Brain networks of novelty-driven involuntary and cued voluntary auditory attention shifting

In everyday life, we need a capacity to flexibly shift attention between alternative sound sources. However, relatively little work has been done to elucidate the mechanisms of attention shifting in the auditory domain. Here, we used a mixed event-related/sparse-sampling fMRI approach to investigate this essential cognitive function. In each 10-sec trial, subjects were instructed to wait for an auditory "cue" signaling the location where a subsequent "target" sound was likely to be presented. The target was occasionally replaced by an unexpected "novel" sound in the uncued ear, to trigger involuntary attention shifting. To maximize the attention effects, cues, targets, and novels were embedded within dichotic 800-Hz vs. 1500-Hz pure-tone "standard" trains. The sound of clustered fMRI acquisition (starting at t?=?7.82 sec) served as a controlled trial-end signal. Our approach revealed notable activation differences between the conditions. Cued voluntary attention shifting activated the superior intra--parietal sulcus (IPS), whereas novelty-triggered involuntary orienting activated the inferior IPS and certain subareas of the precuneus. Clearly more widespread activations were observed during voluntary than involuntary orienting in the premotor cortex, including the frontal eye fields. Moreover, we found -evidence for a frontoinsular-cingular attentional control network, consisting of the anterior insula, inferior frontal cortex, and medial frontal cortices, which were activated during both target discrimination and voluntary attention shifting. Finally, novels and targets activated much wider areas of superior temporal auditory cortices than shifting cues.     

Eider females form non-kin brood-rearing coalitions

Kin selection is a powerful tool for understanding cooperation among individuals, yet its role as the sole explanation of cooperative societies has recently been challenged on empirical grounds. These studies suggest that direct benefits of cooperation are often overlooked, and that partner choice may be a widespread mechanism of cooperation. Female eider ducks (Somateria mollissima) may rear broods alone, or they may pool their broods and share brood-rearing. Females are philopatric, and it has been suggested that colonies may largely consist of related females, which could promote interactions among relatives. Alternatively, shared brood care could be random with respect to relatedness, either because brood amalgamations are accidental and nonadaptive, or through group augmentation, assuming that the fitness of all group members increases with group size. We tested these alternatives by measuring the relatedness of co-tending eider females in enduring coalitions with microsatellite markers. Females formed enduring brood-rearing coalitions with each other at random with respect to relatedness. However, based on previous data, partner choice is nonrandom and dependent on female body condition. We discuss potential mechanisms underlying eider communal brood-rearing decisions, which may be driven by the specific ecological conditions under which sociality has evolved in this species.     

Hormonal response to competition among male coalitions

Previous research has shown that testosterone (T) and cortisol (C) are released in response to a wide variety of social stimuli including dyadic (one on one) competitive events, but humans also compete as groups. Here we report results from a pilot study of hormonal responses to competition between male coalitions. Salivary T and C levels were assessed in adult males from a rural Caribbean village who competed at dominoes, as two-man teams, against (a) familiar men from their own village (within coalition), and (b) strangers from another village (between coalitions). Analyses indicate that both T and C levels were higher and responses more pronounced for between-village competition than for within-village competition, but we could not compare responses to victory and defeat in the between-village case, since our subjects happened to win both such contests. Further studies of endocrine responses in the context of coalitional competition are warranted.     

Greeting,aggression, and coalitions between male baboons: Demographic correlates

Interactions of asymmetrical, symmetrical, and unreciprocated greeting, and episodes of aggression and coalitions observed between 18 males, members of a large multi-harem colony of baboons (Papio hamadryas, P. cynocephalus, and their hybrids) housed in the Madrid Zoo, were recorded throughout 11 time blocks between January 1983 and March 1985. The major question investigated was whether the demographic characteristics of the colony affected the frequency with which males used three behavioural strategies, namely, greeting, aggression, and coalitions. It was found that under demographic conditions eliciting more intense male-male competition, for example, when the ratio of oestrous cycles per adult male was lower, males exchanged frequent greetings, especially the symmetrical form (i.e. notifying) and solicited more coalitions, but did not show any significant change in rates of dyadic aggression. Male phenotype-related effects on rates of greeting and coalitions were found as well. Results are discussed in relation with the suggested role of greeting and of coalition behaviour as strategies used in the negotiation of changes in competitive social relationship (e.g. consort changeovers). These strategies are regarded as social tactics alternative to direct aggression.     

Power capping: a prelude to power shifting

We present a technique that controls the peak power consumption of a high-density server by implementing a feedback controller that uses precise, system-level power measurement to periodically select the highest performance state while keeping the system within a fixed power constraint. A control theoretic methodology is applied to systematically design this control loop with analytic assurances of system stability and controller performance, despite unpredictable workloads and running environments. In a real server we are able to control power over a 1 second period to within 1 W and over an 8 second period to within 0.1 W. Conventional servers respond to power supply constraint situations by using simple open-loop policies to set a safe performance level in order to limit peak power consumption. We show that closed-loop control can provide higher performance under these conditions and implement this technique on an IBM BladeCenter HS20 server. Experimental results demonstrate that closed-loop control provides up to 82% higher application performance compared to open-loop control and up to 17% higher performance compared to a widely used ad-hoc technique.

Which adult male savanna baboons form coalitions?

