We Are Our Brains: From the Womb to Alzheimer's

Introduction

Einstein's brain contained unusually many glial cells
Jacob Moleschott: Just as kidneys produce urine, the brain produces mind.

1. Development, Birth, and Parental Care

Labor is trigger when the child accounts for around 15% of the mother's metabolism.
While still in the womb, the brain cells in the child's hypothalamus respond to a drop in blood sugar level in the same way that they later respond to a lack of food in adulthood, by stimulating the stress axis. This induces a series of hormonal changes, making the uterus contract. The contractions, stimulated by oxytocin, make the baby's head press against the cervix. This in turn triggers a reflex, via the mother's spinal cord, which causes the release of yet more oxytocin. The baby's head then exerts more pressure, triggering the same reflex. The child can only escape from this chain reaction by being born.
We now know that schizophrenia is an early developmental brain disorder largely caused by genetic factors. So a difficult birth can be seen as a failure of interaction between the brains of mother and child.
A difficult labor or premature or delayed labor tends to be the consequence of a problem in fetal brain development.

Maternal Behavior

During pregnancy, the pituitary gland secretes the hormone prolactin, which prompts nesting behavior.Oxytocin, the "bonding hormone" - It's the messenger of affection, generosity, tranquility, trust, and attachment, and has been found to suppress fear by affecting the amygdala, the center of fear and aggression.Vasopressin makes men hostile but women more likely to approach strangers, because they are better at distinguishing friendly features.Society could be improved by giving men a whiff of oxytocin and women a whiff of vasopressin.Abnormal blood levels of vasopressin and oxytocin have been found in people with autism, who also display small genetic variations in the proteins that are the brain's vasopressin and oxytocin receptors.

Paternal Behavior

Patriarchy is though to have developed when our ancestors had to exchange the protection of the jungle for a more vulnerable life in the savanna.
The male's protection of the female and her child had an evolutionary advantage: Humans were able to reproduce every two to three years, while female chimpanzees, who were solely responsible for their young and therefore had to look after them and feed them for much longer, could reproduce only every six years.
Scents given off by the pregnant female may cause the behavioral changes in expectant fathers.
Fatherhood induces changes in the prefrontal cortex. The number of synapses in this area increases suggesting a reorganization of the local network. It also becomes more sensitive to vasopressin, the chemical messanger that promotes social behavior and aids fathers in their new tasks.

Early Brain Development

Children who are seriously neglected during their early development also have smaller brains, their intelligence and linguistic and fine motor control are permanently impaired, and they are impulsive and hyperactive. Their prefrontal cortices can be particularly undersized. Studies have shown that orphans adopted before the age of two go on to develop normal IQs of 100, while those not adopted until 2-6, attain average IQs of 80.
The frontal cortex is the site of Broca's area, which is crucial for language. When adults learn a second language, another sub-area of this region is involved. But if children are brought up bilingually from an early age, both languages use the same frontal areas and the left caudate nucleus check which language system is being used.
When doing mental arithmetic, the Chinese use different parts of the brain than Western Anglophones.
The bond between mother and child is first established during pregnancy through the mother's voice.

2. Threats to the Fetal Brain in the "Safety" of the Womb

Thyroid hormones are necessary for normal brain development but can only function if sufficient iodine is incorporated into the hormone.
Exposure to lead, mercury, DDT, PCBs, dioxins and many other substances can disrupt fetal brain development, as can ingestion of nicotine, alcohol, cocaine, and other addictive substances.
Our levels of aggression and stress are set before birth for the rest of our lives.
Body Integrity Identity Disorder (BIID) - Patients can want to have limbs amputated because they feel they don't belong to them. Scans show that their frontal and parietal cortices respond differently to a touch on the leg according to whether it's the accepted or the rejected leg.

3. Sexual Differentiation of the Brain in the Womb

The brain differentiates along male or female lines in the second half of pregnancy, due to a male baby producing a peak of testosterone or a female baby not doing so. It's in this period that the feeling of being a man or woman - our gender identity - is fixed in our brains for the rest of our lives.
Gender-base behavioral differences are fixed in our brains before birth.
In Western culture women use eye contact to understand other women better while men experience eye contact as testing their place in the hierarchy and can feel threatened by it.
Development after birth seems to have little impact on our sexual orientation.
Homosexual behavior has now been observed in around 1,500 animal species from insects to mammals.
Male-to-female transexuality (MtF) occurs in 1 in 10k individuals while FtM occurs in 1 in 30k.
The differentiation of our sex organs takes place in the first months of pregnancy, while the sexual differentiation of the brain occurs in the second half. In the case of transsexuality we expect to find female structures in the brains of MtF transsexuals and vice versa in FtM and this has been the case.
it may be that the neural body map of MtFs lacks a penis and FtMs lack breasts and so the individuals don't recognize these organs as their own and want to get rid of them.
The smaller the amygdala, the more likely an individual was to commit pedophilic crimes.

