Author: Daryl Ebling DoanPublisher:
ISBN:
Category :
Languages : en
Pages : 182
Book Description
Coding of Sound Motion in the Rat Auditory Cortex
Encoding of Sound Shape in Rat Auditory Cortex
Author: Ahmad OsmanPublisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages :
Book Description
Mammals discriminate temporal “shape†cues in speech and other sounds but the underlying neural pathways and mechanisms remain a mystery. Shape cues include the rising and falling slopes and the duration of change in the sound envelope amplitude over time and are critical for sound perception. The auditory cortices are essential for behavioral discrimination of temporal cues and yet the neural mechanisms underlying this ability remain unknown. Primary (A1) and ventral non-primary auditory cortical fields (VAF SRAF) are physiologically and anatomically organized and specialized to represent distinct spectral and spatial cues in sound. The current study investigates cortical field differences for encoding envelope shape in sound. In the present study, we ask whether A1, VAF and SRAF could utilize spike rate, distinct temporal spiking patterns, including onset and sustained components, to discriminate sound shape. To address these questions we computed a discrimination index based on the spike distance metric. We find response durations and optimal time constants for discriminating sound shape increase in rank order with: A1
Encoding of Shape and Repetition Rate in the Rat Auditory Cortex
Author: Speech Sound Coding and Training-induced Plasticity in Primary Auditory Cortex
Author: Crystal Tasha EngineerPublisher:
ISBN:
Category : Auditory perception
Languages : en
Pages : 212
Book Description
It is important to understand how the human brain processes speech sounds in order to lead to perception. fMRI and EEG studies have shown that certain cortical regions are activated after hearing speech, but these techniques lack the temporal and spatial precision necessary to document the unique pattern of activation evoked by each speech sound. Previous studies have shown that the primary auditory cortex (A1) pattern of activity evoked in response to speech sounds is altered by the temporal features of the sound. In this study, we show that rats' (Rattus norvegicus) behavioral performance on consonant discrimination tasks is similar in key respects to human performance, and can be predicted from the spatiotemporal pattern of rat A1 activity when temporal information is maintained. When temporal information is ignored and the mean firing rate is used, behavioral performance cannot be predicted as accurately. We also document the ability of rats to categorize speech sounds by voicing or gender on the first day of training. This categorization ability is also predicted by the spatiotemporal pattern of A1 activity. Finally, we show that training on multiple speech discrimination tasks increases the proportion of neurons responding to low frequency tones, the threshold of A1 neurons, the response strength to tones, the receptive field size, and response latencies. Passive exposure to speech sounds increases the proportion of neurons responding to high frequency tones, and decreases the threshold of A1 neurons and response latencies. These results indicate that training on multiple speech tasks does not result in stimulus specific response enhancement in primary auditory cortex, but instead, results in generalized enhancement of untrained sounds following speech training. This result suggests that non-primary or higher cortical areas, as opposed to A1, may exhibit stimulus specificity after speech sound training.
Development of Complex Sound Representations in the Primary Auditory Cortex
Author: Michele Nerissa InsanallyPublisher:
ISBN:
Category :
Languages : en
Pages : 84
Book Description
Development of complex sound representations in the primary auditory cortex by Michele Nerissa Insanally Doctor of Philosophy in Neuroscience University of California, Berkeley Professor Shaowen Bao, PhD., Chair The brain has a tremendous ability to change as a result of experience; this property is known as plasticity. Our mastery of soccer, rhetoric, agriculture and instrumentation are all learned skills that require experience. While the brain is plastic throughout life, during early development, the brain demonstrates a heightened sensitivity to experience. This unique epoch during development in which the brain is particularly susceptible to change is called a critical period. During the critical period, sensory experience results in significant modifications in structure and function. The set of studies described in this dissertation aim to investigate how complex sound representation develops during the critical period in the rat primary auditory cortex. Previous examinations of the critical period in the auditory cortex have typically used simple tonal stimuli. Repeated exposure of rat pups to a tone, for instance, has been shown to selectively enlarge cortical representation of the tone and alter perceptual behaviors. However, probing cortical plasticity with a single-frequency tone might not reveal the full complexity and dynamics of critical period plasticity. After all, natural, biologically important sounds are generally complex with respect to their spectrotemporal properties. Natural sounds often have frequencies that vary in time and amplitude modulation. Psychophysical studies indicate that early experience of complex sounds has a profound impact on auditory perception and perceptual behaviors. Experience with speech, for instance, shapes language-specific phonemic perception, enhancing perceptual contrasts of native speech sounds and reducing perceptual contrasts of some foreign speech sounds. At the electrophysiological level, auditory cortical neurons