We investigated the mechanism of alliance formation among adult male savanna baboons by comparing the characteristics of males that formed coalitions frequently with males that never or seldom took part in coalitions. We observed three groups: two of Papio cynocephalus cynocephalusin Amboseli National Park, Kenya, and one of P. c. anubisin the vicinity of Gilgil, Kenya. We considered four hypotheses: (1) Males must be familiar with each other, (2) males must have an affinitive bond, (3) males must have more than average experience, and (4) the combined fighting ability of the coalition partners relative to the fighting ability of their opponent determines the likelihood that a coalition is formed. We conclude that relative fighting ability forms the key factor in coalition formation. High- ranking males do not form coalitions often, since they hardly need them. Low- ranking males rarefy form coalitions, since they cannot form effective coalitions among themselves. Affinity (“friendship”) may play a role as an additional factor. The relation of coalition formation with age and period of residence, which was found in several studies, can be explained largely by the correlation between these parameters and fighting ability.     

Which adult male savanna baboons form coalitions?

We investigated the mechanism of alliance formation among adult male savanna baboons by comparing the characteristics of males that formed coalitions frequently with males that never or seldom took part in coalitions. We observed three groups: two of Papio cynocephalus cynocephalusin Amboseli National Park, Kenya, and one of P. c. anubisin the vicinity of Gilgil, Kenya. We considered four hypotheses: (1) Males must be familiar with each other, (2) males must have an affinitive bond, (3) males must have more than average experience, and (4) the combined fighting ability of the coalition partners relative to the fighting ability of their opponent determines the likelihood that a coalition is formed. We conclude that relative fighting ability forms the key factor in coalition formation. High- ranking males do not form coalitions often, since they hardly need them. Low- ranking males rarefy form coalitions, since they cannot form effective coalitions among themselves. Affinity (“friendship”) may play a role as an additional factor. The relation of coalition formation with age and period of residence, which was found in several studies, can be explained largely by the correlation between these parameters and fighting ability.     

Health research in Canada: a shifting paradigm.

A personal review of medical research in Canadian medical schools over the past 25 years reveals extraordinary contributions. Over this time, medical research evolved from a by-product of faculty members to a commitment that determines the future success of a medical faculty. The increasing competition for health research funding and the high standards created internationally have changed the way research is organized in our medical faculties. Current trends include a move toward group and thematic research, an increased role of research institutes and the development of strategic partnerships with industry. Because of the need for more planning and more critical and timely review of research efforts, the benefits of collaboration enhance the quality and competitiveness of a medical faculty. A broadened vision of the Medical Research Council and provincial foundations and the need to increase resources for research foreshadow even greater change.     

Protein sorting in the Golgi complex: shifting paradigms

The paradigms for transport along the biosynthetic route have changed dramatically over the past 15 years. Unlike the situation 15 years ago, the current paradigm involves sorting signals practically at every step of the pathway. In particular, at the exit from the Golgi complex, apical, basolateral and lysosomal targeting signals result in the generation of a variety of routes. Furthermore, it is now quite clear that not all sorting in the biosynthetic route occurs in the Golgi complex or the Trans Golgi Network (TGN). Sorting may occur distally to the Golgi, in recycling endosomes or in budded tubulosaccular structures, or it may occur proximally to the Golgi complex, at the exit from the ER. Several adaptors are candidates to sort apical and basolateral proteins but only AP1B and AP4 are currently involved. Progress is fast and future work should elucidate many of the open questions.     

Prespecification and plasticity: shifting mechanisms of cell migration

Cell migration is a universal process involving different morphologies and mechanisms in different cell types and tissue environments. Prespecified cell-type-specific patterns of cell migration can be classified into single cell migration (amoeboid, mesenchymal) and collective migration modes (cell sheets, strands, tubes, clusters). These intrinsic molecular programs are associated with a characteristic structure of the actin cytoskeleton, as well as the cell-type-specific use of integrins, matrix-degrading enzymes (matrix metalloproteinases and serine proteases), cell-cell adhesion molecules (cadherins and activated leukocyte adhesion molecule), and signaling towards the cytoskeleton (carried out by RHO GTPases). In response to the gain or loss of these key molecular determinants, significant adaptation reactions can modify the cell's shape, pattern, and migration mechanism; examples of this include the epithelial-mesenchymal transition, mesenchymal-amoeboid transition and collective-amoeboid transition.     

Tyrosine phosphorylation in semaphorin signalling: shifting into overdrive

The semaphorins constitute a large family of molecular signals with regulatory functions in neuronal development, angiogenesis, cancer progression and immune responses. Accumulating data indicate that semaphorins might trigger multiple signalling pathways, and mediate different and sometimes opposing effects, depending on the cellular context and the particular plexin-associated subunits of the receptor complex, which can include receptor-type or cytoplasmic tyrosine kinases such as MET, ERBB2, VEGFR2, FYN, FES, PYK2 and SRC. It has also been shown that a specific plexin can alternatively associate with different tyrosine kinase receptors, eliciting divergent signalling pathways and functional outcomes. Tyrosine phosphorylation is a pivotal post-translational protein modification that regulates intracellular signalling. Therefore, phosphorylation of tyrosines in the intracellular domain of plexins could determine or modify their interactions with additional signal transducers. Here, we discuss the potential relevance of tyrosine phosphorylation in semaphorin-induced signalling, with an emphasis on its probable role in dictating the choice between multiple pathways and functional outcomes. The identification of implicated tyrosine kinases will pave the way to target individual semaphorin-mediated functions.     

细菌鞭毛马达——一种卓越的分子机器

鞭毛马达(flagellar motor)是一种分子旋转马达,它在细菌鞭毛的结构与功能中起着中心作用.鞭毛马达的结构已基本清楚,主要由Mot A、Mot B、Fli G、Fli M和Fli N 5种蛋白组成定子(stator)和转子(rotor),其驱动力来自于跨膜的H⁺或Na⁺流.目前对鞭毛马达的旋转动力学及旋转力矩产生机制已有初步的了解.鞭毛马达可作为研究分子旋转马达的理想模型,对其深入研究将有助于认识生物能量转化利用及细胞运动的机制并具有广泛的生物学意义.