Michael Gazzaniga is one of the most important scientists in the field of cognitive neuroscience. In this video he talks about the relationship between mind and brain and the problem of free will.
The relationship between body and mind
Ever since René Descartes (1556 – 1650) wrote his meditations on the foundations of philosophy, philosophers and scientists are working on the mind-body problem. Descartes employed some thought experiments in his work to find out what we can be certain about. As it turned out, it’s not much. The only thing left is Descartes’ famous phrase: “Cogito, ergo sum” – I think so I am. Descartes argued that there are two substances in the world. Matter which is extended – res extensa – and the thinking substance – res cogitans. Since one can imagine that the soul survives while the body dies, these two substances must be different from each other. But how do these substances interact? This question is the origin of the mind-body problem.
Nowadays, there are hardly any dualists who claim that the mind is a substance besides the physical. Psychology and cognitive sciences are investigating the mind, and neuroscience tries to determine the material basis of the cognitive processes. Often one reads horror stories in the news like: Neuroscientists discovered, humans have no free will. That’s why it’s nice to see how relaxed Michael Gazzaniga talks about his point of view.
In his opinion, there is a mutual influence of mind and brain. As the brain constantly calculates and generates suggestions on how to behave, the mind can make a selection that has repercussions on the brain. In addition, the term “free will” is confused anyway . What should the will be free of? Of physical forces that make everything happen in the first place? From past experiences, information and knowledge? It would be terrible if you could not use all that for your decisions.
Split brain experiments
Gazzaniga is best known for his research on split-brain patients. In these patients, the corpus callosum, which actually connects the two halves of the brain, is damaged or disconnected. Surgery disconnection of the corpus callosum is also carried out, for example, in epilepsy patients as a last resort.
Particularly well-known are two patients of Gazzaniga. Patient W.J. was a World War II soldier hit by a rifle butt on the head. After that, he began having seizures. Through surgery, the corpus callosum and the anterior commissure were severed. After the operation, the patient was shown various visual stimuli such as letters in the left and right visual fields. The stimuli that appeared in the right visual field were processed by the left hemisphere of the brain. There is also the language center of the brain. The patient could press a button and say which letter he saw. However, if the letter was shown in the left visual field, then he could press a button but not verbally report that he had seen anything at all. However, if you changed the experiment and just let the patient point to the object, there was no impairment. The condition also caused conflicts between the two halves of the brain. While one hand tried to open the car door, the other hand tried to stop it.
Patient P.S., a teenage boy, behaved similarly. However, one could find out that the boy could not make verbal statements when the stimuli appeared in the left visual field. If you showed him, for example, the word “crush” , then he was able to put with the help of Scrabble tiles the name “Liz”. Thus, even though the linguistic center is in the left hemisphere of the brain, if the form of language is nonverbal, the right hemisphere is capable of some form of language.