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1.
Bram Tucker 《Human nature (Hawthorne, N.Y.)》2007,18(3):190-208
Governments and non-govermental organizations (NGOs) that plan projects to conserve the environment and alleviate poverty
often attempt to modify rural livelihoods by halting activities they judge to be destructive or inefficient and encouraging
alternatives. Project planners typically do so without understanding how rural people themselves judge the value of their
activities. When the alternatives planners recommend do not replace the value of banned activities, alternatives are unlikely
to be adopted, and local people will refuse to participate. Human behavioral ecology and behavioral economics may provide
useful tools for generating and evaluating hypotheses for how people value economic activities in their portfolios and potential
alternatives. This is demonstrated with a case example from southwestern Madagascar, where plans to create a Mikea Forest
National Park began with the elimination of slash-and-burn maize agriculture and the encouragement to plant labor-intensive
manioc instead. Future park plans could restrict access to wild tuber patches, hunting small game, and fishing. The value
of these activities is considered using observational data informed by optimal foraging theory, and experimental data describing
people’s time preference and covariation perception. Analyses suggest that manioc is not a suitable replacement for maize
for many Mikea because the two crops differ in terms of labor requirements, delay-to-reward, and covariation with rainfall.
Park planners should promote wild tuber foraging and stewardship of tuber patches and the anthropogenic landscapes in which
they are found. To conserve small game, planners must provide alternative sources of protein and cash. Little effort should
be spent protecting lemurs, as they are rarely eaten and never sold. 相似文献
2.
A competitive learning model was introduced in Mehta and Luck (Phys Rev E 60, 5:5218–5230, 1999), in which the learning is outcome-related. Every individual chooses between a pair of existing strategies or types, guided
by a combination of two factors: tendency to conform to the local majority, and a preference for the type with higher perceived success among its neighbors, based on their relative outcomes. Here, an extension of the interfacial model of Mehta and Luck (Phys Rev E 60, 5:5218–5230, 1999) is proposed, in which individuals additionally take into account their own outcomes in arriving at their outcome-based choices. Three possible update rules for handling bulk sites are considered. The corresponding phase diagrams, obtained at coexistence, show systematic departures from the original interfacial model. Possible relationships of these variants with the cooperative model of Mehta and Luck (Phys Rev E 60, 5:5218–5230, 1999) are also touched upon. 相似文献
3.
4.
We define the memory capacity of networks of binary neurons with finite-state synapses in terms of retrieval probabilities of learned patterns under standard asynchronous dynamics with a predetermined threshold. The threshold is set to control
the proportion of non-selective neurons that fire. An optimal inhibition level is chosen to stabilize network behavior. For
any local learning rule we provide a computationally efficient and highly accurate approximation to the retrieval probability
of a pattern as a function of its age. The method is applied to the sequential models (Fusi and Abbott, Nat Neurosci 10:485–493,
2007) and meta-plasticity models (Fusi et al., Neuron 45(4):599–611, 2005; Leibold and Kempter, Cereb Cortex 18:67–77, 2008). We show that as the number of synaptic states increases, the capacity, as defined here, either plateaus or decreases. In
the few cases where multi-state models exceed the capacity of binary synapse models the improvement is small. 相似文献
5.
According to the evolutionary hypothesis of Silverman and Eals (1992, Sex differences in spatial abilities: Evolutionary theory and data. In J. H. Barkow, L. Cosmides, & J. Tooby (Eds.), The adapted mind: Evolutionary psychology and the generation of culture (pp. 533–549). Oxford: Oxford University Press), women evolutionary hypothesis, women surpass men in object location memory
as a result of a sexual division in foraging activities among early humans. After surveying the main anthropological information
on ancestral sex-related foraging, we review the evidence on how robust women’s advantage in object location memory is. This
leads us to suggest that the functional understanding of this type of memory would benefit from comparing men and women in
carefully designed and ecologically meaningful cognitive contexts involving, for instance, incidental versus intentional settings
that call for either the absolute or relative encoding of the locations of common versus uncommon objects. 相似文献
6.
