An olio of responses:
This thread raises so many interesting possibilities, I hardly know where to begin. Here’s a smorgasbord of facts, opinions and experiences. The neurological information is mostly from the book, The Brain, Restak (Bantam Books, 1984).
Language disabilities (aphasias) were the first abnormalities which established the specialization of parts of the brain. In right-handed people, the area known as Broca’s area in the left hemisphere is the center of speech and language ability. The separate hemispheres are posited to offer redundant capabilities in early life, allowing for damage to one side or the other with little loss of function, but beyond childhood, the specialization of brain function becomes fixed. Thus, a child suffering a stroke usually recovers speech function, while complete recovery by an adult is rare.
Postmortem examination of the brains of dyslexics has been limited, but one autopsy disclosed that within the language areas of the left hemisphere were disorganized cortex layers, scrambled and whirled with primitive, larger cells. And, the usually larger size of the planum temporale in the left hemisphere was not evident.
Sex differences in brain development include language capabilities. Females generally speak earlier, learn foreign languages more easily, and outperform males in tests of verbal fluency. Dyslexia, stuttering, delayed speech, and autism all occur with greater frequency in males. No anatomic differences have been found; the developmental differences might be due to chemical changes in brain function caused by the influence of sex hormones in early prenatal development.
The loss of the ability to process language can include lack of comprehension of semantics, grammatical components or prosody (the melodic and stress contours of speech). Incidents of loss of these abilities caused Restak to observe the varying abilities of even normal people to comprehend and appreciate irony, puns and other subtleties of language.
"The right hemisphere seems to contribute the color, the verve, the ‘firepower’ to ordinary speech. In addition to puns and wordplay, it makes possible the expression of enthusiasm, joy, sadness and despair."
Studies of split-brained people (those whose corpus collosum has been severed) demonstrate a divergence in information stored by the hemispheres, which the brains of even normal people do not always integrate into both halves of the brain.
Throughout all this the left hemisphere, with its preference for verbalized, symbolic expression, tends to elaborate reasons, sometimes even spurious ones, for what is going on.
In one test, P.S. was shown two pictures, one projected to the left hemisphere (a chicken claw) and one to the right hemisphere (a snow scene). He was asked to indicate from a series of pictures what picture he had just seen. P.S. selected a picture of a chicken with his right hand and a picture of a snow shovel with his left. When asked why he had made these particular selections, P.S. remarked: ‘That’s easy. The chicken claw goes with the chicken, and you need a shovel to clean out the chicken’s shed.’
In this instance, P.S.’s left hemisphere employed its language superiority to construct a plausible, ‘logical’ explanation for the choices he had selected. But the explanation was wrong, an error that suggests … that our speech and language systems routinely attempt to interpret rather than simply report our activities. If P.S.’s explanation is at all typical of the rest of us, it suggests that the reasons we give for our own behavior may not be the salient ones at all.
… Michael Gazzaniga has concluded that the human brain is organized in terms of a ‘mental society.’ In other words, alongside our verbal system, there may reside any number of ‘mental units [that] can exist, can have memories, values, and emotions, and all of these can be expressed through any of a variety of response systems.’ What makes this whole process so eerie is that these systems may not be in touch with the verbal system at all but rather, have their own existence outside of the areas of our brain responsible for our language and our logic."
I enjoyed reading works on neurology even before my autistic son was born (I especially recommend Oliver Sacks, The Man Who Mistook His Wife for a Hat), but have of course accelerated my reading in the area of autism recently. One of the most pervasive disabilities of autistic people is their inability to process language. Although high functioning, my son cannot comprehend the parts of speech, and must learn each phrase or expression in context, as if he were trying to learn enough of a foreign language to take a holiday in two weeks. He cannot transfer what he has learned to a different context.
And talk about mondegreens!
And so literal: last month, my son’s school entered two of his art works into a competition. The school sent home several forms which were required to be completed, and signed by both my son and me. After I filled out the forms, I called Ben over and told him that he would have to sign the forms several times. I pointed him to the first signature line, where he proceeded to write "Ben Ben Ben Ben…"
Of all the autistic children I have met in the past several years, they are overwhelmingly male, and have an unusually high incidence of left-handedness as well.
This information leads me to believe that language comprehension and development affect overall thought processes and are more central to our core beings than most people even suspect.
