While the preceding two chapters focused on the physiological domains whose motions take place ‘by nature’, that is, involuntarily, this chapter looks at the activities of the physiological system responsible for the motion ‘by will’. Galen depends on Hellenistic anatomists, especially Herophilus, for much of what he knows about the nervous system, but this chapter looks at both inherited knowledge and polemic interaction. In a rare case of disagreement, Galen criticizes Herophilus regarding the claims about the inherent sensitivity of the nerve tissue. The fact that Galen does not accept Herophilus’ experiments and maintains that nerves only receive capacity from the brain shapes his understanding of this physiological domain. The activities of the nervous system encompass not only voluntary motion but also sense perception and pain, and this chapter argues that each of them has distinctive implications for the unity of the living body as a whole.

Over the past three decades, catatonia research has experienced a remarkable renaissance, driven by the application of diverse methodologies and conceptual frameworks. This renewed interest has significantly reshaped our understanding of catatonia, a complex syndrome with multifactorial origins spanning epidemiology, historical context, phenomenology, genetics, immunology, and neurobiology. These advancements have offered a more comprehensive and nuanced perspective, culminating in the recognition of catatonia as a distinct diagnosis in the ICD-11 – a landmark development that underscores its clinical and scientific relevance. Despite these strides, several unresolved issues remain that require future research. Bridging these gaps is crucial not only to enhance our understanding of catatonia but also to identify the most effective treatments and uncover the mechanisms underlying their efficacy. Such advancements hold the promise of developing improved diagnostic markers and tailored therapeutic strategies, offering significant benefits to patients affected by this challenging condition. In this chapter, we explore the profound implications of catatonia research, spanning its impact on clinical psychiatry and neuroscience, as well as its broader contributions to our understanding of the intricate relationship between the brain and mind.

A growing literature examines the relationship between compassion and various aspects of nervous system function, especially the brain. The chapter starts by outlining neuroimaging studies of compassion and then examines the topic of empathy and the brain, noting evidence that observing another person’s emotional state activates parts of the neuronal network that are also involved in processing that same state in oneself. Research suggests that multiple areas within the brain are involved in compassion and compassion training, with some regions more strongly implicated than others. Finally, relevant conclusions are presented and potential directions for future work outlined. Overall, research into the neuroscience of compassion supports the idea that compassion can be cultivated deliberately through training. There is evidence that activities such as compassion training and meditation can increase positive affect, boost resilience, facilitate altruistic behaviour, and possibly even assist with equanimity. These ideas are underpinned by growing neuroscientific evidence of impact on the brain. These valuable findings underscore the importance of developing compassion as a skill and fundamental attribute for healthcare workers across all settings.

This chapter covers the broad topics of neurophysiology. This includes the anatomy and physiology of the brain, in particular the cerebral arterial and venous circulations, cerebral spinal fluid production and function and the clinical relevance in neurocritical care. There is additional focus on the nerve axon, spinal cord and spinal cord reflex arcs.

In times past, an inquisitive physician-scientist must have pondered these questions: How do we unknowingly breathe? What brain structures control our breathing? Why is breathing so perfectly rhythmic? Is there a lung-brain communication, and if so, how? But an even more fundamental question must have been: how much brain injury can one sustain before breathing stops?

It took two centuries (more or less) to answer the above-mentioned questions and gradually add small pieces to a large (still incomplete) puzzle. The respiratory center in the brainstem was identified and characterized in the late 1800s and early 1900s. Similarly, the function of the respiratory muscles and its neural connection with cranial nerves (CN) became better known.

This chapter recounts the history of the neurology of breathing and, thus, the discovery of the respiratory center and the respiratory mechanics. Sections of the chapter review experimental and clinical discoveries of those parts of the central and the peripheral nervous system involved with breathing while acknowledging their interplay.

This chapter comes in two related but distinct parts. The first presents general trends in the neurosciences and considers how these impact upon psychiatry as a clinical science. The second picks up a recent and important development in neuroscience which seeks to explain mental functions such as perception and has been profitably extended into explanations of psychopathology. The second part can be viewed as a working example of the first’s overarching themes.

Accounts of genetic findings involve concepts which can prove challenging. Terminology may be unfamiliar, and some words have specialised meanings and may not always be used consistently. This chapter aims to provide an overview of the key concepts. The subject matter is intrinsically dense and can be hard to take in, so the reader may wish to skim parts of this section and then refer back to it when necessary.

This chapter provides a brief review of basic neuroanatomy, followed by a more detailed description of structures and pathways important for neuropsychiatric practice. The focus will be on the limbic brain and the functional anatomy of emotion, memory, cognition and behaviour. A more comprehensive review of general neuroanatomy can be found in standard textbooks such as Johns, Clinical Neuroscience.

• Information travels through the brain as electrical signals along a complex network of interconnecting nerve cells called neurons.

• Neurons connect to each other at synapses, small gaps where chemicals called neurotransmitters amplify or muffle the electrical signals.

• The reward pathway determines our experience of pleasure and many psychoactive drugs work by over-stimulating this pathway.

• After using psychoactive drugs, the brain needs time to recover. This is often experienced as a psychological ‘crash’ or ‘come down’.

• If a drug is used regularly, the desired effects become harder to achieve – a process called tolerance.

• People who use drugs often increase the amount of drug they take over time in an attempt to overcome tolerance. This increases the risk of drug-related harm.

• Regular psychoactive drug user ends up altering brain functioning, making it much harder to enjoy non-drug experiences. The world can become joyless.

• Adolescence is the period between the onset of puberty and the point at which adult roles are assumed and involves rapid physical, psychological and social change.

• In adolescence, learning takes place as the brain establishes neural networks. These networks are constantly modified by new experiences.

• The adolescent brain develops in stages. One of the last areas to develop are the frontal lobes, the part of the brain responsible for decision-making and assessing risk.

• Just when the adolescent brain is at this delicate developmental phase, it is also most impulsive and drug use is most likely.

• Drug use in adolescence disrupts brain development, which can lead to long-term damage to brain function and increase the risk of further drug use.

• Many adolescents are surprisingly poorly informed about drugs, their effects and the harms they can cause.

• Adolescents tend to seek information about drugs from the internet or friends.

• Accurate information is available and should be highlighted to adolescents.

The beginning of the third millennium, starting in the early noughties and increasing in strength throughout the 2010s, has seen a large shift in theoretical focus in the mind sciences. In what might be called the predictive revolution or the predictive turn, many researchers in the psychological and brain sciences have come to consider the human mind a ‘predictive engine’ or ‘prediction machine.’ Like its predecessor, the cognitive revolution, more than half a century before, the predictive revolution is grand in ambition. It tries to explain all mental processes within one common framework. In this unified theory, the functioning of the mind is no longer best explained as an information processor: Minds have become prediction systems. The predictive revolution promises to reconcile cognition and behavior as the intrinsically connected two sides of the same coin serving human interactions with the environment.