4. Puberty, Love, and Sexual Behavior

Puberty

In puberty, the pituitary gland starts to produce sex hormones. The craving for new experiences, the readiness to take great risks, and the impulsive behavior are all part of preparations to leave the nest.
People with a mutation in the KISS1 system never enter puberty.
Melatonin, a hormone produced by the pineal gland, is one of the substances that prevent the onset of puberty in children.
Normally, the brain cells that stimulate the sex hormones develop at the place where a fetus's nose develops. The cells then migrate along the olfactory nerve to the hypothalamus. This process is distruped in patients with Kallmann syndrome, so that not only do they not enter puberty, they also lack a sense of smell.
A youngster's parents function as his or her temporary prefrontal cortex.
Adults distribute assignments across different brain areas. Adolescent PFCs can sometimes function at an adult level but need to work much harder to do so, as they fail to outsource tasks to other brain areas. As a result, a teenager's PFC reaches the ceiling of its capacity earlier, and distractions can undermine the performance of assigned tasks.
After the age of seventeen, young people commit fewer crimes. It seems logical to assume that this curve reflects the gradual development of the PFC, which inhibits impulsiveness and promotes moral behavior.

Love and Sex

People who are in love also have raised levels of the stress hormone cortisol.
Our partners are determined initially by our ancient reward circuitry. Only when the most intense period of infatuation has passed does the cerebral cortex take over.
Many areas of the brain are constantly busy inhibiting our sexual urges. This is usually effective for around 23 hours a day.
Electrically stimulating the amygdala has been shown to induce pleasant sexual sensations.
To encourage us to truly commit to reproduction, the brain provides orgasm as a reward. It releases dopamine into the nucleus accumbens and oxytocin in the hypothalamus.
The thalamus is the central structure for all erotic sensory information.
DNA polymorphisms, tiny differences in the gene for the protein that receives dopamine's chemical message are correlated to the degree of sexual desire, arousal, and activity.
In brain scans, brain activity during orgasm is similar to the response to a heroin injection.
Activity in the female brain is concentrated in the motor and sensory areas of the cerebral cortex; in the male brain it's mainly in the occipito-temporal cortex and the claustrum.
In both sexes, the cerebellum regulates muscle contractions during orgasm.
Without being aware of it, American female students dress more fashionably around the time of ovulation.
Strippers tips are also much higher around ovulation.
Erotic images provoke greater arousal and brain activity in men than in women.
In men aged 46-55 brain areas like the thalamus and hypothalamus cease to display activity, a sign that aging reduces arousal in response to erotic stimuli
Lesions in the temporal lobe can cause people to develop Klüver-Bucy syndrome with symptoms of hypersexuality and hyperorality. Loss of inhibition has also been reported in individuals with lesions of the thalamus or the subthalamic nucleus.
Depression is associated with higher levels of cortisol, the stress hormone, which can deprive patients of all the pleasure in life (anhedonia).
In able-bodied men, psychogenic erections start in the brain and erotic impulses in the sex organs travel up the spinal cord.
Epileptics whose condition is sparked by a focus in the cerebral cortex sometimes feel as if they are having an orgasm just before a seizure, due to electrical stimulation of the brain cells in that area.

5. Hypothalamus: Survival, Hormones, and Emotions

The idea that brain cells could produce hormones was first suggested in the 1940s by the Scharrers. "Nerve gland cells" proved to be a universal cell type that regulates many bodily processes throughout the animal kingdom by means of hormones. The Scharrers' observations founded the discipline of neuroendocrinology.
The hypothalamus:
- Memory information is transmitted from the hippocampus via the fornix to the mammillary bodies, and the routed to the thalamus.
- The suprachiasmatic nucleus is the biological clock.
- Thermoregulation and sexual activity are governed by the preoptic region, while the tuberomammillary nucleus, the only place where histamine is produced in the brain, is important for focusing our attention.
- The areas that regulate appetite and metabolism are the infundibular (arcuate) nucleus and the paraventricular nucleus.
- The paraventricular nucleus and the suproptic nucleus send fibers to the posterior pituitary, where oxytocin and vasopressin are released.
- The infundibular nucleus sends fibers to the capillaries of the hypophyseal portal system, where neuropeptides are released that regulate the anterior pituitary.

