scholarly journals Auditory midbrain representation of a break in interaural correlation

2015 ◽  
Vol 114 (4) ◽  
pp. 2258-2264 ◽  
Author(s):  
Qian Wang ◽  
Liang Li
Keyword(s):  
Steady State ◽  
Phase Locking ◽  
Center Frequency ◽  
Auditory Midbrain ◽  
Linear Summation ◽  
Temporary Reduction ◽  
Interaural Correlation ◽  
Neuron Populations ◽  
Fine Structures ◽  
Sustained Responses

The auditory peripheral system filters broadband sounds into narrowband waves and decomposes narrowband waves into quickly varying temporal fine structures (TFSs) and slowly varying envelopes. When a noise is presented binaurally (with the interaural correlation being 1), human listeners can detect a transient break in interaural correlation (BIC), which does not alter monaural inputs substantially. The central correlates of BIC are unknown. This study examined whether phase locking-based frequency-following responses (FFRs) of neuron populations in the rat auditory midbrain [inferior colliculus (IC)] to interaurally correlated steady-state narrowband noises are modulated by introduction of a BIC. The results showed that the noise-induced FFR exhibited both a TFS component (FFRTFS) and an envelope component (FFREnv), signaling the center frequency and bandwidth, respectively. Introduction of either a BIC or an interaurally correlated amplitude gap (which had the summated amplitude matched to the BIC) significantly reduced both FFRTFS and FFREnv. However, the BIC-induced FFRTFS reduction and FFREnv reduction were not correlated with the amplitude gap-induced FFRTFS reduction and FFREnv reduction, respectively. Thus, although introduction of a BIC does not affect monaural inputs, it causes a temporary reduction in sustained responses of IC neuron populations to the noise. This BIC-induced FFR reduction is not based on a simple linear summation of noise signals.

scholarly journals Aberrant Auditory Steady-State Response of Awake Mice After Single Application of the NMDA Receptor Antagonist MK-801 Into the Medial Geniculate Body

2020 ◽  
Vol 23 (7) ◽  
pp. 459-468 ◽  
Author(s):  
Xuejiao Wang ◽  
Yingzhuo Li ◽  
Jingyu Chen ◽  
Zijie Li ◽  
Jinhong Li ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Steady State ◽  
Local Field ◽  
Local Field Potential ◽  
Phase Locking ◽  
Field Potential ◽  
Medial Geniculate Body ◽  
Systemic Administration ◽  
Mk 801 ◽  
Medial Geniculate

Abstract Background Systemic administration of noncompetitive N-methyl-D-aspartate receptor (NMDAR) antagonists such as MK-801 is widely used to model psychosis of schizophrenia (SZ). Acute systemic MK-801 in rodents caused an increase of the auditory steady-state responses (ASSRs), the oscillatory neural responses to periodic auditory stimulation, while most studies in patients with SZ reported a decrease of ASSRs. This inconsistency may be attributable to the comprehensive effects of systemic administration of MK-801. Here, we examined how the ASSR is affected by selectively blocking NMDAR in the thalamus. Methods We implanted multiple electrodes in the auditory cortex (AC) and prefrontal cortex to simultaneously record the local field potential and spike activity (SA) of multiple sites from awake mice. Click-trains at a 40-Hz repetition rate were used to evoke the ASSR. We compared the mean trial power and phase-locking factor and the firing rate of SA before and after microinjection of MK-801 (1.5 µg) into the medial geniculate body (MGB). Results We found that both the AC and prefrontal cortex showed a transient local field potential response at the onset of click-train stimulus, which was less affected by the application of MK-801 in the MGB. Following the onset response, the AC also showed a response continuing throughout the stimulus period, corresponding to the ASSR, which was suppressed by the application of MK-801. Conclusion Our data suggest that the MGB is one of the generators of ASSR, and NMDAR hypofunction in the thalamocortical projection may account for the ASSR deficits in SZ.

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.

Phase-locking index and power of 40-Hz auditory steady-state response are not related to major personality trait dimensions

2015 ◽  
Vol 234 (3) ◽  
pp. 711-719 ◽  
Author(s):  
Milena Korostenskaja ◽  
Osvaldas Ruksenas ◽  
Evaldas Pipinis ◽  
Inga Griskova-Bulanova
Keyword(s):  
Steady State ◽  
Personality Trait ◽  
Phase Locking ◽  
Steady State Response ◽  
State Response ◽  
Auditory Steady State Response ◽  
40 Hz

scholarly journals Low-Frequency Envelope Sensitivity Produces Asymmetric Binaural Tuning Curves

2008 ◽  
Vol 100 (4) ◽  
pp. 2381-2396 ◽  
Author(s):  
John P. Agapiou ◽  
David McAlpine
Keyword(s):  
Low Frequency ◽  
Broadband Noise ◽  
Neural Representation ◽  
Superior Olivary Complex ◽  
Auditory Midbrain ◽  
Tuning Curves ◽  
Interaural Correlation ◽  
Rate Asymmetry ◽  
Delay Sensitivity ◽  
Acoustic Space

Neurons in the auditory midbrain are sensitive to differences in the timing of sounds at the two ears—an important sound localization cue. We used broadband noise stimuli to investigate the interaural-delay sensitivity of low-frequency neurons in two midbrain nuclei: the inferior colliculus (IC) and the dorsal nucleus of the lateral lemniscus. Noise-delay functions showed asymmetries not predicted from a linear dependence on interaural correlation: a stretching along the firing-rate dimension ( rate asymmetry), and a skewing along the interaural-delay dimension ( delay asymmetry). These asymmetries were produced by an envelope-sensitive component to the response that could not entirely be accounted for by monaural or binaural nonlinearities, instead indicating an enhancement of envelope sensitivity at or after the level of the superior olivary complex. In IC, the skew-like asymmetry was consistent with intermediate-type responses produced by the convergence of ipsilateral peak-type inputs and contralateral trough-type inputs. This suggests a stereotyped pattern of input to the IC. In the course of this analysis, we were also able to determine the contribution of time and phase components to neurons' internal delays. These findings have important consequences for the neural representation of interaural timing differences and interaural correlation—cues critical to the perception of acoustic space.

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