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. Author manuscript; available in PMC: 2013 Nov 1.

Published in final edited form as: J Commun Disord. 2012 Jun 20;45(6):393–402. doi: 10.1016/j.jcomdis.2012.06.004

Fig. 2 — A. Speech models derived from the feedback control, psycholinguistic, and neurolinguistic literatures are integrated into one framework, presented here. The architecture is fundamentally that of a SFC system with a controller, or set of controllers (Haruno, Wolpert, & Kawato, 2001), localized to primary motor cortex, which generates motor commands to the vocal tract and sends a corollary discharge to an internal model which makes forward predictions about both the dynamic state of the vocal tract and about the sensory consequences of those states. Deviations between predicted auditory states and the intended targets or actual sensory feedback generates an error signal that is used to correct and update the internal model of the vocal tract. The internal model of the vocal tract is instantiated as a “motor phonological system”, which corresponds to the neurolinguistically elucidated phonological output lexicon, and is localized to premotor cortex. Auditory targets and forward predictions of sensory consequences are encoded in the same network, namely the “auditory phonological system”, which corresponds to the neurolinguistically elucidated phonological input lexicon, and is localized to the STG/STS. Motor and auditory phonological systems are linked via an auditory-motor translation system, localized to area Spt. The system is activated via parallel inputs from the lexical-conceptual system to the motor and auditory phonological systems. B. Proposed source of the deficit in conduction aphasia: damage to the auditory-motor translation system. Input from the lexical conceptual system to motor and auditory phonological systems are unaffected allowing for fluent output and accurate activation of sensory targets. However, internal forward sensory predictions are not possible leading to an increase in error rate. Further, errors detected as a consequence of mismatches between sensory targets and actual sensory feedback cannot be used to correct motor commands. Reprinted with permission from (Hickok, Houde, et al., 2011; Hickok & Poeppel, 2004)

Fig. 2 — A. Speech models derived from the feedback control, psycholinguistic, and neurolinguistic literatures are integrated into one framework, presented here. The architecture is fundamentally that of a SFC system with a controller, or set of controllers (Haruno, Wolpert, & Kawato, 2001), localized to primary motor cortex, which generates motor commands to the vocal tract and sends a corollary discharge to an internal model which makes forward predictions about both the dynamic state of the vocal tract and about the sensory consequences of those states. Deviations between predicted auditory states and the intended targets or actual sensory feedback generates an error signal that is used to correct and update the internal model of the vocal tract. The internal model of the vocal tract is instantiated as a “motor phonological system”, which corresponds to the neurolinguistically elucidated phonological output lexicon, and is localized to premotor cortex. Auditory targets and forward predictions of sensory consequences are encoded in the same network, namely the “auditory phonological system”, which corresponds to the neurolinguistically elucidated phonological input lexicon, and is localized to the STG/STS. Motor and auditory phonological systems are linked via an auditory-motor translation system, localized to area Spt. The system is activated via parallel inputs from the lexical-conceptual system to the motor and auditory phonological systems. B. Proposed source of the deficit in conduction aphasia: damage to the auditory-motor translation system. Input from the lexical conceptual system to motor and auditory phonological systems are unaffected allowing for fluent output and accurate activation of sensory targets. However, internal forward sensory predictions are not possible leading to an increase in error rate. Further, errors detected as a consequence of mismatches between sensory targets and actual sensory feedback cannot be used to correct motor commands. Reprinted with permission from (Hickok, Houde, et al., 2011; Hickok & Poeppel, 2004)