In this chapter, we will explore the problem of vagueness and the paradoxes that it seems to engender. Nonclassical logics that try to address these issues by parting ways with the assumption of bivalence will be introduced and evaluated. The most promising of these (from the standpoint of addressing the problem of vagueness) is infinite-valued logic.

This chapter provides a tour of several additional forms of human language communication apart from spoken language. Visual speech (which also contributes to audiovisual speech) requires not only visual cortex, but regions such as posterior temporal sulcus which may help integrate signals across modality. Nonverbal communication, including productions such as crying or laughter, relate to activity in the superior temporal lobes but also in other regions including the cingulate cortex and insula. Reading and the ability to decode written language highlights portions of the visual system, including the ventral occipitotemporal cortex (often referred to as the visual word form area, or VWFA). Learning to read is a complex process that involves written language, knowledge of speech sounds, and motivation. Co-speech gestures are present in children’s language development and can convey semantic information alongside spoken language; integration of such semantic gestures involves left inferior frontal gyrus and premotor cortex.

This chapter covers how the human brain combines meaning across words (compositional semantics), beginning with pairs of words and working up to sentence processing. Concepts that are easy to combine – such as a “red apple” – appear to rely on the lateral anterior temporal lobe and the angular gyrus. Understanding sentences introduces additional demands during comprehension and is often associated with recruitment of left inferior frontal cortex. Additional regions come in to play for specific types of language challenge. When words are associated with multiple meanings, the correct interpretation must be selected based on the surrounding context. This process of semantic disambiguation is associated with additional activity in posterior temporal cortex and left prefrontal cortex. Compared to simpler sentences, understanding sentences with complex syntactic constructions also engages additional regions of posterior superior temporal gyrus and inferior frontal cortex. Finally, ongoing oscillatory activity, especially in the theta range, has been suggested to play key roles in parsing and understanding connected speech.

This chapter reviews how the brain represents concepts and word meanings, often termed semantic memory. A long history of work in people with focal brain damage suggests that different categories of concepts (for example, inanimate objects vs. living things) rely on different parts of the brain, evidenced by category-specific deficits in semantic memory. The notion of distributed semantic representations is further supported by studies showing activations for different concepts relying on different parts of the brain. In addition, there is evidence for unified semantic representations – that is, brain regions that play a role in representing a wide variety of concepts. These include the angular gyrus (active in many functional neuroimaging studies of semantic memory) and portions of the anterior temporal lobe (damage to which in the semantic variant of primary progressive aphasia). Together, frameworks that include a “hub-and-spoke” arrangement – which allow both for regions that are important for many concepts (hubs) and those representing modality-specific information (spokes) – may provide the most comprehensive view of how concepts are represented.

This chapter introduces the methods used in cognitive neuroscience to study language processing in the human brain. It begins by explaining the basics of neural signaling (such as the action potential) and then delves into various brain imaging techniques. Structural imaging methods like MRI and diffusion tensor imaging are covered, which reveal the brain’s anatomy. The chapter then explores functional imaging approaches that measure brain activity, including EEG, MEG, and fMRI. Each method’s spatial and temporal resolution are discussed. The text also touches on non-invasive brain stimulation techniques like TMS and tES. Throughout, the chapter emphasizes the importance of converging evidence from multiple methods to draw robust conclusions about brain function. Methodological considerations such as the need for proper statistical comparisons are highlighted. The chapter concludes with a discussion of how neurodegenerative diseases have informed our understanding of language in the brain. Overall, this comprehensive overview equips readers with the foundational knowledge needed to critically evaluate neuroscience research on language processing.

This chapter provides a comprehensive overview of the structural foundations of language in the human brain, tracing the development of localization theories from phrenology to modern neuroimaging. It introduces key anatomical terminology and landmarks, including major brain regions, gyri, and sulci. The chapter explores the evolution of language localization theories, highlighting influential figures like Broca and Wernicke, and the shift from single-region to network-based models of language processing. It discusses various approaches to brain mapping, including macroanatomical, microanatomical (cytoarchitectonic), and functional definitions. The chapter also covers important anatomical pathways, particularly the dorsal and ventral streams for speech processing, while noting that these simplified models may not fully capture the complexity of language networks. The chapter concludes by acknowledging the challenges in precisely labeling brain regions and the complementary nature of different naming conventions, setting the stage for deeper exploration of language neuroscience in subsequent chapters.

This chapter highlights several aspects of human communication that rely on brain regions outside the traditional fronto-temporal language network. Factors affecting the neural resources needed for communication include the task demands (including acoustic or linguistic aspects), and abilities of individual listeners. When speech is acoustically challenging, as may happen due to background noise or hearing loss, listeners must engage cognitive resources compared to those needed for understanding clear speech. The additional cognitive demands of acoustic challenge are seen most obviously through activity in prefrontal cortex. During conversations, talkers need to plan the content of what they are saying, as well as when to say it – processes that engage the left middle frontal gyrus. And the cerebellum, frequently overlooked in traditional neurobiological models of language, exhibits responses to processing both words and sentences. The chapter ends by concluding that many aspects of human communication rely on parts of the brain outside traditional “language regions,” and that the processes engaged depend a great deal on the specific task required and who is completing it.

This chapter reviews the brain processes underlying human speech production, centered on the idea that a talker wants to communicate through to the execution of a motor plan. Cortical regions associated with motor control –including premotor cortex, supplemental motor area, and pre-supplemental motor area – are routinely implicated in speech planning and execution, complemented by the cerebellum. In addition to generating speech sound waves, speech production relies on somatosensory and auditory feedback, associated with additional regions of the superior temporal gyri and somatosensory cortex. A special point of emphasis is the contribution of the left inferior frontal gyrus (including the area traditionally defined as “Broca’s area”) to fluent speech production. Additional points include speech prosody and sensory-motor feedback. Finally, the chapter concludes by reviewing several common challenges to speech production, including dysarthria, apraxia of speech, and stuttering.

This chapter summarizes how the human auditory system translates the acoustic speech sound from acoustic energy into a neural signal. Initial processing begins with the outer ear, followed by mechanical amplification in the middle ear (via the ossicles). The inner ear contains the cochlea, which is what converts physical energy to a neural signal that is transmitted to the auditory nerve. The subcortical auditory pathway includes the cochlear nucleus, inferior colliculus, and medial geniculate body. Subcortical auditory processing can be assessed with EEG to measure the auditory brainstem response (ABR) or frequency following response (FFR). The cortical area receiving auditory information, auditory cortex, contains a number of distinct subfields. The chapter also reviews common approaches for clinical evaluation of hearing sensitivity, notably the pure-tone audiogram, and common challenges to hearing (including sensory-neural hearing loss, noise induced hearing loss), and the function of cochlear implants.