"My Mind Is Doing It All": No "Brake" to Stop Speech Generation in Jargon Aphasia.

OBJECTIVE To study whether pressure of speech in jargon aphasia arises out of disturbances to core language or executive processes, or at the intersection of conceptual preparation. BACKGROUND Conceptual preparation mechanisms for speech have not been well studied. Several mechanisms have been proposed for jargon aphasia, a fluent, well-articulated, logorrheic propositional speech that is almost incomprehensible. METHODS We studied the vast quantity of jargon speech produced by patient J.A., who had suffered an infarct after the clipping of a middle cerebral artery aneurysm. We gave J.A. baseline cognitive tests and experimental word- and sentence-generation tasks that we had designed for patients with dynamic aphasia, a severely reduced but otherwise fairly normal propositional speech thought to result from deficits in conceptual preparation. RESULTS J.A. had cognitive dysfunction, including executive difficulties, and a language profile characterized by poor repetition and naming in the context of relatively intact single-word comprehension. J.A.'s spontaneous speech was fluent but jargon. He had no difficulty generating sentences; in contrast to dynamic aphasia, his sentences were largely meaningless and not significantly affected by stimulus constraint level. CONCLUSIONS This patient with jargon aphasia highlights that voluminous speech output can arise from disturbances of both language and executive functions. Our previous studies have identified three conceptual preparation mechanisms for speech: generation of novel thoughts, their sequencing, and selection. This study raises the possibility that a "brake" to stop message generation may be a fourth conceptual preparation mechanism behind the pressure of speech characteristic of jargon aphasia.