A.R. Luria on "The Functional Organization of the Brain"

The following extract from Luria's historically important overview (i.e., general entrée level) article on the "new" area of neuropsychology (from Scientific American 1970) includes: (1) his brief description of three functional "blocks" of the human brain; and (2) an equally succinct "functional systems" account of voluntary movements in human beings.

*The historical rationale for posting this clinically based (i.e., pre-CAT/PET/MRI scan) era extract is that anyone now utilizing or reporting results from more modern computer imaging techniques should both:

(1) be cognizant of how Luria's integrative methodology (i.e., nonreductive assumptions, style of argumentation and language of explanation) served to guide his masterful use and interpretation of empirical methods (i.e., measurement or testing techniques); and also

(2) be alerted to the fact that his functional systems approach overlaps significantly with the wider sociohistorical unit of psychological analysis indicative of the work of other historical figures such as G.H. Lewes; John Dewey; and A.N. Leontiev.

Those interested in a detailed account of his integrative functional systems approach to neuropsychological investigation of higher mental functions are encouraged to read not only the original article (in full) but also Luria's The Working Brain (1973). A useful secondary source (which highlights the theoretical tools utilized by Luria) is Goldberg, E. (Ed.). Contemporary Neuropsychology and the Legacy of Luria (1990). Hilsdale: LEA.

*The implied metatheoretical proposal and motive for posting this material is that if Luria could provide such a coherent integrative account of neuropsychologcal functions (with the limited technological tools at his disposal), there should now be a well-funded concerted effort to overcome the current theoretical limitations of standard biopsychology/ neuropsychological training tools (including recent editions of texts by Kalat; Kandel et al.; or Kolb & Wishaw) in this regard.

Paul F. Ballantyne, Ph.D.
pballan@comnet.ca

Luria, A.R. (March 1970). The functional organization of the brain. Scientific American, 222(3), 66-78.

The Functional Organization of the Brain

A.R. Luria
March 1970

The functional organization of the human brain is a problem that is far from solved. I shall describe in this article some recent advances in the mapping of the brain. They open up a new field of exploration having to do with the structures of the brain involved in complex forms of behavior.

So far as sensory and motor functions are concerned, the brain, as is well known, has been mapped in precise detail. Studies by neurologists and psychologists over the past century have defined the centers that are responsible for some elementary functions such as seeing, hearing, other sensory functions and the control of the various muscular systems of the body. From outward symptoms or simple tests disclosing a disturbance of one of these functions it is possible to deduce the location of the lesion (a tumor or a hemorrhage, for example) causing the disturbance. Such a finding is of major importance in neurology and neurosurgery. The sensory and motor centers, however, account for only a small part of the area of the cerebral cortex. At least three-quarters of the cortex has nothing to do with sensory functions or muscle actions. In order to proceed further with the mapping of the brain's functions we must look into the systems responsible for the higher, more complex behavioral processes.

It is obvious that these processes, being social in origin and highly complex in structure and involving the elaboration and storage of information and the programming and control of actions, are not localized in particular centers of the brain. Plainly they must be managed by an elaborate apparatus consisting of various brain structures. Modern psychological investigations have made it clear that each behavioral process is a complex functional system based on a plan or program of operations that leads to a definite goal. The system is self-regulating: the brain judges the result of every action in relation to the basic plan and calls an end to the activity when it arrives at a successful completion of the program. This mechanism is equally applicable to elementary, involuntary forms of behavior such as breathing and walking and to complicated, voluntary ones such as reading, writing, decision-making and problem-solving.

What is the organizational form of this system in the brain? Our present knowledge of neurology indicates that the apparatus directing a complex behavioral process comprises a number of brain structures, each playing a highly specific role and all under coordinated control. One should therefore expect that lesions of the structures involved might result in changes in the behavior, and that the nature of the change would vary according to the particular structure that is damaged.

