Sunday, December 16, 2012

Hypothesis: The Cultural Amygdala

Visual Aid: The Human Amygdala (red area)
On this blog regular readers know that we have discussed the physical Amygdala several times.

If you care to review some of that material, see e.g. the series Hypothesis: Microbes Generate Toxins of Power through Hypothesis: Microbes Generate Toxins of Power - 6, as well as The Toxic Bridge To Everywhere and A Structure RE: Corruption of Memes - 3.

Today, I will go beyond the content of those posts, which contemplated only "the physical Amygdala", to further develop a hypothesis concerning a structure that has been called "the cultural Amygdala" (see Agnotology: The Surge - 2).

The red areas in the graphic above help to depict the two "almond shaped" physical portions of the physical Amygdala in the human brain, while the blue lines attached to it, and winding out from it, are merely additional visual aids for contemplating the concept of the cultural Amygdala (see video below for exact location of the physical amygdala).

In today's post, I will argue that there is a cultural Amygdala, which is a complex web of brain circuits that constitute an "extension" of the physical brain's physical Amygdala.

I use the word "extension", because this hypothetical cultural Amygdala is attached to the physical Amygdala, in the sense that the cultural Amygdala's circuits originate and/or pass through the physical Amygdala, yet extend out into other brain sections as well (e.g. see Hypothesis: The Cultural Amygdala - 3 for connection to the frontal lobe).

I will argue that the cultural Amygdala circuitry is created over a lifetime by the culture one is born and raised in, that is, the beliefs, education, behaviors, and experiences that culture presents to those within it:
We found that amygdala volume correlates with the size and complexity of social networks in adult humans. An exploratory analysis of subcortical structures did not find strong evidence for similar relationships with any other structure, but there were associations between social network variables and cortical thickness in three cortical areas, two of them with amygdala connectivity. These findings indicate that the amygdala is important in social behavior.
(Amygdala Volume and Social Network Size, emphasis added). We begin the basic structure of the hypothesis with the physical Amygdala, set forth in some of the posts linked to above, plus another hint of a cultural Amygdala:
Michael Skinner has just uttered an astounding sentence, but by now he is so used to slaying scientific dogma that his listener has to interrupt and ask if he realizes what he just said. Which was this: “We just published a paper last month confirming epigenetic changes in sperm which are carried forward transgenerationally. This confirms that these changes can become permanently programmed.”

... the life experiences of grandparents and even great-grandparents alter their eggs and sperm so indelibly that the change is passed on to their children, grandchildren, and beyond. It’s called transgenerational epigenetic inheritance: the phenomenon in which something in the environment alters the health not only of the individual exposed to it, but also of that individual’s descendants.
(Sins of the Grandfathers, bold added). That "something in the environment" is the cultural dynamics that every individual is exposed to, yet the "something" varies from group to group (see e.g. Agnotology: The Surge - 3).

It varies from individual to individual, within the same culture, to a lesser degree (see Making Sense of — and Progress in — the American Culture War of Fact, PDF).

According to Skinner, above, some of those impacts of the environment of culture may, in whole or in part, in some cases even be passed on to their progeny.

Over one's lifetime, a cultural Amygdala that is specific to the culture an individual and their descendants are exposed to, is constructed in the brain.

The circuits that comprise the cultural Amygdala have various degrees of permanence, which determines whether they last generations or whether they dissipate in some degree even in one generation.

That is a fundamental difference between the cultural Amygdala and the physical Amygdala, the former is more temporary while the latter is more permanent.

For example, let's hone in on that by recognizing for the moment that a person raised in Mississippi on a small farm, then living there through adulthood, will have a different social awareness and cultural Amygdala when compared to a person who is raised and lives their life in the art district of Paris, France.

The more temporary nature of the cultural Amygdala could be envisioned by imagining that the two individuals, one from Paris and one from Mississippi, were relocated in their teens, the person in Paris relocated to a small farm in Mississippi, and the person in Mississippi relocated to the art district in Paris.

The cultural Amygdala hypothesis would predict, upon relocation, a change over time in the cultural Amydala of both individuals as a result of being placed into very different cultures from the one they experienced through their teen years:
Thought is physical. Learning requires a physical brain change: Receptors for neurotransmitters change at the synapses, which changes neural circuitry. Since thinking is the activation of such circuitry, somewhat different thinking re­quires a somewhat different brain. Brains change as you use them-even unconsciously. It's as if your car changed as you drove it, say from a stick shift gradually to an automatic.
(The Toxic Bridge To Everywhere, quoting Dr. Lakoff). Nevertheless, the cultural Amygdala hypothesis would also predict that the physical Amygdala, by comparison, would experience little to no change.

An additional example of the more temporary nature of the circuits in the cultural Amygdala is illustrated by the following dynamics:
A group of US marketing researchers claim that brand owners can make their customers believe they had a better experience of a product or service than they really did by bombarding them with positive messages after the event. Advocates of the technique, known as "memory morphing", claim it can be used to improve customers' perceptions of products and encourage them to repeat their purchases and recommend brands to friends.

"When asked, many consumers insist that they rely primarily on their own first-hand experience with products – not advertising – in making purchasing decisions. Yet, clearly, advertising can strongly alter what consumers remember about their past, and thus influence their behaviours," he writes in his book, How Customers Think. He says that memories are malleable, changing every time they come to mind, and that brands can use this to their advantage. "What consumers recall about prior product or shopping experiences will differ from their actual experiences if marketers refer to those past experiences in positive ways," he continues.
(Memory Morphing in Advertising, emphasis added). The hypothetical cultural Amygdala circuitry is malleable to the degree of being subject to relatively weak external input in the form of marketing suggestion and stimuli, which, to the contrary the physical Amygdala would not be.

