scholarly journals Binaural Background Noise Enhances Neuromagnetic Responses from Auditory Cortex

Symmetry ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1748
Author(s):  
Dawei Shen ◽  
Claude Alain ◽  
Bernhard Ross
Keyword(s):  
Auditory Cortex ◽  
Background Noise ◽  
Low Noise ◽  
Harmonic Complex ◽  
Optimal Representation ◽  
Complex Tones ◽  
Transient Events ◽  
Auditory Evoked Fields ◽  
Evoked Fields ◽  
Auditory Cortices

The presence of binaural low-level background noise has been shown to enhance the transient evoked N1 response at about 100 ms after sound onset. This increase in N1 amplitude is thought to reflect noise-mediated efferent feedback facilitation from the auditory cortex to lower auditory centers. To test this hypothesis, we recorded auditory-evoked fields using magnetoencephalography while participants were presented with binaural harmonic complex tones embedded in binaural or monaural background noise at signal-to-noise ratios of 25 dB (low noise) or 5 dB (higher noise). Half of the stimuli contained a gap in the middle of the sound. The source activities were measured in bilateral auditory cortices. The onset and gap N1 response increased with low binaural noise, but high binaural and low monaural noise did not affect the N1 amplitudes. P1 and P2 onset and gap responses were consistently attenuated by background noise, and noise level and binaural/monaural presentation showed distinct effects. Moreover, the evoked gamma synchronization was also reduced by background noise, and it showed a lateralized reduction for monaural noise. The effects of noise on the N1 amplitude follow a bell-shaped characteristic that could reflect an optimal representation of acoustic information for transient events embedded in noise.

Consonance and Dissonance of Musical Chords: Neural Correlates in Auditory Cortex of Monkeys and Humans

2001 ◽  
Vol 86 (6) ◽  
pp. 2761-2788 ◽  
Author(s):  
Yonatan I. Fishman ◽  
Igor O. Volkov ◽  
M. Daniel Noh ◽  
P. Charles Garell ◽  
Hans Bakken ◽  
...  
Keyword(s):  
Auditory Cortex ◽  
Current Source ◽  
Intractable Epilepsy ◽  
Auditory Evoked Potential ◽  
Harmonic Complex ◽  
Heschl’S Gyrus ◽  
Complex Tones ◽  
Heschl's Gyrus ◽  
Musical Chords ◽  
Consonance And Dissonance

Some musical chords sound pleasant, or consonant, while others sound unpleasant, or dissonant. Helmholtz's psychoacoustic theory of consonance and dissonance attributes the perception of dissonance to the sensation of “beats” and “roughness” caused by interactions in the auditory periphery between adjacent partials of complex tones comprising a musical chord. Conversely, consonance is characterized by the relative absence of beats and roughness. Physiological studies in monkeys suggest that roughness may be represented in primary auditory cortex (A1) by oscillatory neuronal ensemble responses phase-locked to the amplitude-modulated temporal envelope of complex sounds. However, it remains unknown whether phase-locked responses also underlie the representation of dissonance in auditory cortex. In the present study, responses evoked by musical chords with varying degrees of consonance and dissonance were recorded in A1 of awake macaques and evaluated using auditory-evoked potential (AEP), multiunit activity (MUA), and current-source density (CSD) techniques. In parallel studies, intracranial AEPs evoked by the same musical chords were recorded directly from the auditory cortex of two human subjects undergoing surgical evaluation for medically intractable epilepsy. Chords were composed of two simultaneous harmonic complex tones. The magnitude of oscillatory phase-locked activity in A1 of the monkey correlates with the perceived dissonance of the musical chords. Responses evoked by dissonant chords, such as minor and major seconds, display oscillations phase-locked to the predicted difference frequencies, whereas responses evoked by consonant chords, such as octaves and perfect fifths, display little or no phase-locked activity. AEPs recorded in Heschl's gyrus display strikingly similar oscillatory patterns to those observed in monkey A1, with dissonant chords eliciting greater phase-locked activity than consonant chords. In contrast to recordings in Heschl's gyrus, AEPs recorded in the planum temporale do not display significant phase-locked activity, suggesting functional differentiation of auditory cortical regions in humans. These findings support the relevance of synchronous phase-locked neural ensemble activity in A1 for the physiological representation of sensory dissonance in humans and highlight the merits of complementary monkey/human studies in the investigation of neural substrates underlying auditory perception.

scholarly journals Spectral response patterns of auditory cortex neurons to harmonic complex tones in alert monkey (Macaca mulatta)

1990 ◽  
Vol 64 (1) ◽  
pp. 282-298 ◽  
Author(s):  
D. W. Schwarz ◽  
R. W. Tomlinson
Keyword(s):  
Receptive Field ◽  
Auditory Cortex ◽  
Pure Tone ◽  
Response Pattern ◽  
Response Patterns ◽  
Neuronal Responses ◽  
Harmonic Complex ◽  
Tuning Curves ◽  
Complex Tones ◽  
Pure Tones

