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The destructive competition hypothesis views the brain as a system with finite processing resources, where new cognitive functions compete with evolutionary older ones for cortical space. In contrast, our combined neuroimaging and behavioral evidence points to a different conclusion: The human brain has the remarkable capacity to accommodate new cultural skills, such as reading, while simultaneously enhancing related preexisting abilities, such as face recognition. Rather than impairing older functions, reading acquisition appears to support and refine them.
It has been argued that our scientific discoveries support at least one of two distinct forms of causal reduction thereby making the notion that we irreducible agents obsolete. One is the reduction of the manifestation of causal dispositions to stimulated responses. The other is the reduction of kinds of causes of physical change to those studied in the hard sciences. In this chapter, I argue that neither have any scientific support. Rather, whether either form of reduction is viable won’t ultimately be resolved by scientific advancement but by analytic progress. Furthermore, I argue that attempts at the first are misguided as attempts at reducing what is a process (i.e., the manifestation of a causal disposition) to what can be a result of various processes (i.e., a stimulated response); while attempts at the second ultimately involve not fully taking into account how the specificity of any domain of science limits the generalizability of what can be discovered through it.
The best models for certain neural matters underlying the expression of our agency are stochastic or probabilistic. While this fact has been thought to be consistent with the notion that we are irreducible agents who settle matters that aren’t already settled, this consistency has come under dispute. It has been argued that, given probabilistic models apply to the underlying neural matters, for the way we express the ability to settle matters that aren’t already settled to perfectly align with what should be expected would, over the long run, amount to a wild coincidence. I argue that this objection is an empirical objection that goes against empirical findings. Thus, it isn’t credible. Moreover, what we continue to observe through neuroscience is evocative of the idea that we are irreducible agents who do this sort of settling in the midst of disposing and inclining factors.
Anhedonia and reward-processing deficits are core features of major depressive disorder (MDD) that respond poorly to traditional antidepressants. Ketamine has rapid antidepressant effects, yet its neurofunctional actions within reward circuits remain unclear. We synthesized human neuroimaging evidence on ketamine-related modulation of reward circuitry and implications for anhedonia.
Methods
Following Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, we searched Ovid Embase/MEDLINE/PsycINFO, Cochrane Library, Scopus, Web of Science, and Google Scholar. Eligible studies included adults with MDD receiving ketamine or esketamine and undergoing fMRI, PET, or related imaging during rest or reward/emotion tasks. Thirteen studies met inclusion criteria (N = 623; 482 MDD/TRD, 141 controls), mostly randomized, double-blind, and placebo-controlled; no eligible esketamine neuroimaging studies were identified.
Results
Intravenous ketamine (typically 0.5 mg/kg over 40 min) was associated with short-term modulation of fronto-striatal and limbic networks. Resting-state fMRI commonly showed altered ventral striatal–prefrontal/ACC connectivity and broader DMN/salience/executive network reorganization across acute-to-subacute windows (≈2–48 h), with some effects changing at later follow-up (≈10 days). Task-based fMRI showed altered ventral striatal/putaminal responses during reward anticipation/feedback and modulation of medial prefrontal/cingulate activity during emotion processing. PET findings suggested increased prefrontal–cingulate metabolism and region-specific 5-HT₁B binding/availability changes, with baseline ventral striatal 5-HT₁B measures associated with symptom profiles and symptom change.
Conclusions
Ketamine is associated with rapid reconfiguration of reward-related circuitry, but few studies directly measured anhedonia; findings likely reflect broader reward-processing and antidepressant-associated mechanisms. Larger longitudinal multimodal studies are needed to validate biomarkers and durability.
