This chapter begins with an in-depth exploration of neuroanatomy, including macroscopic features like the cerebral cortex, brain stem, and basal ganglia, as well as the pathways between the brain and body such as the spinal cord and cranial nerves. Against this background, four potential applications are introduced: first, the creation of motor prosthetics that use brain activity to control artificial limbs; second, the development of sensory prosthetics to restore vision or hearing; third, the artificial reactivation of memories through targeted brain stimulation; and fourth, the treatment of anxiety by incorporating either neuroimaging or brain stimulation. Each application is framed in terms of the modularity debate, which focuses on whether specific psychological functions can be localized to distinct brain regions. These four examples illustrate some cases in which it is useful to localize a behavioral function within a single region, but also where it may be more useful to appreciate either the diversity that exists within a region or the coordination that exists across regions.

The chapter opens by exploring different perspectives on defining mental disorders, contrasting Freudian psychoanalytic views with the diagnostic criteria of the DSM and newer alternative frameworks for understanding mental health. It then critiques early modular models of emotion, such as Papez’s circuit and the limbic system, which attempt to localize emotions to specific brain regions but fail to comprehensively explain diverse emotions and their complex manifestations in behavior. The chapter concludes by evaluating the value and limitations of brain stimulation for treating depression, with a focus on modern experiments involving deep-brain stimulation.

This chapter examines the historical development of psychology through the framework of empiricism, beginning with behaviorism’s emphasis on stimulus–response relationships and extending to cognitive psychology’s focus on mental processes. It describes neuroscience’s potential to synthesize these perspectives: preserving the behaviorist mandate of referring only to measurable phenomena while acknowledging the existence of important processes that occur between stimulus and response and that may be rationally characterized using some of the language of psychology. The chapter also introduces a conceptual framework for understanding neuroscience’s practical contributions to psychology while describing critiques of redundancy and the logical difficulties posed by reverse inference. Finally, this chapter advocates for the value of clear empirical communication in describing psychology’s relationship with behavior, citing historical examples of ambiguous language in biological psychology.

The study of behavioral genetics seeks to answer two fundamental questions: To what extent are traits innate? And how can gene sequencing be utilized to predict behavior? This chapter begins with a critical evaluation of twin and adoption studies, describing the challenges of separating genetic influences from gene–environment interactions. The latter part explores modern genetic technologies, such as gene sequencing, and their application in identifying individuals who are at risk for developing neurological conditions, in predicting responses to treatment, and in employing polygenic screening for embryo selection.

This chapter provides a comprehensive overview of the neurotechnologies used to record and stimulate brain activity, from invasive techniques like optogenetics and intracranial electrodes to noninvasive methods such as electroencephalography and functional magnetic resonance imaging. It explains how these technologies are evaluated based on criteria like spatial resolution, temporal resolution, safety, and portability. With this framework, each technology is evaluated in terms of its power and constraints. This chapter highlights the trade-off between technological power and practical constraints, emphasizing the need for safer, more adaptable devices for both clinical and research purposes.

In the popular imagination, presences often mean spirits or ghosts. This chapter focuses on the notion of the spirit and how it connects to presence. During his research, the author met spiritual practitioners, diviners, psychics and mediums – many, but not all, considered themselves spiritualists. For them, there was no great mystery when it came to presence. It was spirit, pure and simple. The author suggests that felt presence could be shaped by our very own models of what is possible in the mind. We draw the boundaries; we decide who gets in and gets out. We might be the architects of where we stop and the other begins.

This chapter recounts the author’s interviews with people who hear voices that others cannot. This hearing of voices is connected to the central notion of ‘the presence feeling’. The author describes how in feeling that something is there, but not via our normal senses, we are sensing something impossible, ‘going beyond’ the ordinary sensory field. At the same time, these experiences don’t quite seem to fit the sensation of presence we have encountered already. They are beyond what someone could conceivably experience, but they do not pick out the social bit – the sense of someone being there. Presences, then, are not new. They have been there all along, with people trying to describe them but unable to pin them down or grasp why they come, why they are there.

Visual hallucinations are known to occur in both Parkinson’s and dementia with Lewy bodies (DLB). This chapter studies both conditions. The author posits that we have at least two different theories to consider. The body theory of felt presence reflects how we think the motor system works and provides a plausible explanation of how presences might be possible in particular situations and conditions. An alternative theory of presence is based on the broader idea of ‘predictive processing’. When we see, hear or feel things around us that aren’t there, our brain attempts to fill in the gaps based on some kind of ingrained expectation. That might not be something we are consciously expecting – it is more like a learned response. We can call this the expectation theory of presence. These models might not be mutually exclusive. Both of these theories could be playing a role in the presences of psychosis or Parkinson’s. They could potentially explain different examples of presence, or they could work in concert in some way, one laying the groundwork, the other offering a finishing touch.

This chapter begins with the story of Leven Brown, who rowed from Cadiz to Tobago. The author talks to Leven to understand more about the link between endurance and presence. There is a dearth of accounts of experiences that sound like presence for extended pursuits done solo: ultrarunners, free divers, long distance swimmers and sailors, for example. But what drives that connection? Is it just isolation, leading us to conjure companions? Is it about people being pushed to the extremes of their limits, mentally and physically? Or is it something more individual than that, something unique to the people who have these experiences? Some of the encounters reported are similar to the classic ‘Third Man’ experiences discussed in chapter 2. They come about in adverse situations, but they occur more in continuity with everyday life. The author is left with some questions: is it stress or adversity that prompts these experiences, or do they tend to occur for a certain kind of person? Do you have to be someone extraordinary already to enter this realm? And if you do need to be a certain kind of person, how can the experience ever be separated from the individual?