The Brain Basis of Language Processing: From Structure to Function

Abstract

Language processing is a trait of human species. The knowledge about its neurobiological basis has been increased considerably over the past decades. Different brain regions in the left and right hemisphere have been identified to support particular language functions. Networks involving the temporal cortex and the inferior frontal cortex with a clear left lateralization were shown to support syntactic processes, whereas less lateralized temporo-frontal networks subserve semantic processes. These networks have been substantiated both by functional as well as by structural connectivity data. Electrophysiological measures indicate that within these networks syntactic processes of local structure building precede the assignment of grammatical and semantic relations in a sentence. Suprasegmental prosodic information overtly available in the acoustic language input is processed predominantly in a temporo-frontal network in the right hemisphere associated with a clear electrophysiological marker. Studies with patients suffering from lesions in the corpus callosum reveal that the posterior portion of this structure plays a crucial role in the interaction of syntactic and prosodic information during language processing.

Disentangling meaning in the brain: Left temporal involvement in agreement processing

“…While the activation for correct verbs found in the pMTG could be equally accounted for by proposals that claim a role for this region in lexical retrieval processes, (Hagoort, 2005(Hagoort, , 2013, as well as positions that argue for pMTG involvement in the analysis of verb-argument relations (Bornkessel-Schleswsky and Schlesewsky, 2013;Friederici, 2011Friederici, , 2012, the same cannot be said for the differential activation profile evidenced by the Person > Number contrast. The verb-argument relation hypothesis would predict activation for person, but not for number agreement anomalies in the pMTG: while the interpretation of person agreement implies the mapping of morphosyntactic information onto specific roles (i.e.…”

“…Hence, a larger response for person compared to number anomalies could be expected in areas involved in the elaboration of the propositional meaning of the sentence, such as the aMTG/STG (Bornkessel-Schlesewsky and Schlesewsky, 2013;Lau et al 2008Lau et al , 2013) and the pars triangularis/orbitalis of the IFG (Friederici, 2011).…”

“…However, pMTG involvement was not limited to correct-agreement sentences: when contrasting the two incorrect conditions (Person > Number Violation contrast), Person Violations were found to generate a greater response in this area than Number violations, suggesting differential sensitivity to the type of information manipulated in verbal morphology. As reviewed above, functional interpretations about the involvement of the pMTG in language processing range from proposals advancing its role in the extraction of morpholological information for building syntactic structure (Pallier et al 2011) or in the retrieval of syntactic frames from 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 20 semantic memory (Hagoort, 2005), to views emphasizing the centrality of this region in mechanisms at the syntax-semantics interface, such as the analysis of verb-argument relations (Bornkessel-Schleswesky and Schleswesky, 2013;Bornkessel et al 2005;Friederici, 2011). The current set of data allows us to distinguish between the two proposals.…”

“…Moreover, the comparison between Person and Number violations revealed a remarkable asymmetry between the two features, with the former producing a significant increase of activation in this area, but not the latter. As reviewed above, activity in this region has been associated with the building of local syntactic structure, thanks to the ventral pathway connecting the anterior portion of the temporal cortex and the frontal operculum (Friederici, 2011;Friederici & Gierhan, 2013). Another interpretation attributes a critical role to the aMTG in the integration of different types of information to derive the propositional meaning of a sentence (Bornkessel-Schlesewsky and Schlesewsky, 2013), a claim that connects with a larger literature on the role of this region in semantic memory and conceptual combination (cf.…”

“…A third view, reflected in Friederici (2011Friederici ( , 2013, holds that integration of linguistic input in syntactic structure is subserved ventrally by a pathway that connects the anterior temporal cortex (ATC) to the frontal operculum in the LIFG (see also Grodzinsky & Friederici, 2006). It should be noticed that this model does not provide any neuro-anatomical distinction between syntactic operations dealing with phrase structure building and mechanisms dealing with feature-consistency checking, such as those primarily involved in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 5 agreement processing.…”