This chapter offers an in-depth discussion of various nanoelectronic and nanoionic synapses along with the operational mechanisms, capabilities and limitations, and directions for further advancements in this field. We begin with overarching mechanisms to design artificial synapses and learning characteristics for neuromorphic computing. Silicon-based synapses using digital CMOS platforms are described followed by emerging device technologies. Filamentary synapses that utilize nanoscale conducting pathways for forming and breaking current shunting routes within two-terminal devices are then discussed. This is followed by ferroelectric devices wherein polarization states of a switchable ferroelectric layer are responsible for synaptic plasticity and memory. Insulator–metal transition-based synapses are described wherein a sharp change in conductance of a layer due to external stimulus offers a route for compact synapse design. Organic materials, 2D van der Waals, and layered semiconductors are discussed. Ionic liquids and solid gate dielectrics for multistate memory and learning are presented. Photonic and spintronic synapses are then discussed in detail.
During the past decade, emerging studies using electrochemistry and nanoscale imaging have demonstrated that partial exocytotic release is prevailing in neuroendocrine cell models. However, due to complicated structure and culture process, few studies have been carried out using neurons, especially human neurons. Here, dopamine (DA) release from individual vesicles and DA content stored within vesicles were quantified from induced pluripotent stem cell-derived DA neurons with electrochemical techniques. The results indicate that around 61% of the total vesicular DA content is released from these neurons during exocytosis. The vesicular content quantified in DA neurons is significantly higher than that in undifferentiated neural progenitor cells, owing to the increased appearance of dense-core vesicles that are able to store more DA molecules than the clear vesicles. When the neurons are differentiated with BAY-K8644, which stimulates neuronal maturation as well as DA release, the release fraction rises to 91%. The use of BAY-K8644 can be considered as chronic stimulation and leads to similar effects on exocytosis as repetitive stimulation, which triggers short-term plasticity. This study demonstrates partial release in DA transmission in human neurons and provides a link between neuronal maturation and the formation of plasticity. Furthermore, this work suggests that the fraction of release in exocytosis at human neurons may be a factor in determining plasticity.
This chapter begins with an overview of the major changes in physical size and proportions and the nature of developmental changes in physical growth. We also examine factors that influence growth and discuss the problem of childhood obesity. We then shift our focus to one of the most important and drastic periods of change in the life span—adolescence and the onset of sexual maturity. We next look at aspects of children’s motor development, examining both gross and fine motor changes in children’s abilities to control their bodies. We then devote a relatively large section to the development of perhaps the body’s most important organ—at least from a psychological perspective—the brain, which is expanded in later chapters.
For different types of environmental conditions, the logarithmic changes in each concentration Xj, denoted by δXj(E), are proportional for almost all components, over a wide range of perturbations, where the proportionality coefficient is given by the ratio of change in cell growth rate δμ(E). Then consider the evolution after applied environmental changes. Let the change in log concentration be δXj(G) and the change in growth rate be δμ(G). The theory suggests that δX_j(G)/ δX_j(E)= δμ(G)/ δμ(E), as confirmed experimentally. With evolution, the right hand term gradually moves toward 0, accordingly the change in concentrations does. This is a process similar to the Le Chatelier principle of thermodynamics. The relationships described above arise because phenotypic changes due to environmental perturbations, noise, and genetic changes are constrained to a common low-dimensional manifold as a result of evolution. This is because the adapted state after evolution should be stable against a variety of perturbations, while phenotypes retain plasticity to change, in order to have evolvability. To achieve this dimensional reduction, there is a separation of a few slow modes in the dynamics for phenotypes. The variance of phenotypes due to noise and mutation is proportional over all phenotypes, leading to the possibility of predicting phenotypic evolution.
