A growing body of research details spatial representation in bat hippocampus, and experiments have yet to explore hippocampal neuron responses to sonar signals in animals that rely on echolocation for spatial navigati...
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A growing body of research details spatial representation in bat hippocampus, and experiments have yet to explore hippocampal neuron responses to sonar signals in animals that rely on echolocation for spatial navigation. To bridge this gap, we investigated bat hippocampal responses to natural echolocation sounds in a non-spatial context. In this experiment, we recorded from CA1 of the hippocampus of three awake bats that listened passively to single echolocation calls, call-echo pairs, or natural echolocation sequences. Our data analysis identified a subset of neurons showing response selectivity to the duration of single echolocation calls. However, the sampled population of CA1 neurons did not respond selectively to call-echo delay, a stimulus dimension posited to simulate target distance in recordings from auditory brain regions of bats. A population analysis revealed ensemble coding of call duration and sequence identity. These findings open the door to many new investigations of auditory coding in the mammalian hippocampus.
Sensory systems process stimuli that greatly vary in intensity and complexity. To maintain efficient information transmission, neural systems need to adjust their properties to these different sensory contexts, yieldi...
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Sensory systems process stimuli that greatly vary in intensity and complexity. To maintain efficient information transmission, neural systems need to adjust their properties to these different sensory contexts, yielding adaptive or stimulus-dependent codes. Here, we demonstrated adaptive spectrotemporal tuning in a small neural network, i.e. the peripheral auditory system of the cricket. We found that tuning of cricket auditory neurons was sharper for complex multi-band than for simple single-band stimuli. Information theoretical considerations revealed that this sharpening improved information transmission by separating the neural representations of individual stimulus components. A network model inspired by the structure of the cricket auditory system suggested two putative mechanisms underlying this adaptive tuning: a saturating peripheral nonlinearity could change the spectral tuning, whereas broad feed-forward inhibition was able to reproduce the observed adaptive sharpening of temporal tuning. Our study revealed a surprisingly dynamic code usually found in more complex nervous systems and suggested that stimulus-dependent codes could be implemented using common neural computations.
This paper demonstrates a speech enhancement system based on an efficient auditory coding approach, coding of time-relative structure using spikes. The spike coding method can more compactly represent the non-stationa...
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ISBN:
(纸本)9781424423538
This paper demonstrates a speech enhancement system based on an efficient auditory coding approach, coding of time-relative structure using spikes. The spike coding method can more compactly represent the non-stationary characteristics of speech signals than the Fourier transform or wavelet transform. Enhancement is accomplished through the use of MMSE thresholding on the spike code. Experimental results show that compared with the spectral domain logSTSA filter, both the subjective spectrogram evaluation and objective SSNR improvement for the proposed approach is better in suppressing noise in high noise situations, with fewer musical artifacts.
作者：
Maney, Donna L.Pinaud, RaphaelUniv Oklahoma
Hlth Sci Ctr Dept Physiol BRC W 975 NE 10th StRoom 1309B Oklahoma City OK 73104 USA Emory Univ
Dept Psychol Atlanta GA 30322 USA Univ Oklahoma
Hlth Sci Ctr Dept Geriatr Med Reynolds Oklahoma Ctr Aging Oklahoma City OK 73104 USA
The steroid hormone estradiol plays an important role in reproductive development and behavior and modulates a wide array of physiological and cognitive processes. Recently, reports from several research groups have c...
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The steroid hormone estradiol plays an important role in reproductive development and behavior and modulates a wide array of physiological and cognitive processes. Recently, reports from several research groups have converged to show that estradiol also powerfully modulates sensory processing, specifically, the physiology of central auditory circuits in songbirds. These investigators have discovered that (1) behaviorally-relevant auditory experience rapidly increases estradiol levels in the auditory forebrain;(2) estradiol instantaneously enhances the responsiveness and coding efficiency of auditory neurons;(3) these changes are mediated by a non-genomic effect of brain-generated estradiol on the strength of inhibitory neurotransmission;and (4) estradiol regulates biochemical cascades that induce the expression of genes involved in synaptic plasticity. Together, these findings have established estradiol as a central regulator of auditory function and intensified the need to consider brain-based mechanisms, in addition to peripheral organ dysfunction, in hearing pathologies associated with estrogen deficiency. (C) 2010 Elsevier Inc. All rights reserved.
Our previous work showed that action potentials (APs) fired in spiral ganglion (SG) neurons broaden gradually as a result of cumulative inactivation of the potassium current (I-K), or with the application of a tinnitu...
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Our previous work showed that action potentials (APs) fired in spiral ganglion (SG) neurons broaden gradually as a result of cumulative inactivation of the potassium current (I-K), or with the application of a tinnitus-inducing drug (quinine). These results led us to speculate that AP width could affect neurotransmission of the auditory nerve under both normal and pathological conditions. This study used both experimental and theoretical approaches to test this hypothesis. We first measured the effect of AP broadening on Ca2+ entry into SG neurons. The effect of pre-synaptic AP broadening on post-synaptic responses was then assessed using computer-simulations. Results showed that wider presynaptic APs augmented responses of all types of postsynaptic glutamatergic receptors mainly by amplifying responses of postsynaptic receptors whose locations were not well aligned with the presynaptic release sites. A cumulative inactivation of I-K in SG neurons significantly enhanced the responses of kainate receptors at all spike rates, while the augmentations for the alpha -amino-3-hydroxy-5-methylisoxazole-4 acid and N-methyl-D-aspartic acid receptors were most prominent below 100 spikes/s. These modeling results suggest that, in addition to the AP firing rate and timing, the width of APs could affect the neurotransmission of the auditory nerve under both normal and pathological conditions. (C) 2001 Elsevier Science B.V. All rights reserved.
There are many common problems in the use of non-verbal auditory warnings in the working environment. They are often too loud, too numerous, and they are frequently confusing. These problems have a range of consequenc...
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There are many common problems in the use of non-verbal auditory warnings in the working environment. They are often too loud, too numerous, and they are frequently confusing. These problems have a range of consequences, many of them serious. However, there now exist a number of guidelines and sets of experimental data that address these problems and provide fairly comprehensive solutions. In this article the underlying problems are highlighted, and the guidelines and research that have addressed the central issues of correct loudness levels and psychological appropriateness, particularly warning confusion and 'urgency mapping', are reviewed and evaluated. It is argued that a proper ergonomics approach to auditory warning design and implementation is not a luxury, but a necessity. A number of projects in which advanced, ergonomic auditory warning systems have been developed are described in detail, and some new research questions are proposed.
Monopolar macroelectrodes were implanted in the dorsal cochlear nucleus and inferior colliculus of four chronic adult cats and the frequency of neuronal discharge was analyzed during stimulation with human voices. The...
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Monopolar macroelectrodes were implanted in the dorsal cochlear nucleus and inferior colliculus of four chronic adult cats and the frequency of neuronal discharge was analyzed during stimulation with human voices. The data showed that the unique patterns of neuronal discharge generated by a particular word tended to be very consistent even when the word was presented by a different voice such as a female rather than a male voice. This discharge pattern was found to be highly reliable between cats. In addition, identifying characteristics of each pattern were found to be very similar at both the cochlear nucleus and at the level of the inferior colliculus. Recordings from the geniculate body or auditory cortex did not exhibit the discharge characteristics found at lower auditory nuclei. The neuronal discharge patterns elicited by a particular stimulus may represent a mechanism whereby identical verbal stimuli are recognizable even though presented by different voices with varying input frequency.
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