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Neuron Oct 2019The brain faces various computational tradeoffs, such as the stability-flexibility dilemma. The major ascending neuromodulatory systems are well suited to dynamically... (Review)
Review
The brain faces various computational tradeoffs, such as the stability-flexibility dilemma. The major ascending neuromodulatory systems are well suited to dynamically regulate these tradeoffs depending on changing task demands. This follows from various general principles of chemical neuromodulation, which are illustrated with evidence from pharmacological neuroimaging studies on striatal dopamine's role in output gating and cost-benefit choice of cognitive tasks. The work raises open questions, including those regarding the top-down cortical control of the midbrain dopamine system, and begins to elucidate the mechanisms underlying the variability in catecholaminergic drug effects. Such drug effects depend on the baseline state of distinct target brain regions, reflecting, in part, the systems' self-regulatory capacity to maintain equilibrium. It is hypothesized that the basal tone of different dopaminergic projection systems reflects the perceived statistics of the environment computed in frontal cortex. By normalizing dopamine levels, dopaminergic drugs might counteract the bias elicited by the perceived environment.
Topics: Brain; Cognition; Dopamine; Dopamine Agents; Frontal Lobe; Homeostasis; Humans; Neostriatum; Neuroimaging
PubMed: 31600509
DOI: 10.1016/j.neuron.2019.09.035 -
Nature Communications Apr 2023In some models, animals approach aversive stimuli more than those housed in an enriched environment. Here, we found that male mice in an impoverished and unstimulating...
In some models, animals approach aversive stimuli more than those housed in an enriched environment. Here, we found that male mice in an impoverished and unstimulating (i.e., boring) chamber without toys sought aversive air puffs more often than those in an enriched chamber. Using this animal model, we identified the insular cortex as a regulator of aversion-seeking behavior. Activation and inhibition of the insular cortex increased and decreased the frequencies of air-puff self-stimulation, respectively, and the firing patterns of insular neuron ensembles predicted the self-stimulation timing. Dopamine levels in the ventrolateral striatum decreased with passive air puffs but increased with actively sought puffs. Around 20% of mice developed intense self-stimulation despite being offered toys, which was prevented by administering opioid receptor antagonists. This study establishes a basis for comprehending the neural underpinnings of usually avoided stimulus-seeking behaviors.
Topics: Mice; Male; Animals; Dopamine; Corpus Striatum; Neurons
PubMed: 37106002
DOI: 10.1038/s41467-023-38130-3 -
Journal of Psychiatry & Neuroscience :... Nov 2007Neurochemical, electrophysiological and behavioural evidence indicates that certain forms of goal-directed behaviours are mediated by complex and reciprocal interactions... (Review)
Review
Neurochemical, electrophysiological and behavioural evidence indicates that certain forms of goal-directed behaviours are mediated by complex and reciprocal interactions between limbic and dopamine (DA) inputs in the nucleus accumbens (NAc). Mesoaccumbens DA transmission appears to be compartmentalized; synaptic DA transmission is mediated by phasic burst firing of DA neurons, whereas extrasynaptic tonic DA levels are regulated by DA neuron population activity and limbic glutamatergic inputs to the NAc. DA release facilitated by limbic inputs and acting on D1 receptors can either potentiate or suppress neural activity driven by separate limbic inputs converging on the same postsynaptic NAc neurons. In turn, D1 receptors in the NAc mediate accuracy of search behaviour regulated by hippocampal-ventral striatal circuitries; D2 receptors appear to mediate motivational aspects of task performance. These findings suggest that dopaminergic modulation of limbic afferents to the NAc may be a cellular mechanism for input selection that governs the smooth coordination of behaviour by permitting information processed by one limbic region to temporarily exert control over the type and intensity of adaptive behavioural responses.
