Much of the research conducted in the lab is driven by the desire for improved diagnosis and therapy of various neurogenic speech disorders.
Advances in basic and applied neuroscience have promoted a growing discussion on the modification or elimination of existing taxonomies of neurogenic speech disorders, in particular sensorimotor speech disorders.
Toward the Reclassification of Neurogenic Motor Speech Disorders
by Mohammad Haghighi
Advances in the fields of cognitive and computational neuroscience have implications with respect to the nature of neurogenic communication disorders, and more specifically motor speech disorders (MSDs). The perception and production of speech are no longer distinct phenomena localized in different areas of the brain. This sensorimotor integration has been supported by dynamic multidimensional models of speech processing (e.g., Chang et al., 2009; Friston et al., 2006; Fuertinger et al., 2015; Hickok, 2012; Hickok & Poeppel, 2007). Several conclusions can be made from these dynamic models, making them more applicable for the assessment and management of neurogenic MSDs:
- The brain is a self-organizing and highly flexible organ (Friston et al., 2006) that makes sensory inferences by integrating information from sensory and motor neurons (Hickok & Poeppel, 2007).
- The relationship between perception and action is bidirectional, regardless of modality (e.g., Chang et al., 2009), which becomes more complex, specific, and selective during the processing of speech sounds (e.g., Fuertinger et al., 2015).
- Speech processing necessitates the integration of bottom-up (perceptual) and top-down (cognitive) processes through a predictive coding mechanism (Hickok, 2012) that enhances the predictability of sensory information based on past experiences to prevent, detect, and correct errors (Friston et al., 2006; Hickok, 2012).
- The forward prediction mechanism is the result of interconnectivity and orchestrated synchronization between and within “neuronal groups” responsible for bottom-up and top-down modulations (Womelsdorf et al., 2007) within multiple time-scale, hierarchical domains (Kiebel, Daunizeau, & Friston, 2008).
- The highly synchronized neuronal activities result in adaptability and efficiency in performance (Fuertinger et al., 2015) during speech perception and production.