The chapter presents and discusses empirical data on the neuropsychology of gesture production. The focus of this chapter is on the specific contributions of the right and left hemispheres to the generation of gestures. Since the respective neuroscientific method has a substantial impact on the study results and different methodologies can even entail apparently opposing results concerning gesture production, different neuropsychological methods, their paradigms, and limitations are presented in detail. Spontaneous gesture production studies evidence a substantial contribution of the right hemisphere to gesture production, while gesture production on command studies show a relevant role of the left hemisphere. Gestures that are generated in association with right hemispheric functions such as spatial cognition, nonverbal emotional expression, global and metaphorical thinking appear to be generated in the right hemisphere, while gestures that are linked to tool use praxis are generated in the left hemisphere. The findings further provide a neuropsychological basis for understanding the complementarity but also the dissociation between gestural and verbal message.

Over the last 10 years or so, I have noticed increasing trouble understanding what people are saying to me, especially if there are several people speaking at the same time, such as at a family dinner, or worse, at a big party. It may be the main reason I find social occasions increasingly difficult and intimidating. When Lois speaks to me, I often have to ask her to repeat what she said. She has learned to say things twice if she wants me to get it. I know that is irritating for her. Often, I just nod or grunt, pretending I understand what she is saying. I have attributed this increasing problem to my Alzheimer’s disease interfering with my ability to understand language, particularly if I don’t hear every word clearly. Aphasias affecting language production (poor word finding) or reception (impaired understanding) are common in the mid-to-late stages of Alzheimer’s, but trouble finding the right word or name is often one of the earliest symptoms of Alzheimer’s.

Language, a hallmark of human cognition, is a complex and universal tool for conveying thoughts and ideas. This chapter navigates the intricate landscape of language development, spanning its various dimensions. We begin by dissecting language into its components, be it spoken or signed, and explore its dual nature – both specific and universal. The chapter illuminates the brains remarkable capacity to derive meaning from linguistic input, pinpointing the neural structures underpinning language comprehension and production. Distinguishing between language quantity and quality, we delve into the role of contingent learning and experiential adaptation in molding linguistic abilities. Additionally, we ponder the evolutionary origins of language, contemplating its exclusive human attribute. Drawing from a diverse pool of research, including neuroimaging, behavioral assessments, and developmental studies, this chapter offers a comprehensive view of language development. It underscores the profound influence of gene–environment interactions in enabling infants to acquire language organically, without explicit instruction.

Disorders of thought include disorders of intelligence, disorders of the stream of thought, disorders of thought possession and obsessions, and disorders of the content and form of thinking. This chapter outlines disorders of intelligence, disorders of thinking, disorders of thought tempo, disorders of the continuity of thinking and disorders of the content of thinking. It presents descriptions of obsessions and primary and secondary delusions, as well as detailed examinations of specific delusions of persecution, infidelity, love, grandiosity, ill-health, guilt, nihilism and poverty. Speech disorders are also explored, along with aphasias. The chapter concludes with suggested questions for eliciting specific symptoms in clinical practice, in addition to standard history-taking and mental state examination. Disorders of thought and speech are central to the manifestation and diagnosis of many psychiatric disorders, including schizophrenia, and this chapter provides both descriptions and explanations of key signs and symptoms in this field.

Chapter 7 shows that abstract concepts are inner/cognitive tools. Inner speech is potent in enhancing our cognition, imagination, and motivation. In this chapter, I propose that we use inner speech more extensively with more abstract concepts, during both their acquisition and use, while monitoring our knowledge during their processing and referring to others to complement and enrich it. I review several studies with children and adults showing that the mouth motor system is more engaged during abstract concept acquisition and elaboration. This mouth activation suggests that language is implicitly activated during abstract language processing. Also, while low numbers engage the hand effector more, the processing of larger numbers might involve language, hence the mouth, more extensively. I overview research on the neural underpinning of abstract concepts, which confirms the importance of linguistic and social neural networks for their representation. Finally, I illustrate studies on abstractness in conditions characterized by impairments in social interaction and inner and overt speech abilities, such as autism, schizophrenia, and aphasia. Overall, the studies reviewed support the idea of a determinant role of language as an inner tool supporting the acquisition and use of abstract concepts.

Aphasia, apraxia, and agnosia are terms we use to describe clinical abnormalities. Each term is applied to a variety of neurologic disorders. In a given case more than one of the terms could be appropriate to describe the deficit. The phenomena to which these words are applied have no uniform patho-anatomic basis.

