Abstract:
:Humans choose actions based on both habit and planning. Habitual control is computationally frugal but adapts slowly to novel circumstances, whereas planning is computationally expensive but can adapt swiftly. Current research emphasizes the competition between habits and plans for behavioral control, yet many complex tasks instead favor their integration. We consider a hierarchical architecture that exploits the computational efficiency of habitual control to select goals while preserving the flexibility of planning to achieve those goals. We formalize this mechanism in a reinforcement learning setting, illustrate its costs and benefits, and experimentally demonstrate its spontaneous application in a sequential decision-making task.
journal_name
Proc Natl Acad Sci U S Aauthors
Cushman F,Morris Adoi
10.1073/pnas.1506367112subject
Has Abstractpub_date
2015-11-10 00:00:00pages
13817-22issue
45eissn
0027-8424issn
1091-6490pii
1506367112journal_volume
112pub_type
杂志文章abstract::Animal models of human cytomegalovirus (CMV) infections have not been available to study pathogenesis or to evaluate antiviral drugs. Severe combined immunodeficient mice implanted with human fetal tissues (SCID-hu) were found to support CMV replication and may provide a model for this species-specific virus. When con...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.90.1.104
更新日期:1993-01-01 00:00:00
abstract::The modern concept of neurogenesis in the adult brain is predicated on the premise that multipotent glial cells give rise to new neurons throughout life. Although extensive evidence exists indicating that this is the case, the transition from glial to neuronal phenotype remains poorly understood. A unique monolayer ce...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0503965102
更新日期:2005-06-28 00:00:00
abstract::Ubiquitination, the crucial posttranslational modification that regulates the eukaryotic proteome, is carried out by a trio of enzymes, known as E1 [ubiquitin (Ub)-activating enzyme], E2 (Ub-conjugating enzyme), and E3 (Ub ligase). Although most E2s can work with any of the three mechanistically distinct classes of E3...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1705060114
更新日期:2017-08-08 00:00:00
abstract::Much discussion has occurred in recent years on whether observed patterns of structure in island bird communities are the result of competitive interactions among species or independent rates of colonization and extinction. Here two patterns of structure are presented for birds on 12 West Indian islands. Each of four ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.79.5.1563
更新日期:1982-03-01 00:00:00
abstract::Micrometeorites with diameter approximately 100-200 microm dominate the flux of extraterrestrial matter on Earth. The vast majority of micrometeorites are chemically, mineralogically, and isotopically related to carbonaceous chondrites, which amount to only 2.5% of meteorite falls. Here, we report the discovery of the...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0900328106
更新日期:2009-04-28 00:00:00
abstract::We developed a method for rapidly generating thermostable enzyme variants. Our strategy is to introduce the gene coding for a given enzyme from a mesophilic organism into a thermophile, Bacillus stearothermophilus. Variants that retain the enzymatic activity at the higher growth temperatures of the thermophile are the...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.83.3.576
更新日期:1986-02-01 00:00:00
abstract::Vibrio cholerae, the causative agent of cholera, has reservoirs in fresh and brackish water where it interacts with virulent bacteriophages. Phages are the most abundant biological entity on earth and coevolve with bacteria. It was reported that concentrations of phage and V. cholerae inversely correlate in aquatic re...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1810138116
更新日期:2019-01-29 00:00:00
abstract::Regional differences in neurons, astrocytes, oligodendrocytes, and microglia exist in the brain during health, and regional differences in the transcriptome may occur for each cell type during neurodegeneration. Multiple sclerosis (MS) is multifocal, and regional differences in the astrocyte transcriptome occur in exp...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1821306116
更新日期:2019-05-14 00:00:00
abstract::In vivo electroporation is a powerful technique for the introduction of genes into organisms. Temporal and spatial regulation of expression of introduced genes, or of RNAi, would further enhance the utility of this method. Here we demonstrate conditional regulation of gene expression from electroporated plasmids in th...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0610155104
更新日期:2007-01-16 00:00:00
abstract::In animals, fatty acid desaturases catalyze key reactions in the synthesis of arachidonic acid and other polyunsaturated fatty acids. A search of the Caenorhabditis elegans DNA databases, using the sequences of Arabidopsis genes, identified several putative desaturases. Here we describe the characterization of the fir...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.94.4.1142
更新日期:1997-02-18 00:00:00
abstract::Solar emission produces copious nitrosonium ions (NO(+)) in the D layer of the ionosphere, 60 to 90 km above the Earth's surface. NO(+) is believed to transfer its charge to water clusters in that region, leading to the formation of gaseous nitrous acid (HONO) and protonated water cluster. The dynamics of this reactio...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1601651113
更新日期:2016-04-26 00:00:00
abstract::The rabbit kappa light chain gene family is characterized by the presence of two constant region (C kappa) genes; the C kappa 1 gene encodes the constant region of the principal rabbit immunoglobulin light chain, the C kappa 2 gene being not or very poorly expressed in domestic rabbits. There exist four major K1 allel...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.83.14.5180
更新日期:1986-07-01 00:00:00
abstract::The retroviral integrase protein (IN) is responsible for catalyzing a concerted integration reaction in which the two termini of linear viral DNA are joined to host DNA. To probe the potential for IN to form protein multimers, we used the yeast two-hybrid system. The coexpression of a GAL4 DNA binding domain-IN fusion...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.90.22.10593
更新日期:1993-11-15 00:00:00
abstract::The yeast flora found in the major substrates of Drosophila mojavensis and in larval guts was studied both qualitatively and quantitatively. Quantitative studies show that, in four of the five substrates tested, the larvae did not contain a random sample of the yeasts present in the substrates. One widely distributed ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.78.7.4435