Emmanuel Perisse Geoffrey Portelli Solène Le Goas Elsa Teste Eric Le Bourg 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2007,193(11):1139-1149
Various learning tasks have been described in Drosophila melanogaster, flies being either tested in groups or at the individual level. Le Bourg and Buecher (Anim Learn Behav 33:330–341, 2002) have designed a task at the individual level: photopositive flies crossing a T-maze learn to prefer the dark exit when the
lighted one is associated with the presence of aversive stimuli (humidity and quinine). Previous studies have reported various
results (e.g. no effect of age) and the present article further characterizes this task by studying the possible effects of:
(1) the intensity of the stimuli (quantity of water or concentration of quinine), (2) various delays between two learning
sessions on the learning score at the second session, (3) the rutabaga learning mutation on the learning score. More concentrated quinine solutions increased learning scores but the quantity of
water had no effect. Learning scores at the second session were higher with shorter delays between the two learning sessions
and retrograde amnesia could decrease this memory score. rutabaga mutants showed learning deficits as in experiments testing groups of flies. This learning task could particularly be used
to verify whether learning mutants isolated after experiments testing flies in groups display similar deficits when tested
at the individual level. 相似文献
7.
Meiotic prophase serves as an arena for the interplay of two important cellular activities, meiotic recombination and synapsis of homologous chromosomes. Synapsis is mediated by the synaptonemal complex (SC), originally characterized as a structure linked to pairing of meiotic chromosomes (Moses (1958) J Biophys Biochem Cytol 4:633–638). In 1975, the first electron micrographs of human pachytene stage SCs were presented (Moses et al. (1975) Science 187:363–365) and over the next 15 years the importance of the SC to normal meiotic progression in human males and females was established (Jhanwar and Chaganti (1980) Hum Genet 54:405–408; Pathak and Elder (1980) Hum Genet 54:171–175; Solari (1980) Chromosoma 81:315–337; Speed (1984) Hum Genet 66:176–180; Wallace and Hulten (1985) Ann Hum Genet 49(Pt 3):215–226). Further, these studies made it clear that abnormalities in the assembly or maintenance of the SC were an important contributor to human infertility (Chaganti et al. (1980) Am J Hum Genet 32:833–848; Vidal et al. (1982) Hum Genet 60:301–304; Bojko (1983) Carlsberg Res Commun 48:285–305; Bojko (1985) Carlsberg Res Commun 50:43–72; Templado et al. (1984) Hum Genet 67:162–165; Navarro et al. (1986) Hum Reprod 1:523–527; Garcia et al. (1989) Hum Genet 2:147–53). However, the utility of these early studies was limited by lack of information on the structural composition of the SC and the identity of other SC-associated proteins. Fortunately, studies of the past 15 years have gone a long way toward remedying this problem. In this minireview, we highlight the most important of these advances as they pertain to human meiosis, focusing on temporal aspects of SC assembly, the relationship between the SC and meiotic recombination, and the contribution of SC abnormalities to human infertility.The synaptonemal complex–50 years 相似文献
8.
Gap-junctional coupling is an important way of communication between neurons and other excitable cells. Strong electrical
coupling synchronizes activity across cell ensembles. Surprisingly, in the presence of noise synchronous oscillations generated
by an electrically coupled network may differ qualitatively from the oscillations produced by uncoupled individual cells forming
the network. A prominent example of such behavior is the synchronized bursting in islets of Langerhans formed by pancreatic
β-cells, which in isolation are known to exhibit irregular spiking (Sherman and Rinzel, Biophys J 54:411–425, 1988; Sherman and Rinzel, Biophys J 59:547–559, 1991). At the heart of this intriguing phenomenon lies denoising, a remarkable ability of electrical coupling to diminish the
effects of noise acting on individual cells. In this paper, building on an earlier analysis of denoising in networks of integrate-and-fire
neurons (Medvedev, Neural Comput 21 (11):3057–3078, 2009) and our recent study of spontaneous activity in a closely related model of the Locus Coeruleus network (Medvedev and Zhuravytska,
The geometry of spontaneous spiking in neuronal networks, submitted, 2012), we derive quantitative estimates characterizing denoising in electrically coupled networks of conductance-based models
of square wave bursting cells. Our analysis reveals the interplay of the intrinsic properties of the individual cells and
network topology and their respective contributions to this important effect. In particular, we show that networks on graphs
with large algebraic connectivity (Fiedler, Czech Math J 23(98):298–305, 1973) or small total effective resistance (Bollobas, Modern graph theory, Graduate Texts in Mathematics, vol. 184, Springer, New
York, 1998) are better equipped for implementing denoising. As a by-product of the analysis of denoising, we analytically estimate the
rate with which trajectories converge to the synchronization subspace and the stability of the latter to random perturbations.