In this chapter, we focus on language development in individuals suffering from language and cognitive disorders. One of the major concerns of families and caregivers of individuals with these disorders is that exposure to more than one language may cause further difficulties, slow down, or hinder linguistic and cognitive development. Scientific research, however, shows that this is an unmotivated prejudice, and that bilingualism does not provide negative effects, but rather, can offer benefits. We explore the interaction between bilingualism and language disorders, discussing in particular developmental language disorders, developmental dyslexia, autism spectrum disorders, hearing loss, Down syndrome, and aphasia.

The past twenty years have brought a revolution in the understanding of how the human brain accomplishes language comprehension, as more sophisticated models have been proposed in response to the discovery of brain regions in the left hemisphere other than Broca’s and Wernicke’s areas involved in syntactic and semantic processing. Nevertheless, some old mysteries remain unsolved. One of these is the surprising finding that some split-brain patients have some linguistic abilities in their isolated right hemisphere, including, for a few, the ability to make grammaticality judgements. If the neural machinery for syntactic processing is found exclusively in the left hemisphere, this should not be possible. This paper proposes an account of this unexpected phenomenon using the grammatical tools of Role and Reference Grammar, and the solution has implications for the theory itself as well as for another old mystery, namely the ability of some aphasics, who cannot correctly interpret reversible passives, to nevertheless judge the grammaticality of sentences.

In this chapter, the author, from the double perspective of ethology and neuropsychiatry, gives an interdisciplinary account of language through the lens of the neurosciences, interweaving diverse scientific discourses. Using phylogenetic and ontogenetic accounts, he describes the transition from sensory perception to symbolic representation in animals and humans, and the way neural circuitry of language coalesces through relating. He thus maps the processes and trajectories of the ‘word-making machine’, corroborated by studies of sensory or institutional deprivation or of illness, abuse, or accidents. Studies carried out on plurilingual speakers recovering from aphasia reveal that the Mother tongue, the most deeply imprinted language, is the one that comes back first. Experiments with newborn babies confirm the origin of the Mother tongue in tactile interuterine stimuli, which are later recognised by the newborn in the lower frequencies of the mother’s voice, creating ‘a reassuring bond of familiarity’. This interdisciplinary approach sheds light on the embedding of language in the body and on the enduring imprint of early language formation in the brain.

Worldwide, we are an aging population, with dementia affecting people in increasing numbers. Here we focus on two types of dementia: Alzheimer's disease because it is the most prevalent form of dementia and the primary progressive aphasia of frontotemporal dementia because of its capacity to enhance creativity in music and visual art. For individuals with progressive dementia, the creative trance is an oasis, a world apart from the daily world of their growing difficulties. Instead, they face the solvable problems of creativity. Iris Murdoch wrote her final novel, Jackson's Dilemma, during the early stages of Alzheimer’s disease, and Willem de Kooning focused on painting as his dementia advanced. Sometimes, dementia can influence work for the better, even if only for a brief time. Frontotemporal dementia gave power to Maurice Ravel’s best-known work, Bolero, and Anne Theresa Adams, who also had frontotemporal dementia, resonated with the music, and transcribed it into visual art.

This chapter investigates whether sentence comprehension difficulty in aphasia can be explained in terms of retrieval processes. By modelling individuals with aphasia (IWAs) separately, we show that different IWAs show impairments along different dimensions: slowed processing, intermittent deficiency, and resource reduction. The parameters in the cue-based retrieval model have a theoretical interpretation that allows these three theories to be implemented within the architecture. In a further investigation, we compare the relative predictive accuracy of the cue-based model with that of the direct-access model. The benchmark data here are from Caplan et al. (2015); k-fold cross-validation is used as in the preceding chapter. The cue-based retrieval model is shown to have a better predictive performance.

Chapter 8 describes the fundamental research questions, empirical approaches and findings of neurolinguistics. It is a highly interdisciplinary linguistic subfield focusing on the relationship between brain and language behaviour. Concentrating on experimental research, methodological issues include considerations on research participants, data types, and techniques of data acquisition and analysis. The chapter ends with recommendations for further reading and a list of short exercises and ideas for small research projects.

In this chapter we consider more closely what we mean by a word. We begin by contrasting the differences between the mental lexicon and dictionaries. We then introduce students to the methods and techniques that psycholinguists use for studying the mental lexicon. We look at reaction time experiments, brain imaging, and the ways in which we can study individuals with aphasia and genetic disorders that affect lexical knowledge. Students are introduced to how children acquire morphology. We then look at English past tense morphology in the context of the ‘storage versus rules’ debate, considering what experimentation, brain imaging, and the study of aphasia and genetic disorders tell us about this controversy. The chapter ends with a brief history of dictionaries.