A New Approach

This concept forms the basis of our new approach to exploration of the functional organization of the brain --a study we call neuropsychology. The study has two objectives. First, by pinpointing the brain lesions responsible for specific behavioral disorders we hope to develop a means of early diagnosis and precise location of brain injuries (including those from tumors or from hemorrhage) so that they can be treated by surgery as soon as possible. Second, neuropsychological investigation should provide us with a factor analysis that will lead to better understanding of the components of complex psychological functions for which the operations of the different parts of the brain are responsible.

The human brain can be considered to be made up of three main blocks incorporating basic functions. Let us examine the responsibilities of each block in turn.

REGIONS OF THE BRAIN are identified. The gross anatomy of the human brain is depicted at upper left. The other drawings identify three major blocks of the brain involved in the organization of behavior. The first block (upper right) includes the brain stem and the old cortex. It regulates wakefulness and the response to stimuli. The second block (lower left) plays a key role in the analysis, coding and storage of information. The third block (lower right) is involved in the formation of intentions and programs.

[The first block]

The first block regulates the energy level and tone of the cortex, providing it with a stable basis for the organization of its various processes. The brilliant researches of Horace W. Magoun, Giuseppe Moruzzi, Herbert H. Jasper and Donald B. Lindsley located the components of the first block in the upper and lower parts of the brain stem and particularly in the reticular formation, which controls wakefulness. If an injury occurs in some part of the first block, the cortex goes into a pathological state: the stability of its dynamic processes breaks down, there is a marked deterioration of wakefulness and memory traces become disorganized.

I.P. Pavlov observed that when the normal tone of the cortex is lowered, the "law of force" is lost and much of the brain's ability to discriminate among stimuli suffers. Normally the cortex reacts powerfully to strong or significant stimuli and responds hardly at all to feeble or insignificant stimuli, which are easily suppressed. A weakened cortex, on the other hand, has about the same response to insignificant stimuli as to significant ones, and in an extremely weakened state it may react even more strongly to weak stimuli than to strong ones. We all know about this loss of the brain's selectivity from common experience. Recall how diffuse and disorganized our thoughts become when we are drowsy, and what bizarre associations the mind may form in a state of fatigue or in dreams.

Obviously the result of injury to the first block in the brain, namely the loss of the selectivity of cortical actions and of normal discrimination of stimuli, will bring about marked changes in behavior. The control of behavior becomes deranged. In our common work with Macdonald Critchley of England such disturbances have been observed in patients who had tumors of the middle parts of the frontal lobes, and other investigators in our laboratory in Moscow have since reported similar effects from lesions in deep parts of the brain.

The Second Block

The second block of the brain has received much more study, and its role in the organization of behavior is better known. Located in the rear parts of the cortex, it plays a decisive role in the analysis, coding and storage of information. In contrast to the functions of the first block, which are mainly of a general nature (for example controlling wakefulness), the systems of the second block have highly specific assignments. We can easily identify areas in the second block that are respectively responsible for the analysis of optic, acoustic, cutaneous and kinesthetic stimuli. Each of these cortical areas has a hierarchical organization: a primary zone that sorts and records the sensory information, a secondary zone that organizes the information further and codes it and a tertiary zone where the data from different sources overlap and are combined to lay the groundwork for the organization of behavior.

Injuries to the parts of the second block produce much more specific effects than lesions in the first block do. An injury in a primary zone of the second block results in a sensory defect (in seeing or hearing, for example); it does not, however, bring about a marked change in complex forms of behavior. A lesion in a secondary zone produces more complicated disturbances. It interferes with analysis of the sensory stimuli the zone receives and, because the coding function is impaired, the lesion leads to disorganization of all the behavioral processes that would normally respond to these particular stimuli. It does not disturb any other behavioral processes, however, which is an important aid for locating the lesion.

Of the various lesions in the second block of the brain those in the tertiary zones are particularly interesting to us as neuropsychologists. Since these zones are responsible for the synthesis of a collection of information inputs from different sources into a coherent whole, a lesion of a tertiary zone can cause such complex disturbances as visual disorientation in space. The lesion seriously impairs the ability to handle complex problems that entail an organization of input in simultaneous matrixes. That is why these lesions may render a person incapable of performing complex operations with numbers or of coping with a complexity in grammar logic or language structure.

