Yes in my opinion the happiness will increase the hippocampal volume because during chronic disorders the volume of this region decreases due to the neurodegenration in this region and down regulation of some genes like CREB during happiness or stressed out condition the volume must increase due to formation of new synaptic processes and neuroregenration and during regenration certain genes needed for increase in volume are upregulated this .process have also been found in hippocampus.Thus we might predict that the happiness will cause increase in volume of hippocampus

Interesting question John,

My hippocampus is swelling with joy as we speak!

:-)

However I wouldn't expect to find a direct correlation between increased hippocampal volume and improved mood, or vice-versa. The more we learn about neuroplasticity the more we realise what a constantly adaptive and responsive organ the brain is.

Many factors can affect the volume of grey matter in the brain besides chronic stress, and different areas of the hippocampus process different types of information, so increases in volume may simply be related to memorising certain types of information or learning certain types of skills, atrophy may simply be a result of disuse, and experiences that increase volume in one section may simultaneously decrease volume in others.

London cab drivers have to learn the whole layout of the city's central business district by heart in great detail before they are licensed- it's a gruelling testing process called "the knowledge" that takes most people years to complete. fMRI scans performed on London cabbies reveal significant increases in the volume of the part of the hippocampus that is most involved in spatial navigation and spatial memory. This increase seems to come at a price however- areas associated with acquiring new visuo-spatial information are atrophied.

London Bus drivers have a very similar job, in terms of stress, to cab drivers, but they are not subjected to the same kind of intense, prolonged, memory-cramming induction, they typically drive the same one or two routes every day and they only rarely have to learn a new one. Signs tell them when and where to turn.

London's bus drivers do not exhibit the same changes in hippocampal volume as cabbies, but they do significantly out-perform them on tests that measure acquisition of new visuo-spatial information.

I would suggest that it is highly unlikely that taxi drivers in London are, on average, significantly happier than bus drivers. It is probably more accurate to view the differences between these two groups as a result of functional neuro-adaptions arising in response to the demands of driving a taxi in London.

See;

http://www.ncbi.nlm.nih.gov/pubmed/17024677

.

A similar study looked at people from religious minorities who report life changing, "born again" religious experiences. In later life their hippocampal volume atrophies, not just shrinking but also growing new connections more slowly than people of the same age who come from less stressed or more open-minded backgrounds.

The researchers suggested that religious minorities may be subjected to more stress than other people because of their beliefs, and that this stress might be an explanation for the hippocampal atrophy.

However, like muscles, axons between neurons become stronger if used, and weaker if they are not. Axonal pruning is the process of your brain removing little used pathways.

An alternative interpretation of this study would be that people who are very certain of what is true and what isn't, who have been schooled in dogmatically narrow ways of thinking or to not question their beliefs, and to think in absolutes and eternal certainties, require less flexibility in the part of their brain that encodes and recalls memory. In this case, reduced hippocampal volume might be viewed as a functional adaption to such environmental influences, rather than "damage".

See:

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0017006

.

Hope this is interesting.

Regards,

Paul.

Dear Paul,

Thank you for sharing! Interesting thoughts. I had forgotten about the cabbie study - must be my shrinking hippocampus.

G'day John,

As I age I find Mark Twain's advice more and more relevant. (Twain wrote that "A person who never tells a lie never has to remember anything!").

I find it interesting that the onset of dementia and cognitive decline appears to be heavily modulated by social factors in the environment. Chronic stress in adult life is of course associated with decreased hippocampal volume, and increased incidence of dementia and rates of cognitive decline in later life. People who do not report chronic stress, but who have lower hippocampal volume in adulthood, are also at higher risk of these problems in old age.

However this is not the whole of the story-

It's not just the volume of grey matter that is relevant to functionality, it's how well adapted whatever neuronal networks you have got are to the demands of your social and physical environment. I'd suggest that if these demands remain highly consistent for long periods of time, you can get away with losing connections in other areas, and with lower grey matter volume in total, without a significant loss of functionality.

You wrote that it > LOL, but hopefully any axonal pruning you are currently experiencing is an adaptive process of increasingly precise and functional pathways being refined, rather than the onset of dementia.

Many elderly people who function well in the community they have lived in for previous decades experience very rapid decline when moved to nursing homes. It is likely that a familiar environment and consistent social contacts are strongly protective, and removal from such an environment, and placement in an under-stimulating environment with a repetitive routine induces or significantly accelerates cognitive decline.

