October 29, 2008
Immune System Changes Emotional Reactions

Hello again puppets. Add immune system mast cells to our list of puppeteers. Anyone still think we have free will?

In the first study ever to genetically link the immune system to normal behavior, scientists at Rockefeller and Columbia universities show that mast cells, known as the pharmacologic bombshells of the immune system, directly influence how mice respond to stressful situations. The work, to appear this week in The Proceedings of The National Academy of Sciences and to be highlighted in Science, chips away at the increasingly stale idea that the two most complex systems in the body have entirely separate modes of operation.

Eight years ago, scientists from Columbia University discovered that mast cells travel to the brain from other organs early on in development. “We now knew that mast cells resided in the brain but we didn’t know their function,” says Rockefeller University’s Donald Pfaff, head of the Laboratory of Neurobiology and Behavior. “But we know that they synthesize a large number of important chemical mediators that could potentially have severe neurophysiological effects.”

Since the immune system ages and becomes less vigorous that suggests that aging of the immune system alters our emotional reactions.

If aging people could get their immune systems rejuvenated they might become more adventurous.

In their work, Pfaff and postdoc Ana Ribeiro, and the Columbia team, led by senior author Rae Silver and graduate student Kate Nautiyal, bred mice that lacked mast cells and compared their behavior in stressful situations to the behavior of mice that had a full or a moderate arsenal of mast cells. The researchers observed how willing the mice were to navigate open and lit environments and high spaces, which mice find anxiety-producing. In the wild, if a mouse is down in its own burrow, it’s not visible to predation. But if it’s bold, that is, if it has low anxiety, it will go out where it can potentially be seen by predators and hunted.

The results were striking. When the researchers placed the mice in an elevated maze with four long arms -- two simulated a canyon and the other two a cliff -- mice that lacked mast cells preferred to stay in the canyons, entering and investigating the doors to the cliffs significantly fewer times than mice with mast cells. When placed in a square box, mast cell-deficient mice preferred to scuttle against the walls, and were more hesitant to venture out to the center of the box than mice with mast cells. They also defecated more, a physiological sign of anxiety. However, the genetically different mice did not show differences in overall arousal or locomotion, suggesting that their behavioral changes were specific to their anxious state.

So an unhealthy immune system can increase anxiety. Do anxious people get colds and flus more often?

Share |      Randall Parker, 2008 October 29 08:00 AM  Brain Emotions

Bob Badour said at October 29, 2008 9:10 AM:
Anyone still think we have free will?

Yes, absolutely. I say that even though I have a disability that interferes with my ability to execute my will. When I was under a period of prolonged extreme stress and just as I reached the cusp of a dopamine collapse with the inevitably ensuing anhedonia, I consciously decided to avoid clinical depression and I succeeded.

Even though I had no option to significantly reduce my stressors, I freely chose to exercise my will and my body to avoid clinical depression. If that's not free will, I don't know what is.

BBM said at October 29, 2008 9:41 AM:

Free will does not mean unlimited freedom of will, of course.

As I said before, no doubt that some of our decisions are made unconsciously. But that's not the same as saying thatthere is no free will at all. Reflective, introspective decisions are good candidates. Even seeming reflexive decisions could be still ultimately based on a conscious free decision.

For example, say I decide to treat others with kindness, and condition my mind to act this way as much as possible. If I do so without thinking about it, is that act still unfree?

Proving that all decisions are determined is a very tall order.

And determinism raises some very serious and difficult philosophical problems, aside from the fact that everything that happens would be determined and therefore inevitable. Theoretically, if determinism were true, the outcome of the election next week would have been determined since the beginning of time.

Faruq Arshad said at October 29, 2008 12:40 PM:

I still thing this is some form of simulation, our universe I mean. Hence the lack of free will.
Well I suffer from severe depression and anxiety. But I don't suffer anymore colds than other ppl. Less so, since I'm slighlty a loner.

Faruq Arshad said at October 29, 2008 2:00 PM:

Bob, having re-read your post in more detail, I'm quite puzzled: Surely no one can avoid clinical depression purely by free will? If you gp through a trauma then depression is almost certain, for the reason that most ppl get sucked into a depression after a traumatic event without even knowing what's going to hit them. It's bad enough that you're going to be raped or physically attacked, but nature is so cruel that she has no mercy for those poor souls and punishses them with the double-whammy of depression too!Also, what does the term 'cusp of a dopamine collapse' mean, please? Thanks Bob.

Brett Bellmore said at October 29, 2008 4:34 PM:

This has nothing to do with free will; Free will doesn't imply that our decisions don't have causes, it implies that they are not externally compelled. The opposite of caused is random, not free.

