scholarly journals Signal processing in auditory cortex underlies degraded speech sound discrimination in noise

2019 ◽  
Author(s):  
Stephen M. Town ◽  
Katherine C. Wood ◽  
Jennifer K. Bizley
Keyword(s):  
Auditory Cortex ◽  
Cortical Neurons ◽  
Speech Sound ◽  
Continuous Exposure ◽  
Behavioral Performance ◽  
Related Activity ◽  
Hearing In Noise ◽  
Neural Populations ◽  
Sound Discrimination ◽  
Underlying Mechanisms

AbstractThe ability to recognize sounds in noise is a key part of hearing, and the mechanisms by which the brain identifies sounds in noise are of considerable interest to scientists, clinicians and engineers. Yet we know little about the necessity of regions such as auditory cortex for hearing in noise, or how cortical processing of sounds is adversely affected by noise. Here we used reversible cortical inactivation and extracellular electrophysiology in ferrets performing a vowel discrimination task to identify and understand the causal contribution of auditory cortex to hearing in noise. Cortical inactivation by cooling impaired task performance in noisy but not clean conditions, while responses of auditory cortical neurons were less informative about vowel identity in noise. Simulations mimicking cortical inactivation indicated that effects of inactivation were related to the loss of information about sounds represented across neural populations. The addition of noise to target sounds drove spiking activity in auditory cortex and recruitment of additional neural populations that were linked to degraded behavioral performance. To suppress noise-related activity, we used continuous exposure to background noise to adapt the auditory system and recover behavioral performance in both ferrets and humans. Inactivation by cooling revealed that the benefits of continuous exposure were not cortically dependent. Together our results highlight the importance of auditory cortex in sound discrimination in noise and the underlying mechanisms through which noise-related activity and adaptation shape hearing.

scholarly journals When and How Does the Auditory Cortex Influence Subcortical Auditory Structures? New Insights About the Roles of Descending Cortical Projections

2021 ◽  
Vol 15 ◽  
Author(s):  
Samira Souffi ◽  
Fernando R. Nodal ◽  
Victoria M. Bajo ◽  
Jean-Marc Edeline
Keyword(s):  
Auditory Cortex ◽  
Cortical Neurons ◽  
Behavioral Responses ◽  
Behavioral Performance ◽  
Subcortical Structures ◽  
Cortical Projections ◽  
Acoustic Conditions ◽  
Functional Circuitry ◽  
Descending Projections ◽  
Better Than

For decades, the corticofugal descending projections have been anatomically well described but their functional role remains a puzzling question. In this review, we will first describe the contributions of neuronal networks in representing communication sounds in various types of degraded acoustic conditions from the cochlear nucleus to the primary and secondary auditory cortex. In such situations, the discrimination abilities of collicular and thalamic neurons are clearly better than those of cortical neurons although the latter remain very little affected by degraded acoustic conditions. Second, we will report the functional effects resulting from activating or inactivating corticofugal projections on functional properties of subcortical neurons. In general, modest effects have been observed in anesthetized and in awake, passively listening, animals. In contrast, in behavioral tasks including challenging conditions, behavioral performance was severely reduced by removing or transiently silencing the corticofugal descending projections. This suggests that the discriminative abilities of subcortical neurons may be sufficient in many acoustic situations. It is only in particularly challenging situations, either due to the task difficulties and/or to the degraded acoustic conditions that the corticofugal descending connections bring additional abilities. Here, we propose that it is both the top-down influences from the prefrontal cortex, and those from the neuromodulatory systems, which allow the cortical descending projections to impact behavioral performance in reshaping the functional circuitry of subcortical structures. We aim at proposing potential scenarios to explain how, and under which circumstances, these projections impact on subcortical processing and on behavioral responses.

Distinctive Phonetic Features as Relevant and Irrelevant Stimulus Dimensions in Speech-Sound Discrimination Learning

1974 ◽  
Vol 17 (3) ◽  
pp. 417-425
Author(s):  
Stuart I. Ritterman ◽  
Nancy C. Freeman
Keyword(s):  
College Students ◽  
Discrimination Learning ◽  
Irrelevant Dimension ◽  
Speech Sound ◽  
Irrelevant Stimulus ◽  
Relevant Dimension ◽  
Phonetic Features ◽  
Sound Discrimination ◽  
Nonsense Syllables

Thirty-two college students were required to learn the relevant dimension in each of two randomized lists of auditorily presented stimuli. The stimuli consisted of seven pairs of CV nonsense syllables differing by two relevant dimension units and from zero to seven irrelevant dimension units. Stimulus dimensions were determined according to Saporta’s units of difference. No significant differences in performance as a function of number of the irrelevant dimensions nor characteristics of the relevant dimension were observed.

