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Auditory nerve
Published in Stanley A. Gelfand, Hearing, 2017
Various stimuli are used to provide different kinds of information about neural coding. Clicks (at least ideally) are discrete and instantaneous in time, with energy distributed equally throughout the frequency range. On the other hand, pure tones (also ideally) extend indefinitely in time, but are discrete in frequency. Thus, click stimuli lend themselves to the study of the temporal characteristics of the discharge pattern, while sinusoids can be used to study frequency-related aspects. Tone bursts can be used to investigate both frequency and temporal characteristics, since they are similar to clicks in their duration and to tones in their frequency specificity (Kiang, 1975). One should remember, however, that a tone burst is a compromise between the two extremes, so that it is really less discrete in time than a click and less discrete in frequency than a pure tone.
Integrative Synchronization Mechanisms and Models in the Cognitive Neurosciences
Published in Harald Maurer, Cognitive Science, 2021
The first part of this chapter provides a brief overview of the experimental methods and techniques in the cognitive neurosciences (chap. 4.1). The methodological principles and schemes of neural coding are then discussed (chap. 4.2), in particular, the schemes of temporal and population coding on which the temporal synchronization hypothesis is based. According to this hypothesis, precise temporal correlations between the impulses of neurons and stimulus-dependent temporal synchronizations of the coherent activity of neuronal populations contribute to solving the general binding problem. After the general binding problem has been explained (chap. 4.3), the most important empirical-experimental models in perception and cognitive neuropsychology, in medical neurophysiology and in cognitive neurobiology are presented, focusing in paticular on dynamic binding models. This means, that those approaches that assume temporal integrative synchronization mechanisms for solving the binding problem (by means of the temporal synchronization of neuronal phase activity of a population of neurons) are presented. This is based on the dynamic, self-organizing processes in the corresponding neural networks. Finally, feature binding in visual perception by means of the integrative neural synchronization mechanisms is discussed in more detail. This is done with reference to the Binding-by-Synchrony Hypothesis put forward by W. Singer, A.K. Engel and P. König et al. This hypothesis thematizes the binding problem with reference to visual information processing in the context of integrative synchronization mechanisms in visual scene analysis (chap. 4.4).
Advances in Neuroscience, Not Devices, Will Determine the Effectiveness of Visual Prostheses
Published in Seminars in Ophthalmology, 2021
Bardia Abbasi, Joseph F. Rizzo
Despite our limitations in both engineering and knowledge of neural coding, it might seem surprising that current devices have had any meaningful success. Perhaps neural plasticity—the ability of the brain to modify its function based upon learning or adaptation—enables the brain to extract value from suboptimal stimuli. The best evidence that neural plasticity may provide such leverage can be gleaned from recipients of cochlear implants, who often initially report metallic, monotonous, and inscrutable sounds, but can frequently hear well enough to hold telephone conversations with long-term rehabilitative training (often up to 1 year in duration).102 In contrast, despite restoration of normal optics in patients treated for early vision loss from corneal injury or congenital cataracts, deficits in complex visual processing (such as identification of three-dimensional forms or gender classification) can persist.103–105 Some such patients have even found their restored visual input frightening or disappointing.105,106 Clearly, the success of any visual prosthetic will depend upon central reorganization following prolonged blindness.
Influence of subcortical auditory processing and cognitive measures on cocktail party listening in younger and older adults
Published in International Journal of Audiology, 2019
Chandni Jain, Vikas Mysore Dwarakanath, Amritha G
Brainstem response to complex auditory stimuli such as speech (syllable) has two classes of separate time-locked responses, transient and sustained which mimic the acoustic characteristics of the speech signal (Skoe and Kraus 2010). It has shown to provide the information regarding the auditory processing of speech signal at the subcortical level; however, based on the constraints of the phase locking properties of the brainstem, the neural coding would be limited to the second formant frequency (F2) of the signal. The sustained portion of speech auditory brainstem response (speech ABR) has shown to provide information regarding the neural response to the harmonic portion of the stimuli (periodic in nature) namely Frequency Following Response (FFR) which reflects the neural phase locking of the stimulus. Here, magnitude and timing measures become important wherein the timing measures would provide information on how the brainstem synchronously responds to the acoustic stimulus. Also, the temporal measures such as the stimulus-response correlations and quiet to noise correlations would provide information on how precisely the response mimics the stimulus and the effect of background noise on response waveform (Russo et al. 2004).
Speech perception in noise, gap detection and amplitude modulation detection in suspected hidden hearing loss
Published in Hearing, Balance and Communication, 2021
Srikar Vijayasarathy, Meghana Mohan, Pratibha Nagalakshmi, Animesh Barman
Kumar et al. [24] hypothesized that synaptopathy might lead to poorer phase-locking and reduced synchrony in auditory nerve firing. Loss of ribbon low spontaneous rate neuron synapses critical for phase locking [12,19] may have a deleterious effect on temporal fidelity of neural encoding. Noise-induced demyelination may be another disrupting factor in the mix [35]. Reduced phase-locking and lower envelope following response amplitudes have been reported in mice exposed to neuropathic noise [20]. Skoe and Tufts [35] not only reported delayed ABR latencies for waves I, III and V, but also showed delayed I–V interpeak latencies at higher repetition rates in the higher noise exposure group.