Depression

All forms of depression feature overreaction of the stress axis. We respond to stress by activating nerve cells in the hypothalamus, which send a substance called corticotropin-releasing hormone (CRH) to the pituitary gland and the brain. The pituitary gland in turn stimulates the adrenal gland to produce the stress hormone cortisol. CRH and cortisol equip our brains and bodies to cope with stressful situations. But if th stress axis becomes overactive, a stressful event can lead to the overproduction of both CRH and cortisol, and these substances can affect the brain so strongly that depression results.
Seasonal affective disorder.
Various cell groups become hyperactive in the hypothalamus of depressive patients. In many cases the stress axis (the hypothalamus-pituitary-adrenal axis) is strongly activated.

Obesity, Anorexia and Narcolepsy

In the Western world, around 60% of adults are overweight and 30% are obese.
The leptin hormone is produced by fat tissue and helps the hypothalamus know how full we are, but if there are mutations in the leptin gene or receptor the hypothalamus will conclude that there's no fat tissue and continually prompt you to eat, resulting in morbid obesity.

The symptoms of narcolepsy are cause by the absence of hypocretin (or orexin) in the hypothalamus.
All the symptoms of anorexia nervosa can also be caused by a cyst, a small tumor, or some other abnormal process in the hypothalamus.
Anorexia sufferers may maintain the process of voluntary starvation because they become addicted to the diet-triggered opiates released by their brains, which activate the reward center at the base of the striatum.

6. Addictive Substances

Addictive substances affect the brain by mimicking its own chemical messengers. Brain cells themselves produce a whole range of opiates and cannabinoids. The nicotine in a cigarette has the same effect as the chemical messenger acetylcholine.
Addictive substances also affect the availability or the action of natural chemical messengers. Ecstasy increases levels of serotonin, oxytocin, and vasopressin.
All such substances have a direct or indirect effect on the brain's dopamine reward system, whether or not via an opiate system.
The sex hormones that circulate after the onset of puberty place an enormous burden on the adolescent brain and can bring on the symptoms of schizophrenia. The same applies to cannabis.
Studies show that cannabis users are twice as likely to develop schizophrenia.
Ecstasy was originally patented as an appetite suppressant in 1914
20 minutes after swallowing ecstasy, increased amounts of serotonin, oxytocin, and vasopressin are released. All tiredness vanishes and you feel happy and want to hug everyone.
Brain scans of ecstasy users show permanently reduced activity in the amygdala, hippocampus, thalamus, and cerebral cortex.

7. The Brain and Consciousness

If something gets in the way of the brain's information supply, it starts to make up information to fill the gaps.
We need the cerebral cortex to think, speak, hear, feel emotion, and move our limbs.
When someone is in a vegetative state, their brain stem functions are still intact.
In locked-in syndrome, the brain and the spinal cord are completely separated due to damage low down in the brain stem that prevents nerve fibers from controlling muscles. The brain is otherwise intact, and the patient is fully alert, but they can't communicate their alertness to their surroundings (except close their eyelids and move their eyes).
Brain-dead means irreversibly fixed pupils, the absence of brain stem reflexes, and the permanent absence of "higher brain functions" like cognition and consciousness.
There are two aspects to consciousness:
- Conscious of our surroundings - Found in every living organism. Even single-celled creatures creep toward food and away from poisonous substances.
- Conscious of ourselves - A child starts to recongize itself in a mirror between the ages of one and two.
The cerebral cortex, the thalamus, and a functional link between the two are all necessary for consciousness.
The thalamus lies in the center of the brain and it's there that all sensory information (except smell) is received and rerouted to the cerebral cortex.
Self-consciousness is not a metaphysical construct. Your brain constantly manufactures the sense that your body belongs to you, using sensory information from muscles, joints, vision, and sensation.
All recent research suggests that the joint activity of enormous numbers of neurons in communication with a number of brain areas provides the foundation for consciousness.

