Central nervous system function depends on synaptic transmission involving either chemical-transmitter-mediated or direct electrical coupling between neurones. Transmitter activation of excitatory and inhibitory synapses respectively produce postsynaptic membrane depolarisation and hyperpolarisation in turn increasing or decreasing likelihoods of action potential firing by the targetted neuron. Further variants of neuron-neuron interactions include inhibition at the level of presynaptic terminals and G-protein dependent slow synaptic potentials. Some central nervous system synapses additionally show longer-term potentiation or depression phenomena with repeated activity produced by intracellular signaling mechanisms; these may underly memory. Finally, direct electrical synaptic connections between cells can synchronise firing between neurones. Release of K+ and transmitter glutamate by central neurones during intense electrical activity potentially perturbs their extracellular environment. This is normally corrected by transport activity in their closely related glial cells. Malfunctions in this buffering function predisposes to cortical spreading depression phenomena clinically associated with migraine aura.

Arrhythmias, frequently diagnosed through their characteristic electrocardiographic abnormalities, pose major public health problems contributing significant clinical morbidity and mortality. They result from breakdown of the normally orderly sequence of electrical activation through the heart. Although initiated by triggering events, they are sustained by the presence of re-entrant substrate arising from compromised, or heterogeneities in, action-potential conduction and/or recovery. These situations can arise from abnormal surface ion channel, Ca2+ homeostatic, cardiomyocyte metabolic function and/or cardiac remodelling or anatomical abnormalities. They proved amenable to study in genetically modified murine systems recapitulating clinically demonstrated abnormalities in their underlying biomolecules. These mirrored the features and mechanisms underlying human pro-arrhythmic conditions, including sinus node disorder, atrial arrhythmias, the Brugada and long QT syndromes, catecholaminergic polymorphic ventricular tachycardia, energetic and ion homeostatic disorders, and longer-term fibrotic or hypertrophic change. This led to recent classifications of arrhythmic mechanisms in different clinical situations, potentially modernising their management.

Culture as shared values/beliefs and behavioral scripts not only influences human behavior and cognition but modulates the underlying brain activity as well. Cultural impacts on the human brain have been investigated by cultural neuroscience research that examines cultural group differences in brain activities involved in specific cognitive/affective processes. The findings, however, do not allow inference of causal relationships between specific cultural values/beliefs and brain activity. Cultural priming approach tests how brain activities underlying various cognitive/affective processes are modulated by recent exposure to specific cultural symbols or activation of specific cultural values/beliefs. Increasing evidence indicates that cultural priming leads to subsequent changes of brain activities in response to perception, attention, reward, self-reflection, etc. The findings suggest that culture provides a key frame in which the human brain develops and functions to mediate multiple cognitive and affective processes.

It has become manifest across the biological sciences that culture is a dynamic component of human brain–body formation and experience. Culture is essential to understanding questions of neuroplasticity, emotional development, interoception, epigenetics, predictive coding, facial recognition, empathy, and so on, yet culture itself is often reduced by those sciences that have come to depend on it. It is "the exterior," or it is "input." The "world," insofar as it introduces contingency to what it is to be human, is not in itself understood as contingent. What happens when culture – both a cause and an effect of human formation – is itself situated, disrupted, historicized? Historians hold the keys to a radical interdisciplinary engagement that complicates the question of culture in ways complementary to the biological disruption of interiority. The cultural brain is an historical artefact. Acknowledging this should change the kinds of questions asked by those who study the brain.

Advancing a radically enactive account of cognition, this chapter argues for the possibility that cultural factors permeate rather than penetrate cognition such that cognition extensively and transactionally incorporates cultural factors in lieu of there being any question of cultural factors having to break into the restricted confines of cognition. We review the limitations of two classical cognitivist, modularist accounts of cognition in addition to a revisionary new order variant of cognitivism – a predictive processing account of cognition (PPC). We argue that the cognitivist interpretation of PPC is conservatively and problematically attached to the idea of inner models and stored knowledge. Instead, we offer a radically enactive alternative account of how cultural factors matter to cognition – one that abandons all vestiges of the idea that cultural factors might contentfully communicate with basic forms of cognition. In place of that idea, we promote the possibility that culture permeates cognition.

