scholarly journals The Role of Accumbal Hypoactivity in Cocaine Addiction.

2007 ◽  
Vol 7 ◽  
pp. 22-45 ◽  
Author(s):  
L. L. Peoples ◽  
A. V. Kravitz ◽  
K. Guillem
Keyword(s):  
Nucleus Accumbens ◽  
Empirical Evidence ◽  
Neural Activity ◽  
Cocaine Addiction ◽  
Present Review ◽  
Firing Patterns ◽  
Motivated Behaviors

Cocaine-induced hypoactivity of the nucleus accumbens (NAC) is hypothesized to contribute to cocaine addiction. There are two important questions related to this hypothesis. First, cocaine addiction is characterized by an increase in drug-directed behavior and a simultaneous weakening of other motivated behaviors. However, the NAC contributes to both drug- and nondrug-directed behavior. Moreover, the nature of the contributions is similar and associated predominantly with excitatory phasic firing patterns. Given these observations it is not clear how hypoactivity of NAC neurons might contribute to the behaviors that characterize cocaine addiction. Second, various types of investigations have documented neurochemical and molecular adaptations that could underlie NAC hypoactivity. However, there is also evidence of other adaptations in the NAC, and in NAC afferents, which are expected to have an excitatory influence on NAC neural activity. In the present review we will briefly overview these issues. We will also describe a hypothesis, and related empirical evidence, that may contribute to answering these questions. Further investigation of the issues and the hypothesis may contribute to a better understanding of the neuroadaptations that contribute to cocaine addiction.

scholarly journals Distinct role of nucleus accumbens D2-MSN projections to ventral pallidum in different phases of motivated behavior

2020 ◽  
Author(s):  
Carina Soares-Cunha ◽  
Raquel Correia ◽  
Ana Verónica Domingues ◽  
Bárbara Coimbra ◽  
Nivaldo AP de Vasconcelos ◽  
...  
Keyword(s):  
Nucleus Accumbens ◽  
Behavioral Effect ◽  
Ventral Pallidum ◽  
Medium Spiny Neurons ◽  
Motivated Behavior ◽  
Spiny Neurons ◽  
Reward Delivery ◽  
Instrumental Task ◽  
Motivated Behaviors

AbstractThe nucleus accumbens (NAc) is a key region in motivated behaviors. NAc medium spiny neurons (MSNs) are divided into those expressing dopamine receptor D1 or D2. Classically, D1- and D2-MSNs have been described as having opposing roles in reinforcement but recent evidence suggests a more complex role for D2-MSNs.Here we show that optogenetic modulation of D2-MSN to ventral pallidum (VP) projections during different stages of motivated behavior has contrasting effects in motivation. Activation of D2-MSN-VP projections during a reward-predicting cue results in increased motivational drive, whereas activation at reward delivery results in decreased motivation; optical inhibition has the opposite behavioral effect. In addition, in a free choice instrumental task, animals prefer the lever that originates one pellet in opposition to pellet plus D2-MSN-VP optogenetic activation, and vice versa for optogenetic inhibition.In summary, D2-MSN-VP projections play different (and even opposing) roles in distinct phases of motivated behavior.

Top-down, bottom-up and selection-history-based control of attention: A failed trichotomy? The case of Priming of pop-out (PoP)

2020 ◽  
Author(s):  
Aniruddha Ramgir ◽  
Dominique Lamy
Keyword(s):  
Empirical Evidence ◽  
Statistical Learning ◽  
Past Experience ◽  
Present Review ◽  
Top Down ◽  
Bottom Up ◽  
Attentional Guidance ◽  
Selection History

When we search for an object, our performance is strongly influenced by our past experience. In the lab, this influence has been demonstrated by investigating a variety of phenomena, including inter-trial priming, statistical learning and reward history, and collectively referred to as selection history. The resulting findings have led researchers to claim that selection history guides attention, thereby challenging the prevailing dichotomy, according to which attentional priority is determined solely by top-down goals and bottom-up salience. The objective of the present review is to reexamine this claim by evaluating the evidence that specifically pertains to the role of selection history in attentional guidance, rather than in later processes occurring after the target is found. We focus on one selection history phenomenon, priming of pop-out (PoP). After demarcating the conditions under which PoP effects can be dissociated from top-down effects, we review the relevant findings, while distinguishing between the main experimental rationales adopted to address this question. We conclude that despite some inconsistencies that should be resolved by further research, most of the extant empirical evidence does not support the idea that PoP affects attentional priority. We call for similar reevaluations of other selection history phenomena and caution against burying the bottom-up vs. top-down dichotomy too hastily.

scholarly journals Role of laterodorsal tegmentum projections to nucleus accumbens in reward-related behaviors

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Bárbara Coimbra ◽  
Carina Soares-Cunha ◽  
Nivaldo A P Vasconcelos ◽  
Ana Verónica Domingues ◽  
Sónia Borges ◽  
...  
Keyword(s):  
Nucleus Accumbens ◽  
Positive Reinforcement ◽  
Excitatory Response ◽  
Neuronal Populations ◽  
And Shifts ◽  
Motivated Behaviors ◽  
Laterodorsal Tegmentum ◽  
Anatomical Evidence ◽  
Glutamatergic Innervation

