A core component of cognitive control – the ability to regulate thoughts and actions in accordance with internally represented behavioral goals – might be its intrinsic variability. In this article, ...I describe the dual mechanisms of control (DMC) framework, which postulates that this variability might arise from qualitative distinctions in temporal dynamics between proactive and reactive modes of control. Proactive control reflects the sustained and anticipatory maintenance of goal-relevant information within lateral prefrontal cortex (PFC) to enable optimal cognitive performance, whereas reactive control reflects transient stimulus-driven goal reactivation that recruits lateral PFC (plus a wider brain network) based on interference demands or episodic associations. I summarize recent research that demonstrates how the DMC framework provides a coherent explanation of three sources of cognitive control variation – intra-individual, inter-individual and between-groups – in terms of proactive versus reactive control biases.
Historically, national borders have evolved in ways that serve the interests of central states in security and the regulation of trade. This volume explores Canada–US border and security policies ...that have evolved from successive trade agreements since the 1950s, punctuated by new and emerging challenges to security in the twenty-first century. The sectoral and geographical diversity of cross-border interdependence of what remains the world’s largest bilateral trade relationship makes the Canada–US border a living laboratory for studying the interaction of trade, security, and other border policies that challenge traditional centralized approaches to national security. The book’s findings show that border governance straddles multiple regional, sectoral, and security scales in ways rarely documented in such detail. These developments have precipitated an Open Border Paradox: extensive, regionally varied flows of trade and people have resulted in a series of nested but interdependent security regimes that function on different scales and vary across economic and policy sectors. These realities have given rise to regional and sectoral specialization in related security regimes. For instance, just-in-time automotive production in the Great Lakes region varies considerably from the governance of maritime and intermodal trade (and port systems) on the Atlantic and Pacific coasts, which in turn is quite different from commodity-based systems that manage diverse agricultural and food trade in the Canadian Prairies and US Great Plains. The paradox of open borders and their legitimacy is a function of robust bilateral and multilevel governance based on effective partnerships with substate governments and the private sector. Effective policy accounts for regional variation in integrated binational security and trade imperatives. At the same time, binational and continental policies are embedded in each country’s trade and security relationships beyond North America.
Many functional network properties of the human brain have been identified during rest and task states, yet it remains unclear how the two relate. We identified a whole-brain network architecture ...present across dozens of task states that was highly similar to the resting-state network architecture. The most frequent functional connectivity strengths across tasks closely matched the strengths observed at rest, suggesting this is an “intrinsic,” standard architecture of functional brain organization. Furthermore, a set of small but consistent changes common across tasks suggests the existence of a task-general network architecture distinguishing task states from rest. These results indicate the brain’s functional network architecture during task performance is shaped primarily by an intrinsic network architecture that is also present during rest, and secondarily by evoked task-general and task-specific network changes. This establishes a strong relationship between resting-state functional connectivity and task-evoked functional connectivity—areas of neuroscientific inquiry typically considered separately.
•There is an “intrinsic” functional network architecture present across many tasks•The intrinsic architecture is highly similar to the resting-state architecture•Tasks modify the intrinsic architecture to produce “evoked” network architectures•Task-evoked changes common across tasks form a task-general network architecture
Cole et al. identify a whole-brain functional network architecture in humans that is intrinsic, as it is present across rest and dozens of tasks. Only small network modifications were observed, but many were consistent, composing a task-general evoked network architecture.
Cognitive control is subjectively costly, suggesting that engagement is modulated in relationship to incentive state. Dopamine appears to play key roles. In particular, dopamine may mediate cognitive ...effort by two broad classes of functions: (1) modulating the functional parameters of working memory circuits subserving effortful cognition, and (2) mediating value-learning and decision-making about effortful cognitive action. Here, we tie together these two lines of research, proposing how dopamine serves “double duty”, translating incentive information into cognitive motivation.
Temporally extended, goal-directed behavior often involves subjectively effortful cognition. Westbrook and Braver review two broad, complementary roles by which DA translates incentive information into cognitive motivation: (1) modulating working memory circuit parameters and (2) training decision value functions for cognitive engagement.
