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HOW DO THE HEMISPHERES WORK?
What does all this mean? Can the brain by its functioning begin to make sense of all these things it has learned about itself? The answer offered here is yes, it may be able to. Part of the biological operation of the human brain seems to be the capacity to consciously make sense of itself. And in so doing we have (it has) gained a powerful perspective for understanding all the activities (from making out a grocery list to choosing to exercise even when it hurts to spending a lifetime studying obscure South American butterflies) and thoughts (who am I, why did she/he do that to me, why does the sun shine) that are the result of that functioning.
Further, if we begin to see our self-aware ability to relate and understand as the crowning achievement of nature at work, the best of God's handiwork, if you will, then gaining insight into the processes of the central nervous system that facilitate this is truly a doorway to understanding all of nature. Our thoughts are literally nature at work or as much of nature as we can know about. (Or, put another way, since we and our brains are a product of nature itself, the study of the brain is, in a very real sense, nature studying itself at the most profound levels.)
So by consciously observing and exploring the organ of thought, our main tool for dealing with the world, we (our brains) can better appreciate the explanations, adaptations, creations and behaviors that are a reflection of its functioning. And, indeed, our brains (we) can learn to better adapt to, quite literally, ourselves and the larger environment of which we are part and, by our actions, profoundly influence.
The questions raised by the seeming half-brain role reversals I just discussed provide some clues I think we need to determine what is actually going on inside our heads. To put together the puzzle we have confronted, let us look at one more piece of research about the functioning cerebral cortex.
Neural Organization
In the mid-60s Josephine Semmes of the National Institute of Mental Health in Bethesda, Maryland undertook an investigation to better understand the organization of neurons in the two hemispheres. Her subjects were 124 veterans who had sustained brain injuries. There were 36 with bilateral damage, 44 with left damage, and 44 with right damage. What she examined was the ability of the contralateral hand to function after damage to the sensorimotor strip in either of the hemispheres. The sensorimotor strip is the area of the cortex where we consciously experience nerve impulses from the body and from whence conscious direction goes out to the body to perform purposefully. Of her results, she says:
...when we asked how deficits on the three cutaneous [sense of touch] tests were related to site of lesion, to our surprise it turned out the question had a different answer for the right and left hands. For the right hand, the incidence and severity of deficits were maximal after lesions of the left sensorimotor region. ...For the left hand, however, deficits on the cutaneous tests were not clearly related to lesions of the right sensorimotor region.26
In other words, there was a correlation between deficits in the right hand and localized damage to the left hemisphere, but the correlation between deficits in the left hand and localized damage to the right hemisphere was not so clear. Semmes could pin down the kind of expected deficit in the right side of the body from a localized lesion in the left hemisphere, but she could not do so with damage to the right hemisphere. What Semmes' research indicated was a highly focused organization of connections among neurons in the left hemisphere and a diffusely organized set of connections among those in the right hemisphere. This means that the organization of neurons in the left hemisphere is compartmentalized, while the neurons on the right side of the brain seem to interconnect such that all are related some nearly direct way to all others.
These two types of neuron organization, she suggested, could be responsible for the functionally asymmetrical modes of processing. Of the left hemisphere, she says:
Where there is a higher concentration of units representing a particular part at one level, the convergence of these units upon those of the next level would bring about a more precise coding of the input and would thus make possible a more finely modulated output.27
And of the right:
In contrast to functions which depend on a high degree of convergence of like elements, spatial functions might depend instead on the convergence of unlike elements—visual, kinesthetic, vestibular, and perhaps others—combining in such a way as to create through experience a single supermodal space.28
In other words, the ability to manipulate the hand in a precise and orderly fashion (and perhaps to think propositionally, create and use language, and speak) requires a highly structured organization of neurons. The ability to experience the world spatially and melodically, conversely, requires that all sensory input be integrated. So here is one more clue to understanding asymmetric brain processing—the relatively discrete connection and organization among neurons in the left hemisphere and the relatively diffuse connections and organization among neurons in the right.
Using the idea of neuron organization as a possible explanation for the different ways the hemispheres process sensations and experience, let us try to analyze further what we have discovered about their functioning as the next step in coming up with a satisfying synthesis of what is going on inside our skulls that is consistent with the research. To do this, let's start with one more review of the capabilities and deficiencies of the left hemisphere.