Abstract The laterodorsal tegmentum (LDT) is associated with reward considering that it modulates VTA neuronal activity, but recent anatomical evidence shows that the LDT also directly projects to nucleus accumbens (NAc). We show that the majority of LDT-NAc inputs are cholinergic, but there is also GABAergic and glutamatergic innervation; activation of LDT induces a predominantly excitatory response in the NAc. Non-selective optogenetic activation of LDT-NAc projections in rats enhances motivational drive and shifts preference to an otherwise equal reward; whereas inhibition of these projections induces the opposite. Activation of these projections also induces robust place preference. In mice, specific activation of LDT-NAc cholinergic inputs (but not glutamatergic or GABAergic) is sufficient to shift preference, increase motivation, and drive positive reinforcement in different behavioral paradigms. These results provide evidence that LDT-NAc projections play an important role in motivated behaviors and positive reinforcement, and that distinct neuronal populations differentially contribute for these behaviors.

Membangun Fondasi Keilmuan Ekonomi Islam: Telaah Metodologi Muhammad Akram Khan

2017 ◽  
Vol 1 (2) ◽  
pp. 152-170
Author(s):  
Ahmad Ubaidillah
Keyword(s):  
General Theory ◽  
Empirical Evidence ◽  
Inductive Method ◽  
Ethical Values ◽  
Institutional Conditions ◽  
Faith Based ◽  
Behavioral Parameters ◽  
Science Methodology ◽  
Islamic Society

Throughout my experience in tracking down and reading books on faith-based economics, in this case Islam, there are no books that specifically list the title of "Islamic economics". If there is, it is only initiated or introduced. Most books coming down to us still use the titles starting with the word, for example, system, concept, principle, or the doctrine of Islamic economics. Why do the authors of the book Islamic economics seem not dared to give his book title with label "science"? I presume that Islamic economics has not been considered as a science. In building a science, methodology is required. Islamic Economics also requires a well-established methodology to build the foundation of science. The study answers questions; how is methodology which is offered by Muhammad Akram Khan to build Islamic economics. The method used in this research is the study of literature with qualitative approach.The result of study concludes that Khan offers methodology of Islamic economics, if summarized, written as follows: First, Islamic economics uses a framework derived from the texts of divinity (revelation). Second, Islamic economics uses the inductive method, which gives witness to the truth or falsity assumptions and predictions about the two criteria of rationality and empirical evidence. Third, Islamic economy is built on ethical values ​​such as justice, virtue, moderation, sacrifice, caring for others, in the analysis, as behavioral parameters. Fourth, Islamic economics is a normative discipline. Islamic Economics investigates ways and means to change the existing economy with Islamic economy. Fifth, Islamic economics ask different questions with conventional economics. Its attention is on welfare (falah) human and creating social and institutional conditions that maximize falah in society. Clearly, Islamic economics strongly supports research programs that help maximize falah. Furthermore, Khan elaborates several issues related to the methodology that often appears in the forum of Islamic economists. There are some problems that Khan proposes, they are the interaction with modern economics, the role of revelation, assuming ideal Islamic society, and the general theory of Islamic economics.

Osteoporosis Entwined with Cardiovascular Disease: The Implication of Osteoprotegerin and Example of Statins

2020 ◽  
Vol 27 ◽  
Author(s):  
Maria V. Deligiorgi ◽  
Mihalis I. Panayiotidis ◽  
Gerasimos Siasos ◽  
Dimitrios T. Trafalis
Keyword(s):  
Cardiovascular Disease ◽  
Physicochemical Characteristics ◽  
Dual Role ◽  
Present Review ◽  
Vascular Cells ◽  
Molecular Fingerprint ◽  
Missing Link ◽  
Epidemiological Factors ◽  
Outstanding Issue

: Beyond being epiphenomenon of shared epidemiological factors, the integration of osteoporosis (OP) with cardiovascular disease (CVD)− termed "calcification paradox"− reflects a continuum of aberrant cardiometabolic status. The present review provides background knowledge on "calcification paradox", focusing on the endocrine aspect of vasculature orchestrated by the osteoblastic molecular fingerprint of vascular cells, acquired via imbalance among established modulators of mineralization. Osteoprotegerin (OPG)–the well-established osteoprotective cytokine−has recently been shown to exert a vessel-modifying role. Prompted by this notion, the present review interrogates OPG as the potential missing link between OP and CVD. However, so far, the confirmation of this hypothesis is hindered by the equivocal role of OPG in CVD, being both proatherosclerotic and antiatherosclerotic. Further research is needed to illuminate whether OPG could be biomarker of the "calcification paradox". Moreover, the present review brings into prominence the dual role of statins−cardioprotective and osteoprotective− as potential illustration of the integration of CVD with OP. Considering that the statins-induced modulation of OPG is central to the statins-driven osteoprotective signalling, statins could be suggested as illustration of the role of OPG in the bone/vessels crosstalk, if further studies consolidate the contribution of OPG to the cardioprotective role of statins. Another outstanding issue that merits further evaluation is the inconsistency of the osteoprotective role of statins. Further understanding of the varying bone-modifying role of statins, likely attributed to the unique profile of different classes of statins defined by distinct physicochemical characteristics, may yield tangible benefits for treating simultaneously OP and CVD.

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