The two components of stuttering

 

My model of stuttering has two primary components: the neurologic speech block and excitation feedback. This two-tiered model is capable of explaining the key manifestations of stuttering, including the Primary Paradox.

1) Neurologic speech block. This is caused by an inborn flaw or glitch in the brain’s speech production circuitry¬†that typically manifests itself in early childhood.

The brain’s motor output signals that tell the articulator muscles how to move to create speech are getting blocked or scrambled in some fashion. Words must get out of the brain before they can get out of the mouth. This is probably the primary flaw causing stuttering.

Recent studies (see studies below) indicate that the neurologic block in PWS may be due to a fundamental flaw in brain organization in which the brains of PWS have competing speech production areas. That is, instead of the speech production areas in one brain hemisphere being dominant (usually the left hemisphere) as it is in most non-PWS, both hemispheres appear to compete in outputting signals for speech production at the same time. This could cause a “bottleneck” resulting in the characteristic speech blocks seen in stuttering.

Think about your speech blocks for a moment. You usually can tell in advance that you’re going to block on an upcoming word, can’t you? It’s like a physical aura, a palpable sensation, a brick wall looming. If you think about the timing of the block, you’ll realize that the internal block (in the brain) comes a beat or two before you even begin initiating speech in the external speech mechanism. What you’re experiencing is a window into your brain, where the block occurs. The reason for all the superfluous movement and struggling of the outer body parts (mouth, face, larynx, etc.) is that you’re trying to force articulator muscles to speak that are getting scrambled motor output signals from the brain. Without electrical activation by the brain, muscles are just motionless slabs of flesh. They can’t do anything by themselves. The problem is in the brain, not in the external body parts.

2) Excitation feedback. This an involuntary physiologic response initiated by awareness that someone is listening to your speech. This appears to aggravate or trigger the neurologic speech block.

This is the component responsible for so much of the confusion about stuttering. This is what may explain the Primary Paradox.

Excitation feedback in PWS may result from a flaw in the brain’s limbic system (the posterior cingulate in Dr. Gerald Maguire’s brain imaging studies).14 The limbic system modulates what Dr. Maguire calls our level of “internal anxiety,” which is analogous to my term “excitation feedback.”

Maguire points out that this “internal” anxiety is not the same as the anxiety caused by external stresses such as asking for a raise or making an important speech. Our internal anxiety levels are not under voluntary control and we may not even be aware of them.

Studies suggest that the limbic system (left cingulate) plays a role in speech motor initiation along with the supplementary motor area (SMA). This would indicate a link between the brain’s limbic system and the brain’s speech motor areas.

The limbic system is an inhibitory area, so there’s an inverse relationship. The less active the limbic system, the higher the internal anxiety level. The more active the limbic system, the lower the internal anxiety level. During fluent speech (e.g., chorus reading), the limbic system of PWS is more active, which indicates a lower internal anxiety. During stuttered speech, the limbic system of PWS is less active, which indicates higher internal anxiety.

An awareness of the presence another person may automatically and involuntarily increase the level of internal anxiety (excitation feedback). (“Presence” doesn’t necessarily mean in the same proximity–a “presence” on the other end of a phone is the same thing.)

This higher level of internal anxiety (or excitation feedback), when transmitted to the cortex areas, somehow aggravates or triggers the neurologic block component of stuttering. There may be a threshold level involved.

This might be the key to understanding the Primary Paradox. Perhaps when a PWS is speaking alone or to a pet, internal anxiety (excitation feedback) remains below the threshold level needed to trigger the neurologic block. That would explain why PWS are more fluent in these situations.

Why can’t we just deliberately pretend we’re alone or with a pet whenever we speak around other people? It seems so simple (and that’s why it leads to so much misunderstanding). Doing that would lessen or bypass the neurologic block and most of us could be fluent. But, as I mentioned before, excitation feedback seems to be an automatic and involuntary response from subcortical brain areas, so that it is not under our conscious control.

We may not have as much “free will” as we like to think. The brain has become so proficient at doing its job transparently that it often takes a fluke occurrence to show just how dependent we are on its proper function. There’s a medical condition called anosognosia, which may occur when a stroke damages the brain’s right parietal cortex. For a couple of weeks following such a stroke, these fully aware patients are unable–not just unwilling–to acknowledge that their paralyzed left limbs belong to them. One patient became so angry that someone else’s leg was cluttering up his hospital bed that he heaved it out and was amazed to find himself on the floor. Another patient claimed that her left arm belonged to her mother.24

I suspect that some PWS who say they have “worked through” their stutter and attribute their fluency to such psychological and emotional elements as addressing conflict and assertiveness issues, etc., may have actually decreased their excitation feedback levels without knowing that was what they were really doing. They may have gone through some of the personal growth or interaction programs and over time have desensitized themselves to the effects of excitation feedback.

The neuropatterning Home Course works to offset and diminish the primary cause of stuttering: the neurologic block component. As you gain fluency and begin interacting more with other people, you’ll also become more desensitized to the effects of excitation feedback.