Getting Connected
2 December 2008
“The brain is a three pound mass you can hold in your hand that can conceive of a universe a hundred billion light years across” Marian C Diamond (2)
In the first American psychology textbook, William James described the brain as the “most mysterious thing in the world.” (1) The mind is arguably the highest, most complicated object that has evolved on earth. Neuroscientists are using brain images to argue that the mind is nothing more than the brain. (10) John Searle, philosopher at University of California said that a “computer is not merely a tool in the study of the mind; rather the appropriately programmed computer really is a mind.” (10)
The brain is often compared to an on-board computer. Like an electronic computer, the mind functions in many different ways. (2) “It can be swiftly reprogrammed to become any machine you like: calculator, word processor, card index, chess master, musical instrument, guess your weight machine, even, I regret to say, astrological soothsayer.” (2) While the animal brain may share similarities with a computer, it operates with very different hardware. (2) Neurons are much slower than the transistors of an electronic processor. (2) However, Neurons operate “in huge parallel networks so that… their numbers compensate for their slower speed, and brains can, in certain respects, outperform digital computers.” (2) The capabilities of artificial intelligence will likely surpass those of the human mind within the next few decades. (10) The human brain can be calculated to have a computational capacity of roughly ten petaflops. (10) This number is arrived at by multiplying the number of neurons, one-hundred billion, and the average number of connections between the neurons, one-hundred trillion. (10) The prefix peta means a quadrillion or a one with fifteen zeros behind it. (10) IBM’s Blue Gene series should achieve this theoretical capacity by 2015. (10) “…With the software, we could be having interesting conversation with the planet’s newest species, as early as 2010.” (10)
The human brain is composed of billions of information processors called neurons. (1) Neurons are cells that communicate to one another with electricity. (1) Many of them combined create the highly interconnected network that is responsible for all of a persons sensation, perception and cognition. (3)These incredible cells unite to form the brain and the nervous system. (1) Neurons are highly specialized to send information through the body’s network. (1) Camillo Golgi developed a staining technique that allowed him to be the first to see the structure of these cells.(1) The cell body contains all of the vitals for keeping the cell alive. Out from the cell body extend dendrites. Dendrites connect to other neurons and receive incoming messages. The outgoing side of the cell is called the axon. This tale like structure carries the message, called an action potential, to other neurons. This signal is propagated, meaning that “once a signal is generated at one end of the axon, it travels to the other end without decreasing in size.” (1) In this parallel network, signals can be transmitted a long distance very quickly, from the sensory organ to the brain.
The space between neurons is called the synapse. When an action potential reaches the end of an axon, it causes structures called synaptic vesicles to release chemicals into the synapse. (1) These chemicals, called neurotransmitters, carry signals from one neuron to the next. In this fashion, signals are carried from the sensory organs to the brain where they processed
When a stimulus first reaches a sensory organ it encounters a sensory receptor attached to a neuron. (1) Through a process called transduction, the stimulus is represented as an electrical signal and sent down the information highway. (1) The visual, auditory, coetaneous, or tactile, and chemical, or olfactory, senses all begin at these sensory receptors which attach to the cell body in place of the dendrites. This message, called a neural code, is similar to the binary code upon which a computer operates. (1 & 8) Binary code utilizes only two digits. A one represents on, and a zero that represents off. Computers use this simple system to store and manipulate all data. Similarly, neurons are either on or off. All of the information that a person will experience will be transmitted through these parallel wires running throughout the body. All objects perceived by an individual are represented through this coding and how it is distrusted across the neural network. (1)
After traveling through the nerves running throughout the body, the information arrives at the brain. This complex collection of neurons is highly specialized. The brain contains many areas localized for particular functions. (1) The cerebral cortex is the outer layer of the brain. (1) This three millimeter thick surface is “responsible for most of the higher mental functions such as perception, memory, language, thinking and problem solving.” (1) The cerebral cortex is divided into four lobes. (1) The temporal lobe is vital for memory, language and hearing. (1) The occipital lobe is the first area to receive visual information. (1) The parietal lobe is mainly responsible for coetaneous senses, attention and action. (3). The frontal area serves in motor function, as well as language and memory. (1) The brain does not only receive information in this bottom-up process, but will also interact with and selectively attend to important items in a top-down manner.