Monaural inhibition in cat auditory cortex

1995 ◽  
Vol 73 (5) ◽  
pp. 1876-1891 ◽  
Author(s):  
M. B. Calford ◽  
M. N. Semple
Keyword(s):  
Auditory Cortex ◽  
Lateral Inhibition ◽  
Cortical Neurons ◽  
Frequency Tuning ◽  
Inhibitory Response ◽  
Forward Masking ◽  
Excitatory Response ◽  
Rate Level ◽  
Wide Range ◽  
Response Area

1. Several studies of auditory cortex have examined the competitive inhibition that can occur when appropriate sounds are presented to each ear. However, most cortical neurons also show both excitation and inhibition in response to presentation of stimuli at one ear alone. The extent of such inhibition has not been described. Forward masking, in which a variable masking stimulus was followed by a fixed probe stimulus (within the excitatory response area), was used to examine the extent of monaural inhibition for neurons in primary auditory cortex of anesthetized cats (barbiturate or barbiturate-ketamine). Both the masking and probe stimuli were 50-ms tone pips presented to the contralateral ear. Most cortical neurons showed significant forward masking at delays beyond which masking effects in the auditory nerve are relatively small compared with those seen in cortical neurons. Analysis was primarily concerned with such components. Standard rate-level functions were also obtained and were examined for nonmonotonicity, an indication of level-dependent monaural inhibition. 2. Consistent with previous reports, a wide range of frequency tuning properties (excitatory response area shapes) was found in cortical neurons. This was matched by a wide range of forward-masking-derived inhibitory response areas. At the most basic level of analysis, these were classified according to the presence of lateral inhibition, i.e., where a probe tone at a neuron's characteristic frequency was masked by tones outside the limits of the excitatory response area. Lateral inhibition was a property of 38% of the sampled neurons. Such neurons represented 77% of those with nonmonotonic rate-level functions, indicating a strong correlation between the two indexes of monaural inhibition; however, the shapes of forward masking inhibitory response areas did not usually correspond with those required to account for the "tuning" of a neuron. In addition, it was found that level-dependent inhibition was not added to by forward masking inhibition. 3. Analysis of the discharges to individual stimulus pair presentations, under conditions of partial masking, revealed that discharges to the probe occurred independently of discharges to the preceding masker. This indicates that even when the masker is within a neuron's excitatory response area, forward masking is not a postdischarge habituation phenomenon. However, for most neurons the degree of masking summed over multiple stimulus presentations appears determined by the same stimulus parameters that determine the probability of response to the masker.(ABSTRACT TRUNCATED AT 400 WORDS)

Another Approach to Evaluating Speech Sound Discrimination

1969 ◽  
Vol 35 (9) ◽  
pp. 745-747 ◽  
Author(s):  
Ronald Goldman ◽  
Macalyne Fristoe
Keyword(s):  
Speech Sound ◽  
Sound Discrimination

Neural Responses in Primary Auditory Cortex Mimic Psychophysical, Across-Frequency-Channel, Gap-Detection Thresholds

2000 ◽  
Vol 84 (3) ◽  
pp. 1453-1463 ◽  
Author(s):  
Jos J. Eggermont
Keyword(s):  
Auditory Cortex ◽  
Cortical Neurons ◽  
Primary Auditory Cortex ◽  
Noise Burst ◽  
Gap Detection ◽  
Frequency Content ◽  
Neural Responses ◽  
Frequency Channel ◽  
Interval Representations ◽  
Onset Response

Responses of single- and multi-units in primary auditory cortex were recorded for gap-in-noise stimuli for different durations of the leading noise burst. Both firing rate and inter-spike interval representations were evaluated. The minimum detectable gap decreased in exponential fashion with the duration of the leading burst to reach an asymptote for durations of 100 ms. Despite the fact that leading and trailing noise bursts had the same frequency content, the dependence on leading burst duration was correlated with psychophysical estimates of across frequency channel (different frequency content of leading and trailing burst) gap thresholds in humans. The duration of the leading burst plus that of the gap was represented in the all-order inter-spike interval histograms for cortical neurons. The recovery functions for cortical neurons could be modeled on basis of fast synaptic depression and after-hyperpolarization produced by the onset response to the leading noise burst. This suggests that the minimum gap representation in the firing pattern of neurons in primary auditory cortex, and minimum gap detection in behavioral tasks is largely determined by properties intrinsic to those, or potentially subcortical, cells.

scholarly journals Fast-spiking GABA circuit dynamics in the auditory cortex predict recovery of sensory processing following peripheral nerve damage

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Jennifer Resnik ◽  
Daniel B Polley
Keyword(s):  
Peripheral Nerve ◽  
Auditory Cortex ◽  
Sensory Processing ◽  
Cortical Neurons ◽  
Sensory Nerve ◽  
Intracortical Inhibition ◽  
Nerve Fibers ◽  
Nerve Damage ◽  
Inhibitory Neurons ◽  
Sound Processing

