Global Metabolic Responses to Salt Stress in Fifteen Species.

Cells constantly adapt to unpredictably changing extracellular solute concentrations. A cornerstone of the cellular osmotic stress response is the metabolic supply of energy and building blocks to mount appropriate defenses. Yet, the extent to which osmotic stress impinges on the metabolic network remains largely unknown.

Circuits that innervate excitatory-inhibitory cells in the inferior colliculus obtained with in vivo whole cell recordings.

Neurons excited by stimulation of one ear and suppressed by the other, called excitatory/inhibitory (EI) neurons, are sensitive to interaural intensity disparities, the cues animals use to localize high frequencies. EI neurons are first formed in lateral superior olive, which then sends excitatory projections to the dorsal nucleus of the lateral lemniscus and the inferior colliculus (IC), both of which contain large populations of EI cells. We evaluate herein the inputs that innervate EI cells in the IC of Mexican free-tailed bats (Tadarida brasilensis mexicana) with in vivo whole-cell recordings from which we derived excitatory and inhibitory conductances.

The dominant role of inhibition in creating response selectivities for communication calls in the brainstem auditory system.

This review is concerned with how communication calls are processed and represented by populations of neurons in both the inferior colliculus (IC), the auditory midbrain nucleus, and the dorsal nucleus of the lateral lemniscus (DNLL), the nucleus just caudal to the IC. The review has five sections where focus in each section is on inhibition and its role in shaping response selectivity for communication calls. In the first section, the lack of response selectivity for calls in DNLL neurons is presented and discusses why inhibition plays virtually no role in shaping selectivity.

Inhibition shapes response selectivity in the inferior colliculus by gain modulation.

Pharmacological block of inhibition is often used to determine if inhibition contributes to spike selectivity, in which a preferred stimulus evokes more spikes than a null stimulus. When inhibitory block reduces spike selectivity, a common interpretation is that differences between the preferred- and null-evoked inhibitions created the selectivity from less-selective excitatory inputs. In models based on empirical properties of cells from the inferior colliculus (IC) of awake bats, we show that inhibitory differences are not required.

Circuits for processing dynamic interaural intensity disparities in the inferior colliculus.

Interaural intensity disparities (IIDs), the cues all animals use to localize high frequency sounds, are initially processed in the lateral superior olive (LSO) by a subtractive process where inputs from one ear excite and inputs from the other ear inhibit LSO neurons. Such cells are called excitatory-inhibitory (EI) neurons and are prominent not only in the LSO but also in higher nuclei, which include the dorsal nucleus of the lateral lemniscus (DNLL) and inferior colliculus (IC). The IC is of particular interest since its EI cells receive diverse innervation patterns from a large number of lower nuclei, which include the DNLLs and LSOs, and thus comprise a population with diverse binaural properties.

Selectivity for spectral motion as a neural computation for encoding natural communication signals in bat inferior colliculus.

This study examines the neural computations performed by neurons in the auditory system to be selective for the direction and velocity of signals sweeping upward or downward in frequency, termed spectral motion. We show that neurons in the auditory midbrain of Mexican free-tailed bats encode multiple spectrotemporal features of natural communication sounds. These features to which each neuron is tuned are nonlinearly combined to produce selectivity for spectral motion cues present in their conspecific calls, such as direction and velocity.

It's about time: how input timing is used and not used to create emergent properties in the auditory system.

The hypothesis for directional selectivity of frequency modulations (FMs) invokes a mechanism with an honored tradition in sensory neurobiology, the relative timing of excitation and inhibition. The proposal is that the timing disparity is created by asymmetrical locations of excitatory tuning and inhibitory sidebands. Thus, cells in which the inhibitory sidebands are tuned to frequencies lower than the excitatory tuning are selective for downward sweeping FMs, because frequencies first generate excitation followed by inhibition.

Discriminating among complex signals: the roles of inhibition for creating response selectivities.