The other facet of adaptation, immutability or homeostasis, is discussed. Dynamical system models that buffer external changes in a few variables to suppress changes in other variables are presented. In this case, some variable makes a transient change depending on the environmental change before returning to the original state. This transient response is shown to obey fold-change detection (or Weber–Fechner law), in which the response rate by environmental changes depends only on how many times the environmental change is to the original value. As for the multicomponent cell model, a critical state in which the abundances of each component are inversely proportional to its rank is maintained as a homeostatic state even when the environmental condition is changed. In biological circadian clocks, the period of oscillation remains almost unchanged against changes in temperature (temperature compensation) or other environmental conditions. When several reactions involved in the cyclic change use a common enzyme, enzyme-limited competition results. This competition among substrates explains the temperature compensation mentioned above. In this case, the reciprocity between the period and the plasticity of biological clocks results.
This chapter presents an overview of the goals of universal biology. It is noted that biological systems are generally hierarchical as molecules-cells-organisms, where the components of each level are quite diverse. How such diversity arises and is maintained is discussed. We then discuss the possibility of understanding such biological systems with diverse components, and explore the possibility of macroscopic theory to reveal and formulate universal properties in living states, noting that robustness, plasticity, and activity are essential to life. Recalling the spirit (not the formulation) of thermodynamics, we explore the possibility of formulating a theory for characterizing universal properties in life, emphasizing macroscopic robustness at each level of the hierarchy and the importance of macro-micro consistency.
Manufacturing Dissent reveals how the early twentieth century's 'lost generation' of writers, artists, and intellectuals combatted disinformation and 'fake news.' Cultural historians, literary scholars, and those interested in the power of literature to encourage critical thought and promote democracy will find this book of particular value. The book is interdisciplinary, focusing on the rich literary and artistic period of American modernism as a new site for examining the psychology of public opinion and the role of cognition in the formation of beliefs. The emerging twentieth-century neuroscience of 'plasticity,' habit, and attention that Harvard psychologist William James helped pioneer becomes fertile ground for an experimental variety of literature that Stephanie L. Hawkins argues is 'mind science' in its own right. Writers as diverse as F. Scott Fitzgerald, Zora Neale Hurston, Ernest Hemingway, and Gertrude Stein sought a public-spirited critique of propaganda and disinformation that expresses their civic engagement in promoting democratic dissent.
In this chapter, we focus on the neuronal networks underlying the socio-affective capacities empathy and compassion. We first provide definitions of empathy and compassion and give an overview of the historical development in social neuroscience related to empathy and compassion research, with a focus on differentiating between empathy, empathic distress, compassion, and related concepts of social understanding like Theory of Mind. We then examine the neuronal networks underlying these distinct social capacities and discuss the latest discoveries in this field. Next, we turn to the plasticity of the social brain and compare training approaches in their efficacy in improving socio-affective and socio-cognitive capacities. This is followed by the exploration of how psychopathological symptoms are differentially related to empathy, compassion, and socio-cognitive skills. Lastly, we conclude the main findings of this chapter and provide questions for future neuroscientific and psychological research on empathy and compassion.
James’s modernism is based directly on the psychology he founded, and specifically on his recognition that the self is malleable (or “plastic”), aggregate, distributed, and capable of mental reform. Yet James’s outspoken critique of US imperialism and the lynching of African Americans reflected his understanding of the dangerous potential of conversion – namely, that revolutions in belief carry a measure of uncertainty and risk, not just to individual believers but to the very fabric of democratic thought. Jamesean conversion therefore dramatizes the processes by which consent is staged from within and from without. The self enacts the drama in the form of an internal dialogue in which one imagines one’s “self” inhabiting a particular temporo-spatial location, as if fulfilling the role of a protagonist in a work of fiction. Against that background, Henry James’s What Maisie Knew and Harold Frederic’s The Damnation of Theron Ware dramatize the processes through which individuals become plastically transformed under the manipulations of powerful “pattern-setters” of public opinion. By fracturing and fragmenting imperial forms of selfhood, these psychological Bildungsromane inaugurate a reform modernism that registers dissent from the imperial sway of groups, demonstrating the strenuous effort required by individuals to transform oppressive systems from within.
