scholarly journals Memory specific to temporal features of sound is formed by cue-selective enhancements in temporal coding enabled by inhibition of an epigenetic regulator

2021 ◽  
Author(s):  
Elena K Rotondo ◽  
Kasia M Bieszczad
Keyword(s):  
Auditory System ◽  
Phase Locking ◽  
Temporal Coding ◽  
Long Term Memory ◽  
Epigenetic Mechanisms ◽  
Behavioral Differences ◽  
Frequency Following Response ◽  
Temporal Features ◽  
Epigenetic Regulator ◽  
Rate Discrimination

Recent investigation of memory-related functions in the auditory system have capitalized on the use of memory-modulating molecules to probe the relationship between memory and its substrates in auditory system coding. For example, epigenetic mechanisms, which regulate gene expression necessary for memory consolidation, are powerful modulators of learning-induced neuroplasticity and long-term memory formation (LTM). Inhibition of the epigenetic regulator histone deacetylase 3 (HDAC3) promotes LTM that is highly specific for spectral features of sound. The present work demonstrates for the first time that HDAC3 inhibition also enables memory for temporal features of sound. Rats trained in an amplitude modulation (AM) rate discrimination task and treated with a selective inhibitor of HDAC3 formed memory that was unusually specific to the AM rate paired with reward. Unusually sound-specific memory revealed behaviorally was associated with a signal-specific enhancement in temporal coding in the auditory system: stronger phase-locking that was specific to the rewarded AM rate was revealed in both the surface-recorded frequency following response (FFR) and auditory cortical multiunit activity in rats treated with the HDAC3 inhibitor. Furthermore, HDAC3 inhibition increased trial-to-trial cortical response consistency (relative to naive and trained vehicle-treated rats) that generalized across different AM rates. Stronger signal-specific phase-locking correlated with individual behavioral differences in memory specificity for the AM signal. Together, these findings support that epigenetic mechanisms regulate activity-dependent processes that enhance discriminability of sensory cues encoded into LTM in both spectral and temporal domains, which may be important for remembering spectrotemporal features of sounds, e.g., as in human voices and speech.

Amplitude-Modulated Auditory Steady-State Responses in Younger and Older Listeners

2006 ◽  
Vol 17 (08) ◽  
pp. 582-597 ◽  
Author(s):  
E. D. Leigh-Paffenroth ◽  
Cynthia G. Fowler
Keyword(s):  
Steady State ◽  
Auditory System ◽  
Carrier Frequency ◽  
Recognition Performance ◽  
Phase Locking ◽  
Timing Analysis ◽  
Temporal Coding ◽  
Steady State Responses ◽  
Auditory Steady State Responses ◽  
State Responses

The primary purpose of this investigation was to determine whether temporal coding in the auditory system was the same for younger and older listeners. Temporal coding was assessed by amplitude-modulated auditory steady-state responses (AM ASSRs) as a physiologic measure of phase-locking capability. The secondary purpose of this study was to determine whether AM ASSRs were related to behavioral speech understanding ability. AM ASSRs showed that the ability of the auditory system to phase lock to a temporally altered signal is dependent on modulation rate, carrier frequency, and age of the listener. Specifically, the interaction of frequency and age showed that younger listeners had more phase locking than old listeners at 500 Hz. The number of phase-locked responses for the 500 Hz carrier frequency was significantly correlated to word-recognition performance. In conclusion, the effect of aging on temporal processing, as measured by phase locking with AM ASSRs, was found for low-frequency stimuli where phase locking in the auditory system should be optimal. The exploration, and use, of electrophysiologic responses to measure auditory timing analysis in humans has the potential to facilitate the understanding of speech perception difficulties in older listeners.

scholarly journals Epigenetic mechanisms modulate differences in Drosophila foraging behavior

2017 ◽  
Vol 114 (47) ◽  
pp. 12518-12523 ◽  
Author(s):  
Ina Anreiter ◽  
Jamie M. Kramer ◽  
Marla B. Sokolowski
Keyword(s):  
Genetic Variation ◽  
Foraging Behavior ◽  
Histone Methylation ◽  
Molecular Mechanisms ◽  
Epigenetic Mechanisms ◽  
Null Mutant ◽  
Behavioral Differences ◽  
Epigenetic Modifier ◽  
Epigenetic Regulator ◽  
Allele Specific

