Inhibition of Manual Movements at Speech Arrest Sites in the Posterior Inferior Frontal Lobe

Abstract

BACKGROUND Intraoperative stimulation of the posterior inferior frontal lobe (IFL) induces speech arrest, which is often interpreted as demonstration of essential language function. However, prior reports have described “negative motor areas” in the IFL, sites where stimulation halts ongoing limb motor activity. OBJECTIVE To investigate the spatial and functional relationship between IFL speech arrest areas and negative motor areas (NMAs). METHODS In this retrospective cohort study, intraoperative stimulation mapping was performed to localize speech and motor function, as well as arrest of hand movement, hand posture, and guitar playing in a set of patients undergoing awake craniotomy for dominant hemisphere pathologies. The incidence and localization of speech arrest and motor inhibition was analyzed. RESULTS Eleven patients underwent intraoperative localization of speech arrest sites and inhibitory motor areas. A total of 17 speech arrest sites were identified in the dominant frontal lobe, and, of these, 5 sites (29.4%) were also identified as NMAs. Speech arrest and arrest of guitar playing was also evoked by a single IFL site in 1 subject. CONCLUSION Inferior frontal gyrus speech arrest sites do not function solely in speech production. These findings provide further evidence for the complexity of language organization, and suggest the need for refined mapping strategies that discern between language-specific sites and inhibitory motor areas.

Functional maps of direct electrical stimulation-induced speech arrest and anomia: a multicentre retrospective study

“…25 , 26 However, a recent study found stimulating some speech arrest sites in vPrCG also elicited the arrest of ongoing manual movements (negative motor responses). 27 It might suggest that speech arrest sites in the lateral frontal cortex could be categorized into two different groups (speech-specific sites and general negative motor response sites). 28 , 29 …”

Understanding Variable Motor Responses to Direct Electrical Stimulation of the Human Motor Cortex During Brain Surgery

“…This phenomenon is distinct from activation and contraction of an opposing muscle group, which would still be considered a PMR. While NMAs were previously thought to be either distributed widely along the lateral aspect of a given cortical hemisphere (79)(80)(81) or somatotopically located in the inferior frontal gyrus (82), more recent work shows NMAs to be more reliably located in several areas within the precentral gyrus (83), although not exclusively (84). In general, NMAs appear to localize in two main regions, a more medial region which includes the SMA and pre-SMA regions, and a more lateral region which includes the inferior frontal gyrus and the premotor cortex (80).…”

A Theoretical Framework for Human and Nonhuman Vocal Interaction

“…However, these systems appear to be motor general as opposed to speech-specific since their disruption results in global motor initiation dysfunction; for example, lesions of the supplemental motor area often result in bradykinesia of speech and nonvocal movements (Laplane et al 1977). Similarly, direct electrical stimulation of cortical loci important for the initiation of speech (Ferpozzi et al 2018) can inhibit or slow both speech and hand movements (Breshears et al 2019), implying these sites represent common initiation circuitry. The kinematic properties of natural speech usage also suggest a domain-general initiation mechanism, as the execution of nonvocal movements has been found to be temporally coordinated to articulation and prosodic structure in many contexts (Krivokapic et al 2017, Mendoza-Denton & Jannedy 2011, Parrell et al 2014, Shattuck-Hufnagel & Ren 2018.…”