Bob Badour said at October 29, 2008 4:38 PM:


Some people don't get depressed. Some soldiers never get PTSD; even though, another soldier who experiences all the same things does.

Different people can cope with different amounts of stress. If one experiences more stress than one can cope with, a sequence of hormonal responses happens. The primary hormonal response relates to cortisol, epinephrine and norepinephrine. These cause a secondary response in serotonin levels. One of the first noticeable symptoms is disturbed sleep as the serotonin gets messed up. If the serotonin levels stay messed up long enough, that causes a tertiary response in dopamine levels.

When dopamine levels decline, unpleasant things feel more unpleasant and pleasant things feel less pleasant. If dopamine remains messed up long enough, one loses the ability to feel joy or happiness and one becomes clinically depressed.

In 2005, I moved from one province to another, got dumped by my girlfriend, and the distributor of my software titles terminated our business relationship. I coped with all of those things, but they put me very close to my coping limit. In fact, I later found a couple of stress load quizzes online, and when I filled them out, I discovered my stress load at that point was basically at or near the median coping limit.

Then in late January 2006, my dog Buddy got t-cell lymphoma. That was a huge stressor that put me way over my coping limit. I noticed a number of changes in myself through February and March starting with disturbed sleep.

By the time April rolled around, I had to admit to myself that I was simply no longer functioning. I was sleep deprived. I could not concentrate. I felt like I was "thinking through molasses". I had great difficulty initiating or switching tasks.

I also noticed that walking in the rain hurt. The April rain felt cold and prickly like hard-blowing sleet or ice pellets.

It was at that point that I started reading up on stress, the stress response, and its connection to depression. I found the stress quizzes etc.

When I read up on the detailed series of events by which acute chronic stress progresses to clinical depression, I could identify them all. I could pinpoint when each of the steps started and where I was in the progression. At that point in time, my dopamine was dropping rapidly as evidenced by my lower tolerance for cold and by the rain feeling painful etc.

When I examined the stressors, I could only remove one or two minor stressors, and that was nowhere near enough to put me back below my coping limit. All I could do was try to increase that coping limit.

I decided I needed exercise and more exposure to the sun in order to avoid clinical depression. I rented a roto-tiller and cut in a 0.5 acre garden. That was enough to start turning things around. My serotonin levels were still whacked, and I continued to have executive function issues, but I avoided clinical depression. I normalized my sleep somewhat. I started functioning better; although, by no means perfectly.

But by exercising my will and my body, I did avoid clinical depression.

Faruq Arshad said at October 29, 2008 6:29 PM:

Thanks Bob. I thought you avoided clinical depression puirely by free will, not by using sunshine and exercise.
I hope that you feel as little pain as this cruel world is able to throw in your direction.
Bye friend.

Bob Badour said at October 30, 2008 7:39 PM:

I don't experience much pain right now at all; even though, I face some challenges.

When you have free will, you are free to choose the tools at your disposal. The tools I had at my disposal were sunshine and exercise. And better rest, but that comes naturally with exercise and sunshine.

If you are clinically depressed, see a doctor. Choose to use all the tools at your disposal.

Jun said at November 1, 2008 2:00 PM:

"Hello again puppets."

Ha! :-))

Bob Badour: "...I consciously decided to avoid clinical depression and I succeeded."

BBM: "...no doubt that some of our decisions are made unconsciously."

You guys, I think, are confusing (what appear to be) conscious decisions with free decisions (I understand "free will" to mean free of any genetic or environmental influences). What makes you think just because a decision is/seems to be conscious that it is, therefore, free? Our seemingly conscious decisions could very well be (seem to be according to most research) just as heavily influenced by our genetics/our environment as our subconscious/reflexive actions.

Bob Badour said at November 1, 2008 3:38 PM:


With all due respect, the difference between determinism and free will is not influence but control. One can have free will influenced by genes and the environment, or genes and the environment can control everything leaving one with no free will.

I freely and consciously chose to avoid clinical depression, and I succeeded. And I did so in spite of a disability that impairs my ability to execute my own will.

Debating it is pointless. If you are a believer in determinism, you will invent fanciful explanations for why my free choices are not free just as a religious believer will invent fanciful explanations for why everything is produced by some silly ghost. Because I believe in free will, none of your fanciful explanations will affect my belief in the slightest.

Believe whatever you choose. I remain convinced of my own free will of my own free choice.

Jun said at November 1, 2008 3:45 PM:

Bob: I freely and consciously chose to avoid clinical depression, and I succeeded.

I just wonder how you know that. How can you be sure?

(I don't believe either way, btw. I think it's still open for debate. But, I lean towards not believing in free will.)

Bob Badour said at November 2, 2008 7:17 AM:


See above at "Debating it is pointless."

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