This would be in line with the neuroplasticity hypothesis I suggested for the results of the study on religiosity and hippocampal atrophy- connections that had been constantly re-enforced and maintained while the elderly person was in their home environment would cease to be stimulated in a nursing home and so would decay. With the much slowed rate of neurogenesis and axonal arborisation in older people, and a much less stimulating environment, significant numbers of new connections simply cannot be forged. The result is a startlingly rapid and irreversible decline.

For anyone interested in this subject, there's a very comprehensive review of these problems, with an enormous list of references, here;

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3345875/

.

Regards,

Paul.

Dear Paul,

Interesting viewpoint. I agree with you. Am also hopeful that my shrinking hippocampus is adaptive processing rather than dementia! But eventually...

That thought is for a new question.

Warm regards,

John

Hello,

after following your discussion I was wondering if a big volume of the hippocampus is maybe not really linked to more happiness but could tend to a more "extravagant" personality...

Actually in respect to the taxi driver study there are also assumptions that a bigger HC is more linked to navigation and map representation which also crucially involves the HC network. However two newer studies on medical students during training and juggling also showed hippocampal plasticity e..g increase in hippocampal size. The first is argued to be caused by learning, the second by learning and exercise. In case you want to read the originals:

Draganski B, Gaser C, Kempermann G, Kuhn HG, Winkler J, Büchel C, May A.

Temporal and spatial dynamics of brain structure changes during extensive

learning. J Neurosci. 2006 Jun 7;26(23):6314-7. PubMed PMID: 16763039.

Boyke J, Driemeyer J, Gaser C, Büchel C, May A. Training-induced brain

structure changes in the elderly. J Neurosci. 2008 Jul 9;28(28):7031-5.

PubMed PMID: 18614670

Also a very recent review might be interesting to you:

Valkanova V, Eguia Rodriguez R, Ebmeier KP. Mind over matter - what do we know

about neuroplasticity in adults? Int Psychogeriatr. 2014 Jan 2:1-19. [Epub ahead

of print] PubMed PMID: 24382194

coming back to the original question: it is not know whether HC degradation happens first which causes depression or depression comes first causing HC shrinkage. We only know that these two things are somehow related. Mood enhancement through for example antidepressants can reverse the HC shrinkage to some degree probably through adult hippocampal neurogenesis. If not drug driven mood elevation causes the same effect seems likely since also psychotherapy can help, but if the underlying mechanisms are identical has not been established to my knowledge. In that respect it could be that a more cheerful personality is indeed protective for your HC.

My personal advice: Drive save in London and don't stress out about possible HC shrinkage -> that will cause shrinkage

Dear Carmen,

Might you clarify what you mean by 'extravagant' personality? Thanks.

Dear Imke,

Interesting thoughts - thank you for sharing them. I will check about accessing the review article. In case this proves difficult, might I trouble you for a copy?

And I like your advice! Maybe throw in some physical exercise and yoga or tai chi?

Warm regards, John

Imke,

Our medical library has no subscription to this on line journal. Might you have a PDF file of the review article that you could send? Otherwise I can request inter library loan.

Thank you in advance, John

Dear John,

actually exercise is in general a good idea to prevent age related cognitive decline including hippocampal shrinkage. It is assumed to train your vascular system, improve oxygen supply of your brain while stressing the system enough to maintain flexibility without causing the negative effects of chronic hypertension. Additionally it has been show to increase progenitor cell numbers in the dentate gyrus of animal models. At least for mice you get the best effect if you combine exercise with environmental enrichment. So if you have time: run to the museum, enjoy the exhibition and run back in a moderate tempo ;-). I'll try to email you the PDF.

Hello John,

to be honest at first I was about to write "maniac". But then I thought that would be a little bit too hard and maybe not hit the idea I had at all. Beside that it would implicate some kind of "illness". Then I thought about artists like Leonardo da Vinci or Salvador Dali. I just couldn't remember the one proper word that describes their personality. However meanhwile it came to mind: The word is eccentric.

Thank you Carmen,

How about genius? Amazing how the terms seem so related.

I know of no such study. With warm regards,

John

Paul and Imke,

Who would have imagined that HC discussions could include such hyperbole? And yet no mention of shape. Which begs the question, does size even matter?

Within certain limits, it appears that it's not what you've got, it"s how you use it.

Imke, thanks for those references.

John, I'll try to source full text pdfs. If I can, I will forward them to you.

regards to you both,

Paul.