This complicated system is the result of natural selection as well as a property of neurons called experience dependant plasticity. (3) Genetic characteristics that enhance an organisms ability to reproduce and thus copy the gene are more likely to be passed to future generations. (5) The brain, like all complex organs, has come to exist through “gradual, step by step transformations from simple beginnings.” (5) The nonrandom survival of random genetic variation over a very long time has produced this and other incredible organs (5). A more capable brain could be beneficial to an organism in a large number of ways. (2) A similar development can be seen in the progression of electronic computer processors. From the humble beginnings of only a few processing units called bits, exponentially more powerful machines, capable of handling gigabytes of data at a time, have grown. Exponential is a good description of this growth. Like the brain, more processing power is greatly beneficial to the computer. Moore’s law originally stated that a computers processing capability will double every two years. (2) The brain by comparison is “a rough equivalent of Moore’s law, slowed down by six orders of magnitude.” (2) Brain size has doubled approximately every one-point-five million years. (2) The human brain over the last million years has been said to be “perhaps the fastest advance recorded for any complex organ.” (2)
One possible reason for this balloon of neurological capacity is the development of language. (2) Unlike other animals which have less sophisticated mental ability, human languages uses a limited number of phonemes to form a potentially infinite number of words. (2) These words can be combined in an equally infinite number of sentences. (2) There no real evidence to say whether or not the ancestors of modern man gradually created a progressively more complex system of language. (2) However, a brain that is better adapted to utilize this new communication system would surely benefit the reproduction of the genetic code that created it. (2) Language gives man the ability to ask questions. (9) “Speech has fundamentally transformed human beings.” (9)
The nature of genetics is complimented by the nurture of experience dependant plasticity. (3) Experience dependant plasticity is a property held by neurons that allows them to change with use. (3) As the neuron fires repeatedly, physical alterations to the neuron at the synapse occur. (3) Here, the receptors on dendrites of the cell body become more sensitive to neurotransmitters when stimulated. (3) This causes the sensory system to be most responsive to stimuli that are frequently present. (3) This plasticity, along with natural selection, is thought to be the cause of the development of highly specialized neural function. (3) Experience dependant plasticity takes these highly developed evolved cells and further specializes and customizes them for the benefit of the individual. (3) Neurons may be tailored to respond to specific orientations, language phonemes, objects or people . (3) Groups of neurons combined represent almost everything contained within perceptual system. (3)
Memory is stored at the synapse. (1) The process of excitatory and inhibitory neurotransmitters sending messages across the synapse causes physical changes in the neurons that are stimulated. (1) This change is called long term potentiation. (1) As neurons are used, synaptic consolidation occurs within minutes, effecting a specific cell. (1) Larger scale change called systems consolidation is a gradual reorganization of the circuits within the brain. (1) This process takes months or possibly years. (1)The ability of neurons to modify according to stimulation is extremely vital to the functions of the sensory and perceptual systems. (3) This property allows learning, the encoding of memory and heightened sensitivity to important stimulus. (3) Every human brain is created by the combination of an evolutionary history and the property of plasticity found in neurons.
Just as nature and nurture are deeply related, so are physiology and psychology. Just as each person has a completely individual personality, their brains are equally original. (6) “…There is not a single organ of the human body the structure of which does not vary… …The characters of the brain vary immensely, nothing being less constant than the form and size of the cerebral hemispheres,” which are responsible for most higher brain function. (6 &1) Every individual will have a very unique brain (6) Distinctions may include “the size and form of the cerebral hemispheres, and the richness of the convolutions upon their surface.” (6) Human skulls often differ from one another not only in absolute size but also in containment area available for brain storage. (6) With all of this personalization of the brain it is no wonder that human personalities can be so extremely varied.