The review deals largely with studies from my laboratory that were prompted by conversations I had with Gerhard Neuweiler more than 15 years ago. The studies were conducted on bats and dealt with mechanisms that enable the population of neurons in the inferior colliculus (IC) to respond selectively to the variety of signals bats emit for both communication and echolocation. The first section is concerned with how neurons in the dorsal nucleus of the lateral lemniscus (DNLL), the nucleus ventral to the IC, respond to species-specific signals and how they compare to responses of IC neurons evoked by the same signals.

Intracellular recordings reveal novel features of neurons that code interaural intensity disparities in the inferior colliculus.

Many cells in the inferior colliculus (IC) are excited by contralateral and inhibited by ipsilateral stimulation and are thought to be important for sound localization. These excitatory-inhibitory (EI) cells comprise a diverse group, even though they exhibit a common binaural response property. Previous extracellular studies showed the diversity results from different circuits that generate the same EI property among the IC population, where some inherit the property from a lower nucleus, some are formed de novo in the IC, and others inherit EI features that are modified by inhibitory circuits.

The dominance of inhibition in the inferior colliculus.

Almost all of the processing that occurs in the various lower auditory nuclei converges upon a common target in the central nucleus of the inferior colliculus (ICc) thus making the ICc the nexus of the auditory system. A variety of new response properties are formed in the ICc through the interactions among the excitatory and inhibitory inputs that converge upon it. Here we review studies that illustrate the dominant role inhibition plays in the ICc.

Inhibitory projections from the ventral nucleus of the lateral lemniscus and superior paraolivary nucleus create directional selectivity of frequency modulations in the inferior colliculus: a comparison of bats with other mammals.

This review considers four auditory brainstem nuclear groups and shows how studies of both bats and other mammals have provided insights into their response properties and the impact of their convergence in the inferior colliculus (IC). The four groups are octopus cells in the cochlear nucleus, their connections with the ventral nucleus of the lateral lemniscus (VNLL) and the superior paraolivary nucleus (SPON), and the connections of the VNLL and SPON with the IC. The theme is that the response properties of neurons in the SPON and VNLL map closely onto the synaptic response features of a unique subpopulation of cells in the IC of bats whose inputs are dominated by inhibition.

Mechanisms underlying directional selectivity for frequency-modulated sweeps in the inferior colliculus revealed by in vivo whole-cell recordings.

Auditory neurons in the inferior colliculus (IC) show remarkable selectively in that they can distinguish between complex sounds that have identical spectral energy but different temporal structure, such as frequency modulations (FMs) that sweep either upward or downward. Extracellular recordings show that blocking inhibition locally reduces or eliminates response selectivity, suggesting that selectivity is created de novo in the IC, with inhibition playing a prominent role. However, these studies can only infer underlying mechanisms based on spike counts.

Versatility and stereotypy of free-tailed bat songs.

In mammals, complex songs are uncommon and few studies have examined song composition or the order of elements in songs, particularly with respect to regional and individual variation. In this study we examine how syllables and phrases are ordered and combined, ie "syntax", of the song of Tadarida brasiliensis, the Brazilian free-tailed bat. Specifically, we test whether phrase and song composition differ among individuals and between two regions, we determine variability across renditions within individuals, and test whether phrases are randomly ordered and combined.

Syllable acoustics, temporal patterns, and call composition vary with behavioral context in Mexican free-tailed bats.

Recent research has shown that some bat species have rich vocal repertoires with diverse syllable acoustics. Few studies, however, have compared vocalizations across different behavioral contexts or examined the temporal emission patterns of vocalizations. In this paper, a comprehensive examination of the vocal repertoire of Mexican free-tailed bats, T.

Whole cell recordings of intrinsic properties and sound-evoked responses from the inferior colliculus.

Response features of inferior colliculus (IC) neurons to both current injections and tone bursts were studied with in vivo whole cell recordings in awake Mexican free-tailed bats. Of 160 cells recorded, 95% displayed one of three general types of discharge patterns in response to the injection of positive current: 1) sustained discharges; 2) adapting discharges; and 3) onset-bursting discharges. Sustained neurons were the most common type (N=78), followed by onset-bursting (N=57).

