NMDAR-Mediated Calcium Transients Elicited by Glutamate Co-Release at Developing Inhibitory Synapses

Before hearing onset, the topographic organization of the inhibitory sound localization pathway from the medial nucleus of the trapezoid body (MNTB) to the lateral superior olive (LSO) is refined by means of synaptic silencing and strengthening. During this refinement period MNTB-LSO synapses not only release GABA and glycine but also release glutamate. This co-released glutamate can elicit postsynaptic currents that are predominantly mediated by NMDA receptors (NMDARs). To gain a better understanding of how glutamate contributes to synaptic signaling at developing MNTB-LSO inhibitory synapses, we investigated to what degree and under what conditions NMDARs contribute to postsynaptic calcium responses. Our results demonstrate that MNTB-LSO synapses can elicit compartmentalized calcium responses along aspiny LSO dendrites. These responses are significantly attenuated by the NMDAR antagonist APV. APV, however, had no effect on somatically recorded electrical postsynaptic responses, indicating little, if any, contribution of NMDARs to spike generation. NMDAR-mediated calcium responses were decreased when increasing extracellular magnesium concentrations to physiological levels indicating that MNTB-LSO synapses activate magnesium sensitive NMDAR on immature LSO dendrites. In Fura-2 AM loaded neurons, blocking GABAA and glycine receptors increased NMDAR contribution to somatic calcium responses suggesting that GABA and glycine, perhaps by shunting backpropagating action potentials, decrease the level of NMDAR activation under strong stimulus conditions

A study in the elements of rapport

Thesis (M.S.)--Boston University, 1950. This item was digitized by the Internet Archive

A Game-Theoretical Winner and Loser Model of Dominance Hierarchy Formation

Many animals spend large parts of their lives in groups. Within such groups, they need to find efficient ways of dividing available resources between them. This is often achieved by means of a dominance hierarchy, which in its most extreme linear form allocates a strict priority order to the individuals. Once a hierarchy is formed, it is often stable over long periods, but the formation of hierarchies among individuals with little or no knowledge of each other can involve aggressive contests. The outcome of such contests can have significant effects on later contests, with previous winners more likely to win (winner effects) and previous losers more likely to lose (loser effects). This scenario has been modelled by a number of authors, in particular by Dugatkin. In his model, individuals engage in aggressive contests if the assessment of their fighting ability relative to their opponent is above a threshold [Formula: see text]. Here we present a model where each individual can choose its own value [Formula: see text]. This enables us to address questions such as how aggressive should individuals be in order to take up one of the first places in the hierarchy? We find that a unique strategy evolves, as opposed to a mixture of strategies. Thus, in any scenario there exists a unique best level of aggression, and individuals should not switch between strategies. We find that for optimal strategy choice, the hierarchy forms quickly, after which there are no mutually aggressive contests

Modelling Dominance Hierarchies Under Winner and Loser Effects

Animals that live in groups commonly form themselves into dominance hierarchies which are used to allocate important resources such as access to mating opportunities and food. In this paper, we develop a model of dominance hierarchy formation based upon the concept of winner and loser effects using a simulation-based model and consider the linearity of our hierarchy using existing and new statistical measures. Two models are analysed: when each individual in a group does not know the real ability of their opponents to win a fight and when they can estimate their opponents' ability every time they fight. This estimation may be accurate or fall within an error bound. For both models, we investigate if we can achieve hierarchy linearity, and if so, when it is established. We are particularly interested in the question of how many fights are necessary to establish a dominance hierarchy

Mice Lacking the Alpha9 Subunit of the Nicotinic Acetylcholine Receptor Exhibit Deficits in Frequency Difference Limens and Sound Localization

Sound processing in the cochlea is modulated by cholinergic efferent axons arising from medial olivocochlear neurons in the brainstem. These axons contact outer hair cells in the mature cochlea and inner hair cells during development and activate nicotinic acetylcholine receptors composed of α9 and α10 subunits. The α9 subunit is necessary for mediating the effects of acetylcholine on hair cells as genetic deletion of the α9 subunit results in functional cholinergic de-efferentation of the cochlea. Cholinergic modulation of spontaneous cochlear activity before hearing onset is important for the maturation of central auditory circuits. In α9KO mice, the developmental refinement of inhibitory afferents to the lateral superior olive is disturbed, resulting in decreased tonotopic organization of this sound localization nucleus. In this study, we used behavioral tests to investigate whether the circuit anomalies in α9KO mice correlate with sound localization or sound frequency processing. Using a conditioned lick suppression task to measure sound localization, we found that three out of four α9KO mice showed impaired minimum audible angles. Using a prepulse inhibition of the acoustic startle response paradigm, we found that the ability of α9KO mice to detect sound frequency changes was impaired, whereas their ability to detect sound intensity changes was not. These results demonstrate that cholinergic, nicotinic α9 subunit mediated transmission in the developing cochlear plays an important role in the maturation of hearing