The Third Block

The third block of the brain, comprising the frontal lobes, is involved in the formation of intentions and programs for behavior. Important contributions to elucidation of the functions of the frontal lobes have been made by S.I. Franz, L. Bianchi, Karl H. Pribram and Jerzy Konorski through studies of animals and by V.M. Bekhterev, C. Kleist and Derek E. Denny-Brown through clinical observations. We have devoted much study to the roles of the third block in our laboratory.

The frontal lobes perform no sensory or motor functions; sensation, movement, perception, speech and similar processes remain entirely unimpaired even after severe injury to these lobes. Nevertheless, the frontal lobes of the human brain are by no means silent. Our findings make it clear that they participate to a highly important degree in every complex behavioral process.

Intimately connected with the brain stem, including its reticular formation, the frontal lobes serve primarily to activate the brain. They regulate attention and concentration. W. Grey Walter showed a number of years ago that the activity of the brain could be measured by the appearance of certain slow brain waves in an electroencephalogram; these waves are evoked when a subject is stimulated to active expectancy and disappear when the subject's attention is exhausted. At about the same time M.N. Livanov, a Russian investigator, found that mental activity is signaled by a complex of electrical excitations in the frontal cortex and that these excitations disappear when the subject subsides to a passive state or is lulled with tranquilizers.

Functional Systems

Now that we have reviewed the functions of the brain's basic blocks, let us see what we can learn about the location of specific parts of the various functional systems. It is clear that every complex form of behavior depends on the joint operation of several faculties located in different zones of the brain. A disturbance of any one faculty will affect the behavior, but each failure of a specific factor presumably will change the behavior in a different way. We have explored these effects in detail with a number of psychological experiments.

To illustrate our findings I shall discuss the results of a neuropsychological analysis of two processes. One is voluntary movements; the other is speech and in particular one of its forms, namely writing.

VOLUNTARY MOVEMENT is controlled by a complex of cortical and subcortical zones. The classical theory was that voluntary movement originated with the large pyramidal cells (arrowhead) of the cortex; they have long axons that conduct impulses to the spinal cord. It is now known that other zones participating in voluntary movement are the post central zone (1), which deals with sensory feedback from the muscles; the parieto-occipital zone (2), which is involved in the spatial orientation of movement; the premotor zone (3), which deals with the separate links of motor behavior, and the frontal zone (4), which programs movements. Lesions in different zones give rise to different behavioral aberrations.

[Voluntary movements]

It was long supposed that voluntary movements are a function of the motor cortex, that is, the large pyramidal cells of the cortex of the anterior convolution of the brain. These cells, discovered by the Russian anatomist V.A. Betz more than 100 years ago, have exceptionally long axons that conduct the excitation toward the roots of the spinal cord. Impulses from these cells result in the constriction of muscles and are supposed to be the neurophysiological basis of voluntary movement.

Up to a certain point this is true, but the mechanism of the formation of a voluntary movement is much more complicated. To think that a voluntary action is formed in the narrow field of the motor cortex would be a mistake similar to an assumption that all the goods exported through a terminal are produced in the terminal. The system of cortical zones participating in the creation of a voluntary movement includes a complex of subcortical and cortical zones, each playing a highly specific role in the whole functional system. That is why lesions of different parts of the brain can result in the disturbance of different voluntary movements.

Let us examine the components of voluntary movement and see how it is affected differently by lesions in different parts of the brain. The first component is a precisely organized system of afferent (sensory) signals. The Russian physiologist N.A. Bernstein has shown in a series of studies that it is impossible to regulate a voluntary movement only by way of efferent impulses from the brain to the muscles. At every moment of the movement the position of the limb is different, and so is the density of the muscles. The brain has to receive feedback from the muscles and joints to correct the program of impulses directed to the motor apparatus. One can recognize the nature of the problem by recalling how difficult it is to start a leg movement if the leg has become numb. This sensory or proprioceptive base is provided by a special part of the brain: the postcentral sensory cortex. If this part of the cortex is destroyed by a wound or other injury, the patient not only loses sensation in the limb but also is unable to fulfill a well-organized voluntary movement.