preferentially respond to certain complex sounds, such as species-specific animal vocalizations. It is unclear how such selectivity for a complex sound emerges, and whether it is innate or shaped by early experience. In order to address this question, we exposed rat pups to a frequency-modulated (FM) sweep in different time windows during early development, and examined the effects of such sensory experience on sound representations in the primary auditory cortex (AI). We found that early exposure to an FM sound resulted in altered characteristic frequency representations and broadened spectral tuning in AI neurons. In contrast, later exposure to the same sound only led to greater selectivity for the sweep rate and direction of the experienced FM sound. These results indicate that cortical representations of different acoustic features are shaped by complex sounds in a series of distinct critical periods. Next, we confirmed this model of brain development in a set of experiments that examine how exposure to noise affects these various critical periods. We examined the influence of pulsed noise experience on the development of sound representations in AI. In naïve animals, FM sweep direction selectivity depends on the characteristic frequency (CF) of the neuron--low CF neurons tend to select for upward sweeps and high CF neurons for downward sweeps. Such a CF dependence was not observed in animals that had received weeklong exposure to pulsed noise in periods from postnatal day 8 (P8) to P15 or from P24 to P39. In addition, AI tonotopicity, tuning bandwidth, intensity threshold, tone-responsiveness, and sweep response magnitude were differentially affected by the noise experience depending on the exposure time windows. These results are consistent with previous findings of feature-dependent multiple sensitive periods. The different effects induced here by pulsed noise and previously by FM sweeps further indicate that plasticity in cortical complex sound representations is specific to the sensory input. Identifying how the developing brain processes sensory information provides a foundation for understanding more complex behaviors. These results advance our understanding of the neuronal mechanisms underlying sensory development and language learning. Specifically, they elucidate the age-dependent effects of complex sound exposure on spectral tuning and complex sound representation in the rat primary auditory cortex. In addition, they provide a foundation for subsequent studies investigating the neural basis of language development.
Cumulated Index Medicus
Author: Ecological Psychoacoustics
Author: John NeuhoffPublisher: BRILL
ISBN: 0080477445
Category : Psychology
Languages : en
Pages : 366
Book Description
"Ecological Psychoacoustics" outlines recent advances in dynamic, cognitive, and ecological investigations of auditory perception and ties this work to findings in more traditional areas of psychoacoustics. The book illuminates some of the converging evidence that is beginning to emerge from these traditionally divergent fields, providing a scientifically rigorous, "real world" perspective on auditory perception, cognition, and action. In a natural listening environment almost all sounds are dynamic, complex, and heard concurrently with other sounds. Yet, historically, traditional psychoacoustics has examined the perception of static, impoverished stimuli presented in isolation. "Ecological Psychoacoustics" examines recent work that challenges some of the traditional ideas about auditory perception that were established with these impoverished stimuli and provides a focused look at the perceptual processes that are more likely to occur in natural settings. It examines basic psychoacoustics from a more cognitive and ecological perspective. It provides broad coverage including both basic and applied research in auditory perception; and coherence and cross referencing among chapters.
Sound Processing in the Auditory Cortex of Rats During Sensory Decision-Making
Author: Elena GronskayaTemporal Processing in Primate Auditory Cortex
Author: Daniel BendorPublisher: LAP Lambert Academic Publishing
ISBN: 9783844324815
Category : Auditory cortex
Languages : en
Pages : 184
Book Description
A cornerstone of the human auditory system is its ability to recognize and appreciate music and speech. At its most basic level, music is made up of melodies and rhythms, which are the relative changes in pitch and temporal rates, respectively, for a series of musical notes. Speech is also composed of sequences of different pitches and temporal rates, however pitch changes carry prosody information (for non-tonal languages), while semantic information in contained in the temporal rate. How is an acoustic signal's temporal rate and pitch encoded in the auditory system? For my dissertation, I have investigated the neural coding of a sound's temporal properties by single neurons in the auditory cortex of the marmoset.
The Auditory Cortex
Author: Jeffery A. WinerPublisher: Springer Science & Business Media
ISBN: 1441900748
Category : Science
Languages : en
Pages : 711
Book Description
There has been substantial progress in understanding the contributions of the auditory forebrain to hearing, sound localization, communication, emotive behavior, and cognition. The Auditory Cortex covers the latest knowledge about the auditory forebrain, including the auditory cortex as well as the medial geniculate body in the thalamus. This book will cover all important aspects of the auditory forebrain organization and function, integrating the auditory thalamus and cortex into a smooth, coherent whole. Volume One covers basic auditory neuroscience. It complements The Auditory Cortex, Volume 2: Integrative Neuroscience, which takes a more applied/clinical perspective.