Functional differentiation in the language network revealed by lesion-symptom mapping

Abstract

Theories of language organization in the brain commonly posit that different regions underlie distinct linguistic mechanisms. However, such theories have been criticized on the grounds that many neuroimaging studies of language processing find similar effects across regions. Moreover, condition by region interaction effects, which provide the strongest evidence of functional differentiation between regions, have rarely been offered in support of these theories. Here we address this by using lesion-symptom mapping in three large, partially-overlapping groups of aphasia patients with left hemisphere brain damage due to stroke ( N = 121, N = 92, N = 218). We identified multiple measure by region interaction effects, associating damage to the posterior middle temporal gyrus with syntactic comprehension deficits, damage to posterior inferior frontal gyrus with expressive agrammatism, and damage to inferior angular gyrus with semantic category word fluency deficits. Our results are inconsistent with recent hypotheses that regions of the language network are undifferentiated with respect to high-level linguistic processing.

Integrity of the Left Arcuate Fasciculus Segments Significantly Affects Language Performance in Individuals with Acute/Subacute Post-Stroke Aphasia: A Cross-Sectional Diffusion Tensor Imaging Study

“…When considering the neural mechanisms underlying PSA, most previous studies have mainly focused on the structural integrity and functional activation of cortical areas in language processing [ 3 , 4 , 5 ]. Progress made by studies using advanced neuroimaging technologies increased our understanding of the mechanisms underlying language impairments following stroke.…”

Verbal working memory and syntactic comprehension segregate into the dorsal and ventral streams

“…Retrospective analyses were conducted on data from 103 participants in a broader clinical trial (clinicaltrials.gov ID: NCT03416738) conducted at the University of South Carolina (USC) and the Medical University of South Carolina (MUSC), which has overlapped with previous publications from our research group. 51–53,68,69 All procedures were approved by the Institutional Review Boards for both institutions, and informed consent was obtained prior to participation.…”

Cleaning up the Brickyard: How Theory and Methodology Shape Experiments in Cognitive Neuroscience of Language

“…Researchers in the field of cognitive neuroscience of language can rely on a large number of neuroimaging, neuro-stimulation and neuro-modulation techniques. For instance, neuroimaging techniques such as fMRI, EEG, and MEG provide correlational evidence on the link between brain functioning and cognition, whereas brain stimulation techniques (Bergmann & Hartwigsen, 2021;Hartwigsen & Silvanto, 2022) and lesion studies (Matchin et al, 2022;Vaidya et al, 2019) allow to draw causal inferences . Additionally, distinct research techniques show a difference in temporal precision, susceptibility to artifacts (e.g., Abbasi et al, 2021;Luck, 2005;Ouyang et al, 2016) and to cancellation of signals from a particular brain area (e.g., Devlin et al, 2000;Gorno-Tempini et al, 2002;Jezzard & Clare, 1999;Ojemann et al, 1997) and sensitivity to the orientation of the electrical currents (e.g., Ahlfors et al, 2009Ahlfors et al, , 2010Cohen & Cuffin, 1991).…”