Little is known about how genetic variation and epigenetic marks interact to shape differences in behavior. The foraging (for) gene regulates behavioral differences between the rover and sitter Drosophila melanogaster strains, but the molecular mechanisms through which it does so have remained elusive. We show that the epigenetic regulator G9a interacts with for to regulate strain-specific adult foraging behavior through allele-specific histone methylation of a for promoter (pr4). Rovers have higher pr4 H3K9me dimethylation, lower pr4 RNA expression, and higher foraging scores than sitters. The rover–sitter differences disappear in the presence of G9a null mutant alleles, showing that G9a is necessary for these differences. Furthermore, rover foraging scores can be phenocopied by transgenically reducing pr4 expression in sitters. This compelling evidence shows that genetic variation can interact with an epigenetic modifier to produce differences in gene expression, establishing a behavioral polymorphism in Drosophila.

scholarly journals Individualized Assays of Temporal Coding in the Ascending Human Auditory System

2021 ◽  
Author(s):  
Agudemu Borjigin ◽  
Alexandra R Hustedt-Mai ◽  
Hari M Bharadwaj
Keyword(s):  
Auditory System ◽  
Phase Locking ◽  
Temporal Coding ◽  
Individual Level ◽  
Growth Metrics ◽  
The Individual ◽  
Lapse Rates ◽  
Timing Sensitivity ◽  
Electroencephalogram Eeg

Neural phase-locking to temporal fluctuations is a fundamental and unique mechanism by which acoustic information is encoded by the auditory system. The perceptual role of this metabolically expensive mechanism, the neural phase-locking to temporal fine structure (TFS) in particular, is debated. Although hypothesized, it is unclear if auditory perceptual deficits in certain clinical populations are attributable to deficits in TFS coding. Efforts to uncover the role of TFS have been impeded by the fact that there are no established assays for quantifying the fidelity of TFS coding at the individual level. While many candidates have been proposed, for an assay to be useful, it should not only intrinsically depend on TFS coding, but should also have the property that individual differences in the assay reflect TFS coding per se over and beyond other sources of variance. Here, we evaluate a range of behavioral and electroencephalogram (EEG)-based measures as candidate individualized measures of TFS sensitivity. Our comparisons of behavioral and EEG-based metrics suggest that extraneous variables dominate both behavioral scores and EEG amplitude metrics, rendering them ineffective. After adjusting behavioral scores using lapse rates, and extracting latency or percent-growth metrics from EEG, interaural timing sensitivity measures exhibit robust behavior-EEG correlations. Together with the fact that unambiguous theoretical links can be made relating binaural measures and phase-locking to TFS, our results suggest that these "adjusted" binaural assays may be well-suited for quantifying individual TFS processing.

Differential Temporal Coding of Rhythmically Diverse Acoustic Signals by a Single Interneuron

2004 ◽  
Vol 92 (2) ◽  
pp. 939-948 ◽  
Author(s):  
G. Marsat ◽  
G. S. Pollack
Keyword(s):  
Carrier Frequency ◽  
Auditory Processing ◽  
High Frequency ◽  
Information Transfer ◽  
Transfer Functions ◽  
Phase Locking ◽  
Temporal Structure ◽  
Temporal Coding ◽  
Temporal Features ◽  
Receptor Neurons

The omega neuron 1 (ON1) of the cricket Teleogryllus oceanicus responds to conspecific signals (4.5 kHz) and to the ultrasonic echolocation sounds used by hunting, insectivorous bats. These signals differ in temporal structure as well as in carrier frequency. We show that ON1's temporal coding properties vary with carrier frequency, allowing it to encode both of these behaviorally important signals. Information-transfer functions show that coding of 4.5 kHz is limited to the range of amplitude-modulation components that occur in cricket songs (<32 Hz), whereas coding of 30-kHz stimuli extends to the higher pulse rates that occur in bat sounds (∼100 Hz). Nonlinear coding contributes to the information content of ON1's spike train, particularly for 30-kHz stimuli with high intensities and large modulation depths. Phase locking to sinusoidal amplitude envelopes also extends to higher AM frequencies for ultrasound stimuli. ON1s frequency-specific behavior cannot be ascribed to differences in the shapes of information-transfer functions of low- and high-frequency-tuned receptor neurons, both of which are tuned more broadly to AM frequencies than ON1. Coding properties are nearly unaffected by contralateral deafferentation. ON1's role in auditory processing is to increase binaural contrast through contralateral inhibition. We hypothesize that its frequency-specific temporal coding properties optimize binaural contrast for sounds with both the spectral and temporal features of behaviorally relevant signals.

