That cognitive ability cannot be viewed simply as a processing of sensory infor-mation by a central intelligence extraction system is confirmed by individuals with anomalous abilities. Idiot savants, or simply savants, who have serious men-tal handicaps, either from developmental disability or major mental illness, per-form spectacularly at certain tasks. Anomalous performance has been noted in the areas of mathematical and calendar calculations; music; art, including paint-ing, drawing or sculpting; mechanical ability; prodigious memory (mnemonism); unusual sensory discrimination or "extrasensory" perception. The abilities of these savants and of mnemonists cannot be understood in the framework of a monolithic mind.

Oliver Sacks, in his book The Man Who Mistook His Wife for a Hat (1985) describes two twenty-six year old twins, John and Michael, with IQs of sixty who are remarkable at calendrical calculations even though "they cannot do simple addition or subtraction with any accuracy, and cannot even comprehend what multiplication means." More impressive is their ability to factor numbers into primes since "primeness" is an abstract concept. Looking from an evolutionary perspective, it is hard to see that performing abstract numerical calculations related to primes would provide an advantage?

From a quantum (implicate) view of reality, one may assume that the senses unpack it in chunks of familiar associations, which look like scripts of a movie. The remarkable observations of the neurosurgeon Wilder Penfield nearly forty years ago in which the patients undergoing brain surgery narrated their experience on the stimulation of the outer layer of the cortex at different points, may be interpreted as showing how the brain works in terms of gestalts. The stimulation appeared to evoke vivid memories. Subsequent stimulation of the same site did not necessarily produce the same memory, and stimulation of some other site could evoke the same memory. Furthermore, there was no evidence that these memories represented actual experiences in the patient's past. They had a dreamlike quality, as if they consisted of generic scripts out of which real memories are combined. When the patients heard music they could not generally recall the tune or they saw individuals who they could not identify and so on. The events did not appear to have a specific space-time locus.

It appears that generic scripts of this kind taken together form the stuff of real, waking experiences. The workings of the mind may be described in terms of the scripts and their relationships. The architecture of the brain provides clues to the relationships amongst the agents, and this architecture is illuminated by examining deficits in function caused by injury. In the next section we consider impairment of language function.

In reality, the relationship between these capacities is very complex. In aphasia, many of these capacities, by themselves or in groups, can be destroyed or spared in isolation from the others. Historically, several capacities related to language have been examined. These include fluency in conversation, repe­tition, comprehension of spoken language, word-finding disability, and reading disturbances.

Wernicke's aphasia A lesion in the posterior portion of the left temporal lobe, the Wernicke area, causes a receptive aphasia in which the speech produc-tion is maintained but comprehension is much more seriously affected. Depend-ing on the extent of damage, it may vary from being slightly odd to completely meaningless.

The Wernicke patient may speak at a abnormally fast pace and augment additional syllables to the end of words or additional worlds or phrases to the end of sentences. The speech is effortless, the phrase length is normal, and generally there is an acceptable grammatical structure and no problems of ei-ther articulation or prosody. But the speech shows a deficiency of meaningful, substantive words, so that despite the torrent of words ideas are not mean-ingfully conveyed, a phenomenon called empty speech. Paraphasia is another characteristic of Wernicke's aphasia. Here words from the same general class may be inappropriately substituted, or syllables in the wrong order generated, or an utterance produced which is somewhat similar to the correct word. For example, the patient may call a table a "chair" or an elbow a "knee" or butter as "tubber" and so on.

There exist other aphasias such as anomic (with word-finding difficulty), con­duction (with good comprehension but difficulty with repetition), and transcor-tical (with varying degree of comprehension byt excellent repetition). In agraphia there is a loss or an impairment of the ability to produce written language

Alexia In alexia, the subject is able to write while unable to read; in alexia combined with agraphia, the subject is unable to write or read while retain-ing other language faculties; in acalculia, the subject has selective difficulty in dealing with numbers.

Alexia has been known for a long time, but its first clinical description was made over a hundred years ago. One of these patients had suffered a cerebral vascular accident after which he could no longer read. Originally, the patient also suffered from some aphasia and agraphia but the aphasia cleared in due course. The other patient suddenly lost the ability to read but had no other language deficit. This patient, although unable to read except for some individual letters, could write adequately.

Three major varieties of alexia have been described: parietal-temporal, oc-cipital, and frontal. In occipital alexia, there is no accompanying agraphia. In this spectacular condition, there is a serious inability to read contrasted with an almost uncanny preservation of writing ability.

Apraxia Our movements are almost automatic. These movements involve a whole sequence of intermediate steps which are performed in the right order with the correct timing. These movements may be considered an expression of a body language and, therefore, in parallel with aphasia, one would expect to see disorders related to body movements. Apraxia is the inability to perform certain learned or purposeful movements despite the absence of paralysis or sensory loss. Several types of apraxia have been described in the literature.

In kinetic or motor apraxia there is an impairment in the finer movements of one upper extremity, as in holding a pen or placing a letter in an envelope. This is a result of injury in the premotor area of the frontal lobe on the side opposite to the affected side of the body. Kinetic apraxia is thought to be a result of a breakdown in the program of the motor sequence necessary to execute a certain act.

In ideomotor apraxia the patient is unable to perform certain complex acts on command, although they will be performed spontaneously in appropriate situations. Thus the patient will be unable to mime the act of brushing the teeth although the actual brushing will be easily done. It is believed that this apraxia is caused by the disconnection of the center of verbal formulation and the motor areas of the frotal lobe.

When the sequence of actions for an act are not performed appropriately, this is called ideational apraxia. The individual movements can be performed correctly but there is difficulty in putting these together. Rather than using a match, the patient may strike the cover of a matchbox with the candletip.

Constructional apraxia is the loss in the ability to construct or reproduce figures by assembling or drawing. It seems to be a result of a loss of visual guidance or an impairment in visualizing a manipulative output. This apraxia is a result of a variety of lesions in either one or both of the hemispheres.

The complex manner in which these aphasias manifest establishes that lan-guage production is a very intricate process. More specifically, it means that at

least certain components of the language functioning process operate in a yes/no fashion. These components include comprehension, production, repetition, and various abstract processes. But to view each as a separate module only tells half the story. There exists very subtle interrelationships between these capabilities which all come into operation in normal behavior.

Attempts to find neuroanatomical localization of individual language func­tions have not been successful. In fact critique of the approach of the localiza-tionists led to a holistic attitudes to brain's function. The anatomical centers, such as the areas of Broca or Wernicke, for the various syndromes are to be viewed as "focus" areas at a lower level and not exclusive processing centers. The actual centers are defined at some higher levels of abstraction.