Ten simple rules for principled simulation modelling

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The Genetic Foundations of Attitude Formation: The Case of Left-Right Political Orientations

Kandler C, Bell E, Shikishima C, Yamagata S, Riemann R. The Genetic Foundations of Attitude Formation: The Case of Left-Right Political Orientations. In: R. A. S, S. M. K, eds. Emerging Trends in the Social and Behavioral Sciences: Interdisciplinary Directions. In Press.Since the pioneering work of Eaves and Eysenck (1974) appeared in Nature some 40 years ago,psychologists, sociologists, political scientists, and behavioral geneticists have investigated the effects of nature and nurture on the formation of social attitudes. It has consistently been found that manifestations of social attitudes (i.e., preferences, values, and beliefs pertaining to things like politics, religion, the treatment of ingroups and outgroups, etc.) are genetically influenced. More recently, researchers have focused their efforts on the psycho-physiological pathways between gene activity and attitudes. In particular, a broad body of research examines how personality traits may be a link between genetic factors and political orientations. The latter are typically treated as either a single left-right dimension or divided into two core aspects: resistance to change/authoritarian conservatism and acceptance of inequality/social dominance orientation. In this article, we provide an overview of this research, present some findings from our recent international behavioral genetic study on the topic, and identify key issues for future research. We suggest that future studies treat attitude formation as a complex process in which genetic factors and the psycho-physiological phenomena that stem from them are affected by the surrounding social environment and culture. Such research will require: (1) international study designs capturing individual and cultural levels of variation; and: (2) interdisciplinary collaboration among scientists and researchers in various fields of study such as genetics, psychology, sociology, political science, neuroscience, and human biology

A generative inference framework for analysing patterns of cultural change in sparse population data with evidence for fashion trends in LBK culture

Cultural change can be quantified by temporal changes in frequency of different cultural artefacts and it is a central question to identify what underlying cultural transmission processes could have caused the observed frequency changes. Observed changes, however, often describe the dynamics in samples of the population of artefacts, whereas transmission processes act on the whole population. Here we develop a modelling framework aimed at addressing this inference problem. To do so, we firstly generate population structures from which the observed sample could have been drawn randomly and then determine theoretical samples at a later time t2 produced under the assumption that changes in frequencies are caused by a specific transmission process. Thereby we also account for the potential effect of time-averaging processes in the generation of the observed sample. Subsequent statistical comparisons (e.g. using Bayesian inference) of the theoretical and observed samples at t2 can establish which processes could have produced the observed frequency data. In this way, we infer underlying transmission processes directly from available data without any equilibrium assumption. We apply this framework to a dataset describing pottery from settlements of some of the first farmers in Europe (the LBK culture) and conclude that the observed frequency dynamic of different types of decorated pottery is consistent with age-dependent selection, a preference for 'young' pottery types which is potentially indicative of fashion trends

New particle formation and sub-10nm size distribution measurements during the A-LIFE field experiment in Paphos, Cyprus

Atmospheric particle size distributions were measured in Paphos, Cyprus, during the A-LIFE (absorbing aerosol layers in a changing climate: ageing, lifetime and dynamics) field experiment from 3 to 30 April 2017. The newly developed differential mobility analyser train (DMAtrain) was deployed for the first time in an atmospheric environment for the direct measurement of the nucleation mode size range between 1.8 and 10 nm diameter. The DMA-train set-up consists of seven size channels, of which five are set to fixed particle mobility diameters and two additional diameters are obtained by alternating voltage settings in one DMA every 10 s. In combination with a conventional mobility particle size spectrometer (MPSS) and an aerodynamic particle sizer (APS) the complete atmospheric aerosol size distribution from 1.8 nm to 10 μ m was covered. The focus of the A-LIFE study was to characterize new particle formation (NPF) in the eastern Mediterranean region at a measurement site with strong local pollution sources. The nearby Paphos airport was found to be a large emission source for nucleation mode particles, and we analysed the size distribution of the airport emission plumes at approximately 500 m from the main runway. The analysis yielded nine NPF events in 27 measurement days from the combined analysis of the DMAtrain, MPSS and trace gas monitors. Growth rate calculations were performed, and a size dependency of the initial growth rate (< 10 nm) was observed for one event case. Fast changes of the sub-10 nm size distribution on a timescale of a few minutes were captured by the DMA-train measurement during early particle growth and are discussed in a second event case. In two cases, particle formation and growth were detected in the nucleation mode size range which did not exceed the 10 nm threshold. This finding implies that NPF likely occurs more frequently than estimated from studies where the lower nanometre size regime is not covered by the size distribution measurements. © 2020 Author(s)