Take a global tour of childhood that spans 50 countries and explore everyday questions such as 'Why does love matter?', 'How do children learn right from wrong'? and 'Why do adolescent relationships feel like a matter of life and death?' Combining psychology, anthropology, and evolution, you will learn about topics such as language, morality, empathy, creativity, learning and cooperation. Discover how children's skills develop, how they adapt to solve challenges, and what makes you, you. Divided into three chronological sections – early years, middle childhood, and adolescence – this book is enriched with a full set of pedagogical features, including key points to help you retain the main takeaway of each section, space for recap, a glossary of key terms, learning outcomes and chapter summaries. Embedded videos and animations throughout bring ideas to life and explain the methods researchers use to reveal the secrets of child development.
Describe some important features of infant–caregiver relationships; evaluate the role of early life experiences on later development; understand what emotions are for and how they develop.
Describe the challenges children face in learning language; understand key features of child language development; explain the strategies children use to learn sounds, words, and grammar.
This chapter addresses the premodern history of maternal impressions, the enduring belief that the emotions and experiences of a pregnant woman could leave permanent marks on her unborn child. The idea of the reactive womb has been present across multiple cultures, geographies, and centuries; however, it contrasts starkly against the recent view of the womb as boundaried. While we are not suggesting that maternal impression is a direct predecessor of the Developmental Origins of Health and Disease (DOHaD), with this overview we are reminding of the ubiquitous interest in pregnancy as ’an active project requiring self-discipline and work on the part of expectant mothers’ (1) in multiple medical systems. We focus on Greek, Roman, Latin Mediaeval, Jewish, Arabic, Chinese, Japanese, and Ayurvedic sources before and alongside the rise of modern biomedicine and analyse their view of the pregnant female body. We locate our reading in the wider context of a cross-cultural perception of body porosity and the power of environmental factors to shape the physical and moral traits of people. By delving into historical examples and engaging a longue durée perspective, this chapter aims to situate the current postgenomic claims linked with DOHaD findings that ‘soft inheritance has now been reborn’ (2).
The effect of freezing and thawing on the rheological behavior of illite suspensions was studied by examining viscosity and plasticity. Stability of suspensions was characterized by a hysteresis loop of thixotropy. Thermal gravimetric and differential scanning calorimetry analysis were also used. After initial freezing and thawing, the flow curves of the suspensions show an increased viscosity, an “irregular up line”, and a greater hysteresis loop of thixotropy. The ratios of mean viscosity of previously frozen (F) and control (O) samples (ηF/ηO) for non-expandable 2:1 phyllosilicates ranges from 1.3 to 2.1. Addition of monovalent (0.1% Na2SiO3) and divalent cations (0.3% CaCl2 or BaCl2) increase and decrease the shear-stress difference between F and O samples, respectively. Prior freezing of clay samples results in an increase of plasticity by ∼20–30%. The thermal analysis data of F samples show an increase in weight loss, and a decrease in enthalpy of dehydration. The changes of physico-chemical properties from cycles of freezing and thawing are long lasting. The freezing memory effect of illite-type clays is expected to play an important role in ceramic processing, i.e., casting processes, plastic formation, and sintering.
This chapter offers a thorough examination of the processes and outcomes of brain plasticity. We begin by unraveling the historical milestones and breakthroughs that initiated the study of brain plasticity. Exploring the intricate world of cellular mechanisms, we outline the core processes underpinning brain plasticity, making this complex topic accessible. We then delve into the three primary types of brain plasticity: experience-independent, experience-expectant, and experience-dependent, showcasing how they depend on environmental inputs to varying degrees. The concept of critical periods emerges as a central theme. We explore the regulatory mechanisms governing the opening and closing of critical periods and why this adaptive feature is essential for brain development. Further, we outline the expansion-normalization hypothesis, providing evidence that sheds light on how brain plasticity evolves over the course of development. Finally, we explore the profound impact of early life adversity on shaping the developing brain, offering insights into the lifelong consequences of such experiences