Topics: Adaptation, Physiological; Corpus Striatum; Dopamine; Humans; Limbic System; Nerve Net; Nucleus Accumbens; Signal Transduction
PubMed: 18043763
DOI: No ID Found -
The Yale Journal of Biology and Medicine Jun 2019Circadian rhythms, or biological oscillations of approximately 24 hours, impact almost all aspects of our lives by regulating the sleep-wake cycle, hormone release, body... (Review)
Review
Circadian rhythms, or biological oscillations of approximately 24 hours, impact almost all aspects of our lives by regulating the sleep-wake cycle, hormone release, body temperature fluctuation, and timing of food consumption. The molecular machinery governing these rhythms is similar across organisms ranging from unicellular fungi to insects, rodents, and humans. Circadian entrainment, or temporal synchrony with one's environment, is essential for survival. In mammals, the central circadian pacemaker is located in the suprachiasmatic nucleus (SCN) of the hypothalamus and mediates entrainment to environmental conditions. While the light:dark cycle is the primary environmental cue, arousal-inducing, non-photic signals such as food consumption, exercise, and social interaction are also potent synchronizers. Many of these stimuli enhance dopaminergic signaling suggesting that a cohesive circadian physiology depends on the relationship between circadian clocks and the neuronal circuits responsible for detecting salient events. Here, we review the inner workings of mammalian circadian entrainment, and describe the health consequences of circadian rhythm disruptions with an emphasis on dopamine signaling.
Topics: Animals; Circadian Clocks; Circadian Rhythm; Dopamine; Dopaminergic Neurons; Humans; Photoperiod; Signal Transduction; Suprachiasmatic Nucleus
PubMed: 31249488
DOI: No ID Found -
Trends in Neurosciences May 2019Social interactions are fundamental to survival and overall health. The mechanisms underlying social behavior are complex, but we now know that immune signaling plays a... (Review)
Review
Social interactions are fundamental to survival and overall health. The mechanisms underlying social behavior are complex, but we now know that immune signaling plays a fundamental role in the regulation of social interactions. Prolonged or exaggerated alterations in social behavior often accompany altered immune signaling and function in pathological states. Thus, unraveling the link between social behavior and immune signaling is a fundamental challenge, not only to advance our understanding of human health and development, but for the design of comprehensive therapeutic approaches for neural disorders. In this review, we synthesize literature demonstrating the bidirectional relationship between social behavior and immune signaling and highlight recent work linking social behavior, immune function, and dopaminergic signaling in adolescent neural and behavioral development.
Topics: Animals; Brain; Dopamine; Humans; Immunity, Cellular; Neuroimmunomodulation; Reward; Social Behavior
PubMed: 30890276
DOI: 10.1016/j.tins.2019.02.005 -
American Journal of Physiology.... Jan 2004
Topics: Animals; Dopamine; Food; Humans; Reward
PubMed: 14660469
DOI: 10.1152/ajpregu.00590.2003 -
F1000Research 2019The latest animal neurophysiology has revealed that the dopamine reward prediction error signal drives neuronal learning in addition to behavioral learning and reflects... (Review)
Review
The latest animal neurophysiology has revealed that the dopamine reward prediction error signal drives neuronal learning in addition to behavioral learning and reflects subjective reward representations beyond explicit contingency. The signal complies with formal economic concepts and functions in real-world consumer choice and social interaction. An early response component is influenced by physical impact, reward environment, and novelty but does not fully code prediction error. Some dopamine neurons are activated by aversive stimuli, which may reflect physical stimulus impact or true aversiveness, but they do not seem to code general negative value or aversive prediction error. The reward prediction error signal is complemented by distinct, heterogeneous, smaller and slower changes reflecting sensory and motor contributors to behavioral activation, such as substantial movement (as opposed to precise motor control), reward expectation, spatial choice, vigor, and motivation. The different dopamine signals seem to defy a simple unifying concept and should be distinguished to better understand phasic dopamine functions.
Topics: Animals; Dopamine; Dopaminergic Neurons; Learning; Motivation; Reward
PubMed: 31588354
DOI: 10.12688/f1000research.19793.1 -
Frontiers in Neural Circuits 2014In this review, we provide a brief overview over the current knowledge about the role of dopamine transmission in the prefrontal cortex during learning and memory. We... (Review)
Review
In this review, we provide a brief overview over the current knowledge about the role of dopamine transmission in the prefrontal cortex during learning and memory. We discuss work in humans, monkeys, rats, and birds in order to provide a basis for comparison across species that might help identify crucial features and constraints of the dopaminergic system in executive function. Computational models of dopamine function are introduced to provide a framework for such a comparison. We also provide a brief evolutionary perspective showing that the dopaminergic system is highly preserved across mammals. Even birds, following a largely independent evolution of higher cognitive abilities, have evolved a comparable dopaminergic system. Finally, we discuss the unique advantages and challenges of using different animal models for advancing our understanding of dopamine function in the healthy and diseased brain.
