The Tell-Tale Brain: A Neuroscientist's Quest for What Makes Us Human

2. Many studies have confirmed my original observation (made with Lindsay Oberman, Eric Altschuler, and Jaime Pineda) of a dysfunctional mirror-neuron system (MNS) in autism (which we accomplished by using mu-wave suppression and fMRI). There is an fMRI study, however, claiming that in one specific brain region (the ventral premotor area, or Broca’s area), autistic children have normal mirror-neuron-like activity. Even if we accept this observation at face value (despite the inherent limitations of fMRI), my theoretical reasons for postulating such a dysfunction will still stand. More important, such observations highlight the fact that the MNS is composed of many far-flung subsystems in the brain that are interconnected for a common function: action and observation. (As an analogy, consider the lymphatic system of the body, which is distributed throughout the body but is functionally a distinct system.)

     It is also possible that this part of the MNS itself is normal but its projections or recipient zones in the brain are abnormal. The net result would be the same kind of dysfunction that I originally suggested. In another analogy, consider the fact that diabetes is fundamentally a disturbance of carbohydrate metabolism; no one disputes that. While it is sometimes caused by damage to the pancreatic islet cells, causing a reduction of insulin and an elevation of blood glucose, it can also be caused by a reduction of insulin receptors on cell surfaces throughout the body. This would produce the same syndrome as diabetes without damage to the islets (for islets in the pancreas, think “mirror neurons in the brain’s premotor area called F5”), but the logic of the original argument is unaffected.

     Having said all this, let me emphasize that the evidence for MNS dysfunction in autism is, at this point, compelling but not conclusive.

3. The treatments I have proposed for autism in this chapter were inspired in part by the mirror-neuron hypothesis. But their plausibility does not in itself depend on the hypothesis; they would be interesting to try anyway.

4. To further test the mirror-neuron hypothesis of autism, it would be interesting to monitor the activity of the mylohyoid muscle and vocal cords to determine whether autistic children do not show unconscious subvocalization when listening to others talking (unlike normal children, who do). This might provide an early diagnostic tool.

CHAPTER 6 THE POWER OF BABBLE: THE EVOLUTION OF LANGUAGE

1. This approach was pioneered by Brent Berlin. For cross-cultural studies similar to Berlin’s, see Nuckolls (1999).

2. The gestural theory of language origins is also supported by several other ingenious arguments. See Corballis (2009).

3. Even though Wernicke’s area was discovered more than a century ago, we know very little about how it works. One of our main questions in this chapter has been, What aspects of thought require Wernicke’s language area? In collaboration with Laura Case, Shai Azoulai, and Elizabeth Seckel, I examined two patients (LC and KC) on whom I did several experiments (in addition to the ones described in the chapter); here is a brief description of these and other casual observations that are revealing:

     (a) LC was shown two boxes: one with a cookie, one without. A student volunteer entered the room and looked at each box expectantly, hoping to open the one with the cookie. I had previously winked to the patient, gesturing him to “lie.” Without hesitation LC pointed out the empty box to the student. (KC responded to this situation the same way.) This experiment shows you don’t need language for a theory-of-mind task.

     (b) KC had a sense of humor, laughing at nonverbal Gary Larson cartoons and playing a practical joke on me.

     (c) Both KC and LC could play a reasonable game of chess and tic-tac-toe, implying that they have at least a tacit knowledge of if-then conditionals.

     (d) Both could understand visual analogy (for example, airplane is to bird as submarine is to fish) when probed nonverbally using pictorial multiple choice.

     (e) Both could be trained to use symbols designating the abstract idea “similar but not identical” (wolf and dog, for example).

     (f) Both were blissfully unaware of their profound language problem, even though they were producing gibberish. When I spoke to them in Tamil (a south Indian language), one of them said, “Spanish,” while the other nodded as if in understanding and replied in gibberish. When we played a DVD recording of LC’s own utterances back to him, LC nodded and said, “It’s okay.”

     (g) LC had profound dyscalculia (for example, reporting 14 minus 5 as 3). Yet he could do nonverbal subtraction. We showed him two opaque cups A and B, and dropped three cookies in A and four in B while he watched. When we removed two cookies from B (as he watched), LC subsequently went straight for A. (KC was not tested.)