Temporal coding of envelopes and their interaural delays in the inferior colliculus of the unanesthetized rabbit

1989 ◽  
Vol 61 (2) ◽  
pp. 257-268 ◽  
Author(s):  
R. Batra ◽  
S. Kuwada ◽  
T. R. Stanford
Keyword(s):  
Inferior Colliculus ◽  
Phase Locking ◽  
Acoustic Stimulus ◽  
Low Frequency ◽  
Auditory Pathway ◽  
Temporal Coding ◽  
Time Of Arrival ◽  
Unanesthetized Rabbit ◽  
The Difference ◽  
Ipsilateral Stimulation

1. The difference in the time of arrival of a sound at the two ears can be used to locate its source along the azimuth. Traditionally, it has been thought that only the on-going interaural temporal disparities (ITDs) produced by sounds of lower frequency (approximately less than 2 kHz) could be used for this purpose. However, ongoing ITDs of low frequency are also produced by envelopes of amplitude-modulated (AM) tones. These ITDs can be detected and used to lateralize complex high-frequency sounds (1, 8, 12, 15, 22, 24, 26). Auditory neurons synchronize to the modulation envelope, but do so at progressively lower modulation frequencies at higher levels of the auditory pathway. Some neurons of the cochlear nucleus synchronize best to frequencies as high as 700 Hz, but those of the inferior colliculus (IC) exhibit their best synchrony below 200 Hz. Even though synchrony to higher modulation frequencies is reduced at higher levels of the auditory pathway, is information about ITDs retained? 2. We answered this question by extracellularly recording the responses of neurons in the IC of the unanesthetized rabbit. We used an unanesthetized preparation because anesthesia alters the responses of neurons in the IC to both monaurally presented tones and ITDs. The unanesthetized rabbit is ideal for auditory research. Recordings can be maintained for long periods, and the acoustic stimulus to each ear can be independently controlled. 3. We studied the responses of 89 units to sinusoidally AM tones presented to the contralateral ear. For each unit, we recorded the response at several modulation frequencies. The degree of phase locking to the envelope at each frequency was measured using the synchronization coefficient. Two measures were used to assess the range of modulation frequencies over which phase locking occurred. The "best AM frequency" was the frequency at which we observed the greatest phase locking. The "highest AM frequency" was the highest frequency at which significant phase locking (0.001 level) was observed. We could not assess synchrony to ipsilateral AM tones directly, because most units did not respond to ipsilateral stimulation. 4. We studied the sensitivity of 63 units to ITDs produced by the envelopes of AM tones. Sensitivity to ITDs was tested by presenting AM tones to the two ears that had the same carrier frequency, but modulation frequencies that differed by 1 Hz. Units that were sensitive to ITDs responded to this stimulus by varying their response rate cyclically at the difference frequency, i.e., 1 Hz.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Perceptual Weighting of Binaural Lateralization Cues across Frequency Bands

2020 ◽  
Vol 21 (6) ◽  
pp. 485-496
Author(s):  
Axel Ahrens ◽  
Suyash Narendra Joshi ◽  
Bastian Epp
Keyword(s):  
Auditory System ◽  
Phase Locking ◽  
Linear Regression Analysis ◽  
Multiple Linear Regression Analysis ◽  
Low Frequencies ◽  
Frequency Bands ◽  
Relative Contribution ◽  
Highest Weight ◽  
Auditory Enhancement ◽  
Spectral Weighting