Topics: Animals; Birds; Dopamine; Humans; Learning; Memory, Short-Term; Models, Neurological; Prefrontal Cortex; Rats
PubMed: 25140130
DOI: 10.3389/fncir.2014.00093 -
Frontiers in Neural Circuits 2014The spinal cord contains networks of neurons that can produce locomotor patterns. To readily respond to environmental conditions, these networks must be flexible yet at... (Review)
Review
The spinal cord contains networks of neurons that can produce locomotor patterns. To readily respond to environmental conditions, these networks must be flexible yet at the same time robust. Neuromodulators play a key role in contributing to network flexibility in a variety of invertebrate and vertebrate networks. For example, neuromodulators contribute to altering intrinsic properties and synaptic weights that, in extreme cases, can lead to neurons switching between networks. Here we focus on the role of dopamine in the control of stepping networks in the spinal cord. We first review the role of dopamine in modulating rhythmic activity in the stomatogastric ganglion (STG) and the leech, since work from these preparations provides a foundation to understand its role in vertebrate systems. We then move to a discussion of dopamine's role in modulation of swimming in aquatic species such as the larval xenopus, lamprey and zebrafish. The control of terrestrial walking in vertebrates by dopamine is less studied and we review current evidence in mammals with a focus on rodent species. We discuss data suggesting that the source of dopamine within the spinal cord is mainly from the A11 area of the diencephalon, and then turn to a discussion of dopamine's role in modulating walking patterns from both in vivo and in vitro preparations. Similar to the descending serotonergic system, the dopaminergic system may serve as a potential target to promote recovery of locomotor function following spinal cord injury (SCI); evidence suggests that dopaminergic agonists can promote recovery of function following SCI. We discuss pharmacogenetic and optogenetic approaches that could be deployed in SCI and their potential tractability. Throughout the review we draw parallels with both noradrenergic and serotonergic modulatory effects on spinal cord networks. In all likelihood, a complementary monoaminergic enhancement strategy should be deployed following SCI.
Topics: Animals; Dopamine; Dopaminergic Neurons; Locomotion; Nerve Net; Spinal Cord
PubMed: 24982614
DOI: 10.3389/fncir.2014.00055 -
Biology Letters May 2023Many organisms exhibit phenotypic plasticity, in which developmental processes result in different phenotypes depending on their environmental context. Here we focus on...
Many organisms exhibit phenotypic plasticity, in which developmental processes result in different phenotypes depending on their environmental context. Here we focus on the molecular mechanisms underlying that environmental response. Pea aphids () exhibit a wing dimorphism, in which pea aphid mothers produce winged or wingless daughters when exposed to a crowded or low-density environment, respectively. We investigated the role of dopamine in mediating this wing plasticity, motivated by a previous study that found higher dopamine titres in wingless- versus winged-producing aphid mothers. In this study, we found that manipulating dopamine levels in aphid mothers affected the numbers of winged offspring they produced. Specifically, asexual female adults injected with a dopamine agonist produced a lower percentage of winged offspring, while asexual females injected with a dopamine antagonist produced a higher percentage of winged offspring, matching expectations based on the titre difference. We also found that genes involved in dopamine synthesis, degradation and signalling were not differentially expressed between wingless- and winged-producing aphids. This result indicates that titre regulation possibly happens in a non-transcriptional manner or that sampling of additional timepoints or tissues is necessary. Overall, our work emphasizes that dopamine is an important component of how organisms process information about their environments.
Topics: Female; Animals; Aphids; Dopamine; Pisum sativum; Phenotype; Wings, Animal
PubMed: 37194256
DOI: 10.1098/rsbl.2023.0024