Proceedings of the Natural Academy of Sciences

Proceedings of the National Academy of Sciences RSS feed -- current issue
  • Predicting higher visual cortex neural responses [Neuroscience]
    [Jun 2014]

    The ventral visual stream underlies key human visual object recognition abilities. However, neural encoding in the higher areas of the ventral stream remains poorly understood. Here, we describe a modeling approach that yields a quantitatively accurate model of inferior temporal (IT) cortex, the highest ventral cortical area. Using high-throughput computational...
    Categories: Journal Articles
  • Local photic entrainment of the murine retina [Neuroscience]
    [Jun 2014]

    Synchronization of the mammalian master circadian pacemaker to the daily light/dark cycle is mediated exclusively through retinal photoreceptors. The mammalian retina itself is also a self-sustained circadian oscillator. Here we report that the retinal molecular circadian clock can be entrained by lighting cycles in vitro, but that rods, cones, and...
    Categories: Journal Articles
  • Cognitive flexibility and {beta}-catenin stabilization [Neuroscience]
    [Jun 2014]

    The cadherin/β-catenin adhesion complex is a key mediator of the bidirectional changes in synapse strength which are believed to underlie complex learning and memory. In the present study, we demonstrate that stabilization of β-catenin in the hippocampus of adult mice results in significant impairments in cognitive flexibility and spatial reversal...
    Categories: Journal Articles
  • Oxytocin and 5-HT1A [Neuroscience]
    [Jun 2014]

    Serotonin (5-HT) and oxytocin (OXT) are two neuromodulators involved in human affect and sociality and in disorders like depression and autism. We asked whether these chemical messengers interact in the regulation of emotion-based behavior by administering OXT or placebo to 24 healthy subjects and mapping cerebral 5-HT system by using...
    Categories: Journal Articles
  • Impact of puberty on cerebral perfusion [Neuroscience]
    [Jun 2014]

    Puberty is the defining biological process of adolescent development, yet its effects on fundamental properties of brain physiology such as cerebral blood flow (CBF) have never been investigated. Capitalizing on a sample of 922 youths ages 8–22 y imaged using arterial spin labeled MRI as part of the Philadelphia Neurodevelopmental...
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  • NMDAR antagonists as rapid antidepressants [Neuroscience]
    [Jun 2014]

    Ketamine is an NMDA receptor (NMDAR) antagonist that elicits rapid antidepressant responses in patients with treatment-resistant depression. However, ketamine can also produce psychotomimetic effects that limit its utility as an antidepressant, raising the question of whether the clinically tolerated NMDAR antagonist memantine possesses antidepressant properties. Despite its similar potency to...
    Categories: Journal Articles
  • Fast release at ribbon synapses [Neuroscience]
    [Jun 2014]

    Ribbon synapses of photoreceptor cells and second-order bipolar neurons in the retina are specialized to transmit graded signals that encode light intensity. Neurotransmitter release at ribbon synapses exhibits two kinetically distinct components, which serve different sensory functions. The faster component is depleted within milliseconds and generates transient postsynaptic responses that...
    Categories: Journal Articles
  • Heavy electron quantum criticality [Physics]
    [Jun 2014]

    Quantum critical behavior in heavy electron materials is typically brought about by changes in pressure or magnetic field. In this paper, we develop a simple unified model for the combined influence of pressure and magnetic field on the effectiveness of the hybridization that plays a central role in the two-fluid...
    Categories: Journal Articles
  • Active learning boosts performance in STEM courses [Psychological and Cognitive Sciences]
    [Jun 2014]

    To test the hypothesis that lecturing maximizes learning and course performance, we metaanalyzed 225 studies that reported data on examination scores or failure rates when comparing student performance in undergraduate science, technology, engineering, and mathematics (STEM) courses under traditional lecturing versus active learning. The effect sizes indicate that on average,...
    Categories: Journal Articles
  • Explaining Asian Americans' academic advantage [Social Sciences]
    [Jun 2014]