Rethinking tuning: in vivo whole-cell recordings of the inferior colliculus in awake bats.

Tuning curves were recorded with patch electrodes from the inferior colliculus (IC) of awake bats to evaluate the tuning of the inputs to IC neurons, reflected in their synaptic tuning, compared with the tuning of their outputs, expressed in their discharge tuning. A number of unexpected features were revealed with whole-cell recordings. Among these was that most neurons responded to tones with inhibition and/or subthreshold excitation over a surprisingly broad frequency range.

Spectrotemporal receptive fields in the inferior colliculus revealing selectivity for spectral motion in conspecific vocalizations.

Frequency modulations are a prominent feature of animal vocalizations and human speech. Here we investigated how neurons in the inferior colliculus (IC) of Mexican free-tailed bats respond to the frequency-modulated (FM) direction and velocity of complex signals by extracting their spectrotemporal receptive fields (STRFs) using a family of upward- and downward-moving ripple stimuli. STRFs were obtained in more than half of the cells that were sampled.

MDA improvement technique for lung counter measurements of uranium workers.

A practical and simple method was employed to improve the minimum detectable activity (MDA) for lung counting measurements by summing several accumulated spectra. The method was checked for natural uranium, which produces peaks due to photon energies of 63.3, 92.

Inhibiting the inhibition: a neuronal network for sound localization in reverberant environments.

The precedence effect describes the phenomenon whereby echoes are spatially fused to the location of an initial sound by selectively suppressing the directional information of lagging sounds (echo suppression). Echo suppression is a prerequisite for faithful sound localization in natural environments but can break down depending on the behavioral context. To date, the neural mechanisms that suppress echo directional information without suppressing the perception of echoes themselves are not understood.

Malignant mixed Müllerian tumor with heterologous component arising in the fallopian tube--a case report.

Primary malignant mixed Müllerian tumors (MMMTs) of the fallopian tube are rarities in gynecologic oncology with only 26 cases of MMMTs with a heterologous component reported thus far. We report a case of FIGO Stage II primary MMMT of the fallopian tube with a heterologous tumor portion in an 80-year-old woman presenting with abdominal discomfort at the time of primary diagnosis. After performance of total abdominal hysterectomy, bilateral salpingo-oophorectomy and omentectomy follow-up examination three months postoperatively did not show signs of disease recurrence.

Salt fluoridation in Central and Eastern Europe.

For decades Central European countries have been interested in preventive dentistry. Water fluoridation played a major role in the former German Democratic and Czechoslovak Republics and a minor one in Poland. These schemes were abandoned after 1989.

Differing roles of inhibition in hierarchical processing of species-specific calls in auditory brainstem nuclei.

Here we report on response properties and the roles of inhibition in three brain stem nuclei of Mexican-free tailed bats: the inferior colliculus (IC), the dorsal nucleus of the lateral lemniscus (DNLL) and the intermediate nucleus of the lateral lemniscus (INLL). In each nucleus, we documented the response properties evoked by both tonal and species-specific signals and evaluated the same features when inhibition was blocked. There are three main findings.

Serotonin shifts first-spike latencies of inferior colliculus neurons.

Many studies of neuromodulators have focused on changes in the magnitudes of neural responses, but fewer studies have examined neuromodulator effects on response latency. Across sensory systems, response latency is important for encoding not only the temporal structure but also the identity of stimuli. In the auditory system, latency is a fundamental response property that varies with many features of sound, including intensity, frequency, and duration.

Serotonin modulates responses to species-specific vocalizations in the inferior colliculus.

Neuromodulators such as serotonin are capable of altering the neural processing of stimuli across many sensory modalities. In the inferior colliculus, a major midbrain auditory gateway, serotonin alters the way that individual neurons respond to simple tone bursts and linear frequency modulated sweeps. The effects of serotonin are complex, and vary among neurons.