更新日期:1981-07-01 00:00:00
abstract::We have utilized a recombinant vector system designed to study gene control elements by fusing them to the Escherichia coli galactokinase gene (galK) to examine the effects of gene expression that result from introducing changes into the 5' noncoding leader region of the galK transcription unit. We varied the length o...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.81.24.7698
更新日期:1984-12-01 00:00:00
abstract::The challenging problem of ultra-high-energy-density, high-efficiency, and small-scale portable power generation is addressed here using a distinctive thermophotovoltaic energy conversion mechanism and chip-based system design, which we name the microthermophotovoltaic (μTPV) generator. The approach is predicted to be...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1301004110
更新日期:2013-04-02 00:00:00
abstract::Characteristic patterns of gene expression measured by DNA microarrays have been used to classify tumors into clinically relevant subgroups. In this study, we have refined the previously defined subtypes of breast tumors that could be distinguished by their distinct patterns of gene expression. A total of 115 malignan...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0932692100
更新日期:2003-07-08 00:00:00
abstract::This study uses a multiisotope (carbon, nitrogen, oxygen, and strontium) approach to examine early animal management in the Maya region. An analysis of faunal specimens across almost 2,000 years (1000 BC to AD 950) at the site of Ceibal, Guatemala, reveals the earliest evidence for live-traded dogs and possible captiv...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 历史文章,杂志文章
doi:10.1073/pnas.1713880115
更新日期:2018-04-03 00:00:00
abstract::Many changes have been described in the brains of Alzheimer's disease (AD) patients, including loss of neurons and formation of senile plaques and neurofibrillary tangles. The molecular mechanisms underlying these pathologies are unclear. Northern blot, dot-blot, and reverse transcription-coupled PCR analyses have dem...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.95.16.9620
更新日期:1998-08-04 00:00:00
abstract::In all three domains of life, DNA replication begins at specialized loci termed replication origins. In bacteria, replication initiates from a single, clearly defined site. In contrast, eukaryotic organisms exploit a multitude of replication origins, dividing their genomes into an array of short contiguous units. Rece...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0700206104
更新日期:2007-04-03 00:00:00
abstract::The present paper summarizes future needs in information and tools, technology, infrastructure, training, funding, and bioinformatics, to provide the genomic knowledge and tools for breeding and biotechnological goals in maize. The National Corn Genome Initiative (NCGA) has developed through actions taken by the Natio...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.95.5.2029
更新日期:1998-03-03 00:00:00
abstract::Induction of longstanding immunologic tolerance is essential for survival of transplanted organs and tissues. Despite recent advances in immunosuppression protocols, allograft damage inflicted by antibody specific for donor organs continues to represent a major obstacle to graft survival. Here we report that activatio...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1918950117
更新日期:2020-03-17 00:00:00
abstract::The Wiskott-Aldrich syndrome protein (WASp) plays a major role in coupling T cell antigen receptor (TCR) stimulation to induction of actin cytoskeletal changes required for T cell activation. Here, we report that WASp inducibly binds the sorting nexin 9 (SNX9) in T cells and that WASp, SNX9, p85, and CD28 colocalize w...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0610543104
更新日期:2007-01-30 00:00:00
abstract::The Toll/IL-1 receptor (TIR) domains are crucial signaling modules during innate immune responses involving the Toll-like receptors (TLRs) and IL-1 receptor (IL-1R). Myeloid differential factor 88 (MyD88) is a central TIR domain-containing adapter molecule responsible for nearly all TLR-mediated signaling and is targe...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1215770110
更新日期:2013-04-23 00:00:00
abstract::Cell adhesion molecules (CAMs) may act as regulators of morphogenesis by constraining cell motion, forming borders, and controlling intercellular communications that lead to embryonic induction. This postulated causal role of CAMs in inductive events was tested here in an in vitro system of feather induction. In the d...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.83.21.8235
更新日期:1986-11-01 00:00:00
abstract::Soon after the initiation of sporulation, Bacillus subtilis divides asymmetrically to produce sister cells that have very different developmental fates. Recently, it has been proposed that the differential gene expression which begins soon after this division is due to cell-specific activation of the transcription fac...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.91.9.3849
更新日期:1994-04-26 00:00:00
abstract::Inflammation is a hallmark of many diseases, such as atherosclerosis, chronic obstructive pulmonary disease, arthritis, infectious diseases, and cancer. Although steroids and cyclooxygenase inhibitors are effective antiinflammatory therapeutical agents, they may cause serious side effects. Therefore, developing unique...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0914414107
更新日期:2010-05-25 00:00:00
abstract::Some realistic galaxy models have been found to support discrete unstable spiral modes. Here, through the study of the relevant physical mechanisms and an extensive numerical investigation of the properties of the dominant modes in a wide class of galactic equilibria, we show how spiral structures are excited with dif...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.79.12.3908
更新日期:1982-06-01 00:00:00
abstract::In isogamous species of Chlamydomonas, such as Chlamydomonas reinhardtii and Chlamydomonas eugametos, the sexual process involves the use of flagella agglutinins by which the gametes of compatible strains adhere through chance encounter and ultimately pair and fuse to form zygotes. In a newly described heterogamous sp...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.92.2.641
更新日期:1995-01-17 00:00:00
abstract::The temperature coefficient of equilibrium isotope fractionation in the heavy elements is shown to be larger at high temperatures than that expected from the well-studied vibrational isotope effects. The difference in the isotopic behavior of the heavy elements as compared with the light elements is due to the large n...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.93.18.9393
更新日期:1996-09-03 00:00:00