Language, mind and brain

Abstract

Language serves as a cornerstone of human cognition. However, our knowledge about its neural basis is still a matter of debate, partly because ‘language’ is often ill-defined. Rather than equating language with ‘speech’ or ‘communication’, we propose that language is best described as a biologically determined computational cognitive mechanism that yields an unbounded array of hierarchically structured expressions. The results of recent brain imaging studies are consistent with this view of language as an autonomous cognitive mechanism, leading to a view of its neural organization, whereby language involves dynamic interactions of syntactic and semantic aspects represented in neural networks that connect the inferior frontal and superior temporal cortices functionally and structurally. Our conceptions of the neural mechanisms of language have developed in tandem with our understanding of the nature of the language faculty as a cognitive system. Initially, research focused on frontal and temporal cortical regions as being involved in vocal production and speech perception, respectively. Since speech is the main medium of language used for communication, it may seem natural to equate language with speech or even ‘acoustic communication’1. This view, however, is too narrow. Speech is just one possible way of externalizing language (with sign or writing being other examples), ancillary to the internal computational system. In addition, ‘communication’ is merely a possible function of the language faculty, and cannot be equated with it. We argue that language is a species- and domain-specific human cognitive capacity (Box 1)2,3,4,5,6. In essence, language is an internal computational mechanism that yields an unbounded array of structured phrases and sentences. These must be minimally interpreted at two interfaces—that is, internal thoughts on the one hand, and externalization via sounds, writing or signs on the other (Box 1)4,5,7,8. Neurolinguistics focuses on the study of the neural substrates underlying the computational cognitive mechanism that lies at the core of human language. From a theoretical linguistic standpoint—that of generative grammar—language is posited to be a process described at a formal level, divided into functionally separable or autonomous components, such as syntax, morphology, and so on. The immediate question of interest that then arises is whether the formal representations exploited in generative grammar correspond to actual brain architecture. We will discuss independent lines of research converging on the result that syntactic processes are in fact independently computed in the brain

Neural substrates of word category information as the basis of syntactic processing

“…Therefore, the left FG was assumed to be intrinsically connected with the left STG in our models. The interconnections between the Broca's area (BA 45 and BA 44) and the left STG were also intrinsic (see Friederici et al, 2017 and the related references therein). The functional connections among the VOIs were modeled to be bidirectional (cf.…”

“…Although the underlying cognitive mechanisms were not demonstrated, both Zaccarella and and Goucha and Friederici (2015) have revealed the candidate brain areas for individuals' successful retrieving of the combinatorial rules operating on labels (also see the comments of Goucha et al, 2017), and these areas might be the candidate neural substrates of the WCI as the basis of the syntactic processing. Such a dorsal pathway connecting Broca's area and the left temporal cortex (esp, the STG) is reported to be critical for (complex) syntactic processing (for a recent review, see Friederici, Chomsky, Berwick, Moro, & Bolhuis, 2017) in ontogenetical (Brauer, Anwander, Perani, & Friederici, 2013;Skeide, Brauer, & Friederici, 2016), second language acquisition (Yamamoto & Sakai, 2017), cross species (Dick, Bernal, & Tremblay, 2014), and primary progressive aphasia studies (Wilson et al, 2011), while the ventral tract connecting these brain regions might be involved in the semantic processing and local syntactic processing (Makuuchi & Friederici, 2013) or low-level syntactic feature identification (Friederici, 2012;. Such a dorsal pathway connecting Broca's area and the left temporal cortex (esp, the STG) is reported to be critical for (complex) syntactic processing (for a recent review, see Friederici, Chomsky, Berwick, Moro, & Bolhuis, 2017) in ontogenetical (Brauer, Anwander, Perani, & Friederici, 2013;Skeide, Brauer, & Friederici, 2016), second language acquisition (Yamamoto & Sakai, 2017), cross species (Dick, Bernal, & Tremblay, 2014), and primary progressive aphasia studies (Wilson et al, 2011), while the ventral tract connecting these brain regions might be involved in the semantic processing and local syntactic processing (Makuuchi & Friederici, 2013) or low-level syntactic feature identification (Friederici, 2012;.…”

“…Furthermore, Goucha et al (2017) proposed that the Broca's area, the left superior temporal gyrus (STG), and the dorsal pathway connecting them might be in support of labeling. Such a dorsal pathway connecting Broca's area and the left temporal cortex (esp, the STG) is reported to be critical for (complex) syntactic processing (for a recent review, see Friederici, Chomsky, Berwick, Moro, & Bolhuis, 2017) in ontogenetical (Brauer, Anwander, Perani, & Friederici, 2013;Skeide, Brauer, & Friederici, 2016), second language acquisition (Yamamoto & Sakai, 2017), cross species (Dick, Bernal, & Tremblay, 2014), and primary progressive aphasia studies (Wilson et al, 2011), while the ventral tract connecting these brain regions might be involved in the semantic processing and local syntactic processing (Makuuchi & Friederici, 2013) or low-level syntactic feature identification (Friederici, 2012;. These researches mentioned above imply that the WCIbased complex hierarchical syntactic structure processing might be supported by the Broca's area, the left STG and their dorsal connections.…”

“…and the left STG were also intrinsic (seeFriederici et al, 2017 and the related references therein). The functional connections among the VOIs were modeled to be bidirectional (cf Makuuchi & Friederici, 2013).…”

Disentangling sound from syntax: electrophysiological analysis of linguistics expressions

“…Meaning is computed by interpreting syntactic structures but it is not strictly necessary to generate well-formed linguistics expressions, given the possibility to construe meaningless structures such as this triangle is a circle 1,2 . The role of syntax in this complex system is crucial for at least three distinct empirical and theoretical reasons: first, syntax can generate new meaning by permuting the same set of words (so for example, Abel killed Cain is different from Cain killed Abel); second, there is no upper limit to the number of words that can enter the syntactic composition: syntax can potentially generate an infinite set of structures; third, it appears to be the real species-specific boundary distinguishing human language from that of all other animals 3 . Unfortunately, given this integrated and complex design characterizing language, isolating electrophysiological information solely related to syntax seems to be impossible by definition, since sound is inevitably intertwined with syntactic information 4,5 even during inner speech 6 : in fact, sound representation is already associated to the words in the lexicon before entering the syntactic computation.…”