One More Time: The Left Hemisphere
We saw that the left hemisphere is not able to comprehend sensory perceptions for which it does not have names, or, conversely, it will only understand its experiences to the degree that it can use words to describe, define, and fix these experiences. That is, it must be able to associate in fixed fashion a specific sound or set of sounds, words (or an alternative set of symbols), with a set of objects and actions. Without this fixed one-to-one relationship, the isolated left hemisphere does not comprehend what it senses.
In Levy's block identification test, for example, the right hand examination consisted of manipulation with constant verbalizing of specific characteristics. And in a whole series of tests thereafter we saw how there must be a pre-set association between object and word for the left hemisphere to respond. This is an important point to remember. If the left hemisphere does not have a linguistic cue to connect with its sensory experience, including bodily sensations, it cannot know what it is experiencing and thus ignores these perceptions or, at best, comes up with a linguistic association which may or may not be correct or appropriate.
The left hemisphere has no ability to distinguish one particular object of the same class from another, as the face identification test, for example, shows. Rather it perceives objects as members of a class rather than as individual entities, and any object will stand for the class of objects of which it is a part.
Its ability to distinguish individual items is directly tied to its storehouse of words used to distinguish smaller and smaller classes of objects. In everyday life, for example, this is demonstrated by observing that one aim of advertising is to promote brands (names) that will facilitate easy distinction of one product from another. However, as we have noted, if the left hemisphere does not have a word to classify what it perceives there is no comprehension. It cannot understand its perceptions in and of themselves separate from this linguistic classifying process. To the left hemisphere, words, then, are not arbitrary symbols but devices absolutely necessary for conscious purposeful cognition.
Besides classifying groups of things, we may ask what other meaning the left hemisphere takes from its words since they do not suggest distinctive individual items. Let us again consider Jerre Levy's chimeric figure test, in which objects were to be matched functionally or visually. The left hemisphere matched objects it saw in terms of function. Since we know that this hemisphere only understands objects as words or symbols for classes of items, we must assume that the objects seen suggest words that were then matched according to what the left hemisphere knows them to mean. We see that assigned meaning has to do with function. Names classify objects by function, that is, by what they do purposefully through time. For example, the word car does not mean four-wheeled object to the left hemisphere, it means four-wheeled transportation among other functions we might also assign to it.
For the left hemisphere, knowing is distinguishing classes of objects by what they do. The world of the left hemisphere is one of preconceived notions, a world of fixed associations and meanings based on function. It is a world of pieces that fit according to how the left hemisphere has learned they fit. For example, Richard Restak, in his book The Brain: The Last Frontier, tells of a patient with right hemisphere damage who upon being shown a picture of a wedding saw it as a funeral because people were crying and the woman was wearing a veil.29 This is a reasonable assumption if one looks at individual parts of the picture and associates what is seen with crying and veils, but it makes no sense when the picture is seen as a whole—something we know the left hemisphere is unable to do.
We now have a further perspective for elaborating on those seeming role reversals in the disconnected left and right hemispheres. The left hemisphere was unable to differentiate among faces, musical pitch, or other items that require pure sensory discrimination without the use of language. We saw that the separated left hemisphere's world was stereotyped and seemingly tied to concrete reality, and that it perceived the things that make up its world not in terms what they look like objectively, but in terms of their subjectively assigned functions. And we also saw that the left hemisphere does not sense the passage of time.
Linguistic thoughts, since they consist of a sequence of words, are by their nature sequential. If sensations can only be perceived in terms of words, this means the left hemisphere can only deal with the world in a sequential fashion, one aspect at a time. It's as if one were in a moving car rushing down the highway but only perceiving what is going on inside the car, where everything seems still. Such sequential operation seems to preclude the ability to perceive sequence, that is a changing, dynamic world, thus preventing any meaningful recognition of the passage of time.
Looking back at the role reversals that concerned time, to try to objectively associate the left hemisphere by itself with the idea of time becomes a rather fruitless exercise. Sequence may characterize its operation but time and sequence are not within its consciousness. Separated from the right hemisphere, its world, as we have seen from the research, becomes timeless.
