As a neuroscience
student, I was particularly interested to catch up on Charlie Rose's year-long "Brain" series, which featured top experts in the field. For those of you who haven't watched it, here is my "cheat sheet" on the first episode.
Making sense of our experiences with the world around us is a problem philosophers have wrestled with for centuries. Modern neuroscientists think that, with the recent advances in science, they are poised to solve it.
The brain is the great frontier in the pursuit of understanding everyone's favorite subject, ourselves. The brain is at the center of our individuality. Throughout history, we've attempted to shine light on the human experience through literature, art and philosophy as well as biology. Neuroscience is a natural bridge between the humanities and biological science. Scientific advances have helped us understand how the brain processes consciousness, free will, perception, cognition, emotion and memory.
To delve into the intricacies of the brain, Rose turned to the experts—leading neuroscientists and philosophers. Nobel-laureate and pioneering memory neuroscientist Eric Kandel joined Rose as the co-host of this round table discussion. Participants included John Searle, preeminent philosopher of free will in the brain; Gerald Fischbach, neurologist and autism expert; Cornelia Bargmann, who studies the brains of microscopic worms; and Anthony Movshon, a psychologist and neuroscientist who studies the visual system of monkeys. Together, they discussed our current understanding of the brain, its structure, and the keys to cracking the mysteries that still confront us.
The human mind is created from the activity of our brain cells; without these cells we couldn't see, think or decide what to have for dinner.
We are one part nature, one part nurture.
There is a genetically-determined, universal logic behind the brain's macro-architecture. All human brains are put together similarly, with two hemispheres and the same regional specificity for seeing, hearing and feeling. On a smaller level, every brain is unique based upon the person's experiences and the things they've learned. Each human brain has a hippocampus that looks roughly the same and serves the same function, but the memories contained within the hippocampus are as unique as our fingerprints.
The brain is constantly changing.
The brain is not hard-wired, as was once believed. Everything we do in the course of our lives, from reading a book to chatting with our friends, causes our brains to change. As we learn, the brain must adapt to store that knowledge. The brain creates memories by strengthening or establishing new connections between cells. Conversely, by breaking the connections between cells, memories can be forgotten. This can happen on a short-term basis, like we when hear a telephone number, but then can't recall it ten minutes later. In this case, the brain undergoes a functional change, but it doesn't undergo an anatomical change. When we learn something on a long-term basis, part of the brain's anatomy is forever different. Cells restructure to account for the memory, and actively maintain the new structure for as long as the memory persists.
The complexity of the brain lies in the cell, the most basic unit of life.
It is not the size of our brain or the number of cells we possess that provides us with extraordinary processing power. Human intelligence arises from the genetic code that tells our brain cells how to function. This code is responsible for creating the connections between cells, the unique structure of our brains and our ability to adapt to our environment.
Our brain is amazingly fragile.
The brain, a three pound organ, consumes 20% of all the body's energy. A lapse in blood flow for a few seconds will cause the death of thousands of cells, as they're deprived of the vital energy from blood. A muscle cell, by contrast, can be deprived of blood for minutes at a time without serious damage.
Brain malfunction is instructive.
One of the best ways to understand the brain is to observe it when it's not working. When a brain region is damaged, through a stroke, injury or disease, we gain insight into the purpose of that region. One of the first examples comes from the work of Paul Broca, a French physician and anatomist during the mid-19th century. Broca had a patient who had lost the ability to speak, but otherwise had no change in mental function. When this patient died, Broca did an autopsy and found a syphilitic lesion in the frontal part of the left hemisphere of his brain. "We speak with the left hemisphere," Broca announced. This gave us concrete evidence that the brain's functions were localized to specific regions and demonstrated the area responsible for language, now known as Broca's Region.
Analysis and Future Directions
Unsolved mysteries of the brain.
Understanding how the brain turns our sensory experiences into a conscious reality is a three-step process. First we must find the neural correlates of activity. What brain regions, and which cells, are active during experiences and actions? Second we must determine whether this relationship is causal, or merely a correlation. Is that particular brain region necessary for an action or experience to take place? Finally, this must be synthesized into a theory. We need a framework to place the idea in to see if it can explain complex phenomena.
The elegance of modern neuroscience is the ability to study simple systems and apply the findings to complex systems. The principles of brain function hold true across species; we have a genetically-determined structure and cells learn through strengthening or creating connections. Much of our insight into human learning comes from research on the genetic and cellular properties of worm and slug brains.
The brain is the executive officer of our personhood, and it oversees the productivity of all the branches which comprise our conscious experience, from vision to language. Although there are discrete compartments of the brain responsible for each of our individual senses and abilities, we don't experience a segmented reality. We experience one cohesive reality that is qualitative and subjective. This gets into consciousness, creativity and free will. But how does the brain do it? As Kandel concludes, "This is the most profound question western thought has ever asked, and we're beginning to mass the troops to answer it."
Major publications of the round table participants:
Principles of Neural Science, Fourth Edition. Ed. Kandel, Schwartz and Jessell. McGraw-Hill, New York 2000
Jazayeri and Movshon (2007). A new perceptual illusion reveals mechanisms of sensory decoding. Nature 446: 912-915.
Searle "Putting Consciousness back in the Brain", Neuroscience and Philosophy, New York: Columbia University Press, 2007.
Fischbach GD. NRG1 and synaptic function in the CNS. Neuron. 2007 May 24;54(4):495-7.
Chalasani SH, Kato S, Albrecht DR, Nakagawa T, Abbott LF, Bargmann CI. Neuropeptide feedback modifies odor-evoked dynamics in Caenorhabditis elegans olfactory neurons. Nat Neurosci. 2010 May;13(5):615-21.