The following case of an invasion of the physical Amygdala by toxoplasma gondii also engenders the inquiry "which Amygdala is being affected?" by that parasite:
Next, we then saw that Toxo would take the dendrites, the branch and cables that neurons have to connect to each other, and shriveled them up in the amygdala. It was disconnecting circuits. You wind up with fewer cells there. This is a parasite that is unwiring this stuff in the critical part of the brain for fear and anxiety... It knows how to find that particular circuitry... Meanwhile, there is a well-characterized circuit that has to do with sexual attraction. And as it happens, part of this circuit courses through the amygdala, which is pretty interesting in and of itself, and then goes to different areas of the brain than the fear pathways... Toxo knows how to hijack the sexual reward pathway.
...
On a certain level, this is a protozoan parasite that knows more about the neurobiology of anxiety and fear than 25,000 neuroscientists standing on each other's shoulders... But no doubt it's also a tip of the iceberg of God knows what other parasitic stuff is going on out there. Even in the larger sense, God knows what other unseen realms of biology make our behavior far less autonomous than lots of folks would like to think.
(A Talk With Dr. Sapolsky, emphasis added). The argument can be made that the parasitic invasion affects both Amygdalas (physical & cultural), or either one individually, depending on the severity and target of the invasion by those toxoplasma parasites (but the obvious default primary suspect is the physical Amygdala).

Either way, the cases above support the hypothesis that we have a malleable cultural Amygdala, and in some cases a malleable physical Amygdala, even though the latter is not as malleable in any significant degree.

This hypothetical cultural Amygdala is also "weaker" than the physical Amygdala, if the following case is instructive:
... [Whitman] killed a receptionist with the butt of his rifle. Two families of tourists came up the stairwell; he shot at them at point-blank range. Then he began to fire indiscriminately from the deck at people below. The first woman he shot was pregnant. As her boyfriend knelt to help her, Whitman shot him as well. He shot pedestrians in the street and an ambulance driver who came to rescue them.

The evening before, Whitman had sat at his typewriter and composed a suicide note:
I don’t really understand myself these days. I am supposed to be an average reasonable and intelligent young man. However, lately (I can’t recall when it started) I have been a victim of many unusual and irrational thoughts.
By the time the police shot him dead, Whitman had killed 13 people and wounded 32 more. The story of his rampage dominated national headlines the next day. And when police went to investigate his home for clues, the story became even stranger: in the early hours of the morning on the day of the shooting, he had murdered his mother and stabbed his wife to death in her sleep.
It was after much thought that I decided to kill my wife, Kathy, tonight … I love her dearly, and she has been as fine a wife to me as any man could ever hope to have. I cannot rationa[l]ly pinpoint any specific reason for doing this …
Along with the shock of the murders lay another, more hidden, surprise: the juxtaposition of his aberrant actions with his unremarkable personal life. Whitman was an Eagle Scout and a former marine, studied architectural engineering at the University of Texas, and briefly worked as a bank teller and volunteered as a scoutmaster for Austin’s Boy Scout Troop 5. As a child, he’d scored 138 on the Stanford-Binet IQ test, placing in the 99th percentile. So after his shooting spree from the University of Texas Tower, everyone wanted answers.

For that matter, so did Whitman. He requested in his suicide note that an autopsy be performed to determine if something had changed in his brain — because he suspected it had.
I talked with a Doctor once for about two hours and tried to convey to him my fears that I felt [overcome by] overwhelming violent impulses. After one session I never saw the Doctor again, and since then I have been fighting my mental turmoil alone, and seemingly to no avail.
Whitman’s body was taken to the morgue, his skull was put under the bone saw, and the medical examiner lifted the brain from its vault. He discovered that Whitman’s brain harbored a tumor the diameter of a nickel. This tumor, called a glioblastoma, had blossomed from beneath a structure called the thalamus, impinged on the hypothalamus, and compressed a third region called the amygdala.
(Atlantic Monthly, emphasis added). The compression of the physical Amygdala could impair or alter input from the eyes, ears, nose, taste buds, and touch because all those data-flows go directly to the physical Amygdala first (see video below).

In the Whitman case that tumor likely caused the physical Amygdala to malfunction,  override the cultural Amygdala, and thereby impair the self-awareness Whitman had of himself.

Whitman's statement "I don't really understand myself these days" is indicative of his well developed self-awareness, in terms of thinking patterns and emotional composition, and that he was detecting ongoing changes within himself that were not normal to him (which may link the cultural Amygdala to self awareness -- see e.g. Self-Awareness Require Complex Brain?).

Some of the functions of the cultural Amygdala as well as the physical Amygdala could be implicated by those changes.

Whitman perceived a malfunction but was not able to get any useful handle on it, even with the help of mental health professionals.

This post is getting a bit long, so, more to come in future posts of this series (including the relation of the cultural Amygdala to the toxins of power).

The next post in this series is here.

Professor Joseph LeDoux on the physical Amygdala (transcript):


It's like this kid ...

2 comments:

Randy said...

A research paper recently published may support the hypothesis: Link

Dredd said...

Some French structuralists maintain that culture goes deep into the brain, the U.S. counterparts are less convinced (Culture Debates).