Cortical neurons remap their receptive fields and rescale sensitivity to spared peripheral inputs following sensory nerve damage. To address how these plasticity processes are coordinated over the course of functional recovery, we tracked receptive field reorganization, spontaneous activity, and response gain from individual principal neurons in the adult mouse auditory cortex over a 50-day period surrounding either moderate or massive auditory nerve damage. We related the day-by-day recovery of sound processing to dynamic changes in the strength of intracortical inhibition from parvalbumin-expressing (PV) inhibitory neurons. Whereas the status of brainstem-evoked potentials did not predict the recovery of sensory responses to surviving nerve fibers, homeostatic adjustments in PV-mediated inhibition during the first days following injury could predict the eventual recovery of cortical sound processing weeks later. These findings underscore the potential importance of self-regulated inhibitory dynamics for the restoration of sensory processing in excitatory neurons following peripheral nerve injuries.

scholarly journals Serotonin Transporter Defect Disturbs Structure and Function of the Auditory Cortex in Mice

2021 ◽  
Vol 15 ◽  
Author(s):  
Wenlu Pan ◽  
Jing Pan ◽  
Yan Zhao ◽  
Hongzheng Zhang ◽  
Jie Tang
Keyword(s):  
Auditory Cortex ◽  
Serotonin Transporter ◽  
Cortical Neurons ◽  
Pyramidal Neurons ◽  
Frequency Tuning ◽  
Primary Auditory Cortex ◽  
Neuronal Morphology ◽  
Neuronal Connections ◽  
The Central Nervous System ◽  
And Function

Serotonin transporter (SERT) modulates the level of 5-HT and significantly affects the activity of serotonergic neurons in the central nervous system. The manipulation of SERT has lasting neurobiological and behavioral consequences, including developmental dysfunction, depression, and anxiety. Auditory disorders have been widely reported as the adverse events of these mental diseases. It is unclear how SERT impacts neuronal connections/interactions and what mechanism(s) may elicit the disruption of normal neural network functions in auditory cortex. In the present study, we report on the neuronal morphology and function of auditory cortex in SERT knockout (KO) mice. We show that the dendritic length of the fourth layer (L-IV) pyramidal neurons and the second-to-third layer (L-II/III) interneurons were reduced in the auditory cortex of the SERT KO mice. The number and density of dendritic spines of these neurons were significantly less than those of wild-type neurons. Also, the frequency-tonotopic organization of primary auditory cortex was disrupted in SERT KO mice. The auditory neurons of SERT KO mice exhibited border frequency tuning with high-intensity thresholds. These findings indicate that SERT plays a key role in development and functional maintenance of auditory cortical neurons. Auditory function should be examined when SERT is selected as a target in the treatment for psychiatric disorders.

scholarly journals Aberrant activation within auditory network is associated with psychiatric comorbidities in interictal migraineurs without aura

2020 ◽  
Author(s):  
Heng-Le Wei ◽  
Yu-Chen Chen ◽  
Yu-Sheng Yu ◽  
Xi Guo ◽  
Gang-Ping Zhou ◽  
...  
Keyword(s):  
Auditory Cortex ◽  
Resting State ◽  
Psychiatric Symptoms ◽  
Brain Activation ◽  
Superior Temporal Gyrus ◽  
Anxiety And Depression ◽  
Intracranial Volume ◽  
Healthy Controls ◽  
Postcentral Gyrus ◽  
Underlying Mechanisms

Abstract Background: Resting-state functional magnetic resonance imaging has confirmed auditory network dysfunction in migraine without aura (MwoA). Epidemiological investigations have disclosed that migraine is comorbid with many psychiatric symptoms. However, the underlying mechanisms of auditory cortex dysfunction linked to psychiatric disorders in MwoA remain unclear. The present study aimed to explore associations between brain activation in the auditory cortex and clinical and psychiatric characteristics in patients with MwoA during interictal periods.Methods: Resting-state data were acquired from patients with episodic MwoA (n=34) and healthy controls (n=30). Independent component analysis was used to extract and calculate the resting-state auditory network. Subsequently, we analyzed the correlations between spontaneous activation in the auditory cortex and clinical and psychiatric features in MwoA.Results: Compared with healthy controls, patients with MwoA showed increased activation in the left auditory cortex (i.e., superior temporal gyrus (STG), postcentral gyrus (PoCG) and insula). Brain activation in the left STG was positively correlated with anxiety scores, and activation in the left PoCG was negatively correlated with anxiety and depression scores. No significant differences were found in intracranial volume between the two groups.Conclusions: This study indicated that functional impairment and altered integration within the auditory cortex existed in patients with MwoA in the interictal period, suggesting that auditory cortex disruption as a biomarker may be implemented for the early diagnosis and prediction of neuropsychiatric impairment in MwoA.

Sign in / Sign up

Export Citation Format

Share Document