Brain Hemisphere Specialization, Autism & Anosognosia.


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Our personal world is a complex network made up of countless elements. To make sense of it all, our mind forms a matrix which ties together our experience and knowledge. This essay suggests how the left and right brain hemispheres generate this structure. See conclusions for more information.

The two hemispheres of our brain serve different function and process information differently. The left hemisphere can focus on the detail and is sequential, logical and analytical. It is better at tasks that entail discrete steps or which require us to concentrate on a particular aspect of the environment. This hemisphere also decodes the sequence and structure of language.

The right hemisphere processes information holistically and is associated with imagination and spatial perception. This hemisphere provides an overview of our environment and the objects that surround us. It is better at understanding humor, emotion and metaphor. It can 'see' the overall, background picture.


Spatial Perception	Poor	Superior; Distance 3-D analysis
Thinking	Symbolic, analysis	Holistic, imagination
Focus	Foreground, Specific	Background, General
Aware of	Detail	Overall picture
Better at	Structured tasks	Open-ended tasks
Language	Decoding, literal surface meaning	Context, meaning humor, metaphor

To examine the functions carried out by each hemisphere, neurologists scanned the brain of subjects while they were shown a series of letter navons. A letter navon is a large letter composed of smaller letters as shown below. The researchers soon found out that while the subjects concentrated on the small F's, the left hemisphere showed greater activity; when they focused on the big S, the right hemisphere became active.

Thus, they had demonstrated that the left hemisphere focused on the details, while the right perceived the overall, background picture. Besides these differences in processing stimuli, I think that the hemispheres function differently when connecting information with our acquired knowledge of the world.

The ideas presented here rest on the assumption that our world view, our notion of ourselves and the world, exists as a neural structure, and that it is accessed and modified by both brain hemispheres through two distinct processes.

Left Hemisphere

The diagram shows event integration into the reality framework. Through analytical processing, the left hemisphere will focus on a specific aspect of an object and establish a specific and direct connection to the matrix. If necessary, the event is broken down into its constituent parts, thus providing highly localized integration within the reality structure. The left hemisphere, however, is unable to connect events with the overall matrix content, and therefore incapable of grasping context within the world.

Analytical processing provides an understanding of the specific, allowing us to anticipate change and progress. But for meaning and context within the world at large, we must rely on global processing and the right hemisphere.

Right Hemisphere

The right hemisphere maintains the matrix through global processing. A connection is immediately established between the perceived information and the overall reality structure. Global processing, however, can only focus on superficial properties, and will conceptualize an object's overall characteristics. This process will establish a relationship between the specific and the 'big picture,' providing context within our knowledge of the world at large.

As we have seen, the left hemisphere integrates our perceptions into a localized matrix area. This makes it more conservative; it works well in a stable and familiar environment. In contrast, the right hemisphere can anticipate and adapt to change, and can maintain a stable matrix even in fast changing and unpredictable environments.

Effects of Stroke

We have discussed how both hemispheres may function to connect our perceptions with what we have already experienced. Brain damage can have a devastating effect on this process and may forever alter our ability to understand and interact with our environment.

The left hemisphere, which builds the reality structure through analytical processing, responds to stimuli by providing very specific knowledge and past experience. In this way, we analyze and understand our perceptions, and solve any difficulties that we may encounter. Patients who have suffered a stroke in the left side of their brain may lose these mental faculties and may find themselves unable to perform difficult tasks without constant supervision and guidance.

In contrast, survivors of right hemisphere stroke may develop an impulsive and dangerous behavioral style. Often, these patients have inadequate understanding of their condition and are certain of their ability to perform the same tasks as before the stroke. Their apparent indifference to their predicament can be extremely dangerous since the patient may attempt hazardous activities or fail to follow treatment essential to their recovery.

As explained above, global processing will simultaneously access and modify large areas of the cognitive structure. It finds a relationship between our perceptions and our overall knowledge of the world, a process that is necessary to evaluate the repercussions of any particular situation. Victims of right hemisphere stroke, therefore, have poor awareness of global pattern and possibilities. Their failure to follow treatment derives not from a lack of understanding, but from indifference to the adverse effects of their condition.

It is important to note here that any situation is undesirable only to the extent to which it can (potentially) damage our concept of reality. Our likes and dislikes have this as their basis.

Damage to the right hemisphere can also cause subtle language deficiencies. Although it is not involved in decoding the structure of language, by connecting experience with the overall cognitive structure, the right hemisphere can grasp extralinguistic context, such as emotion, humor and metaphor. Consequently, patients with right hemispheric damage may fail to understand a joke, or may develop a robot-like, unemotional tone in their speech.

Anosognosia

Anosognosia usually happens to people who have been paralyzed from the effects of a stroke in the right hemisphere of their brain. It is a bizarre syndrome because, despite their condition, these patients claim to be completely healthy. Even after failing to move or perform a simple task, the anogognosiac will insist that the paralyzed arm or leg is functioning properly.