In this introductory chapter, we outline some conceptual building blocks for an ecosocial view of the co-construction of mind, brain, and culture. The brain is the organ of culture; mind and experience are processes located in loops of active engagement of brain and body with the social world. This engagement occurs on multiple time scales, from evolution and co-evolutionary adaptation to humanly designed niches, through the cultural history of populations and communities, to individual developmental trajectories, narratives of the self, and moment-to-moment engagements with social contexts. We are born biologically equipped to acquire culture and, across our lifespan, we become attuned to particular social and cultural environments. The niches we inhabit are cooperatively constructed and presented to us as cultural affordances that enable our cognitive capacities, sense of self, adaptive skills, and meaning-making capacity. The rewiring of brain circuits, synaptic plasticity, and underlying changes in gene regulation only make sense in relation to the particular resources, affordances, and adaptive tasks presented to us by specific cultural environments. Answering the question of what makes us human then turns out to involve not just an evolutionary story in deep time, but also cultural and individual stories in historical, developmental, and biographical time.

Three broad social factors – childhood adversity, immigration, and urban living – are robustly associated with an increased risk of schizophrenia. To date, however, there is no consensus on what it is about these phenomena that raises the risk of psychotic illness. In 2005, J. P. Selten and E. Cantor-Graae proposed a “social defeat” hypothesis according to which the social determinants of schizophrenia are best characterized as experiences of social subordination. In recent years, the social-defeat hypothesis has been broadened to include experiences of social exclusion. In this chapter, we review the different versions of the social defeat hypothesis and argue that it fails to account for the urban effect. We further argue for the potential utility of paying greater attention to social science when theorizing about the social determinants of schizophrenia.

In this epilogue, we reflect on the prospects for advancing interdisciplinarity in the sciences of culture, mind, and brain. Neuroscience is increasingly applied to address questions of central concern to the social sciences. Social sciences, in turn, can contribute to neuroscience research in a variety of ways, including: (1) the study of social factors that influence the brain across the lifespan; (2) the context-sensitive translation of neuroscience research into applications in clinical and other social settings; (3) critical social analyses of cultural, conceptual, and institutional framing and constraints on neuroscience research, knowledge production, and applications; and (4) integration of each of these approaches in an ecosocial view of the brain in its social-cultural niche. Obstacles to interdisciplinarity stem from institutional structures, methodological strategies, epistemic commitments, and divergent ontologies. We describe strategies to surmount these obstacles, including: (1) institutionally, creating spaces for collaborative work, supporting interdisciplinary career tracks, and ensuring sustained funding; (2) conceptually, borrowing models and metaphors across disciplines, establishing boundary objects of common interest, using system diagrams to locate diverse levels and processes in the same model; and (3) methodologically, establishing convergent validity through mixed and hybrid methods, and creating shared databases and pipelines to facilitate integration of multiple perspectives.

Culture is composed of meanings (e.g., values, beliefs, and norms) and practices (e.g., conventions, scripts, and routines) that are shared, albeit unevenly, in a given community and group. Culture is integral to biological adaptation, not an overlay to the human mind but part and parcel of how the human mind functions. Since the mind is shaped through culture, it also contributes to the reproduction of culture. This chapter highlights a broad contrast thought to separate the West from the “rest,” with Westerners being more independent or less interdependent than non-Westerners, although non-Western regions themselves are highly variable, reflecting diverse adaptive strategies for achieving interdependence under varying socio-ecological conditions. We review existing behavioral and neuroscience evidence to support a broad distinction between the West and the non-West based on three core features of interdependence: predictors of happiness, holistic attention, and holistic social cognition. We also summarize recent evidence suggesting that culture influences cortical volume in specific brain regions. We conclude by pointing out that while cultural shaping of mentality is highly idiosyncratic at the individual level, it can nonetheless be systematic at the collective level, enabling faithful reproduction of the cultural system by which individuals have been trained and shaped.

This chapter offers a cultural epidemiology of digital communities, describing how these groups emerge, bond, and come to develop shared embodied experiences. We argue that online communities, while seemingly novel and often “strange," can offer insights into fundamental mechanisms of human sociality albeit on an unprecedented speed and scale due to specific affordances of cyberspace. After framing this argument, we outline a noncomprehensive anthropological survey of online communities of interest. Our hope is to provide a model for how online communities grow to share interphenomenal experiences despite lack of face-to-face interaction, and how this might inform our understanding of ordinary social cognition.