Synaptic Inhibition Influences the Temporal Coding Properties of Medial Superior Olivary Neurons. An in vitro Study

The medial superior olive (MSO) functions as a coincidence detector for interaural time and phase differences by integrating excitatory synaptic inputs. Recent studies demonstrating glycinergic projections to MSO neurons suggest that coincidence detection results from the temporal integration of both EPSPs and IPSPs. We examined the impact of synaptic inhibition on the temporal coding properties of gerbil MSO neurons in vitro with intracellular recordings and electrical stimulation. For low-level bilateral electric stimulation, the EPSPs summated to produce an action potential in 73% of MSO neurons if they occurred within 50–500 microseconds of one another. Synaptic inhibition became more prominent at higher stimulus amplitudes in 73% of MSO neurons, and could block an evoked action potential if the stimuli to each pathway were delivered within 250 microseconds of one another. The glycine receptor antagonist strychnine influenced the response to simulated interaural time differences. In the presence of strychnine, interstimulus delays that originally resulted in full action potential suppression were sufficient to evoke an action potential. For trains of stimuli, as stimulus intensity increased (spatial summation), or as stimulus repetition rate increased to 100–500 Hz (temporal summation), there was a decrease in the number of stimulus pulses that evoked an action potential. In the presence of strychnine, MSO neurons generated a greater percentage of action potentials to the stimulus trains. When stimulus trains were delivered bilaterally, MSO neurons fired a greater number of action potentials at specific interstimulus time differences, and were selectively inhibited at other time differences.(ABSTRACT TRUNCATED AT 250 WORDS)</jats:p

Spiking Neurons Learning Phase Delays

Time differences between the two ears are an important cue for animals to azimuthally locate a sound source. The first binaural brainstem nucleus, in mammals the medial superior olive, is generally believed to perform the necessary computations. Its cells are sensitive to variations of interaural time differences of about 10 μs. The classical explanation of such a neuronal time-difference tuning is based on the physical concept of delay lines. Recent data, however, are inconsistent with a temporal delay and rather favor a phase delay. By means of a biophysical model we show how spike-timing-dependent synaptic learning explains precise interplay of excitation and inhibition and, hence, accounts for a physical realization of a phase delay

Runaway electrification of friable self-replicating granular matter

We establish that the nonlinear dynamics of collisions between particles favors the charging of a insulating, friable, self-replicating granular material that undergoes nucleation, growth, and fission processes; we demonstrate with a minimal dynamical model that secondary nucleation produces a positive feedback in an electrification mechanism that leads to runaway charging. We discuss ice as an example of such a self-replicating granular material: We confirm with laboratory experiments in which we grow ice from the vapor phase in situ within an environmental scanning electron microscope that charging causes fast-growing and easily breakable palm-like structures to form, which when broken off may form secondary nuclei. We propose that thunderstorms, both terrestrial and on other planets, and lightning in the solar nebula are instances of such runaway charging arising from this nonlinear dynamics in self-replicating granular matter

Trapping and observing single atoms in the dark

A single atom strongly coupled to a cavity mode is stored by three-dimensional confinement in blue-detuned cavity modes of different longitudinal and transverse order. The vanishing light intensity at the trap center reduces the light shift of all atomic energy levels. This is exploited to detect a single atom by means of a dispersive measurement with 95% confidence in 0.010 ms, limited by the photon-detection efficiency. As the atom switches resonant cavity transmission into cavity reflection, the atom can be detected while scattering about one photon

Smart Emission - Building a Spatial Data Infrastructure for an Environmental Citizen Sensor Network

Item does not contain fulltextSmart Emission is a citizen sensor network using low-cost sensors that enables citizens to gather data about environmental quality, like air quality, noise load, vibrations, light intensities and heat stress. This paper introduces the design and development of the data infrastructure for the Smart Emission initiative and discusses challenges for the future. The Spatial Data Infrastructure (SDI) is open and accessible on the Internet using open geospatial standards and (Web-) client applications. Smart Emission as a citizen sensor network offers several possibilities for heterogonous applications, from health determination to spatial planning purposes, environmental monitoring for sustainable traffic management, climate adaptation in cities and city planning.Geospatial Sensor Webs Conference 2016 (GSW 2016), 29 augustus 201

Solvates, salts, and cocrystals : a proposal for a feasible classification system

The design of pharmaceutical cocrystals has initiated widespread debate on the classification of cocrystals. Current attempts to classify multicomponent crystals suffer from ambiguity, which has led to inconsistent definitions for cocrystals and for multicomponent crystals in general. Inspired by the work of Aitipamula et al. (Cryst. Growth Des. 2012, 12, 2147-2152), we present a feasible classification system for all multicomponent crystals. The present classification enables us to analyze and classify multicomponent crystal structures present in the Cambridge Structural Database (CSD). This reveals that all seven classes proposed are relevant in terms of frequency of occurrence. Lists of CSD refcodes for all classes are provided. We identified over 5000 cocrystals in the CSD, as well as over 12 000 crystals with more than two components. This illustrates that the possibilities for alternative drug formulations can be increased significantly by considering more than two components in drug design

Glycinergic inhibition tunes coincidence detection in the auditory brainstem

Neurons in the medial superior olive (MSO) detect microsecond differences in the arrival time of sounds between the ears (interaural time differences or ITDs),a crucial binaural cue for sound localization. Synaptic inhibition has been implicated in tuning ITD sensitivity, but the cellular mechanisms underlying its influence on coincidence detection are debated. Here we determine the impact of inhibition on coincidence detection in adult Mongolian gerbil MSO brain slices by testing precise temporal integration of measured synaptic responses using conductance-clamp. We find that inhibition dynamically shifts the peak timing of excitation, depending on its relative arrival time, which in turn modulates the timing of best coincidence detection. Inhibitory control of coincidence detection timing is consistent with the diversity of ITD functions observed in vivo and is robust under physiologically relevant conditions. Our results provide strong evidence that temporal interactions between excitation and inhibition on microsecond timescales are critical for binaural processing

The relationship between CSF tau markers, hippocampal volume and delayed primacy performance in cognitively intact elderly individuals.

BACKGROUND: Primacy performance in recall has been shown to predict cognitive decline in cognitively intact elderly, and conversion from mild cognitive impairment (MCI) to Alzheimer's disease (AD). Delayed primacy performance, but not delayed non-primacy performance, has been shown to be associated with hippocampal volume in cognitively intact older individuals. Since presence of neurofibrillary tangles is an early sign of AD-related pathology, we set out to test whether cerebrospinal fluid (CSF) levels of tau had an effect on delayed primacy performance, while controlling for hippocampal volume and CSF Aβ 1-42 levels. METHODS: Forty-seven individuals, 60 or older and cognitively intact, underwent a multi-session study including lumbar puncture, an MRI scan of the head and memory testing. RESULTS: Our regression analyses show that CSF levels of hyperphosphorylated (P) tau are only associated with reduced delayed primacy performance when hippocampal volumes are smaller. CONCLUSION: Our findings suggest that hippocampal size may play a protective role against the negative effects of P tau on memory