Acquisition of multi-verb predicates in Nungon

Studies of the acquisition of verbs tend to focus on one-verb predicates of the prevalent English type. But in hundreds of languages around the world, multi-verb predicates like serial verb constructions are widely used. It could be reasoned that children should begin producing simple, single-verb predicates before they are able to produce multi-verb predicates. But alternatively, many multi-verb predicates are idiomatic and could, as chunks, lend themselves to holophrastic acquisition by small children. This article examines early productions of multi-verb predicates in the speech of three children (aged 1;1–2;4, 2;1–3;3, and 2;10–3;3) acquiring the Papuan language Nungon, comparing patterns there with productions in the child-directed speech of their parents, and with the children’s productions of simple, one-verb predicates. The study’s youngest child never produces multi-verb predicates in the study period, but the child studied for the widest age range produces them from age 2;4, when she has still not acquired productive use of all verbal inflections, and both older children show proportionally increasing trends in multi-verb predicate use. Semantically, the earliest multi-verb predicates can be analyzed as describing multidimensional unitary events, with this expanding to events that can be divided into multiple distinct components at later ages. Delays in production of certain other multi-verb predicate types that are robustly present in parental input at all ages cannot be linked to a single factor, but likely relate to a combination of increased phonological or morphological complexity and increased conceptual difficulty.

The Process of Revolutionary Protest: Development and Democracy in the Tunisian Revolution

Research on democratic revolution treats revolutionary protest, and revolutionary protest participation, as unitary events. This conceptualization is at odds with how 'revolutionary' protest often unfolds—protest does not begin life as democratic or revolutionary but grows in a process of positive feedback, incorporating new constituencies and generating new demands. Using an original protest event catalogue for the twenty-nine days of the Tunisian Revolution, alongside survey data, I show that the correlates of protest occurrence and participation change significantly during the uprising. The effect of economic development on protest diffusion reverses sign, while a commitment to democracy is a substantive predictor of protest participation only at its close. If protest is not revolutionary at its onset, I argue, theory should reflect this and be able to explain the endogenous emergence of democratic demands. In this understanding, the formation of protest coalitions becomes essential, rather than incidental, to democratic revolution.

Multiple Tests Based on a Gaussian Approximation of the Unitary Events Method with Delayed Coincidence Count

The unitary events (UE) method is one of the most popular and efficient methods used over the past decade to detect patterns of coincident joint spike activity among simultaneously recorded neurons. The detection of coincidences is usually based on binned coincidence count (Grün, 1996 ), which is known to be subject to loss in synchrony detection (Grün, Diesmann, Grammont, Riehle, & Aertsen, 1999 ). This defect has been corrected by the multiple shift coincidence count (Grün et al., 1999 ). The statistical properties of this count have not been further investigated until this work, the formula being more difficult to deal with than the original binned count. First, we propose a new notion of coincidence count, the delayed coincidence count, which is equal to the multiple shift coincidence count when discretized point processes are involved as models for the spike trains. Moreover, it generalizes this notion to nondiscretized point processes, allowing us to propose a new gaussian approximation of the count. Since unknown parameters are involved in the approximation, we perform a plug-in step, where unknown parameters are replaced by estimated ones, leading to a modification of the approximating distribution. Finally the method takes the multiplicity of the tests into account via a Benjamini and Hochberg approach (Benjamini & Hochberg, 1995 ), to guarantee a prescribed control of the false discovery rate. We compare our new method, MTGAUE (multiple tests based on a gaussian approximation of the unitary events) and the UE method proposed in Grün et al. ( 1999 ) over various simulations, showing that MTGAUE extends the validity of the previous method. In particular, MTGAUE is able to detect both profusion and lack of coincidences with respect to the independence case and is robust to changes in the underlying model. Furthermore MTGAUE is applied on real data.

Dynamics of Stimulus-Evoked Spike Timing Correlations in the Cat Lateral Geniculate Nucleus

