Complex syntax in the isolated right hemisphere: Receptive grammatical abilities after cerebral hemispherectomy

Abstract

Objectives: In this study, we explored the syntactic competence of the right hemisphere (RH) after left cerebral hemispherectomy, on the premise that it (syntactic competence) is known to be one of the most strongly leftlateralized language functions. As basic syntactic development for individuals in this subject pool has already been extensively explored, we focused instead on the investigation of complex syntactic constructions that are normally acquired later in childhood, i.e., between 7 and 9 years of age. Methods: Grammatical competence in 10 participants who had undergone left cerebral hemispherectomy was compared to that of a group of normally developing children, with the two groups matched by the size of their vocabulary. The two tests we used for this research were created by the 1st language acquisition linguists and were designed to test sets of constructions categorized and differentiated by the order in which they are normally acquired and by the type of grammatical competence that they involve. Results: We found that both groups followed the same developmental sequence of syntactic development with five (50%) postsurgical participants (all with prenatal etiologies) reaching nearly mature command of sentence grammar. Seizures negatively impacted performance on all tests. Conclusions: The isolated RH has the potential to support the complex grammatical categories that emerge relatively late in the normal acquisition of English by native speakers. Successful performance may be related to the timing of the initial insult and seizure control following hemispherectomy.

When left‐hemisphere reading is compromised: Comparing reading ability in participants after left cerebral hemispherectomy and participants with developmental dyslexia

“…Maximal professional intervention documented postsurgically was weekly sessions with a speech‐language pathologist (SLP) during the academic year. All participants in the prenatal infarct group had age‐appropriate speech and comprehension of language at testing, based on data using previously published assessments, although detailed examination revealed subtle syntactic deficits in some of them . All families reported no history of left‐handedness in the family, and each participant's use of his/her left hand from early on was probably due to the hemiparesis associated with stroke.…”

Language Dysfunction in Pediatric Epilepsy

“…Imaging studies have shown that children with large left hemispheric lesions who undergo early hemispherotomy will remap language to the intact right hemisphere in a thorough enough manner to have complete acquisition of syntax and grammatical construction. (53) Language recovery has been reported to be more rapid and complete in younger children after hemispherotomy(58), suggesting a critical window for remodeling after surgery that would support an “earlier is better” approach to large resections in terms of language recovery. A recent analysis of language reorganization after acquired unilateral insults during childhood supports this notion, suggesting more complete and functional reorganization to the non-dominant hemisphere after acute lesions occurring before, as opposed to after, age 5 years.…”

Neural encoding of phrases and sentences in spoken language comprehension

“…Lastly, phrases and sentences differed most strongly over right-posterior parietal cortex, which is broadly consistent with previous research on speech comprehension. Functional Magnetic Resonance Imaging (fMRI) studies implicate the posterior right hemisphere in processing syntactic structure (de Bode, Smets, Mathern, & Dubinsky, 2015;Grodzinsky, 2000;Grodzinsky & Friederici, 2006;Maess, Koelsch, Gunter, & Friederici, 2001). Neurophysiological research also suggests the involvement of right hemisphere in extraction of slow timescale information extraction (Abrams, Nicol, Zecker, & Kraus, 2008;Giraud et al, 2007;Morillon, Liégeois-Chauvel, Arnal, Bénar, & Giraud, 2012;Poeppel, 2003).…”