Abstract The auditory system uses interaural time and level differences (ITD and ILD) as cues to localize and lateralize sounds. The availability of ITDs and ILDs in the auditory system is limited by neural phase-locking and by the head size, respectively. Although the frequency-specific limitations are well known, the relative contribution of ITDs and ILDs in individual frequency bands in broadband stimuli is unknown. To determine these relative contributions, or spectral weights, listeners were asked to lateralize stimuli consisting of eleven simultaneously presented 1-ERB-wide noise bands centered between 442 and 5544 Hz and separated by 1-ERB-wide gaps. Either ITDs or ILDs were varied independently across each noise band, while fixing the other interaural disparity to either 0 dB or 0 μs. The weights were obtained using a multiple linear regression analysis. In a second experiment, the effect of auditory enhancement on the spectral weights was investigated. The enhancement of single noise bands was realized by presenting ten of the noise bands as preceding and following sounds (pre- and post-cursors, respectively). Listeners were asked to lateralize the stimuli as in the first experiment. Results show that in the absence of pre- and post-cursors, only the lowest or highest frequency band received highest weight for ITD and ILD, respectively. Auditory enhancement led to significantly enhanced weights given to the band without the pre- and post-cursor. The weight enhancement could only be observed at low frequencies, when determined with ITD cues and for low and high frequencies for ILDs. Hence, the auditory system seems to be able to change the spectral weighting of binaural information depending on the information content.

Neural Transformation of Dissonant Intervals in the Auditory Brainstem

2015 ◽  
Vol 32 (5) ◽  
pp. 445-459 ◽  
Author(s):  
Kyung Myun Lee ◽  
Erika Skoe ◽  
Nina Kraus ◽  
Richard Ashley
Keyword(s):  
Auditory System ◽  
Auditory Processing ◽  
Response Spectrum ◽  
Phase Locking ◽  
Auditory Pathway ◽  
Auditory Brainstem ◽  
Neural Representation ◽  
Auditory Brainstem Responses ◽  
Distortion Products ◽  
Stimulus Waveform

Acoustic periodicity is an important factor for discriminating consonant and dissonant intervals. While previous studies have found that the periodicity of musical intervals is temporally encoded by neural phase locking throughout the auditory system, how the nonlinearities of the auditory pathway influence the encoding of periodicity and how this effect is related to sensory consonance has been underexplored. By measuring human auditory brainstem responses (ABRs) to four diotically presented musical intervals with increasing degrees of dissonance, this study seeks to explicate how the subcortical auditory system transforms the neural representation of acoustic periodicity for consonant versus dissonant intervals. ABRs faithfully reflect neural activity in the brainstem synchronized to the stimulus while also capturing nonlinear aspects of auditory processing. Results show that for the most dissonant interval, which has a less periodic stimulus waveform than the most consonant interval, the aperiodicity of the stimulus is intensified in the subcortical response. The decreased periodicity of dissonant intervals is related to a larger number of nonlinearities (i.e., distortion products) in the response spectrum. Our findings suggest that the auditory system transforms the periodicity of dissonant intervals resulting in consonant and dissonant intervals becoming more distinct in the neural code than if they were to be processed by a linear auditory system.

scholarly journals Sensory Cortical Plasticity Participates in the Epigenetic Regulation of Robust Memory Formation

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Mimi L. Phan ◽  
Kasia M. Bieszczad
Keyword(s):  
Epigenetic Regulation ◽  
Neural Plasticity ◽  
Cortical Plasticity ◽  
Memory Formation ◽  
Sensory Cortex ◽  
Long Term Memory ◽  
Epigenetic Mechanisms ◽  
Significant Information ◽  
Expression Of Genes ◽  
Open Question

Neuroplasticity remodels sensory cortex across the lifespan. A function of adult sensory cortical plasticity may be capturing available information during perception for memory formation. The degree of experience-dependent remodeling in sensory cortex appears to determine memory strength and specificity for important sensory signals. A key open question is how plasticity is engaged to induce different degrees of sensory cortical remodeling. Neural plasticity for long-term memory requires the expression of genes underlying stable changes in neuronal function, structure, connectivity, and, ultimately, behavior. Lasting changes in transcriptional activity may depend on epigenetic mechanisms; some of the best studied in behavioral neuroscience are DNA methylation and histone acetylation and deacetylation, which, respectively, promote and repress gene expression. One purpose of this review is to propose epigenetic regulation of sensory cortical remodeling as a mechanism enabling the transformation of significant information from experiences into content-rich memories of those experiences. Recent evidence suggests how epigenetic mechanisms regulate highly specific reorganization of sensory cortical representations that establish a widespread network for memory. Thus, epigenetic mechanisms could initiate events to establish exceptionally persistent and robust memories at a systems-wide level by engaging sensory cortical plasticity for gatingwhatandhow muchinformation becomes encoded.

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