Who Am I?: Notes

Who Am I?

All experiences shape the microscopic details of your brain. Your brain rewrites its circuitry, making your identity a moving target.

The Physicality of the Brain

The brain weighs about three pounds and has the consistency of firm jelly. Thoughts, dreams, memories originate from neural material.

Born Unfinished

Humans are born helpless compared to other mammals. Dolphins can swim at birth and zebras can run within 45 minutes. Human brain is remarkably unfinished and shaped by life experience.

Livewiring

Many animals are born genetically preprogrammed (hardwired). Human brains are more incomplete at birth. Genes provide general directions, and experience fine-tunes the wiring.

Childhood Pruning: Exposing the Statue in the Marble

At birth, neurons are disparate. By age two, a child has over one hundred trillion synapses, double the number an adult has. Neural pruning occurs as you mature, with 50% of synapses pared back. Synapses that participate successfully in a circuit are strengthened, while unused ones are eliminated. Becoming who you are involves removing possibilities.

Nature's Gamble

Developing brains needs a nurturing environment. The Jensen family adopted orphans from Romanian state-run orphanages who endured appalling conditions. Dr. Charles Nelson's Bucharest Early Intervention Program assessed children and found they had IQs in the sixties and seventies. Children showed signs of underdeveloped brains and delayed language and reduced neural activity.
In 1966, Romanian president Nicolae Ceauşescu banned contraception and abortion, leading to many children being given over to state-run institutions and most of the Romanian orphans have been returned to their parents or removed to government foster care. By 2005, Romania made it illegal for children to be institutionalized before the age of two, unless severely disabled.

The Teen Years

Brain development takes up to twenty-five years. The teen years involve neural reorganization and change, affecting behavior. An experiment measured emotional response using galvanic skin response (GSR). Teenagers have greater social anxiety than adults and the medial prefrontal cortex (mPFC) becomes more active in social situations peaking at around fifteen years old.

Sculpting of the Adolescent Brain

After childhood, the prefrontal cortex sprouts new cells and connections, followed by pruning during teenage years. The dorsolateral prefrontal cortex matures later, impacting impulse control. Teens are set up to take risks because of an immature orbitofrontal cortex. Areas involved in social considerations are strongly coupled to other brain regions.

Plasticity in Adulthood

Adult brains continue to change due to experience. London cab drivers undergo intensive training. Neuroscientists scanned cab drivers' brains and found differences in hippocampus size relating to spatial memory. The longer a cabbie has been doing his job, the bigger the change in that brain region, suggesting that the result was not simply reflecting a pre-existing condition of people who go into the profession, but instead resulted from practice.
Einstein's brain showed the brain area devoted to his left fingers had expanded, forming a giant fold due to violin playing.

Pathological Changes

Changes in the brain due to disease or injury can alter who we are. Charles Whitman had a brain tumor pressing against his amygdala which is involved in fear and aggression in 1966 leading to a shooting spree and requested an autopsy in his suicide note. Drugs, alcohol, movies impacts reshaping neural networks.

Memory and Identity

Every four months red blood cells are replaced and skin cells are replaced every few weeks. Within about seven years every atom in the body will be replaced by other atoms. Continuity may be an illusion with memories being fragile brain states. Neurons that are active at the same time will establish stronger connections between them and each new event needs to establish new relationships among a finite number of neurons. Since the split dinner with intervened year, knowledge changes the memory of that memory.

Fallibility of Memory

Professor Elizabeth Loftus showed how susceptible memories are. Loftus devised an experiment in which she invited volunteers to watch films of car crashes, and then asked them a series of questions to test what they remembered
False memories can be implanted and embellished over time.

The Aging Brain

Diseases like Alzheimer’s and Parkinson’s attack brain tissue and environment and behavior are important. An experimental surgery removed Henry Molaison's hippocampus and left him unable to establish new memories, or imagine the future. The hippocampus plays a key role in assembling an imagined future by recombining information from our past.

Memory of the Future

Henry Molaison's misfortune reveals that function of brain mechanisms underlie memories and allow us to project forward to the future.
The Religious Orders Study explores aging on the brain. Data collection began in 1994 and they found that psychological and experiential factors determined the loss of cognition and cognitive exercise. Therefore positive traits are protective and the participants with diseased neural tissue have built up cognitive reserve where areas of the brain compensate those neurons. Nuns' brains protect our brains helps slow effects of aging.

I am Sentient

When you’re awake you have consciousness, and when you’re in deep sleep you don’t. EEG measures the difference in firing by picking up weak electrical signals, and captures a summary of billions of neurons. During sleep, neurons coordinate with one another differently, entering a more synchronized, rhythmic state. Who you are at any given moment depends on neuronal firing and complexity.

The Mind–Body Problem

Philosopher René Descartes assumed an immaterial soul exists separately from the brain and modern neuroscience works to tease out the relationship of neural activity to consciousness. Brains are like snowflakes with webs of associations. The meaning is unique to one's history of experiences and because we are constantly changing, we are works in progress.

Brains are Like Snowflakes

The meaning of something to you is about gwebs of associations, based on life experiences. Perceptions depend on perspective and all brains have different internal lives. The pattern of new connections means that no one like you has ever existed, or will exist again. The experience of your conscious awareness is unique to you.