One of our co-workers has studied the physiological mechanism of such a disturbance and has shown that in lesions of the sensory part of the cortex every voluntary impulse loses its specific "address" and arrives equally at all muscles, both flexors and extensors. No organized movement can be elicited in such conditions. That is why neurologists have called this kind of motor disturbance afferent paresis.

A second component of voluntary movement is the spatial field. The movement has to be precisely oriented toward a certain point in space. Spatial analysis is done in another zone of the cortex: the tertiary parts of the parieto-occipital areas. Lesions of these highly complicated parts of the cortex result in a different kind of disturbance of voluntary movement. The sensory base of the movement remains intact, but the patient fails in a precise spatial organization of the movement. He loses the ability to evaluate spatial relations and confuses left and right. Such a patient may be unable to find his way in a familiar place or may be confused in such matters as evaluating the position of the hands of a watch or in distinguishing east and west on a map.

The sensory and spatial factors in the organization of a movement are basic but still insufficient to allow the completion of the movement. A voluntary movement is the result of a sequence of events. A skilled movement is really a kinetic melody of such interchangeable links. Only if one already fulfilled part of the movement is blocked and the impulse is shifted to another link can an organized skilled movement be made.

An important finding, first described by Karl S. Lashley and John F. Fulton and carefully studied in our laboratory for many years, is that a totally different part of the brain --the premotor cortex-- is responsible for sequential interchanges of separate links of motor behavior. A skilled movement disintegrates when this part of the brain is injured. Such a patient still has sensory feedback and spatial orientation, but he loses the ability to arrest one of the steps of the movement and to make a transition from one step to the next.

Even now I have not fully described the brain's organization of a voluntary movement. Every movement has to be subordinated to a stable program or a stable intention. They are provided in the prefrontal lobes of the brain (included in the third block). If the frontal lobes are injured, the sensory base, spatial organization and plasticity of the movement remain but goal-linked actions are replaced by meaningless repetitions of already fulfilled movements or impulsive answers to outside stimuli. The whole purposive conduct of the patient is disturbed.

Speech and Writing

....

Factor Analyses

....

[Luria's concluding remarks]

Finally, the neuropsychological approach gives us a new insight into the effects of learning on the brain's processes. There is a well-known story of a patient of the 19th-centry English neurologist Sir William Gowers who, after many unsuccessful attempts to repeat the word "no" in response to his instruction, at last burst out: "No, doctor, I can't say 'no.'" We have observed many cases of automatic performances of this kind in brain-injured patients who could not achieve a given task when they thought about it. One was an old lady who was unable to write a single word on instruction, but when she was asked to write a whole sentence quickly (a kinetic skill), she did so without hesitation. Patients who cannot write from dictation are often able to sign their names readily. It appears, therefore, that training or habituation changes the organization of the brain's activity, so that the brain comes to perform accustomed tasks without recourse to the processes of analysis. That is to say, that task may invoke a stereotype based on a network of cortical zones quite different from the one that was called on originally when the performance required the help of the analytical apparatus.

Neuropsychology has put us on a new path in the investigation of how the brain functions, and we can suppose that it is likely to lead the way to substantial changes in the design of psychological research in the future.

Other Luria links:

(1) Luria Biography (by M. Cole); links; bibliography and Photos.

(2) From The Problem (1974) and then published in Chapter 1 of his Cognitive Development: Its Social and Cultural Foundations,1976:

"Our experiments could succeed only if they adequately reflected the major differences in the thinking of people at different stages of sociohistorical development, and could thus reveal a pattern or syndrome. The essential features of mental processes depend on the way they reflect reality; therefore a particular form of mental activity should correspond to a particular level of reflection.

We hypothesized that people with a primarily graphical reflection of reality would show a different system of mental process from people with a predominantly abstract, verbal, and logical approach to reality. Any changes in the encoding process should invariable show up in the organization of the mental processes behind these activities. In our studies, the subjects could solve the problems either on a concrete, graphic-functional level or on an abstract, verbal, and logical one."

(3) Related Socio-Cultural Theory Link