Precisely synchronized neuronal activity has been commonly observed in the mammalian visual pathway. Spike timing correlations in the lateral geniculate nucleus (LGN) often take the form of phase synchronized oscillations in the high gamma frequency range. To study the relations between oscillatory activity, synchrony, and their time-dependent properties, we recorded activity from multiple single units in the cat LGN under stimulation by stationary spots of light. Autocorrelation analysis showed that approximately one third of the cells exhibited oscillatory firing with a mean frequency ∼80 Hz. Cross-correlation analysis showed that 30% of unit pairs showed significant synchronization, and 61% of these pairs consisted of synchronous oscillations. Cross-correlation analysis assumes that synchronous firing is stationary and maintained throughout the period of stimulation. We tested this assumption by applying unitary events analysis (UEA). We found that UEA was more sensitive to weak and transient synchrony than cross-correlation analysis and detected a higher incidence (49% of cell pairs) of significant synchrony (unitary events). In many unit pairs, the unitary events were optimally characterized at a bin width of 1 ms, indicating that neural synchrony has a high degree of temporal precision. We also found that approximately one half of the unit pairs showed nonstationary changes in synchrony that could not be predicted by the modulation of firing rates. Population statistics showed that the onset of synchrony between LGN cells occurred significantly later than that observed between retinal afferents and LGN cells. The synchrony detected among unit pairs recorded on separate tetrodes tended to be more transient and have a later onset than that observed between adjacent units. These findings show that stimulus-evoked synchronous activity within the LGN is often rhythmic, highly nonstationary, and modulated by endogenous processes that are not tightly correlated with firing rate.

Data-Driven Significance Estimation for Precise Spike Correlation

The mechanisms underlying neuronal coding and, in particular, the role of temporal spike coordination are hotly debated. However, this debate is often confounded by an implicit discussion about the use of appropriate analysis methods. To avoid incorrect interpretation of data, the analysis of simultaneous spike trains for precise spike correlation needs to be properly adjusted to the features of the experimental spike trains. In particular, nonstationarity of the firing of individual neurons in time or across trials, a spike train structure deviating from Poisson, or a co-occurrence of such features in parallel spike trains are potent generators of false positives. Problems can be avoided by including these features in the null hypothesis of the significance test. In this context, the use of surrogate data becomes increasingly important, because the complexity of the data typically prevents analytical solutions. This review provides an overview of the potential obstacles in the correlation analysis of parallel spike data and possible routes to overcome them. The discussion is illustrated at every stage of the argument by referring to a specific analysis tool (the Unitary Events method). The conclusions, however, are of a general nature and hold for other analysis techniques. Thorough testing and calibration of analysis tools and the impact of potentially erroneous preprocessing stages are emphasized.

Connexin Hemichannel Composition Determines the FGF-1–induced Membrane Permeability and Free [Ca2+]i Responses

Cell surface hemichannels (HCs) composed of different connexin (Cx) types are present in diverse cells and their possible role on FGF-1–induced cellular responses remains unknown. Here, we show that FGF-1 transiently (4–14 h, maximal at 7 h) increases the membrane permeability through HCs in HeLa cells expressing Cx43 or Cx45 under physiological extracellular Ca2+/Mg2+ concentrations. The effect does not occur in HeLa cells expressing HCs constituted of Cx26 or Cx43 with its C-terminus truncated at aa 257, or in parental nontransfected HeLa cells. The increase in membrane permeability is associated with a rise in HC levels at the cell surface and a proportional increase in HC unitary events. The response requires an early intracellular free Ca2+ concentration increase, activation of a p38 MAP kinase-dependent pathway, and a regulatory site of Cx subunit C-terminus. The FGF-1–induced rise in membrane permeability is also associated with a late increase in intracellular free Ca2+ concentration, suggesting that responsive HCs allow Ca2+ influx. The cell density of Cx26 and Cx43 HeLa transfectants cultured in serum-free medium was differentially affected by FGF-1. Thus, the FGF-1–induced cell permeabilization and derived consequences depend on the Cx composition of HCs.

Topological Modelling of Grammatical and Lexical Aspect in English

This paper stems from a broader research project entitled Analog-based Modelling of Meaning Representations in English (Skrzypczak 2006), and aims to present grammatical aspect and lexical aspect as two modes of encoding the temporal profiles within the conceptualisation of processes (terminologically, in Langackerian sense, imperfective and perfective processes, otherwise, variously labelled as stative and dynamic verbs, i. e. states vs. discrete ‘unitary’ events and nondiscrete ‘unbounded’ processes). It is assumed that aspect in both cases – as a process-profiling category – is analogous to the profiling of things and atemporal relations (in the sense of Langacker 1987, 1990, 2000), given the maximisation of the temporal domain in the characterisation of processes (perfective and imperfective, hence: dynamic and stative), and minimalisation of the temporal domain during the conceptualisation of things (conceptually independent entities) and atemporal relations (conceptually dependent atemporal configurations). The analogy between nouns and verbs in terms of ‘granularity’ has been so far variously addressed by Langacker (1990), Jackendoff (1991) and Talmy (2001), and also constitutes the core assumption in my research on topological modelling.

Central Synaptic Integration: Linear After All?

Unitary synaptic currents in hippocampus show small variability. Experimental evidence suggests that the neuron is endowed with mechanisms to reduce location-dependent differences in amplitude and time course of synaptic events, contributing to small variability. These mechanisms may allow the neuron to count individual quanta and thereby linearize integration of unitary events.