These estimates reveal the role of the network topology in synchronization. The analysis is complemented by numerical simulations
of electrically coupled conductance-based networks. Taken together, these results explain the mechanisms underlying synchronization
and denoising in an important class of biological models. 相似文献
9.
A Closer Look at Amphetamine-Induced Reverse Transport and Trafficking of the Dopamine and Norepinephrine Transporters 总被引:1,自引:0,他引:1
Amphetamine (AMPH) and its derivatives are regularly used in the treatment of a wide array of disorders such as attention-deficit
hyperactivity disorder (ADHD), obesity, traumatic brain injury, and narcolepsy (Prog Neurobiol 75:406–433, 2005; J Am Med Assoc 105:2051–2054, 1935; J Am Acad Child Adolesc Psychiatry 41:514–521, 2002; Neuron 43:261–269, 2004; Annu Rev Pharmacol Toxicol 47:681–698, 2007; Drugs Aging 21:67–79, 2004). Despite the important medicinal role for AMPH, it is more widely known for its psychostimulant and addictive properties
as a drug of abuse. The primary molecular targets of AMPH are both the vesicular monoamine transporters (VMATs) and plasma
membrane monoamine—dopamine (DA), norepinephrine (NE), and serotonin (5-HT)—transporters. The rewarding and addicting properties
of AMPH rely on its ability to act as a substrate for these transporters and ultimately increase extracellular levels of monoamines.
AMPH achieves this elevation in extracellular levels of neurotransmitter by inducing synaptic vesicle depletion, which increases
intracellular monoamine levels, and also by promoting reverse transport (efflux) through plasma membrane monoamine transporters
(J Biol Chem 237:2311–2317, 1962; Med Exp Int J Exp Med 6:47–53, 1962; Neuron 19:1271–1283, 1997; J Physiol 144:314–336, 1958; J Neurosci 18:1979–1986, 1998; Science 237:1219–1223, 1987; J Neurosc 15:4102–4108, 1995). This review will focus on two important aspects of AMPH-induced regulation of the plasma membrane monoamine transporters—transporter
mediated monoamine efflux and transporter trafficking. 相似文献
10.
In this work we present an approach to understand neuronal mechanisms underlying perceptual learning. Experimental results
achieved with stimulus patterns of coherently moving dots are considered to build a simple neuronal model. The design of the
model is made transparent and underlying behavioral assumptions made explicit. The key aspect of the suggested neuronal model
is the learning algorithm used: We evaluated an implementation of Hebbian learning and are thus able to provide a straight-forward
model capable to explain the neuronal dynamics underlying perceptual learning. Moreover, the simulation results suggest a
very simple explanation for the aspect of “sub-threshold” learning (Watanabe et al. in Nature 413:844–884, 2001) as well as the relearning of motion discrimination after damage to primary visual cortex as recently reported (Huxlin et al.
in J Neurosci 29:3981–3991, 2009) and at least indicate that perceptual learning might only occur when accompanied by conscious percepts. 相似文献
11.
