Ray Kurzweil - How to Create a Mind - The Secret of Human Thought Revealed

The system of global neurotransmitter levels, such as serotonin, and hormone levels, such as dopamine, is intricate, and we could spend the rest of this book on the issue (as a great many books have done), but it is worth pointing out that the bandwidth of information (the rate of information processing) in this system is very low compared with the bandwidth of the neocortex. There are only a limited number of substances involved and the levels of these chemicals tend to change slowly and are relatively universal across the brain, as compared with the neocortex, which is composed of hundreds of trillions of connections that can change quickly.

It is fair to say that our emotional experiences take place in both the old and the new brains. Thinking takes place in the new brain (the neocortex), but feeling takes place in both. Any emulation of human behavior will therefore need to model both. However, if it is just human cognitive intelligence that we are after, the neocortex is sufficient. We can replace the old brain with the more direct motivation of a nonbiological neocortex to achieve the goals that we assign to it. For example, in the case of Watson, the goal was simply stated: Come up with correct answers to Jeopardy! queries (albeit these were further modulated by a program that understood Jeopardy! wagering). In the case of the new Watson system being jointly developed by Nuance and IBM for medical knowledge, the goal is to help treat human disease. Future systems can have goals such as actually curing disease and alleviating poverty. A lot of the pleasure-fear struggle is already obsolete for humans, as the old brain evolved long before even primitive human society got started; indeed most of it is reptilian.

There is a continual struggle in the human brain as to whether the old or the new brain is in charge. The old brain tries to set the agenda with its control of pleasure and fear experiences, whereas the new brain is continually trying to understand the relatively primitive algorithms of the old brain and seeking to manipulate it to its own agenda. Keep in mind that the amygdala is unable to evaluate danger on its own—in the human brain it relies on the neocortex to make those judgments. Is that person a friend or a foe, a lover or a threat? Only the neocortex can decide.

To the extent that we are not directly engaged in mortal combat and hunting for food, we have succeeded in at least partially sublimating our ancient drives to more creative endeavors. On that note, we’ll discuss creativity and love in the next chapter.

Our emotional thoughts also take place in the neocortex but are influenced by portions of the brain ranging from ancient brain regions such as the amygdala to some evolutionarily recent brain structures such as the spindle neurons, which appear to play a key role in higher-level emotions. Unlike the regular and logical recursive structures found in the cerebral cortex, the spindle neurons have highly irregular shapes and connections. They are the largest neurons in the human brain, spanning its entire breadth. They are deeply interconnected, with hundreds of thousands of connections tying together diverse portions of the neocortex.

As mentioned earlier, the insula helps process sensory signals, but it also plays a key role in higher-level emotions. It is this region from which the spindle cells originate. Functional magnetic resonance imaging (fMRI) scans have revealed that these cells are particularly active when a person is dealing with emotions such as love, anger, sadness, and sexual desire. Situations that strongly activate them include when a subject looks at her partner or hears her child crying.

Spindle cells have long neural filaments called apical dendrites, which are able to connect to faraway neocortical regions. Such “deep” interconnectedness, in which certain neurons provide connections across numerous regions, is a feature that occurs increasingly as we go up the evolutionary ladder. It is not surprising that the spindle cells, involved as they are in handling emotion and moral judgment, would have this form of connectedness, given the ability of higher-level emotional reactions to touch on diverse topics and thoughts. Because of their links to many other parts of the brain, the high-level emotions that spindle cells process are affected by all of our perceptual and cognitive regions. It is important to point out that these cells are not doing rational problem solving, which is why we don’t have rational control over our responses to music or over falling in love. The rest of the brain is heavily engaged, however, in trying to make sense of our mysterious high-level emotions.

There are relatively few spindle cells: only about 80,000, with approximately 45,000 in the right hemisphere and 35,000 in the left. This disparity is at least one reason for the perception that emotional intelligence is the province of the right brain, although the disproportion is modest. Gorillas have about 16,000 of these cells, bonobos about 2,100, and chimpanzees about 1,800. Other mammals lack them completely.

Anthropologists believe that spindle cells made their first appearance 10 to 15 million years ago in the as yet undiscovered common ancestor to apes and hominids (precursors to humans) and rapidly increased in numbers around 100,000 years ago. Interestingly, spindle cells do not exist in newborn humans but begin to appear only at around the age of four months and increase significantly in number from ages one to three. Children’s ability to deal with moral issues and perceive such higher-level emotions as love develop during this same period.

Wolfgang Amadeus Mozart (1756–1791) wrote a minuet when he was five. At age six he performed for the empress Maria Theresa at the imperial court in Vienna. He went on to compose six hundred pieces, including forty-one symphonies, before his death at age thirty-five, and is widely regarded as the greatest composer in the European classical tradition. One might say that he had an aptitude for music.

So what does this mean in the context of the pattern recognition theory of mind? Clearly part of what we regard as aptitude is the product of nurture, that is to say, the influences of environment and other people. Mozart was born into a musical family. His father, Leopold, was a composer and kapellmeister (literally musical leader) of the court orchestra of the archbishop of Salzburg. The young Mozart was immersed in music, and his father started teaching him the violin and clavier (a keyboard instrument) at the age of three.

However, environmental influences alone do not fully explain Mozart’s genius. There is clearly a nature component as well. What form does this take? As I wrote in chapter 4, different regions of the neocortex have become optimized (by biological evolution) for certain types of patterns. Even though the basic pattern recognition algorithm of the modules is uniform across the neocortex, since certain types of patterns tend to flow through particular regions (faces through the fusiform gyrus, for example), those regions will become better at processing the associated patterns. However, there are numerous parameters that govern how the algorithm is actually carried out in each module. For example, how close a match is required for a pattern to be recognized? How is that threshold modified if a higher-level module sends a signal that its pattern is “expected”? How are the size parameters considered? These and other factors have been set differently in different regions to be advantageous for particular types of patterns. In our work with similar methods in artificial intelligence, we have noticed the same phenomenon and have used simulations of evolution to optimize these parameters.