We have seen that the associations among words and images are fixed for the left hemisphere. Similarly, the left hemisphere's associations maong words themselves (and thus the objects and/or actions for which they stand) are also fixed in a way that is consistent with our grammar and syntax. This creates, quite literally, a kind of grammar of reality itself. To further understand this, we might think of the brain as the digestive system of experience. Like an animal whose system is designed by nature to digest only certain foods in certain ways, so the separated left hemisphere can only process human experiences in certain ways—ways that are consistent with the concrete meaning of words and grammar it has come to know.
Now let's try to understand the left hemisphere's inability to perceive tone of voice. Because tone has to do with the way a word is spoken and not the word itself, we can see that it is impossible to create a word to symbolize a particular tone of voice and the object/action it stands for at the same time. We can talk about harsh or playful tones of voice, but words do not duplicate those tones.
The fact that the left hemisphere, apparently by its neural structure, can only consciously deal with words helps us to understand why it is unable to distinguish among tones. It's like a blind person's reliance on sound and touch to perceive the world. To this person, rich visual images will have no meaning. So, too, literal interpretation of language becomes the only alternative to the hemisphere that is, by its nature, atonal and thus unable to pick up on the verbal and non-verbal cues indicated by tone of voice.
However, it is usually the tone as well as the spatial and emotional context in which words are spoken that give them meaning in any particular situation. Being unable to grasp this contextual data, the only resource the person with an intact left hemisphere has in dealing with the world is language which, in the absence of contextual data, can only be interpreted literally. Like the blind man who, when confronted with a situation in which only sight will help, will find himself lost, so it is with the left hemisphere which becomes almost as lost when forced to use static, literal interpretations to negotiate within a dynamic, metaphoric world.
Observing this behavior, scientific observers have labeled the world of the left hemisphere as stereotyped and rigid, literal and concrete. However, since we know that to this person, words are symbols for objects and their functions, and objects and what they do are likewise symbols for words, perhaps a better way to characterize this world is as one that is entirely symbolic. It is a fixed world of symbols that are manipulated in fixed ways. This idea might be obscured by the fact that we normally do not think of language and the objects and actions to which our words refer as symbols for each other. Thus we get judgments by researchers of stereotyped, concrete repetitious behavior in those with only a functioning left hemisphere, but within this fixed symbolic world, such behavior makes perfect sense.
In terms of the hemisphere role reversals, whether we label behavior symbolic or concrete, then, depends on our perspective and the context of our definition (thus facilitating reversing the roles of the hemispheres as shown earlier when the context of the definitions was changed). Ironically, the ability to appreciate different perspectives is missing from the left hemisphere functioning alone.
Before dismissing the left hemisphere as a mental cripple, let's make a general observation here. Our world, reality as we know it, is organized sequentially through time and space. Change (or reorganization) is the one constant. And this organizing process is always going on, which means that everything that makes up reality is "functioning," that is, doing something through time. So despite the left hemisphere's inability to perceive space and time (that is the neural organization that allows us to order and sequence our thoughts using language seems to preclude the ability to perceive space and the passage of time independent of those thoughts), its innate understanding of the world in terms of function is correct. The question we may ask is, given its perceptual deficiencies, how does the left brain come to this correct understanding?
Before attempting to answer this, there is one final point we need to address with regard to the left hemisphere. What we have seen so far is that this half of the brain operates by perceiving or conceiving one piece of reality at a time (a word) through time. And it can only deal with those percepts or concepts for which it has words. But words are human-created symbols used to define experience, and they do not exist if humans do not exist. This means that the left hemisphere in its operation can only understand its perceptions in human terms—as words, our symbols for bits of human reality. Words, then, are the precursors of conscious left hemisphere functioning. The question arises: where is it that the left hemisphere gets its words and grammar? By what mechanism is it motivated to develop and use the language (words, grammar, syntax) capability necessary for it to function properly in the first place?
One More Time: The Right Hemisphere
The answers to these and other questions raised above, I believe, lie in continuing our examination of the right hemisphere. The research shows that this half of the brain correctly hears tones and can identify environmental sounds such as surf. The right brain easily sees and identifies faces and other forms and can direct the left hand to copy simple figures. It is able to distinguish various shapes manipulated by the left hand out of sight. And though it is aware of the passage of time by its ability to perceive changes in space, it is not able perceive the time patterns (rhythm) of music distinct from the music itself.
While there is neglect of the left side of space with left hemisphere damage (and note the left hemisphere ignores the half of the body it is on), there is no right side neglect when only the right hemisphere is functioning properly. Furthermore, the behavior of the person with only a right hemisphere manifests appropriate emotional responses to a changing reality with little loss of personality traits. In other words, the right hemisphere seems to get things right perceptually.