Hello John, I am finally able to respond......After looking at your question carefully, I have some conclusions:

- Enriched learning and memory (good environmental input) increases hippocampal volume

- Studies indicate (though more evidence is required) that the hippocampus may play a role in contributing to the existence of a mood state rather than vice versa

- Factors such as exercise and good environmental input, play a role in increasing hippocampal volume

- The 5-HTTP gene short alleles are linked to reduced serotonin levels which may be linked to hippocampal volume loss. I would then hypothesize that if you have the right combination of alleles ( preferrably long alleles),you would have higher levels of serotonin, which would act as a buffer against environmental triggers that are related to mood disorders. As a result you would have 'normal' hippocampal volume (I have seen research which indicates the finite volume of the hippocampus). Thus one could say that should you experience on a long term basis a happy state of being your hippocampus would retain a normal size, however if you had experienced a trauma, physiological or emotional, the gene allele factor may play a role in the long term repair to hippocampal volume, or reduction of volume. Please note that I am aware that many other variables also play a role, such as physiological factors, emotional factors, exercise, gender etc.

- In the case of the amygdala, it becomes increased in volume and reduced in volume in mental disorders, the findings seem to conflict in this area.

I have started putting together some of the studies for you, I should be done with that in the next few days. Hope this information is of interest - have a wonderful evening!

Thank you Cheryl, I appreciate how you integrated so many complementary thoughts. Am betting that your hippocampus is at least a wee bit bulkier for it!

Hee hee John, I think your question increased the volume by at least 1.5%!

I couldn't get fulltext either, sorry. I thought I had it saved.

Dear Imke, No worries. I will request a copy via interlibrary loan. Thanks, John

Cheryl, do you think giggles help too?

Release of serotonin - giggles may help....

I can post the full text of those three articles Imke mentioned sometime next week. Monday is a public holiday down here, but I should have them on Tuesday.

Incidentally I just spent four days on leave, camping on an island about 12 kilometers off shore and snorkeling on coral reefs with my daughters. Judging by my mood back at work today, I think Cheryl is on to something with the exercise and good environmental input!

Paul.

Here's one...

Here's another.

The third hasn't come through yet.

I suppose that chronic depressive state could decrease the hippocampal volume due to degenerative changes. Antidepressive drugs and or physical therapy could protect from this degeneration and preserve the hippocampal volume.

Exercise should be tested separately from the mood enhancing pharmacological drugs and electroconvulsive therapies, as factors affecting the hippocampal cells and volume.

It would be very interesting to study the hippocampal volume in people who is trained in Laughter Yoga. LY is renowned to increase serotonine, endorphines, wellbeing and so on. I'm very curious about this issue. Let me know about your discoveries.

There are some interesting bits of research emerging indicating increases in BDNF with respect to both positive mood and pursuing meaning and purpose in life as opposed to hedonistic self-gratification. BDNF facilitates both immune protection as well as neuronal growth across the brain of which the hippocampus is but one element in the network.

Dear Paul and Cheryl,

Thank you for the articles! Am still getting through them. I was away at the Mid Winter Brains Conference for the week - highly recommended if you get opportunity to attend. Plus I got to stimulate BDNF in my brain while skiing with friends! Warm regards,

John

G'day John,

Beware! Mid Winter Brains may suffer Seasonal Affective Disorder (which would be SAD).

http://www.ncbi.nlm.nih.gov/pubmed/23879697

.

http://www.ncbi.nlm.nih.gov/pubmed/21851822

.

http://www.ncbi.nlm.nih.gov/pubmed/15872099

.

Actually I have no doubt that the positive effect of skiing with friends would not be negated by any effect of reduced photo-period upon your hippocampus....

Paul.

Paul, haha such a jokester you are! A sunny beach does sound good about now. This is becoming a looong COLD MN winter!

Now I know why hamsters do bite... I always thought they are maybe like... hungy? But depression makes even more sense. Tomorrow we will start a phototherapy. And I will switch the cage against a little greenhouse. Just because I just read this one: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2635004/

Just jumping back a bit in the conversation,

Imke, you wrote;

>

The cab drivers show increases in only certain regions of the HC, and they are the regions implicated in spatial awareness and navigation. They show lower than "normal" volume in those regions of the HC implicated in acquiring new visuo-spatial information. I think it's reasonable to assume that this trade-off represents a functional adaption to the intensive conditioning involved in learning "the Knowledge" and the demands of the intuitive navigational skills needs to negotiate London under all the differing traffic conditions at different times of day.

>

I not sure how we can separate these two influences, whether in observational or lab studies...

