Introduction
- The brain contains 100 billion neurons and neurons are outnumbered ten to one by glial cells.
- Glia are cruical to the transfer of chemical messages and therefore to all brain processes’ including the formation of long-term memory. Interestingly, Einstein’s brain contained unusually many glial cells.
- A typical brain’s energy consumption is equal to that of a fifteen-watt lightbulb.
Development, Birth and Parental Care
Various psychiatric disorders are associated with a difficult birth.
- It has long been known that a high percentage of patients with schizophrenia experienced problems at birth such as low birth weight, premature birth, premature breaking of the waters, or time spent in an incubator.
- A recent study of women who had been emotionally neglected or physically or sexually abused showed greatly reduced oxytocin levels in their cerebral fluid, causing concern that their problems would be passed on to the next generation.
- EEG measurements show a response to pain stimuli from twenty-five to twenty-nine weeks. So at that stage, pain stimuli are arriving in the cerebral cortex.
Oxytocin has been found to suppress fear by affecting the amygdala, the center of fear and aggression.
- It has been found extensive networks of brain cells and axons containing oxytocin in a number of brain structures. Those fibres made contact with other neurons, transferring oxytocin to them in the form of a chemical messenger.
The brain produces a closely related substance to oxytocin: vasopressin.
- Vasopressin plays a cruical role in maternal behavior, including maternal aggression prompted by threats to offspring. It’s also involved in other aspects of social behavior , like pair-bonding.
- Men with tiny variation ina DNA building block for the vasopressin receptor( the protein that receives vasopressin’s message in the brain) are twice as likely to experience marital difficulties and
be unfaithful.
- People with autism display small genetic variations in the vasopressin and oxytocin receptor proteins.
The Importance Of A Stimulating Environment
When animals are placed in an “enriched environment”, their brains grow and develop more synapses.
- Children who are seriously neglected during their early development also have smaller brains; their intelligence and linguistic and fine motor control are permanently impaired, they are impulsive and hyperactive. Their prefrontal cortices can be particularly undersized. The neglected brain tend to have larger ventricles and have much larger spaces between the convolutions of the brain due to shrinking of the cerebral cortex.
- Studies have shown that orphans adopted before the age of two go on to develop normal IQs, while children who are not adopted until between the ages of two and six attain average IQs of 80.
-Our linguistic and cultural environments also determine how facial expressions are interpreted and how we can scan images and their surroundings. For example, Japanese and New Guineans find it difficult to distinguish between a face expressing fear and a face expressing surprise.
- When surveying a scene, Chinese individuals, unlike Americans, don’t focus on a single object at a time but look at it in relation to its surroundings. When doing mental arithmetic, the Chinese speakers make more use of visual motor systems. This can be explained by the fact that Chinese grow up learning characters.
Disorder Of The Brain and Sexuality
- A shift from adult heterosexuality to homosexuality is sometimes seen in patients with brain tumours or with brain disorders like damage to the temporal lobe that cause inhibited sexual behavior.
Pedophilia
- Pedophilia can have different causes. If an adult suddenly experiences pedophilic urges, they may have a brain tumor in the prefrontal cortex, temporal cortex, or hypothalamus. Sometimes it is a symptom of dementia.
- A sudden switch in sexual inclination to pedophilia has also been caused by operations to cure epilepsy by removing part of the anterior temporal lobe.
-Pedophilia can also be caused by infections of the brain, Parkinson’s, MS, and brain trauma. But a neurological cause for pedophilia is rare.
- Pedophiles have less grey matter (neurons) in various areas of the brain, like the hypothalamus, the bed nucleus of the stria terminals whose size also differs in transsexuals and the amygdala.
- The smaller the amygdala, the more likely an individual was to commit pedophilic crimes.
- Exposure to emotional and erotic images of adults sparks less activity in the hypothalamus and prefrontal cortex of pedophile men than in control group men, which ties in with the fact that pedophiles are less sexually interested in adults.
Puberty, Love and Sexual Behaviour
- Our brain structures spring into action when we fall in love, sending messages via the spinal cord and the autonomic nervous system preparing our sex organs for that one true purpose of existence: the fertilisation of an egg. To encourage us to truly commit to that objective, the brain provides orgasm as a reward.
- Impulses caused by the stimulation of our sex organs travel via the spinal cord to the brain, arriving at the thalamus, the central structure for all erotic sensory information. These then travel on to the ventral segmental area, with its dopamine-delivering reward circuitry, and the hypothalamus.
- Love at first sight is pure biology(perspiration, insomnia, strongly focused attention, beating heart, heightened energy...)
- Brain scans of people who had just fallen deeply in love and who were shown a photograph of their significant other showed activity exclusively in brain structures below the cerebral cortex. Their reward circuitry was particularly active.
-People who are in love have raised levels of cortisol (stress hormone). The level of testosterone increases in women who are in love, while in men cortisol reduces the testicular production of testosterone.
- If stable pair formation ensues, the activity in the stress axis dies down and testosterone levels return to normal.
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