The major thing the right hemisphere cannot do is speak propositionally. It cannot abstract out pieces of reality, assign words to those pieces, and sequence those into logical thoughts and statements. But what it does do is make the connection between the real world situations in which it finds itself and the somatic sensations and emotions that are indicators of our bodily state at any time. It is the diffuse organization in the right hemisphere as described by Semmes that seems to provide for the integration of all sensations simultaneously, both somatic and emotional and those sensations of the environment pouring in through the sense organs. And it is this ability to connect up emotions with the situation in which we find ourselves, as we have seen earlier, that defines the quality of personal involvement in any experience. But the neural organization that facilitates this also seems to preclude the abilities necessary to create and use words and language to define, and think about this experience. Before trying to get at exactly what is going on here with these different hemispheric capabilities and deficiencies, let's talk just a little more about this idea of the brain only being able to see the world in relation to the body of which it is a part.
The Brain, the Body, and the World
We may think of the right hemisphere as the "melting pot" of human sensation. As we have noted, it is not possible for the right hemisphere, which perceives the world as it actually looks, sounds, and feels to operate without also perceiving, at the same time, the internal sensations of the body. We saw that the left hemisphere is unable to process that for which it does not have words, and that words internally symbolize fixed relationships between the body and brain and the external world. Likewise, the right hemisphere cannot process external sensations without integrating those with the internal feelings and emotions it is experiencing at the same time.
The point of this is that what we perceive is not a world separate from ourselves, but one that automatically, by the nature of our brain processes, takes in ourselves. We might even say that each conscious brain is a kind of individualized control center for the internal and external environment in which it exists.
It is uniquely designed to discover, seek to understand, relate and adapt to, shape, and control our bodies and every other aspect of the environment so as to preserve itself and the entire environment it has deemed through its experience (physical, as well as, for example, psychological, economic, political, social, ecological, philosophic, and spiritual) to be necessary for that preservation.
Indeed the whole concept of self becomes one of working out the relationships (and the myriad ways these can be defined and interpreted) among the things that make up the world including one's physical and biological being as simply one more part of that world. The body and brain are simply the tools through which this happens. In other words, when we look around, we do not see a world independent of ourselves, but to the degree our brains make any sense of the world, they are perceiving only the myriad human rationalized connections among the objects (including, among those objects, the body and brain) that ultimately make up and define what the notion of "self" is in the first place to each one of us.
"Self," then, does not mean you or me as individuals, but you and me as a personally defined set of relationships among all the things that make up our subjective worlds. The functioning of both hemispheres, one in which human-created language defines our connections with what we are sensing and the other in which emotional, somatic, and environmental sensations are integrated together, confirms this important point.
In terms of behavior, the reason there is not a change in the personality or emotions of individuals with only a functioning right hemisphere is because they continue to perceive the relationship of themselves to the larger world in the same ways they always have. Behaving successfully in the full range of human situations must include personal feelings that are not only a part of any situation but provide the cues needed to understand the situation correctly (in the personal definition of that word). The right hemisphere's ability to respond, though, is severely limited by its inability to use language in a propositional manner.
Things are different for those with only a functioning left hemisphere. Without the ability to perceive the world independent of language and grasp the larger context of any particular situation in which we might find ourselves, what to do becomes dependent on our use of language to interpret literally what is going on. Because so much of any situation depends on context rather than the concrete meanings of the words we use to abstractly define the situation, the behavior of the left hemisphere person becomes strange and often inappropriate. We might even say that behavior under the circumstances is highly irrational, helping us to see why the defining the left hemisphere functioning as "rational" breaks down when it is separated from the right hemisphere.
So is there a parallel between what the left hemisphere's absolute dependence on language to define its connection to any particular situation and the right hemisphere's automatic integration of emotion and somatic sensation with its perceptions of the larger environment? Indeed, this question is related directly to those we raised earlier about role reversals and these questions as well: Since the left hemisphere cannot perceive space and the passage of time, how does it come to know the meaning of words in terms of function? And since words are the precursors of the purposeful functioning of the left hemisphere, by what mechanism is it motivated to use its capacity for words and grammar in the first place?
Continue to "A Satisfying Synthesis of Conscious Brain Function"
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