Cognitive effort has been implicated in numerous theories regarding normal and aberrant behavior and the physiological response to engagement with demanding tasks. Yet, despite broad interest, no ...unifying, operational definition of cognitive effort itself has been proposed. Here, we argue that the most intuitive and epistemologically valuable treatment is in terms of effort-based decision-making, and advocate a neuroeconomics-focused research strategy. We first outline psychological and neuroscientific theories of cognitive effort. Then we describe the benefits of a neuroeconomic research strategy, highlighting how it affords greater inferential traction than do traditional markers of cognitive effort, including self-reports and physiologic markers of autonomic arousal. Finally, we sketch a future series of studies that can leverage the full potential of the neuroeconomic approach toward understanding the cognitive and neural mechanisms that give rise to phenomenal, subjective cognitive effort.
It has long been assumed that people treat cognitive effort as costly, but also that such effort costs may vary greatly across individuals. Individual differences in subjective effort could present a ...major and pervasive confound in behavioral and neuroscience assessments, by conflating cognitive ability with cognitive motivation. Self-report cognitive effort scales have been developed, but objective measures are lacking. In this study, we use the behavioral economic approach of revealed preferences to quantify subjective effort. Specifically, we adapted a well-established discounting paradigm to measure the extent to which cognitive effort causes participants to discount monetary rewards. The resulting metrics are sensitive to both within-individual factors, including objective load and reward amount, and between-individual factors, including age and trait cognitive engagement. We further validate cognitive effort discounting by benchmarking it against well-established measures of delay discounting. The results highlight the promise and utility of behavioral economic tools for assessing trait and state influences on cognitive motivation.
The life cycle of endogenous retroviruses (ERVs), also called long terminal repeat (LTR) retrotransposons, begins with transcription by RNA polymerase II followed by reverse transcription and ...re-integration into the host genome. While most ERVs are relics of ancient integration events, “young” proviruses competent for retrotransposition—found in many mammals, but not humans—represent an ongoing threat to host fitness. As a consequence, several restriction pathways have evolved to suppress their activity at both transcriptional and post-transcriptional stages of the viral life cycle. Nevertheless, accumulating evidence has revealed that LTR sequences derived from distantly related ERVs have been exapted as regulatory sequences for many host genes in a wide range of cell types throughout mammalian evolution. Here, we focus on emerging themes from recent studies cataloging the diversity of ERV LTRs acting as important transcriptional regulatory elements in mammals and explore the molecular features that likely account for LTR exaptation in developmental and tissue-specific gene regulation.
Solitary long terminal repeats (LTRs) have been frequently domesticated into gene regulatory elements in mammals. Here, Thompson et al. evaluate the features of LTRs that account for the prevalence of this phenomenon and highlight recent studies providing insight into the molecular mechanisms that influence the exaptation of LTRs.
Kruppel-associated box zinc-finger proteins (KRAB-ZFPs) make up the largest family of transcription factors in humans. These proteins emerged in the last common ancestor of coelacanth and tetrapods, ...and have expanded and diversified in the mammalian lineage. Although their mechanism of transcriptional repression has been well studied for over a decade, the DNA-binding activities and the biological functions of these proteins have been largely unexplored. Recent large-scale ChIP-seq studies and loss-of-function experiments have revealed that KRAB-ZFPs play a major role in the recognition and transcriptional silencing of transposable elements (TEs), consistent with an ‘arms race model’ of KRAB-ZFP evolution against invading TEs. However, this model is insufficient to explain the evolution of many KRAB-ZFPs that appear to domesticate TEs for novel host functions. We highlight some of the mammalian regulatory innovations driven by specific KRAB-ZFPs, including genomic imprinting, meiotic recombination hotspot choice, and placental growth.
KRAB-ZFPs make up the largest class of DNA-binding transcription factors in mammals.
The KRAB-domain is a potent transcriptional repression domain that functions via recruitment of the TRIM28 corepressor which recruits heterochromatin-inducing machinery.
KRAB-ZFPs are rapidly evolving in mammals, primarily at the level of expansion of KRAB-ZFP gene clusters, likely in response to invading waves of TEs.
The majority of KRAB-ZFPs (∼2/3 in humans) interact with TEs via specific DNA-binding motifs.
Loss-of-function studies of KRAB-ZFP corepressors and individual KRAB-ZFPs demonstrate that KRAB-ZFPs transcriptionally repress target TEs and prevent latent enhancer/promoter activity within TEs from affecting nearby genes.
The continuous cycle of KRAB-ZFP evolution against TEs provides a driving force for new adaptations in mammals.
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