Many ask where exactly this personality, or consciousness is located. Human consciousness has been a mystery and still is today. (7) In 528 BC, the Indian philosopher Siddhartha Gautama began a study focused on consciousness. (7) In 401 AD, Saint Augustine said “I understand that I understand”. (7) In the 17th century, Rene Descartes attempted to explain consciousness as separate from the physical matter of the brain. (7) This idea is know as Cartesian Dualism. (7) William Wundt, said to be the father of experimental psychology, began the modern approach in 1874 with focus on analytic introspection. (7) Descartes’ position was disproved in the mid 1800s with the use of anesthetics. (7) When under anesthetics, the brain will cease conscious activity. (7) Another revelation came in 1929 when German neurologist Hans Berger placed electrodes on the skulls of his subjects and measured electrical activity occurring in the brain during various situations. (7) This technique, known as the electroencephalogram, allowed Berger to detect Alpha and Beta waves in the brain. (7) Alpha waves seem to coincide with consciousness. (7) Alpha waves fade during sleep or anesthesia. (7) Berger’s findings pioneered the neural correlates of consciousness. (7) Many scientists think that this measurement of activity within the brain is the key to understanding consciousness. (7) Jeff Hawkins, Palm-Pilot inventor, said “consciousness is simply what it feels like to have a neocortex” (10)
The mind is only conscious or aware of a small percentage of the stimulus it is receiving. (3) This tiny fraction of incoming information being broadcasted to the senses at all times is called a person’s attended stimulus. (3) In experiments performed by Benjamin Libet, subjects were exposed to various stimuli that would cause electrical activity, signifying that the brain did detect the stimulus; however, the patients would be totally oblivious to the stimulus. (7) Our eyes transmit information at a rate of approximately a megabyte per second, but most of this is ignored by consciousness. (7) Decision and sensory processing both cause significant delays. (7) Electrical pulses occur sometimes a second before a person can say they are aware of any thought. (7) Some think that this may spell doom for the concept of free will, as the evidence shows the brain working first and consciousness being affected by this change. (7)
Dopamine, a neurotransmitter, displays “tantalizing connections between the peculiar habits of our neurons and the peculiar habits of real people.” (8) Dopamine is involved with the processing of pleasure from rewards like food or sex. (8) In 1954, two neuroscientists at McGill University, named James Olds and Peter Milner, implanted an electrode deep inside a rat brain next to the nucleus accumbens. (8) This part of the brain is dense with dopamine neurons. (8) When Olds and Milner artificially stimulated this area by running a current through the electrode, “the rats would just cower in the corner of their cage, transfixed by their bliss.” (8) Within days, the rats were dead from thirst. (8) This stimulation flooded the brain with dopamine which “overwhelmed the rodents with ecstasy” similar to the way addictive drugs work in humans. (8) This physiological utilitarian model of chemical rewarding in the brain is supported by evidence from positive reinforcement. (8) Positive reinforcement is the process of making a behavior more likely by rewarding its’ performance. When a primate is first presented with a unconditioned stimulus there is no change in dopamine production. (8) Once the stimulus has become conditioned through successive rewards, dopamine production will increase at the presentation of the stimulus even if the reward is not present. (8) An interesting aspect of these dopamine cells is that they are often more concerned with prediction of the reward than with the reward itself. (8) When the now conditioned stimulus is first presented, the firing rate of these neurons increased for a short while but abruptly decreased when the reward did not follow, causing the monkey to get upset. (8) This evidence is leading some to say that dopamine may play a large role in decision making. (8) If the anticipation of a reward can be represented by the firing rate of dopamine neurons, the brain may economically choose the option that causes more production of the neurotransmitter. (8)
“The human brain is complex beyond anybody’s imagining, let alone comprehension” (9) Neuroscience is a new practice. Modern brain imaging techniques have been developed “in the past ten or fifteen years.” (9) Much of the future for neuroscience includes social processes of humans. (9)
“The twentieth century view is that our brains are biological computers and that free will is an illusion.” (10) In his 1996 essay, Tom Wolf apologized “Sorry, but Your Soul Just Died.” (10) A project called “Neuroscience and the Law” is asking questions about free will and causality. (9) “There are these casual forces that make us do the things we do.” (9) “By the time you’re consciously aware of something, your brain has already done it.” (9) Some call this concept “materialism.” (9) Like computers, programmed through genetics and the environment, an individual can do nothing to change his or her programming. (9) “The scientist says ‘we are machines.’ There’s no ghost in the machine” (9) “This machine has no free choice. It is programmed…” (9) A person is a brain that has been interacting with the environment since birth. (9) The brain bases many decision on experience and makes an economical judgment. (9 & 8) It seems as though there is no longer any room for choice or true originality. One of the scientists that discovered the structure of DNA‘s double helix, Francis Crick called this “‘the astonishing hypothesis;’ what we used to call the soul is all just neural activity.” (10)
Works Cited
1. Goldstein, Bruce. Cognitive Psychology: Connecting Mind, Research, and Everyday Experience, Second Edition. Belmont: Thomson Higher Education, 2008
2. Dawkins, Richard. Unweaving the Rainbow. New York; Mariner, 1998
3. Goldstein, Bruce. Sensation and Perception. Seventh Edition. Belmont; Thomson Higher Education, 2007
4. Dorn, Janice, “This is Your Brain on Trading.” 2007 http://www.sharpbrains.com/blog/2008/06/05/your-brain-on-trading-101/
5. Dawkins, Richard. The Blind Watchmaker. New York; W.W. Norton & Company, 1986
6. Huxley, Thomas. Evidence as to Man’s Place in Nature. New York; Barnes & Noble. orig 1963
7. Mathews, Robert. “Big Idea: Consciousness.” BBC Knowledge September/October 2008
8. Lehrer, Jonah. “A New State of Mind.” Seed. July/August 2008
9. Wolfe, Tom and Michael Gazzaniga. “Seed Salon” Seed July/August 2008
10. Dooling, Richard. Rapture for the Geeks. New York; Harmony 2008
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