The Protein Kinase C family of enzymes is a group of serine/threonine kinases that play central roles in cell-cycle regulation,
development and cancer. A key step in the activation of PKC is translocation to membranes and binding of membrane-associated
activators including diacylglycerol (DAG). Interaction of novel and conventional isotypes of PKC with DAG and phorbol esters
occurs through the two C1 regulatory domains (C1A and C1B), which exhibit distinct ligand binding selectivity that likely
controls enzyme activation by different co-activators. PKC has also been implicated in physiological responses to alcohol
consumption and it has been proposed that PKCα (Slater et al. J Biol Chem 272(10):6167–6173, 1997; Slater et al. Biochemistry 43(23):7601–7609, 2004), PKCε (Das et al. Biochem J 421(3):405–413, 2009) and PKCδ (Das et al. J Biol Chem 279(36):37964–37972, 2004; Das et al. Protein Sci 15(9):2107–2119, 2006) contain specific alcohol-binding sites in their C1 domains. We are interested in understanding how ethanol affects signal
transduction processes through its affects on the structure and function of the C1 domains of PKC. Here we present the 1H, 15N and 13C NMR chemical shift assignments for the Rattus norvegicus PKCδ C1A and C1B proteins. 相似文献
12.
In plants, reactive oxygen species (ROS) are short-lived molecules produced through various cellular mechanisms in response
to biotic and abiotic stimuli. ROS function as second messengers for hormone signaling, development, oxygen deprivation, programmed
cell death, and plant–pathogen interactions. Recent research on ROS-mediated responses has produced stimulating findings such
as the specific sources of ROS production, molecular elements that work in ROS-mediated signaling and homeostasis, and a ROS-regulated
gene network (Neill et al., Curr Opin Plant Biol 5:388–395, 2002a; Apel and Hirt, Annu Rev Plant Biol 55:373–399, 2004; Mittler et al., Trends Plant Sci 9:490–498, 2004; Mori and Schroeder, Plant Physiol 135:702–708, 2004; Kwak et al., Plant Physiol 141:323–329, 2006; Torres et al., Plant Physiol 141:373–378, 2006; Miller et al., Physiol Plant 133:481–489, 2008). In this review, we highlight new discoveries in ROS-mediated abscisic acid (ABA) signaling.
Drs. Daeshik Cho and June M. Kwak are the corresponding authors for this paper. 相似文献
13.
14.
Temperature controls a latitudinal gradient in the proportion of watershed nitrogen exported to coastal ecosystems 总被引:5,自引:4,他引:1
Increased export of biologically available nitrogen (N) to the coastal zone is strongly linked to eutrophication, which is
a major problem in coastal marine ecosystems (NRC (2000) Clean Coastal Waters: Understanding and Reducing the Effects of Nutrient Pollution. National Academy Press, Washington,
DC; Bricker et al. (1999) National Estuarine Eutrophication Assessment. Effects of nutrient enrichment in the nation’s estuaries. NOAA-NOS Special
Projects Office, Silver Spring, MD). However, not all of the nitrogen input to a watershed is exported to the coast (Howarth
et al. (1996) Biogeochemistry 35:75–139; Jordan and Weller (1996) Bioscience 46:655–664). Global estimates of nitrogen export to coasts have been taken to be 25% of watershed input, based
largely on northeastern U.S. observations (Galloway et al. (2004) Biogeochemistry 70:153–226; Boyer et al. (2006) Global Biogeochem Cycle 20:Art. No. GB1S91). We applied the N budgeting methodology developed for the International SCOPE
Nitrogen project (Howarth et al. (1996) Biogeochemistry 35:75–139; Boyer et al. (2002) Biogeochemistry 57:137–169) to 12 watersheds in the southeastern U.S., and compared them with estimates of N export for
16 watersheds in the northeastern U.S. (Boyer et al. (2002) Biogeochemistry 57:137–169). In southeastern watersheds, average N export was only 9% of input, suggesting the need for
downward revision of global estimates. The difference between northern and southern watersheds is not a function of the absolute
value of N inputs, which spanned a comparable range and were positively related to export in both cases. Rather, the proportion
of N exported was significantly related to average watershed temperature (% N export = 58.41 e−0.11 * temperature; R
2 = 0.76), with lower proportionate nitrogen export in warmer watersheds. In addition, we identified a threshold in proportionate
N export at 38°N latitude that corresponds to a reported breakpoint in the rate of denitrification at 10–12°C. We hypothesize
that temperature, by regulating denitrification, results in increased proportionate N export at higher latitudes. Regardless
of the mechanism, these observations suggest that temperature increases associated with future climate change may well reduce
the amount of nitrogen that reaches estuaries, which will have implications for coastal eutrophication. 相似文献
15.
