This chapter covers all forms of neuronal communication, from neuron-to-neuron signaling to communication with the body and external world. It begins with an overview of electrophysiology, focusing on how action potentials and ion channels drive electrical signaling in neurons. It then explains neurotransmission, detailing how neurotransmitters are synthesized, released, and regulated through processes like reuptake and degradation. The chapter then expands upon the concept of neuronal communication to include how neurons control body functions, such as muscle movement and hormone release, and how they process sensory input like light, sound, and touch through specialized receptors. Finally, the chapter incorporates plasticity, describing how neuronal communication affects synaptic restructuring via processes like long-term potentiation.

This chapter explores the development and use of speech prosthetic technologies, from early devices like sip-and-puff systems to modern brain–computer interfaces. It reviews fundamental research on language lateralization, Broca’s and Wernicke’s areas, and the distributed representation of word meanings in the brain. The chapter also assesses the status of speech neuroprosthetics, focusing on technologies that decode covert and intended speech from brain activity. Future advancements, such as inferring thought directly through neural recordings, are explored, including the ethical considerations of such breakthroughs.

This book was written with many people in mind, but none more than future scientists. The Preface to this text posed a question: How can psychological research progress when our most powerful neurotechnologies are too invasive for widespread human use?

This chapter explores the role of drugs in understanding neurotransmitter systems and addressing behavioral problems. It begins by discussing drug administration methods such as oral, intravenous, and inhalation, explaining how these routes influence pharmacokinetics, including drug absorption and metabolism. Like Chapter 6, the chapter then covers several practical applications, including in depression, anxiety and trauma, eating behavior (obesity), addiction, cognitive enhancement, and sleep. These examples underscore the progress that neuroscience has made (e.g., psychiatric medication), the progress that it continues to make (e.g., in psychedelic medicine), and the ongoing need for research and technological innovation. Furthermore, each example illustrates the complex and often ambiguous relationship between neurotransmitters and behavior, where neurotransmitters can influence multiple behaviors, and behaviors can be influenced by multiple neurotransmitter systems.

Reinforcement and addiction are commonly attributed to dopamine and its release along the pathway from the ventral tegmental area to the nucleus accumbens. This chapter traces the historical development of research linking dopamine to reinforcement, reward prediction error, and incentive salience. It then evaluates the evidence for and against the dopamine theory of addiction and discusses challenges in testing this theory in human studies. The chapter concludes with a speculative exploration of potential dopamine-based treatments for addiction.

This chapter focuses on the foundations of study design and statistical analysis in psychological research. It explores strategies for ensuring internal validity, such as randomization, control groups, and large sample sizes. Additionally, it addresses the complexity of human behavior by exploring multivariate experiments and the use of artificial intelligence and machine learning in neuroscience. The chapter also discusses the replication crisis and the emergence of open science practices, encouraging students to think critically about isolated scientific findings and offering tools for identifying credible research. Lastly, it critiques null hypothesis significance testing and p-values while providing an overview of key statistical topics like correlation coefficients, standardized mean differences, and regression.

This chapter addresses the role of oxytocin and vasopressin in shaping social behavior, reviewing both human and animal studies. The chapter critiques the early optimism around oxytocin’s ability to foster trust and emotional understanding, providing evidence from failed replication studies and highlighting the effects of sex, context, and brain region-specific interactions. It also assesses clinical research on oxytocin as a potential treatment for autism spectrum disorder, pointing out the limitations of current approaches and the complexity of translating animal research into human applications.

This chapter explores the genetic and cellular foundations of biopsychology, focusing on the diversity that exists at the molecular and cellular levels within the brain. It explains the key processes of gene expression, including DNA transcription and translation, emphasizing how variation in these processes contributes to neuronal diversity. Moreover, this chapter provides a high-level overview of advanced techniques, such as transcriptomics, describing how these techniques are informing the process of classifying neuron types. The chapter also explores cellular anatomy by analyzing the wide range of neuronal shapes and the complexity of their connections. This foundation sets the stage for future discussions of neurotechnologies, for which an understanding of genetic constructs will enable students to better grasp the capabilities of tools like optogenetics and calcium imaging.

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.