Tightly coordinated diabetes 10 order actoplus met 500mg visa, simultaneous singing of the same song diabetes obesity actoplus met 500mg generic, so frequent in human music diabetes hands foundation order 500 mg actoplus met, is not a phenomenon that appears to blood glucose greater than 400 cheap 500 mg actoplus met amex occur elsewhere in nature. Duetting is a different matter: here two birds contribute to a song, often in a tightly coordinated fashion. Indeed, whereas bouts may overlap, the sounds themselves may not do so, the birds tting their sounds together so precisely that it is hard to believe that more than one individual is involved. This form of duetting, in which male and female use different notes and sing alternately, is known as antiphonal singing (Hooker and Hooker 1969) and has been documented in a wide variety of species 58 Peter J. Duetting is most common in the tropics, and this probably relates to the fact that birds there frequently hold year-round territories (Farabaugh 1982). One other association often claimed is that between duetting and sexual monomorphism, and although Farabaugh (1982) failed to nd this, she said that that could be because her de nition of duetting was a rather undemanding one. It is certainly striking that many species with tight antiphonal duets that have been studied are monomorphic. Duetting may have a role in maintaining the long-term pair bond and in keeping contact between members of a pair, especially in the dense and noisy environment of a species-rich tropical forest (Hooker and Hooker 1969). However, evidence on these matters is equivocal (Todt and Hultsch 1982; Wickler 1976). Wickler (1976) maintains that, in addi tion to possible roles within the pair, duetting is primarily a signal used in cooperative territory guarding. The idea that duetting pairs are jointly defending their territories raises the question of why this evolved in certain species but not in others in which only the male sings. The answer must lie in detailed eld studies of the species concerned, and few of these have been conducted to date. One study on bay wrens (Thyothorus nigricapillus) in Panama suggests an intriguing answer (Levin 1996a, b). In many duets, one bird sings an initial section that is followed by a reply from the other. It has often been assumed that the duet is initiated by the male, with the reply being the contribution of the female. Although these birds are monomorphic, she examined them using a technique called laparotomy and found that the individuals leading the duets were female. She suggests that duetting in these birds may have originated because, for some reason, females are the more ter ritorial sex. They therefore sing just like female European robins in winter to defend their territories and attract prospective mates. However, bay wrens are monogamous, and once a female has attracted a male, he deters others by adding a coda to her song. This idea for different roles of the sexes in duetting species is an inge nious one and may also apply to other species. Despite the fact that the phenomenon has been extensively documented, few studies in the eld went beyond the stage of observation and description, and the subject of duetting calls for more experimental work. As yet, any possible link between this aspect of birdsong and coordinated singing in humans would be decidedly tenuous! The rst point is that any similarity is more likely to be by analogy than homology because humans shared a musical ancestor with other singing animals. Our closest living relatives, the great apes, communicate more by gesture and by facial expression than by sound. They do have loud vocal displays, such as the pant-hoot of chimpanzees (Pan troglodytes), but these are far from elaborate or musical. Further more, little evidence exists that any monkey or nonhuman ape learns sounds that it produces from other individuals (Janik and Slater 1997). Humans obviously do so, and this is also the way in which whales and songbirds, the most notable singers elsewhere in the animal kingdom, obtain their sounds. For some reason, therefore, elaborate singing behavior arose quite separately in different animal groups, and in our case this was in the relatively recent past, since the common ancestor that we shared with chimpanzees died about two million years ago. Straight comparison may not be justi ed, but does analogy with birds help to suggest why singing and other musical attributes in humans may have arisen With any complex or varied display, sexual selection is a prime suspect, and the fact that in many cultures singing (and in our own culture, composition) is predominantly a feature of young males (see Miller, this volume) con rms that suspicion. However, why singing behavior should have been favored in early humans in particular rather than in other species remains a matter of speculation. The singing of humans also has some features, such as the simultaneous chanting of the same tune by groups of individuals (see Nettl and Merker, this volume), that have not been described among animals. This is not an easy question to answer, partly because no de nition of music seems to be universally agreed upon. A regular rhythm is shown by a mechanism operating at its resonant frequency, and this is where energy cost is least. Concentrating all the energy in a narrow frequency band to produce fairly pure sounds is also economi cal as the sounds carry further. But rhythmical and tonal sounds may have arisen in the animal kingdom for other good reasons. For most animal signals, and especially those concerned with attracting mates and repelling rivals, it is essential that the signal incorporate species identity. To stand out against both this cacophony of sound and other environmental noises, and to be distinctive, may impose features such as tone and rhythm as each species homes in on its own broadcasting bandwidth. Complex pat terns of songs and species differences in the rules that underlie them may also have their origins in the need for distinctiveness. It is not dif cult to nd examples in animal song of complex features that we would also attribute to music. Considering only songbirds (oscine passerines), there are close to 4,000 species in the world, and all of them are thought to learn their songs. The variety in the form