8. Aggression

Boys are more aggressive than girls and this is determined before birth. Girls with adrenal gland abnormalities that cause them to produce too much testosterone before birth are also more aggressive later.
Some children are markedly more aggressive than other and they are more likely to commit crimes. 72% of young offenders in Dutch prisons have been sentenced for crimes of aggression.
In addition, delinquency is strongly linked to substance abuse, psychoses and ADHD.
Darwin: "education and environment produce only a small effect on the mind of anyone... most of our qualities are innate."
Men are 5x more likely than women to commit a murder.
Men murder a relative or acquaintance in only 20% of cases, while for women it is 60%.
The incidence of murder peaks around the age of 20-24. After this age, the decline is due to the late development of the prefrontal cortex, which restrains impulsiveness and promotes moral behavior.
Decisions to go to war are more influenced by the amount of daylight and the temperature than by military strategy. In the northern and southern hemisphere, wars are typically declared in the summer, while around the equator, season doesn't play a role.
Studies show that 90% of young people in prison have a psychiatric disorder, and 30% of individuals detained under hospital orders have ADHD.
Some psychopaths have a malfunction of the amygdala, which prevents them from seeing from their victims' facial expressions that they are suffering and thus from feeling empathy for them.
During dream sleep we exhibit many of the characteristics of psychiatric and neurological disorders. Our higher visual centers are activated and we hallucinate like patients with schizophrenia.
Some sleepwalkers who are extremely mild and amiable when awake are shockingly violent when asleep.

9. Autism

People with autism often have synesthesia, a condition in which sensory and cognitive pathways are interlinked. Synesthetes have unusually strong connections between the various areas of the cerebral cortex. As a result, the visual cortex, which normally occupies itself only with the sense of sight, receives extra information about calculation going on in other areas of the brain. Complex calculations suddenly become easy when they are translated into images.
But Daniel Tammet also has extraordinary linguistic abilities, being able to learn a new language in a single week, even Icelandic! That's an unusual combination, but what makes Tammet unique as a savant are his well-developed social skills, which tend to be lacking in autistic savants.
There are blurry borders between what is considered normal and what is classified as a psychiatric problem. The dividing line between psychiatric disorders and great gifts is often a very narrow one and strongly depends on how someone is viewed by their surroundings.
Autism is marked by severely disrupted social skills and a very confined repertoire of activities and interests.
In was first described, independently, in
- 1943 by Leo Kanner in Baltimore - who described mentally subnormal children who scarcely spoke and displayed symptoms that were mostly neurological.
- 1944 by Hans Asperger in Vienna - who described the children as intelligence machines, who had a precocious grasp of language, could talk about their experiences and feelings, and were normally abled.
Brain development in autism is atypical. From ages 2 to 4 there is too much brain volume, delaying growth in some areas and prematurely terminating it in others. The main cause is genetic.
The syndrome is 10x more likely if the father is in his 50s rather than his 20s.
The symptoms appear early, around age three. Children with autism don't make contact with others and have motor problems due to a developmental disorder of the cerebellum.
People with autism have trouble interpreting emotion and empathy. They don't understand why another child is crying.
Temple Grandin built a "hug machine" in which she could lie, with the sides controlled by air pressure, squeezing against her.

Savants

Half of savants have an autistic spectrum disorder, and the other half have brain damage or a brain disease.
They are able to make unconscious use of algorithms
The term "idiot savant", coined in 1887 by John Langdon Down, is used to describe the combination of an exceptional gift and low IQ (0 to 70)
Savants appear to store all the information that enters their short-term memory in their long-term memory too. They can remember vast quantities of trivial facts, like license plates and railway timetables; it's as if they are unable to forget information.
Stephen Wiltshire is known for his ability to draw a landscape from memory after seeing it just once. Artistic savants always have a strong preference for a particular subject and a particular technique. They almost never draw people; the social brain is their Achilles' heel.
It's thought that the brain damage allows links with other brain structures to be reinforced, enhancing the functioning of the visual cortex.
Kim Peek, who was born without a corpus callosum, (his brain had no connection between the right and left hemispheres), would read two pages of a book simultaneously. He read 9,000 books about the history of the US and knew them all from memory.
Epilepsy is often associated with autism.
One theory is that everyone possesses potential savant talents localized in the "lower" regions below the cerebral cortex that are suppressed by "higher" processes. Darold Treffert calls this the "little Rainman" that each of us possesses.
Talents sometimes disappear with age. One autistic girl Nadia, lost her remarkable talent for drawing horses by the time she was nine. It would seem that the improved functioning of the left side of the brain, which is responsible for speech, inhibited here drawing skills.

