. The words inside that envelope will change his life.

It’s too thin, Harold thinks. It must be a rejection letter. That would mean that he’d have to go back to his life as a chef. He likes cooking but after ten years, he has become bored of doing it for a living. He took a five year break to try making a living as a sculptor. These five have been the best years of his life. He doesn’t want to stop but he has used up all his savings. Harold is engaged to be married and wants to start a family soon. He is 41 years old and wants to have a stable career soon, one way or another. This is his last chance to be financially stable while living his passion.

Harold opens the envelope.

Congratulation, it says. Harold stares. He reads and read again. “Congratulations. We would like to hire you to design and sculpt the elephant sculpture for the newest branch of our restaurant. You will also be designing unique sculptures for each one of our 21 restaurants worldwide.” There are instructions on going to a website to complete the paperwork.

Harold is too shocked to react. He hears the front door open. His fiancée walks in. She is sweating from her daily jog and is heading for the bathroom when he leaps up to go talk to her. He gushes out the news. He says it so fast that she has to ask him to repeat himself.

There are chemical activities in Harold’s brain causing his happiness. These chemicals are called neurotransmitters because they transmit signals amongst the brain’s neurons. The primary neurotransmitters spurting in Harold’s brain is dopamine and serotonin. The brain spurts dopamine when it gets what it wants. It secretes serotonin when it feels a sense of pride.

His fiancée is also happy. In addition to dopamine, her brain is spurting endorphin from the runner’s high that she has just had. It is possible that she might also be releasing serotonin via association with someone who has just established a job which will ensure survival related safety and security for her.

As mentioned in the book Meet Your Happy Chemicals: Dopamine, Endorphin, Oxytocin, Serotonin, Dr. Loretta Breuning talks about a fourth chemical, oxytocin. This is the neurotransmitter that Harold and his fiancée’s brains secrete on a consistent basis. Oxytocin is released as a part of developing a trust based relationship with another human being. Sexual intimacy and other bonding activities, like touching, also cause a spike in oxytocin levels. Harold and his fiancée have a healthy level of oxytocin in their system because they live together within the framework of a trusting relationship.

Harold and his fiancée are both experiencing a burst of many happy chemicals and thus a burst of joy. But the happy chemicals exploding in their brains are not all the same, so their happiness level is not exactly the same.

Earlier in the day, while Harold was teetering on the verge of opening the envelope, his brain was probably spiking with cortisol, a chemical produced by the brain when it feels stressed. His cortisol level is down but not completely gone and he has no reason to have endorphin in his system. His fiancée has endorphin in her system but no reason to have cortisol. They both have dopamine, serotonin, and oxytocin circulating around. The levels of the chemical might be higher in Harold’s system because he is directly affected by the news. Without sophisticated machines, it is not easy to say who is happier, but it’s easier to guess the comparative levels of chemicals in each person’s neural circuits.

“Your brain is always seeking ways to get more serotonin without losing oxytocin or increasing cortisol,” says Dr. Breuning in her book. The brain does not want cortisol, the “unhappy” drug. Everyday life, of course, creates spurts of cortisol, and the brain struggles to lower the level. It is always trying to maximize its happy drugs and minimize the unhappy ones. But sometimes it has to negotiate. For example, in order to secure oxytocin from a bonding relationship, e.g., friendship, the brain might have to sacrifice serotonin that comes from pride. It needs to calculate whether the serotonin sacrifice is worth the oxytocin gain.

All these chemicals are managed by the brain’s limbic system, also known as the reptilian brain. The limbic system consists of the amygdala, hippocampus, hypothalamus, and other parts. All mammals have a limbic system and thus the ability to secrete these happy hormones. From an evolutionary perspective, these chemicals serve as a reward mechanism to train the brain. For example, romantic love and sexual intercourse produce dopamine and oxytocin. This trains the mind to seek love and sex and thus contribute to the propagation and survival of the species. Success at a job can produce serotonin and thus train the brain to seek more success and thus secure financial security required for survival. Exercise produces pain, which results in endorphin production. The pain is masked by the endorphins and the body is trained to seek more exercise, thus equipping the body with better survival mechanism.

Since the theory of evolution is widely accepted and relatively well understood in scientific circles, it seems to have become fashionable to explain the brain’s chemical secretions in terms of survival mechanisms. The explanations seem to fit and make sense, but human beings are different than other mammals and not necessarily at the mercy of evolution. In Harold’s example, if he feels stressed while designing the elephant structure, he can reduce the cortisol level in his brain by seeking his fiancée’s company, which could increase the oxytocin level. Or he can go for a run to increase the endorphin levels. He can also visualize what it would be like to see his sculptor inside the restaurant which could help increase the serotonin. Another option would be to increase his dopamine level by treating himself to a good meal or to something else that he wants. The more Harold knows about how the neurotransmitter can help him maintain a joyful life, the better he can manage them to negotiate happiness.


References:

1. Breuning, Loretta Graziano (2012-02-14). Meet Your Happy Chemicals: Dopamine, Endorphin, Oxytocin, Serotonin. System Integrity Press.

2. Ratey, John J. MD. A User’s Guide to the Brain: Perception, Attention, and the Four Theatres of the Brain. Random House, Inc.