Dr. V.S. Ramachandran, Director of the Center for Brain and Cognition at UC San Diego, has proposed an interesting hypothesis that may help explain anosognosia. He believes that to make sense of our complex environment, the human brain forms a coherent belief system, and suggests how each hemisphere participates in its creation. According to Ramachandran, our beliefs about ourselves and the world develop in the left side of our brain. The function of the right hemisphere is to detect anomalies, forcing the left to revise the established belief structure. Through this process, we generate a unified model of reality, a consistent storyline that allows us to live without confusion and indecision.

In anosognosiacs, the 'anomaly detector' is impaired due to damage to the right hemisphere. The belief structure cannot be altered, and the patient is left with no choice but to deny his paralysis. Based on the ideas discussed above, I would like to offer an alternative explanation.

A fear of change, of losing the familiar, is common to many of us. This fear, however, can be much more intense in someone who has suffered damage to the right brain hemisphere. There are two reasons for this. Firstly, as we have said, the left hemisphere is more conservative, it tends to build upon the information that is already there. Secondly, global access to the cognitive structure is necessary to anticipate and adapt to unfamiliar circumstances. I would like to suggest that anosognosia is a psychological defense mechanism. In this case, a denial of reality that is neccessary because adaptation to new conditions is no longer possible.

One may then ask whether anosognosiacs are aware of their predicament. The left hemisphere can 'see and understand' the paralysis itself, so the patients have full awareness of their condition. Without the capacity to globally modify the cognitive matrix, though, congruency between brain structure and the environment is now only possible through denial.

An interesting experiment performed by Ramachandran was based on the findings of the Italian scientist Eduardo Bisiach, who showed that pouring cold water into the left ear would temporarily allow the patients to acknowledge their condition. The cold water irrigation has the curious effect of triggering rapid-eye-movements (REM), and this link, between anosognosia and REM sleep can, I think, tell us something important about dreams.

During waking life, and despite our shadow side and the chaos and complexity of our environment, our actions and thoughts help provide a stable map of reality. Life then becomes a struggle. While we sleep, however, we often experience feelings of peace and tranquility, and this, I argue, is because psychological defenses are inactive in this state. In other words, conscious experience need not conform to a pre-existing mental pattern. This is evident from the bizarre content of dreams and feelings of uneasiness and insecurity which kick in just after we wake up.

The main reason behind my attempt to explain anosognosia is to show the reader how important it is for the brain to generate a coherent model of reality, and the extent to which we shape our beliefs to make them consistent with this structure.

Autism

Autistic individuals are shy, unresponsive, and prefer to be left alone. They avoid emotional and physical contact with others, including their parents, and may be painfully sensitive to touch, sound, sight, or smell. While playing, autistic children do not engage in fantasy or role playing, instead their play is rigid and repetitive. The autistic child may also show a delay or total lack of language development.

It seems to me that autism is a disorder in which the brain is unable to form a stable reality structure through which to interpret experience. The reason for this, I think, is because the autistic mind relies completely on the analytical processes of the left hemisphere to form the matrix, making it inadequate, and incapable of processing anything but the most basic stimuli.

Autism, then, is an absence of global processing, a function that is necessary both to anticipate and adapt to change, and to conceptualize our overall environment. Although the cognitive structure may contain detailed and precise information of the immediate environment, it provides no concept of the world at large, and therefore no real understanding. Moreover, without the capacity to generate anticipations, autistic people experience anxiety and hypersensitivity, possibly due to extreme fear of change and the unknown.

The intense struggle to form a stable construct of reality becomes clear when we examine autistic thought patterns and behavior. For instance, autistic people often develop symbols and ideas which are meaningless to everyone but themselves. These mental connections are what one would expect from the analytical processes of the left hemisphere - specific, detailed and sequential. And although they avoid most objects, they can be strongly drawn to others, but interaction is obsessive, rigid and repetitive.

Associated with autism, the savant is someone who has extraordinary skills in a specific area such as drawing, music, or maths. The autistic savant may, for example, be able to solve complex mathematical problems, perform memory feats, or draw life-like pictures.

As the reader may now realize, our cognitive matrix is a tremendously complex information structure that is put together by powerful unconscious processes. Autistic people are unable to develop a normal reality structure, and this processing power is then directed onto highly specific aspects of the environment. This, unfortunately, is the only way in which coherence and stability can be maintained, i.e., by focusing on the specific while shunning everything else. Building the entire framework from such a limited spectrum of events brings about incredible abilities at the expense of normal understanding and personality development.

The same unconscious processes that are responsible for savant abilities are present in all of us. In the normal brain, however, these generate a matrix that is not only adequate to process a wider range of experiences, but the interpretation and meaning that is then assigned is shared among many individuals. If we could somehow learn to control and affect these low-level mental processes we could, for example, increase our cognitive abilities or alter our personality.

Autistic savants sometimes lose their abilities when their social skills improve. For example, a child named Nadia, whose drawings of horses have been compared to those of Rembrandt, lost her amazing skills when she began to speak. The most likely explanation is that interacting with others allows the child to develop a stable matrix that can now safely conceptualize wider segments of reality. The world is then less threatening, and the savant abilities disappear because the brain no longer needs to focus on the specific to maintain stability and security.

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