This book combines review author’s life history and his scientific experience. Most interesting are stories about scientific discoveries related to the functioning of a human brain especially the separation of duties between its left and right hemispheres. The method of research was direct experiment with individuals who due to an illness had these parts surgically separated and functioning as two brains in the same body.
Part 1 Discovering the Brain.
Chapter 1 Diving Into Science
This chapter is about history of author’s initial involvement with Caltech program in psychology and its outgrowing into neurobiological research. It is also an interesting review of California scene of higher education, scientific research, and even politics in 1960s.
Chapter 2 Discovering the Mind Divided
This is description of initial split-brain research conducted in early 1960s and personalities of leading scientists who participated in this development, their achievement, attitudes, and squabbles. The important discussion here is about difference in scientific research then and now, including continuing growth of dependency on government grants and bureaucratic approvals. Based in this it looks like achievements of 1960s would not be possible today due to bureaucratic red tape. It is also a description of important discoveries such as relative independence of some functions of left and right parts of the brain such as visual perception, combined with significant specialization in some other areas such as speech being nearly exclusively domain of left hemisphere. At the same time some sensory-motor integration was working across semi-spheres. An very interesting experiment demonstrated that some split-brain patients were able to control ipsilateral arm, but not hand, while just about everybody had good control of contralateral hand and arm. The outcome of this puzzle was the great discovery of absence of hierarchical central control system that researches expected to find in the brain. It turned out that it is rather loose combination of the multitude of semi-autonomous and sometime completely autonomous systems only partially synchronized.
Chapter 3 Searching for the Brain’s Morse code
This chapter reviews attempt to find communication code used within brain leading to discovery that such code does not exists. In reality coordination is achieved by using cueing strategy that allowed hemispheres transfer information via external cues even if they were surgically separated. This chapter also describes interaction and cooperation with David Premack and his development of “theory of mind”, meaning ability of a mind to continuously develop and test a theory about status of another mind. The ability to create and use theory of mind could be found in animals, but only to very limited extent. It fully blossoms only in humans and could be considered a very important point of differentiation between humans and other animals.
Part 2 Hemispheres Together and Apart
Chapter 4 Unmasking More Modules
This chapter moves to motivation mechanisms. The experiment was with rats who where fixed to be either want to drink or to run and indifferent to other activity so the setup was to incite rat to do what it does not like in order to get ability to do what it likes. As one would expect animals learned connection and successfully used means to ends procedures. It also describes a number of experiments using people with split brain to identify links between various methods of perception as related to use of right or left hemisphere. Another interesting experiment was with role of emotions. Left hemisphere was trained to make selection by using feedback for right and wrong, while right was not. Initially trained hemisphere quickly learned to make correct choice while untrained, as expected, did not. However after provided emotional feedback allowed untrained hemisphere to learn what is expected and select right answer. Another important discovery was identifying “interpreter” in left hemisphere. When split-brain patient had some stimuli presented to right hemisphere to make him do something and then asked why he did it, the left hemisphere responsible for logic and language processing had no knowledge about the stimuli so it would come up with some logical, even if complicate and twisted explanation of action through conscious intention that was obviously not the case. So instead of a little controller and “leader” in our head we actually have just a spin master who is continuously trying to make sense from whatever we do.
Chapter 5 Brain Imaging Confirms Split Brain Surgeries
This starts with review of experiment demonstrating “double simultaneous extinction” that allowed to demonstrate role of unconscious in making conscious decision even if person does not understand this role. From here author goes to the creation of cognitive neuroscience that he defines as “the study of how the brain creates the mind”. Here is diagram to illustrate this approach:
The final part describes arrival of MRI and with it some limited ability to see what’s going on inside living brain.
Chapter 6 Still Split
This chapter is about farther development based on advances in fMRI, PET and other technologies. Then it followed by description of the next adventure when new experiments seem to be demonstrated connections between hemispheres of split brain. Eventually it was proved experimentally that it was cueing and other non-direct method of communications developed by patients with long experience of being tested that explained 78% accuracy of responses. Another series of experiments directed to mechanism of attentions demonstrated that each hemisphere had its own mechanism of attention control, but at the end attention was unifocal due to demand of resources when attention was on. Finally the chapter describes experiments with patients who had only partially split brain.
Part 3 Evolution and Integration
Chapter 7 The Right Brain Has Something to Say
This one is about new technology that allowed to record brain electric activity and its timing in different parts of brain during experiments. Based on this experiments they were able to identify synchronization mechanism of the brain. Another interesting phenomenon discovered was ability of right hemisphere slowly developing language ability after the split, even if this ability was limited. However it was based more on ability to transfer cues to the left hemisphere than actual development of the new functionality by the right hemisphere. This chapter also describes participation of psychologists in split-brain research that allowed identifying patterns of semantic and episodic memory with both hemispheres capable to do it, but each doing better in its area of specialization: right for visual data and left for verbal.
Chapter 8 Stately living and Call to Service
This chapter contains additional discussion of “interpreter” – the brain mechanics of making sense out of received information regardless of its having sense in the first place. There is an interesting discussion of human propensity to making mistakes as evolutionary advantage of making action possible even when information is incomplete or misleading. This chapter also describes initiation of Human brain mapping project based on dramatically increased capability of computers and neuroimaging.
Part 4 Brain Layers
Chapter 9 Layers and Dynamics: Seeking New Perspectives
The final chapter includes summary of the Brain principles:
- Brain comes with a lot of inherent programs – neurospecificity to handle environment
- Processes of underlying behavior, cognition, and even consciousness are highly modular and work in parallel.
- It has high levels of redundancy and plasticity to resist small to moderate damage.
- Lots of brain processes are not accessible to conscious perception so brain splitting that removes connection between hemispheres makes sensual right hemisphere inaccessible for logical left hemisphere and vice versa creating two conscious entities in one body each perceiving that nothing changed.
- Modularity of control functions is not limited to brain, but rather extended to all systems of the body making it into distributed network of analog control systems.
- Brain is built on an emergence principal when lower level complex systems organize into a new structure, with new properties that did not exist before.
- One issue author believes is still open is application of Supersede notion to the brain, which means that there could be no difference in high level function of the system unless there is some difference in physical condition of underlying lower level systems.
- Brain has layered architecture with different layers being semi-independent.
Author provides a nice metaphor for a brain: symphony orchestra with array of instruments organized into complex sequence of actions creating music, but cautions that in case of brain there is no central control to direct this orchestra.
MY TAKE ON IT:
From my point of view author’s lifetime of experimentation with split-brain patients provides a great insight into working of human brain that is very much consistent with my view at it. I believe that there is no mind/brain duality whatsoever, but rather fully material complex network of semi-autonomous biological analog systems working at some level of synchronization developed through continuing experimentation / system training when millions of experiments result in development of proper response to a multitude of environmental situations. On the higher level of consciousness brain is a complex instrument for past explanation building / future prediction development / communication and coordination with other brains to synchronize explanation-prediction-action / results analysis / explanation-prediction update for next action. All this together evolutionary justify complexity and cost of brain maintenance due to superior ability it provides for adjusting to continuously changing environment via complex cooperative actions.