Here we address three misconceptions stated by Rice et al. in their observations of our article Paz-y-Mi?o and Espinosa (Evo
Edu Outreach 2:655–675, 2009), published in this journal. The five authors titled their note “The Theory of Evolution is Not an Explanation for the Origin of Life.” First, we argue that it is fallacious to believe that because the formulation of the theory of evolution, as conceived
in the 1800s, did not include an explanation for the origin of life, nor of the universe, the concept of evolution would not
allow us to hypothesize the possible beginnings of life and its connections to the cosmos. Not only Stanley Miller’s experiments
of 1953 led scientists to envision a continuum from the inorganic world to the origin and diversification of life, but also
Darwin’s own writings of 1871. Second, to dismiss the notion of Rice et al. that evolution does not provide explanations concerning
the universe or the cosmos, we identify compelling scientific discussions on the topics: Zaikowski et al. (Evo Edu Outreach
1:65–73, 2008), Krauss (Evo Edu Outreach 3:193–197, 2010), Peretó et al. (Orig Life Evol Biosph 39:395–406, 2009) and Follmann and Brownson (Naturwissenschaften 96:1265–1292, 2009). Third, although we acknowledge that the term Darwinism may not be inclusive of all new discoveries in evolution, and also that creationists and Intelligent Designers hijack the
term to portray evolution as ideology, we demonstrate that there is no statistical evidence suggesting that the word Darwinism
interferes with public acceptance of evolution, nor does the inclusion of the origin of life or the universe within the concept
of evolution. We examine the epistemological and empirical distinction between the theory of evolution and the concept of evolution and conclude that, although the distinction is important, it should not compromise scientific logic. 相似文献
16.
Emiliano Manzo Paola Bartolommei J. Marcus Rowcliffe Roberto Cozzolino 《Acta theriologica》2012,57(2):165-172
Evaluating presence and abundance of small carnivores is essential for their conservation. In Italy, there is scarce information
on European pine marten distribution, and no data are published on its abundance. Camera traps have been widely used to estimate
population density applying capture–recapture models for species in which individual recognition is possible. Here we estimate
the abundance of European pine martens in central Italy using camera trapping and a model that allows the estimation of population
density without the need for individual recognition Rowcliffe et al. (Anim Conserv 11:185–186, 2008). Camera trapping was also used to evaluate habitat use patterns by martens. Fifteen camera traps were deployed in 90 placements
for 15 days each, for a total of 1,334 camera days. Pine martens were captured in 24% of camera trap placements with a mean
trap success rate of 0.33 photographs per camera placement. Estimated pine marten population density in the study area was
0.34 individuals km−2. Marten trap rate was not strongly associated with any habitat type, although there were trends towards lower probability
of records at locations with high coverage of cultivated fields and higher probability of records at locations with high coverage
of human-made woodland. The results suggest that pine martens in this area are not confined to wooded habitat. To our knowledge,
this study is the first application of the Rowcliffe et al. (Anim Conserv 11:185–186, 2008) method to a wild carnivore population and, furthermore, the first estimation of population density of pine martens in Italy. 相似文献
17.
Rauschenbach IY Bogomolova EV Karpova EK Adonyeva NV Faddeeva NV Menshanov PN Gruntenko NE 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2011,181(1):19-26
20-hydroxyecdysone (20E) and the juvenile hormone (JH) have an age-specific effect on total dopamine (DA) content in Drosophila (Gruntenko and Rauschenbach 2008). Earlier we studied the mechanism of influence of 20E and JH on DA metabolism in young females (Rauschenbach et al. in J
Insect Physiol 53:587–591, 2007a: Arch Insect Biochem Physiol 65:95–102, 2008a; Gruntenko et al. in Arch Insect Biochem Physiol 72:263–269, 2009). Here we investigate the effects of 20E and JH on the activities of the alkaline phosphatase (ALP), tyrosine hydroxylase
(TH) and DA-dependent arylalkylamine N-acetyltransferase (AANAT) in mature females of wild type D. virilis under normal conditions and under heat stress (38°C). 20E feeding of the flies led to a substantial decrease in ALP and TH
activities and to an increase in AANAT activity in mature females. JH application resulted in an increasing of ALP and TH
activities, but did not influence AANAT activity in mature females. A rise in JH and 20E levels was found to change ALP and
TH stress reactivities. Mechanisms of age-specific regulation of DA level by 20E and JH in Drosophila females are discussed. 相似文献
18.