and patterning of these songs is impressive, and it is likely that many possible patterns remain unexplored given this huge array of species. It would thus not be surprising if almost any characteristic found in human music were discovered in one or a few of them. But such sim ilarities are likely to be coincidental, and certainly due to convergence rather than because features of music arose in a common ancestor. Nevertheless, although animals may not share music in the strict sense with us, there is no doubt that some of them do have complex and beautiful vocal displays. Understanding the reasons why they evolved may help to shed light on why only we among the primates have gone along a similar pathway. It is suggested from time to time that the songs of some birds that seem to us especially beautiful may be more so than is strictly necessary for their biological function (Thorpe 1961; Boswall 1983). Could this indicate some primitive aesthetic sense, and that the bird is taking pleasure in song for its own sake Candidates would be songs of the song thrush in Europe, the superb lyrebird (Menura novaehollandiae; Robinson and Curtis 1996) in Australia, and the mockingbird (Mimus polyglottos; Wildenthal 1965) in North America, all of which have large, varied, and beautiful repertoires. Sexual selection is an open ended process that will lead to larger and larger song repertoires until other constraints, such as storage space in the brain, set limits. Where it is responsible, it is unlikely that song could be more elaborate than it demanded. On the other hand, there is nothing incompatible between this and either aesthetics or the enjoyment of song; indeed, sexual selec tion is likely to have been the basis for its evolution in humans. We personally feel enjoyment in hearing or performing music, and we know that other humans do too, 61 Birdsong Repertoires as we can ask them about it and discuss their feelings with them. When it comes to animals, however, we have no access to their inner feelings, so that the question can only be a matter of speculation (Slater in press). Acknowledgments this chapter is based in part on ideas about song repertoires and about the relationship between animal sounds and music that I developed elsewhere. However, it also gained enormously from the novel interdisciplinary per spective provided by the rst Florentine Workshop in Biomusicology. I am very grateful to the Institute of Biomusicology for arranging this, and to Nils Wallin and Bjorn Merker in particular for inviting me to it. Sexual response of female yellowhammers to differences in regional song dialects and repertoire sizes.
Pre-existing plaques may harbour the seeding material to diabetes prevention us purchase cheap actoplus met on line seed new plaques – be it oligomers or some other A aggregates diabetic juice fast buy actoplus met discount. Plaques have been shown to diabetes medication linked to bladder cancer discount generic actoplus met canada co-localise with and be surrounded by soluble A oligomers (Koffie et al diabetes type 2 medicines new 500 mg actoplus met overnight delivery. Therefore, it is possible that 70 plaques harbour the material necessary to seed new plaques and would seed new plaques in their direct vicinity. As reviewed in the introduction, plaques are toxic to neurons in the near vicinity (Bittner et al. This being true, the presence of a pre-existing plaque could damage the local neurons, releasing intracellular plaque seeding material. Thereby a new plaque would be more likely to form in the vicinity of a pre-existing plaque. Taken together, there is a lot of evidence for the non-random deposition of new plaques. It is therefore possible that both factors are involved in this phenomenon, but more research is needed to fully elucidate the many influences on localisation of plaque deposition. Merger of Plaques over Time the second major conclusion of this study is that clusters of plaques can merge over time to form a single, large plaque. This is supported by previous studies that also found examples of multicored plaques (Condello et al. However, this thesis provided a detailed quantification of this plaque population and mapped their fate over time. Plaques that 2 merged over time made up a sizable proportion (13%) of all large (> 300 µm) plaques and ~25% of these multicores merged over a four month period. It would be interesting to conduct a longer study to determine if more cores would merge over a longer period, or if some cores remain separate for very long periods, and whether there is a particular point in the pathological progression of plaques where cluster fusion happens. In the first scenario, the two plaques simply grow uniformly and the space between them slowly decreases so that they automatically gradually merge together. This scenario is certainly attractively simple, but a second scenario, whereby the space in between two close plaques is preferential for A deposition is also intriguing. The surfaces of the two close plaques presumably offers lots of fibril ends to which A molecules 71 can bind and elongate the fibres (Jucker & Walker, 2011). But in the space between the two plaques, the density of fibril ends is higher and so the probability of a ‘passing’ A molecule to bind to a fibril within this space is higher than for it to bind to the rest of the plaques’ surfaces. Thereby, the amount of A deposition in between the two close plaques may be higher than other places on the spherical plaques favouring the fusion of the two plaques. The third scenario is that the diffuse A halo surrounding the dense cores of the two plaques can change conformation over time to a dense core conformation and thereby the cores merge over time. In fact, new dense core material was observed developing nearby and seemingly within diffuse A material (Figure 30). It is tempting to speculate that the new cores emerging in the halo of diffuse A had developed directly from the diffuse A and that diffuse A can change conformation into an amyloid structure. One theory, still widely debated, suggests that dense core plaques develop out of diffuse plaques (Fiala, 2007) and that diffuse A deposits are the precursors to cored plaques. One study examined the conformation of plaques in young and aged mice using fluorescent probes and