New and Exciting in PLoS Biology and PLoS Medicine

It's Monday night - time for new articles in PLoS Biology and PLoS Medicine:

On the Emergence and Awareness of Auditory Objects:

Anyone who has walked into a crowded reverberant nightclub, with a hubbub of multiple conversations amidst blaring music, will recall the initial impression of the sound as loud and undifferentiated noise. In short order, however, different sound streams begin to emerge as one attends to individual speakers, listens to the melody from the band, or even hears one instrument in it. Humans perform this remarkable feat effortlessly. Our extraordinary abilities to extract signal from noise have evolved in natural environments that are often extremely auditorily cluttered. Many animals have developed abilities to navigate their complex auditory scenes in order to mate, locate prey, feed their young, and avoid predators. It is likely that these abilities are mediated by similar mechanisms that have evolved in many animals and include a mix of "bottom-up" automatic processes with complex "top-down" behaviors involving attention, expectation, learning, and memory (as illustrated schematically in Figure 1). However, little is known about the underlying computational details, or the manner in which these diverse processes interact to give rise to this auditory ability. And it is therefore no coincidence that we still lack engineering systems that can recognize speech robustly in realistic environments, or reliably transcribe polyphonic music.

Beyond Competition: Incorporating Positive Interactions between Species to Predict Ecosystem Invasibility:

One of the many unintended consequences of global commerce has been the translocation of countless plants and animals to new regions, continents, and oceans [1,2]. Such "exotic" species have colonized nearly every habitat on Earth, and modern ecosystems are now made up largely of species originating from geographically distinct regions [3-5]. Most exotic species have negligible or no negative effects, but a small handful have had substantial impacts on native species and ecosystem processes [3,6]. For example, the introduction of the Nile perch (Lates niloticus) into Lake Victoria has not only caused the extinction of two-thirds of the endemic fish fauna, but has changed the entire food web of the lake by reducing the grazing by phytoplanktivores [7,8].

Given the sizable ecological and economic costs of species invasions [9], understanding the environmental factors that regulate them has become a major goal for basic and applied ecologists. One major research theme is the investigation of the relationship between native species richness (the number of local native species) and the ability of exotic species to colonize and thrive in new habitats (termed community "invasibility") [10,11]. A longstanding concept in ecology is that habitats with high levels of diversity are difficult to invade (the biotic resistance hypothesis--see Glossary) [11-15]. This is because, in theory, a more diverse assemblage of plants or animals can utilize resources more fully than a less diverse community, thus increasing the intensity of competition and making it harder for new species to become established. Predictions from this model are, however, based on the assumption that natural communities are largely structured by competitive interactions and that the effects of native species on invaders are predominantly negative.

Drug Development for Maternal Health Cannot Be Left to the Whims of the Market:

In an essay published in this month's PLoS Medicine, Nicholas White and colleagues [1] lament that an insufficient understanding of even well-established drugs has led to a lack of effective treatments in pregnancy. They conclude that "we do not know how best to treat most tropical infectious diseases in pregnancy"--an alarming and shameful situation--and lay out causes of this ignorance. For example, concern about teratogenicity has led to the exclusion of pregnant women from clinical trials regardless of their stage of pregnancy, resulting in a crucial lack of evidence even in late pregnancy, when teratogenicity is not a concern. Gaps in the evidence on pharmacokinetics of some antimalarial drugs have often led to under-dosing of pregnant women, and in some cases the erroneous conclusion that such drugs are not effective in pregnancy. The authors note that "'better safe than sorry' is the mantra of our risk-averse age." But since severe malaria has a mortality approaching 50% in late pregnancy, we concur with the authors that this mantra has actually produced harm.

Guidelines for Reporting Health Research: The EQUATOR Network's Survey of Guideline Authors:

Scientific publications are one of the most important outputs of any research, as they are the primary means of sharing the findings with the broader research community. The quality and relevance of research is mostly judged through the published report, which is often the only public record that the research was done. Unclear reporting of a study's methodology and findings prevents critical appraisal of the study and limits effective dissemination. Inadequate reporting of medical research carries with it an additional risk of inadequate and misleading study results being used by patients and health care providers. Patients may be harmed and scarce health care resources may be expended on ineffective health care treatments through such inadequate reporting. There is a wealth of evidence that much of published medical research is reported poorly [1-12]. Yet a good report is an essential component of good research.

Effect of a Brief Video Intervention on Incident Infection among Patients Attending Sexually Transmitted Disease Clinics:

In the US alone there are 19 million new cases of sexually transmitted diseases (STDs) every year. STDs are infections that pass between people during sexual activity (through semen, vaginal fluids, blood, or skin-to-skin contact). Some STDs are caused by bacteria (for example, chlamydia, gonorrhea, and syphilis). Others are caused by parasites (for example, trichomoniasis) or viruses (for example, herpes simplex virus and HIV). Symptoms vary among STDs but may include sores, unusual lumps and itching in the genital region, pain when urinating, and unusual genital discharge. While symptoms are generally more common in men than women, many STDs cause no symptoms. Untreated STDs are more serious for women and may include pelvic inflammatory disease (PID), ectopic pregnancy, infertility, and chronic pain. Bacterial and parasitic STDs can be cured with various drugs; STDs caused by viruses cannot be cured although they can be treated with antiviral drugs.

How Well Do Clinical Pain Assessment Tools Reflect Pain in Infants?:

Pain is a sensory and emotional experience. It is normally triggered by messages transmitted from specialized receptors (nociceptors) in the body to integrative centers in the spinal cord and brainstem and on to the brain, where it undergoes higher sensory and cognitive analysis, allowing the body to respond appropriately to the stimuli. While the experience of pain may be considered to be unpleasant, it is a useful tool in communicating to us and to others that there is something wrong with our bodies. Ultimately, these responses help restrict further damage to the body and start the process of healing.

In a clinical setting, the ability to communicate about pain allows an individual to seek strategies to ease the pain, such as taking analgesics. Being unable to effectively communicate one's experience of pain leaves the individual vulnerable to prolonged suffering. One such vulnerable group is infants.

Ignored and untreated pain in infants has been shown to have immediate and long-term effects as a result of structural and physiological changes within the nervous system. For example, the body responds to untreated pain by increased release of stress hormones, which may be associated with increased morbidity and mortality in the short term. Long-term effects of pain may include altered pain perception, chronic pain syndromes, and somatic complaints such as sleep disturbances, feeding problems, and inability to self-regulate in response to internal and external stressors. It has been proposed that attention deficit disorders, learning disorders, and behavioral problems in later childhood may be linked to repetitive pain in the preterm infant.