In my last long-ago post, I brought up the fact that the recent NIH study of stuttering genetics suggested that mutations in 3 genes associated with stuttering in 9% of people who stutter were expressed in the mammalian hippocampus, a brain structure not commonly associated with speech.
How can that be?
To date, all of the genetic mutations found to be associated with stuttering are in the lysosomal system of the cell. The is the so-called “housekeeping” system, where the mutation causes the wrong protein to be generated, resulting in lowered efficiency of the cell due to the buildup of waste products. Because the hippocampus is one of the primary areas of the brain that is associated with memory, proprioception (spacial and motor movement awareness), and emotion, virtually all higher brain functions rely on the prompt completion of its actions to work properly. Lagging or inaccurate response by the hippocampus could contribute to the minor sorts of motor “glitches” that are thought to be associated with beginning stuttering. The close association of the hippocampus with the amygdala in the production of emotional memories might play some role as well.