Tarnow E 《Cognitive neurodynamics》2010,4(4):367-376
Theories of short term memory often include a limited capacity “buffer”. Such a buffer contains items which do not decay at
all but are overwritten by new data. I show that one of the experiments that fueled the buffer concept, the free recall experiments
by Murdock (J Exp Psychol 64(5):482–488, 1962), does not contain such a buffer. 相似文献
19.
Development of addiction to alcohol or other substances can be attributed in part to exposure-dependent modifications at synaptic
efficacy leading to an organism which functions at an altered homeostatic setpoint. Genetic factors may also influence setpoints
and the stability of the homeostatic system of an organism. Quantitative genetic analysis of voluntary alcohol drinking, and
mapping of the involved genes in the quasi-congenic Recombinant QTL Introgression strain system, identified Eac2 as a Quantitative Trait Locus (QTL) on mouse chromosome 6 which explained 18% of the variance with an effect size of 2.09 g/kg/day
alcohol consumption, and Grm7 as a quantitative trait gene underlying Eac2 [Vadasz et al. in Neurochem Res 32:1099–1112, 100, Genomics 90:690–702, 102]. In earlier studies, the product of Grm7 mGluR7, a G protein-coupled receptor, has been implicated in stress systems [Mitsukawa et al. in Proc Natl Acad Sci USA 102:18712–18717,
63], anxiety-like behaviors [Cryan et al. in Eur J Neurosci 17:2409–2417, 14], memory [Holscher et al. in Learn Mem 12:450–455, 26], and psychiatric disorders (e.g., [Mick et al. in Am J Med Genet B Neuropsychiatr Genet 147B:1412–1418, 61; Ohtsuki et al. in Schizophr Res 101:9–16, 72; Pergadia et al. in Paper presented at the 38th Annual Meeting of the Behavior Genetics Association, Louisville, Kentucky,
USA, 76]. Here, in experiments with mice, we show that (1) Grm7 knockout mice express increased alcohol consumption, (2) sub-congenic, and congenic mice carrying a Grm7 variant characterized by higher Grm7 mRNA drink less alcohol, and show a tendency for higher circadian dark phase motor activity in a wheel running paradigm,
respectively, and (3) there are significant genetic differences in Grm7 mRNA abundance in the mouse brain between congenic and background mice identifying brain areas whose function is implicated
in addiction related processes. We hypothesize that metabotropic glutamate receptors may function as regulators of homeostasis,
and Grm7 (mGluR7) is involved in multiple processes (including stress, circadian activity, reward control, memory, etc.) which interact
with substance use and the development of addiction. In conclusion, we suggest that mGluR7 is a significant new therapeutic
target in addiction and related neurobehavioral disorders. 相似文献
20.
Camperi and Wang (Comput Neurosci 5:383–405, 1998) presented a network model for working memory that combines intrinsic cellular bistability with the recurrent network architecture
of the neocortex. While Fall and Rinzel (Comput Neurosci 20:97–107, 2006) replaced this intrinsic bistability with a biological mechanism-Ca2+ release subsystem. In this study, we aim to further expand the above work. We integrate the traditional firing-rate network
with Ca2+ subsystem-induced bistability, amend the synaptic weights and suggest that Ca2+ concentration only increase the efficacy of synaptic input but has nothing to do with the external input for the transient
cue. We found that our network model maintained the persistent activity in response to a brief transient stimulus like that
of the previous two models and the working memory performance was resistant to noise and distraction stimulus if Ca2+ subsystem was tuned to be bistable. 相似文献