Lesion correlates of conversational speech production deficits

Abstract

We assess brain areas involved in speech production using a recently developed lesion-symptom mapping method (voxel-based lesion-symptom mapping, VLSM) with 50 aphasic patients with left-hemisphere lesions. Conversational speech was collected through a standardized biographical interview, and used to determine mean length of utterance in morphemes (MLU), type token ratio (TTR) and overall tokens spoken for each patient. These metrics are used as indicators of grammatical complexity, semantic variation, and amount of speech, respectively. VLSM analysis revealed that damage to the anterior insula was predictive of low scores on MLU and tokens, consistent with prior findings of the role of this region in speech production [Dronkers, N. F. (1996). A new brain region for coordinating speech articulation. Nature, 384(6605), 159-161]. Additionally, the inferior frontal gyrus, sensorimotor and anterior temporal areas were also associated with lower scores on both of these measures. Overall, token and MLU maps were highly similar, suggesting an overlap between grammatical language networks and overall fluency. TTR maps also shared some portions of this network, but damage to posterior temporal regions also reduced scores on this measure. These results represent the first voxel-based lesion analysis of speech production performance in aphasic patients.

Lesion correlates of patholinguistic profiles in chronic aphasia: comparisons of syndrome-, modality- and symptom-level assessment

“…8) in line with previous reports assessing verbal fluency but also conversational speech (Borovsky et al, 2007).…”

“…Studies on verbal fluency (Bates et al, 2003;Baldo et al, 2006), sentence comprehension of varying syntactic complexity Magnusdottir et al, 2012), speech production (Dronkers and Ogar, 2004;Borovsky et al, 2007), noun versus verb naming (Piras and Marangolo, 2007), verbal and nonverbal semantics (Acres et al, 2009;Schwartz et al, 2009;Walker et al, 2011), picture naming (Rudrauf et al, 2008;Cloutman et al, 2009;Parkinson et al, 2009;Piras and Marangolo, 2010) word and number reading (Piras and Marangolo, 2009), and speech repetition (Fridriksson et al, 2010) provide an increasingly detailed map of areas mandatory for specific linguistic subfunctions. Additionally the overlap between linguistic and more general cognitive processing has been targeted (Leff et al, 2009) and subcortical connections constituting the network have been investigated (Turken and Dronkers, 2011;Kummerer et al, 2013).…”

Brain regions recruited for the effortful comprehension of noise-vocoded words

“…Although the anterior insula is often associated with the processing of disgust or other emotionally valent stimuli (Schienle et al, 2002), it has also been shown to have very strong connections with the inferior frontal gyri (Jabbi & Keysers, 2008) and to contribute to speech production (Ackermann & Riecker, 2004;Borovsky, Saygin, Bates, & Dronkers, 2007). For instance, it has been suggested that the insulae play a role in the control of vocal tract musculature (Ackermann & Riecker, 2004Ackermann & Riecker, 2010Riecker, Ackermann, Wildgruber, Dogil, & Grodd, 2000), and neuropsychological evidence associates lesions to the anterior insula with speech production deficits (Dronkers, 1996).…”

The role of the insula in speech and language processing

“…Patients with articulatory dysfunction in the absence of a muscular problem (i.e., dysarthria), had lesions in the left superior tip of the precentral gyrus of the insula (Dronkers, 1996). Other studies with patients with progressive apraxia (Nestor el al., 2003), reduced fluency (Bates et al, 2003;Borovsky et al, 2007), or impairments with rapidly changing articulatory movements (Baldo et al, 2011) were also reported to have left anterior insular damage. Neuroimaging studies with healthy studies also suggested that the left precentral gyrus of the insula is involved in articulatory coordination (Murphy et al, 1997).…”