showed that A likely changes conformation within plaques as plaques in older animals had less immature fibrils and more mature filaments than plaques in younger animals (Nystrom et al. The method employed in this thesis does not, unfortunately, have the temporal resolution to explore this possibility. It is nevertheless a compelling notion, and with advances in in vivo imaging techniques, this issue can hopefully be further investigated in the near future. The three scenarios discussed are all possible ways how multiple close plaques could merge over time, but to fully understand the precise mechanism behind merging plaques more experiments are needed. Data with Differences between Young and Older Mice There were two sets of data in this thesis where there were clear differences in shorter and longer incubation time groups. However, the differences in the plaque development between these groups are most likely due to technical artefacts as discussed below. The two older groups – 1 month and 4 months were not significantly different from chance levels. To explain this, it is important to keep in mind that the older groups have a higher plaque density than the younger group and this even has a significant negative correlation to the chance of a new plaque being close to a pre-existing plaque. This seems a plausible explanation for the disparity between groups – a higher plaque density makes it more likely that plaques will deposit by chance in the vicinity of a pre-existing plaque. Moreover, if there are more plaques in the cortex, then the deposition becomes more ‘general’ and more random as the niches that were particularly conducive to plaque development are saturated. Another explanation for the discrepancy between the groups in the rotation data could be that in the older groups, the analysis underestimates the amount of close new plaques. If several new plaques formed over the longer time point, some of the later new plaques probably formed nearby the earlier new plaques. Therefore, the method used here, with only two ‘snap-shots’ of plaque development, would not discern all the plaques that developed close to a pre-existing plaque and thereby underestimating the amount of close new plaques. Secondly, the older groups have larger plaques than the younger groups (Figure 16). The large plaques often had large diffuse halos surrounding the initial Methoxy X04 positive core. This could mean that subsequent plaques that formed very close to pre existing plaques would have been engulfed by the large plaque and would be counted as a single, multicored plaque (Figure 30). Thus, these new close plaques would not be counted as new and therefore the real amount of close new plaques in the longer time point groups was underestimated. Thirdly, we cannot rule out the possibility that Methoxy-X04 continues to label plaques after the injection and binds to new plaques, which would then not count as new plaques. Any, or a mixture of all three explanations would lead to an underestimation of new plaques in later time points and therefore a bias in the rotation data for the older groups. The second data set with discrepancies between age groups was the analysis of the exact distances between new plaques and their close pre-existing plaque neighbours (Figure 26). In 73 this data set, the data from the younger animals behaving differently from the two older groups: the younger animals show a peak between 5 and 15 µm, followed by a drop to a steady plateau at 20-25 µm, whereas the two older groups show most of their new plaques 20-25 µm away (Figure 26). Again, because of the increase in larger plaques in the older animals, this could obscure any very close new plaques, and therefore the older groups show very few very close (5-15 µm) new plaques. The younger animals have very few large plaques and so very close new plaques are not obscured and are still apparent. If one were to take out the very close distance groups, the plateau phases look very similar. The staining artefacts discussed are likely explanations for the discrepancies seen in the two data sets. Further analysis with shorter incubation times might definitively address these issues. A -plaque Associated Therapeutic Strategies the study of plaque formation and development is important for the advance of new, disease modifying treatment strategies; many therapeutics in development are based on preventing the formation of plaques, or removing the aggregated A that has already deposited (Citron, 2010). Whether this would prevent further plaque formation once the disease has started and rescue the disease pathology requires detailed knowledge of the influences on A deposition. Another strategy is to promote aggregation, so that A quickly aggregates to amyloid fibrils and thereby also avoids the toxic oligomer stage – this would create more plaques, and so knowledge of how they form would be very useful for this line of therapy. However, as postulated by (Selkoe, 2011), plaques may only ‘trap’ oligomeric A up to a certain saturation level. Thereafter, once the brain is full of plaques, they may actually act as reservoirs to store A oligomers and 74 increase toxicity. By targeting A, antibodies reduce the amount of A available and thereby reduce the formation of plaques. Immunotherapy against A is thought to reduce plaques by one or more of three mechanisms (Citron, 2010). Secondly, the antibodies themselves may directly resolve the plaque material, but due to the low penetrance of antibodies (just 0. Thirdly, peripheral antibodies could capture A, thereby acting as a ‘peripheral sink’ and reducing the A concentration in the brain parenchyma and clearing plaques in that way (DeMattos et al. This thesis expands knowledge of plaque deposition and formation and may help understand plaque clearing strategies better and target them more effectively to plaque-forming niches. The clustering hypothesis describes how large plaques in particular can arise and the formation of large plaque is particularly interesting as they have been shown to have different properties compared with smaller plaques. An in vivo study in mice investigating oxidative stress in the neurons surrounding plaques found more oxidised neurites in the vicinity of larger plaques (Xie et al.
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