Someone who learns the piano shows changes in volume in some regions of the HC, but we don't assume that all those new connections are being formed because of the physical exercise involved in fingering the keyboard.

Surely if someone learns a new motor skill as complex as juggling, this learning is sufficient to account for the changes to HC volume, without assuming the physical exercise is also responsible?

Or not?

Rather than a study observing students learning a new and very complex exercise (say, juggling), do you know of any studies that demonstrate an increase in HC volume associated with an increase in the amount of an already very familiar (preferably boring) exercise (say, walking on a treadmill)?

Or...

If we give the hamster who has been sitting in the dark a hamster wheel, and it's tiny little hippocampus increases in volume, is that because adding the wheel has made the environment more stimulating and relieved the hamster's boredom, or is it because the physical exercise of running in the wheel improves mood?

Or a bit of both?

How do we know?

Paul.

Let's say you are like 1 or 2 years old. Your parents are getting you a really cool rocking horse... is it only physical exercise to rock your horse? Or fun? And does the fun start when your hippocampus is big enough? Or when exactly does it improve your mood? I can still remember when I rocked my rocking bear... And as far as I remember it was not only the movement that fascinated me but the idea to ride away... that inner picture which came up. The trouble is: We cannot ask the hamster if he/she feels the same and has that inner idea of "running away" with all the pictures that pop up inside. You know... it could be those inner pictures that occure which are connected to the movement. But I guess there is no study about that topic.

Dear Paul,

Stimulating thoughts! Both explanations seem very plausible. I think that studies in caged mice might prove difficult since both experience and exercise are so intimately linked. A study comparing mice reared in an 'enhanced environment' vs. mice in a simple environment with forced wheel running might prove informative? See:

http://physrev.physiology.org/content/94/1/189.abstract

Any measurable differences in hippocampal volume might be expected to be small. Plus as Carmen so aptly raised the notion: memories and internal 'pictures' may be recalled while performing the activity, thus linking the two.

Perhaps if the resolution of functional imaging was improved we might compare hippocamal volume of mentally active but sedentary individuals with that of active athletes with lower IQ? Does determining which component has more efficacy even matter? Both seem so important for good health. And both require active participation, as opposed to the relative simplicity of popping a pill.

Dear Paul,

in the field of adult hippocampal neurogenesis several groups have shown that the addition of a running wheel to the standard housing cage allready stimulates proliferation of the present adult stem cells, thus inducing hippocampal plasticity. Also, excerise has been shown to impact synaptic plasticity to some degree. The negative bias here is whether standard lab housing is maybe diminishing plasticity by being far from reality. Hans-Peter Lipp did some research in a setup for mice that is very close to wildness and also looked at changes in brain anatomy, you could dig into his publications, if you like.

If you can study the effect of simple exercise independent of learning in human is still the big question. Even if you would let an experienced swimmer swim, this person would still rely on previous knowledge and likely refine his skills further. If it is the joy of swimming which would drive an effect could also only be assessed by including participants that do not enjoy it. But these participants are more likely to be less experienced, thus you will get a bias, since the learning curve in this group might be different as well as the blood cortisol level which inhibits plasticity, very grossly speaking.

Related to this question in general is also, if size really reflects function, or if connectivity is the key. This question is still far from being resolved and probably a mixture of both is true. Otherwise you would expect people with larger brains to be more intelligent. Given the literature (as well as my own tiny head) this seems not to be true!

As a brief anecdote:

A friend of mine from Cardiology even claims all this is only due to a better blood support/oxygen support of the brain caused by exercise. Thus, cardiology is the key discipline, not neurosciences ;-)

Have a good one,

Imke

Carmen,

As a youngster I too enjoyed galloping away on my rocking horse - repeatedly rocking the spring-hinged frame to 'death' and challenging my father to resurrect for the next ride. Whereas a ride on that horse was always fun, the most exhilarating life-like experiences were while wearing my cowboy shirt and pants, stetson hat, holster, and spurred boots. I like to think that such experiences impacted my hippocampus positively.

To quote Paul, "my hippocampus is swelling with joy" at recalling these memories. Which makes me ponder: might a specially outfitted rocking chair be of value during my declining years? On this note, I will plan to keep a cowboy outfit on hand just in case.

John

@ John Henley, I read the abstract you posted. It is very interesting. Thanks for posting it. Would you have a pdf copy of the paper for me?

John, try: http://physrev.physiology.org/content/94/1/189.full

Cheers, John

Thanks John