10. Schizophrenia and Other Reasons for Hallucinations

Up until the 1950s, schizophrenia was "treated" by means of a lobotomy, and outpatient procedure that involved severing the connections to and from the prefrontal cortex. Opponents called it "partial euthanasia" since it turned patients into robots.
Schizophrenia affects 1% of the population. Around 10% of schizophrenics try to kill themselves.
It is characterized by:
- "Positive" symptoms - Abnormal experiences, like delusions and hallucinations. They can't be distinguished from real experiences because they take place in the same areas of the brain where external stimuli are normally processed.
- "Negative" symptoms - The loss of normal abilities, like taking initiative, organizing one's life, tidying up one's room, and looking after oneself. These are caused by reduced activity in the prefrontal cortex. A current therapy is to apply transcranial magnetic stimulation to that area. Stimulating areas of the cerebral cortex that are extra active can also reduce hallucinations.
Changing hormone levels during puberty and menopause bring on the disease, though a predisposition for it arises in the womb.
As the disease progresses, the brain shrinks and its ventricles (cavities) become larger, creating too much space between the convolutions of the brain.
There are no brain changes that are specific to schizophrenia, so diagnosis is entirely dependent on psychiatric investigation.
Schizophrenia is around 80% genetic.
Birth is the first functional test of a child's brain.
After birth, an environment full of stimuli increases the right of schizophrenia. You're more likely to develop the disease if you live in a city rather than the country.
Whether cannabis induces the disease or simply brings forward the moment at which symptoms occur is still a subject of fierce debate.
In schizophrenics, a high percentage of cells in the hippocampus are in disarray - something that can only happen in the first half of pregnancy. Abnormal patterns of brain convolution are also found, as well as groups of cells that have failed to migrate to the right place in the cerebral cortex. This too can only happen during early development.

Hallucinations Due to Lack of Stimuli

If brain structures stop receiving information in a normal way, they start making up information. This applies both to sensory information - from eyes, ears, and limbs - and memory information.
When your brain manufactures information on the spot where it's normally processed, it's interpreted as if it had entered from outside via the normal route.
The brain stops producing old information once it receives fresh input again, and it makes no difference whether the input is meaningful or has no information content.
Phantom sensations following amputation appear to be based on the same principle. Lacking customary input from a limb, the brain "makes up" the presence of the missing arm or leg.
In schizophrenia, input to areas of the cerebral cortex is also reduced, so the hallucinations provoked could be caused by the same mechanism.
Mountaineers, especially when alone, sometimes have very vivid hallucinations (hearing voices, seeing people, or have out-of-body experiences) or are overcome by fear. So it's interesting that the revelations received by the leaders of the world's three main religions were preceded by a period of isolation in the mountains. When the brain is very isolated it starts to use stored experiences and thoughts to manufacture things - sometimes even new religions.

Other Hallucinations

Mark Twain: "When we remember we are all mad, the mysteries disappear and life stands explained."
For an old brain, an anesthetic is like a dose of near-lethal poison. In intensive care, up to 80% of patients experience delerium.
The condition sometimes resembles dementia, but delirium strikes all of a sudden, while the onset of dementia is gradual.
Delirium is basically caused by an overdoes of the chemical messenger dopamine.
Around a third of people over 65 who experience delirium die within a few months.

Hearing Voices

There are people who aren't psychotic and yet hear voices. Between 7-15% of the population hear voices, yet only a fraction have mental health problems.
Unlike psychotic patients, healthy people can control their voices. They can call them up as well as order them to go away at inconvenient times. Functional brain scans show that in the healthy group, brain activity isn't very different from that of patients with psychosis.
In people who hear nasty voices, the right side of the brain is much more active.

11. Repair and Electric Stimulation

Since performing compulsive actions makes people with OCD feel good, it's thought that the brain's reward system is involved.
Our taste for sweet food depends on a single hedonistic hotspot at the base of the brain. Disabling that area makes sweet food taste repellent. Likewise, the hypothalamus is necessary for infatuation, maternal love, and pair forming.
Oxytocin and vasopressin play a role in infatuation, orgasm, pair forming, and maternal love. Deficiencies in those two chemical messengers are associated with autism.
If fetal donor tissue is implanted in your brain, what characteristics might you acquire from the donor?
In gene therapy, pieces of DNA containing the code for a particular protein (a gene) are inserted into a cell. The cell then starts to produce medicine in the form of the gene product, that is, a new protein.

12. The Brain and Sports

Around 17% of professional boxers (including Muhammed Ali) have Parkinson's.

13. Moral Behavior

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14. Memory

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15. Neurotheology: The Brain and Religion

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16. There Isn't More Between Heaven and Earth

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17. Free Will, a Pleasant Illusion

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18. Alzheimer's Disease

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19. Death

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20. Evolution

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21. Conclusions

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