The Hippocampus and Depression
July 8, 2015
The brain is a fantastic organ. It allows us to create meaning, by integrating sensory, and cognitive processes.
This integration is accomplished by associations, otherwise known as memories.
Memories define our reality, and are stored throughout our vast cortex.
Not only can the brain store incredible amounts of information (See ‘Love Bytes’ at http://wp.me/p67ZVU-2e), it has techniques to retrieve them very quickly.
That makes sense, because it has been anthropologically important for early Homo sapiens to recognize threat from safety.
Any given thought or memory, requires many areas of the cortex to light up simultaneously.
These twinkling stars, inside the skull’s night sky, correspond to both external sensory signals, and inner feelings, like hunger or arousal, associated with the original experience.
There are close to an infinite amount of memories and thoughts at your disposal, like there are an infinite amount of songs, within any piano.
The drama of the song, or intensity of the memory, is related to how many distinct brain areas are activated, and in what order.
This would be similar to the notion that the sentence you are currently reading, creates its meaning, from the individual words chosen, in this specific sequence.
Actually, the piano is a good metaphor for the brain, if you consider that any one memory, or mental note, is the result of playing a specific combination of neurons, throughout the brain.
Some pieces of life are more dramatic, and strike chords that activate many brain centers simultaneously.
This understanding helps explain the notion of ‘Why humans only use 10% of their brain at any one time’.
The rest is not lazy tapioca.
The ‘unused’ portion of the cortex, represents a potential inventory of almost infinite thoughts. If we used ALL of our brain at once, the mind would experience the equivalent of playing all of the notes on the keyboard at once; noise without meaning.
If thoughts were colors, the mind would be blinded by the light, and see nothing else.
So the brain is the entire Orchestra, creating the music of your reality, and drawing upon different instruments and accompaniments, as situations demand.
And to help us along, there is a Memory Maestro in the Mind’s Midst.
If members of the Orchestra were parts of the cortex; it is this Memory Maestro that coordinates when some neurons play, or don’t. It also keeps the diverse functional sections working together, in harmony.
In the brain, your HIPPOCAMPUS conducts the various instruments, of your memory.
This graceful looking structure, with a Seahorse body, is buried deep; under the entire ocean of the cerebral cortex.
These bilateral horses gallop quickly, when thoughts race.
And with long Dendritic tentacles, stretching throughout your concert hall, it sifts through your mind’s songs; silently singing in cells.
The Hippocampus is the Conductor of our memories, selecting which numbers are played together.
By using associations, every familiar image we encounter, is instantly reunited with former band members.
For more information, see the following:
It seems that the Hippo’s main job, is one of ‘PATTERN COMPLETION’, as it organizes Episodic Memories.
This is the phenomenon experienced, when the smell of cinnamon hearts, reminds one of Valentine’s Day.
Studies demonstrate that if we experience 2 things together, they become associated as a memory. Later, if we are shown only 1 of those things, the Hippocampus automatically retrieves both things, for our mind. The purpose of these additional accents playing ‘backup’, is to enrich our perception, of the real-time performance of life.
Again, if I ask you to think about Balloons, there may be too many associations to come up with 1 specific memory experience.
If I ask you to think of a number, like 99, many of you will think of Mr. Gretzky, or your GPA (hopefully!).
But if I ask you to think about 99 Red Balloons, I have a feeling, there will be music playing in your head.
In 2004, Dr. Glenda McQueen, a Psychiatrist from Calgary, Canada, examined the relationship, between the Hippocampus, and Depression.
She examined: post mortem studies of depressed people, animal models of stress, and compared levels of depression, with the size of the Hippocampus, in humans.
Clinical Major Depressive Disorder is often characterized by episodes of poor concentration, sad mood, and inability to enjoy oneself, among other symptoms.
When clinically Depressed, much of life can feel overwhelming; hunger and sleep can feel like strangers, suicide can seem like a solution.
This perception of stress, during Major Depressive Disorder, causes the brain to produce CORTISOL.
Cortisol is like a Lightsaber in your brain.
It is sometimes very helpful, to use The Force of this chemical; to keep the body going, in stressful situations.
When levels of Cortisol stay high for weeks to months, the chemical heat of this survival weapon, burns the cells of the brain.
It has been demonstrated, in Clinical Depression; that elevated levels of Cortisol can preferentially damage the HIPPOCAMPUS itself.
MRI data indicates that prolonged episodes, or multiple severe episodes, can result in brain damage, where the HIPPOCAMPUS ACTUALLY SHRINKS IN SIZE.
Can you imagine how an orchestra would react, if the conductor forgot the song?
Like anyone who feels a bit lost, the Hippocampus tries to fake its way through Depression. Even though it is disintegrating.
When this happens, the playlist becomes redundant; sad songs, with dull notes.
Then the concert of life suffers.
The depressed person grows tired of group sing-along, and avoids parties, relationships, and the chorus of supports they once harmonized with.
This may explain why depressed people describe ‘forcing themselves to smile’, or ‘sucking it up’, as almost impossible.
The Hippocampus cannot find the Joy Division.
On a brighter note, Dr. McQeen’s research also indicated that successful treatment of depression, through antidepressant medications, or talk therapy, seems to heal the Hippo.
Successful treatment often lowers perceived stress; boiling Cortisol levels start to cool.
In the brain’s healing process, treatment also increases another very helpful chemical, called BDNF (BRAIN DERIVED NEUROTROPHIC FACTOR).
BDNF acts like CHIA-PET™ seeds, in your brain.
Check out the original commercial.
With less Cortisol, and more BDNF, the Hippocampus can repair itself. The salvation, of this Seahorse, has been demonstrated to parallel an improvement, in the clinical symptoms of Depression.
Perhaps in the future, Depression will receive a different billing.
Although ‘Cortisol-Induced Hippocampal Damage Syndrome‘ doesn’t exactly roll off the tongue.
Until next time.
Simon Trepel, MD
Simon Trepel, MD FRCPC, is a practicing Child and Adolescent Psychiatrist, in Winnipeg, Canada. He is an Assistant Professor, at the University Of Manitoba, in the Faculty of Medicine, and the Co-founder of the GDAAY Clinic. He is, more importantly, the proud Father of 2 beautiful Daughters. He writes in his spare time about things he knows something about, and occasionally about things he doesn’t; like Yoga, and Italian flavored coffees. He was not referring to coffee that tastes like an Italian person.
Check out his Blog, called Simon Says Psych Stuff, at