    The superior academic achievement of Asian Americans is a well-documented phenomenon that lacks a widely accepted explanation. Asian Americans’ advantage in this respect has been attributed to three groups of factors: (i) socio-demographic characteristics, (ii) cognitive ability, and (iii) academic effort as measured by characteristics such as attentiveness and work...
    Categories: Journal Articles
  • In This Issue [This Week in PNAS]
    [Jun 2014]

    Active learning and STEM education A graduating class. Image courtesy of iStockphoto/janniswerner. The push to produce STEM teachers and graduates as a means of improving innovative capacity in the United States has raised the question of what constitutes effective STEM education. To investigate the success of different teaching methods, Scott...
    Categories: Journal Articles
  • Profile of Bruce Levin [Profiles]
    [Jun 2014]

    For population biologist Bruce Levin, opening the incubator to see how yesterday’s experiment worked is his ideal way to start the day. That anticipation has kept the Emory University professor of biology excited about his research on the population and evolutionary biology of bacteria for more than 40 years, and...
    Categories: Journal Articles
  • Large-scale comparison of STEM teaching methods [Psychological and Cognitive Sciences]
    [Jun 2014]

    The quality of science, technology, engineering, and mathematics (STEM) education in the United States has long been an area of national concern, but that concern has not resulted in improvement. Recently, there has been a growing sense that an opportunity for progress at the higher education level lies in the...
    Categories: Journal Articles
  • Asian Americans' academic advantage [Social Sciences]
    [Jun 2014]

    Scholars have long debated the reasons underlying Asian Americans’ exceptional educational outcomes. Psychologists emphasize individual cognitive ability and the effects of stereotypes on performance (1). Culturalists point to values, beliefs, norms, and behavioral patterns unique and intrinsic to ethnicity (2). Structuralists focus on socioeconomic status within and beyond the family,...
    Categories: Journal Articles
  • Protein splicing hangs from the branch [Biochemistry]
    [Jun 2014]

    Inteins perform a macromolecular vanishing act that continues to impress as its secrets are revealed. Dispersed through all domains of life, these autocatalytic domains exit the folds of ostensibly unrelated proteins soon after translation. Inteins bust at the seams, severing peptide bonds that immediately precede and follow their sequence. Critically,...
    Categories: Journal Articles
  • Embryonic origin of subplate diversity [Neuroscience]
    [Jun 2014]

    An Extracortical Source of Subplate Neurons The proper wiring of neuronal circuits during development is a prerequisite for normal brain function. Moreover, complex brain function is possible in part because of the extraordinary diversity in neuronal cell types that provides the substrate for networks required for a variety of computational...
    Categories: Journal Articles
  • Catching up to human vision [Neuroscience]
    [Jun 2014]

    In the course of our daily lives, we rely on our ability to quickly recognize visual objects despite variations in the viewing angle or lighting conditions (1). Most of the time, this process occurs so naturally that it is easy to underestimate the computational challenge it poses. In fact, as...
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  • Mechanically tunable block polymers from sugar [Applied Biological Sciences]
    [Jun 2014]

    Development of sustainable and biodegradable materials is essential for future growth of the chemical industry. For a renewable product to be commercially competitive, it must be economically viable on an industrial scale and possess properties akin or superior to existing petroleum-derived analogs. Few biobased polymers have met this formidable challenge....
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  • Boundary singularities in soap-film motion [Applied Mathematics]
    [Jun 2014]

    Recent work has shown that a Möbius strip soap film rendered unstable by deforming its frame changes topology to that of a disk through a “neck-pinching” boundary singularity. This behavior is unlike that of the catenoid, which transitions to two disks through a bulk singularity. It is not yet understood...
    Categories: Journal Articles
  • Navigability of interconnected networks [Applied Physical Sciences]
    [Jun 2014]

    Assessing the navigability of interconnected networks (transporting information, people, or goods) under eventual random failures is of utmost importance to design and protect critical infrastructures. Random walks are a good proxy to determine this navigability, specifically the coverage time of random walks, which is a measure of the dynamical functionality...
    Categories: Journal Articles