- Language in our brain. The origins of a uniquely human capacity by Angela D. Friederici
Language in our brain presents an in-depth exploration of the neural substrates linked to the language network, according to the current literature. The development, evolution and ontology of the language circuit are also considered, with a particular focus on the syntactic underpinnings of language.
In Part I, the author explores the neurological substrates associated with the numerous stages of language processing, which are necessary for any given communication event.
In Chapter 1, “Language Functions in the Brain: From Auditory Input to Sentence Comprehension”, the author proposes a model for language comprehension at the auditory level. The model is supported by a review of crucial literature with [End Page 132] respect to each of its levels: lexical, syntactic, semantic and prosodic. Friederici particularly emphasizes the temporal and spatial neural underpinnings of each of these processing levels. All the while, the cascading nature of language processing is considered.
In Chapter 2, “Excursions’, the author demonstrates that language comprehension and language production use a shared knowledge base (as proposed in early models; see Friederici and Levelt 1988). These models are supported throughout the chapter by seminal work on disordered language, early work using speech error analyses, and finally other empirical findings based on studies of online processing. Friederici then explores why certain communicative aspects, such as pragmatic abilities and hand gestures, are not believed to be part of the core language system. In Part II, the author examines the manner in which the level-specific neural regions from Part I are interconnected, and how they cooperate to form a human language network.
In Chapter 3, “The Structural Language Network”, the linguistic role of the primary white fiber tracts is discussed. Friederici examines the ventral and dorsal neuroanatomic pathways while discussing the evolution of their structural and functional interpretation, with particular emphasis on evidence from syntactic processes. The author concludes that the dorsal tract is primarily related to the comprehension of syntactically complex processes, while the ventral tract is responsible for the combinatorial processing of syntactically simple sentences.
In Chapter 4, “The Functional Language Network”, Friederici reviews the neural connections between white matter involved in the language network and how these connections can be investigated by utilizing resting-state or task-related approaches. The author discusses the manner in which linguistic information is encoded and transmitted (e.g., neurotransmitters, mirror neuronal ensembles, etc.), and finally, a ‘dynamic temporo-frontal’ (p. 141) model for the language circuit is proposed and supported.
In Part III, Friederici turns to a discussion of the human language faculty prior to maturation and situates Lenneberg’s 1967 seminal critical period hypothesis in the neurolinguistic literature.
In Chapter 5, “The Brain’s Critical Period for Language Acquisition”, the author discusses the debates about the length and the nature of the critical period, in relation to both first and second language (L2) acquisition. She suggests that different levels of processing may possess different age-thresholds and rigidities for their respective critical periods. It is shown that the critical period, characteristic of human language, is largely contingent on neural maturation, and is thus independent of input modality. In Chapter 6, “Ontogeny of the Neural Language Network”, the various levels of linguistic processing are separated and the timeline of their development during language acquisition is examined. Broadly, very young infants’ processing is prosody-dependant, while older children may call upon higher-level processing. The author suggests that initial language development thus occurs on a bottom-up basis, and top-down processes are only employed with age. Thus, the ventral and dorsal white fiber tracts associated with each of these processes possess different maturation timelines; the ventral tract develops earlier than the dorsal pathway. [End Page 133]
In Part IV, the evolution of the human language faculty is examined; Friederici maintains that language, as a uniquely human capability, is the consequence of our neural composition.
In Chapter 7, “Evolution of Language”, the author discusses evolutionary theories, such as the idea...