1. The auditory cortex in the superior temporal region of the alert rhesus monkey was explored for neuronal responses to pure and harmonic complex tones and noise. The monkeys had been previously trained to recognize the similarity between harmonic complex tones with and without fundamentals. Because this suggested that they could preceive the pitch of the lacking fundamental similarly to humans, we searched for neuronal responses relevant to this perception. 2. Combination-sensitive neurons that might explain pitch perception were not found in the surveyed cortical regions. Such neurons would exhibit similar responses to stimuli with similar periodicities but differing spectral compositions. The fact that no neuron with responses to a fundamental frequency responded also to a corresponding harmonic complex missing the fundamental indicates that cochlear distortion products at the fundamental may not have been responsible for missing fundamental-pitch perception in these monkeys. 3. Neuronal responses can be expressed as relatively simple filter functions. Neurons with excitatory response areas (tuning curves) displayed various inhibitory sidebands at lower and/or higher frequencies. Thus responses varied along a continuum of combined excitatory and inhibitory filter functions. 4. Five elementary response classes along this continuum are presented to illustrate the range of response patterns. 5. “Filter (F) neurons” had little or no inhibitory sidebands and responded well when any component of a complex tone entered its pure-tone receptive field. Bandwidths increased with intensity. Filter functions of these neurons were thus similar to cochlear nerve-fiber tuning curves. 6. ”High-resolution filter (HRF) neurons” displayed narrow tuning curves with narrowband widths that displayed little growth with intensity. Such cells were able to resolve up to the lowest seven components of harmonic complex tones as distinct responses. They also responded well to wideband stimuli. 7. “Fundamental (F0) neurons” displayed similar tuning bandwidths for pure tones and corresponding fundamentals of harmonic complexes. This response pattern was due to lower harmonic complexes. This response pattern was due to lower inhibitory sidebands. Thus these cells cannot respond to missing fundamentals of harmonic complexes. Only physically present components in the pure-tone receptive field would excite such neurons. 8. Cells with no or very weak responses to pure tones or other narrowband stimuli responded well to harmonic complexes or wideband noise.(ABSTRACT TRUNCATED AT 400 WORDS)

Pitch vs. spectral encoding of harmonic complex tones in primary auditory cortex of the awake monkey

1998 ◽  
Vol 786 (1-2) ◽  
pp. 18-30 ◽  
Author(s):  
Yonatan I. Fishman ◽  
David H. Reser ◽  
Joseph C. Arezzo ◽  
Mitchell Steinschneider
Keyword(s):  
Auditory Cortex ◽  
Primary Auditory Cortex ◽  
Harmonic Complex ◽  
Awake Monkey ◽  
Spectral Encoding ◽  
Complex Tones

How anatomical asymmetry of human auditory cortex can lead to a rightward bias in auditory evoked fields

NeuroImage ◽  
2013 ◽  
Vol 74 ◽  
pp. 22-29 ◽  
Author(s):  
Marnie E. Shaw ◽  
Matti S. Hämäläinen ◽  
Alexander Gutschalk
Keyword(s):  
Auditory Cortex ◽  
Auditory Evoked Fields ◽  
Evoked Fields ◽  
Human Auditory Cortex

scholarly journals MEG auditory evoked fields suggest altered structural/functional asymmetry in primary but not secondary auditory cortex in bipolar disorder

2009 ◽  
Vol 11 (4) ◽  
pp. 371-381 ◽  
Author(s):  
Martin Reite ◽  
Peter Teale ◽  
Donald C Rojas ◽  
Erik Reite ◽  
Ryan Asherin ◽  
...  
Keyword(s):  
Bipolar Disorder ◽  
Auditory Cortex ◽  
Functional Asymmetry ◽  
Auditory Evoked Fields ◽  
Evoked Fields

Representation of Auditory-Filter Phase Characteristics in the Cortex of Human Listeners

2008 ◽  
Vol 99 (3) ◽  
pp. 1152-1162 ◽  
Author(s):  
André Rupp ◽  
Norman Sieroka ◽  
Alexander Gutschalk ◽  
Torsten Dau
Keyword(s):  
Auditory Cortex ◽  
Neural Activity ◽  
Auditory Processing ◽  
Pure Tone ◽  
Basilar Membrane ◽  
Neural Representation ◽  
Auditory Filter ◽  
Long Duration ◽  
Auditory Evoked Fields ◽  
Evoked Fields

Harmonic tone complexes with component phases, adjusted using a variant of a method proposed by Schroeder, can produce pure-tone masked thresholds differing by >20 dB. This phenomenon has been qualitatively explained by the phase characteristics of the auditory filters on the basilar membrane, which differently affect the flat envelopes of the Schroeder-phase maskers. We examined the influence of auditory-filter phase characteristics on the neural representation in the auditory cortex by investigating cortical auditory evoked fields (AEFs). We found that the P1m component exhibited larger amplitudes when a long-duration tone was presented in a repeating linearly downward sweeping (Schroeder positive, or m+) masker than in a repeating linearly upward sweeping (Schroeder negative, or m−) masker. We also examined the neural representation of short-duration tone pulses presented at different temporal positions within a single period of three maskers differing in their component phases ( m+, m−, and sine phase m0). The P1m amplitude varied with the position of the tone pulse in the masker and depended strongly on the masker waveform. The neuromagnetic results in all cases were consistent with the perceptual data obtained with the same stimuli and with results from simulations of neural activity at the output of cochlear preprocessing. These findings demonstrate that phase effects in peripheral auditory processing are accurately reflected up to the level of the auditory cortex.

scholarly journals Different Modes of Pitch Perception and Learning-Induced Neuronal Plasticity of the Human Auditory Cortex

2002 ◽  
Vol 9 (3) ◽  
pp. 161-175 ◽  
Author(s):  
Michael Schulte ◽  
Arne Knief ◽  
Annemarie Seither-Preisler ◽  
Christo Pantev
Keyword(s):  
Auditory Cortex ◽  
Neuronal Plasticity ◽  
Pitch Perception ◽  
Gamma Band ◽  
Base Line ◽  
Band Frequency ◽  
Harmonic Complex ◽  
Fundamental Frequencies ◽  
Complex Tones ◽  
Virtual Pitch

We designed a melody perception experiment involving eight harmonic complex tones of missing fundamental frequencies (hidden auditory object) to study the short-term neuronal plasticity of the auditory cortex. In this experiment, the fundamental frequencies of the complex tones followed the beginning of the virtual melody of the tune “Frère Jacques”. The harmonics of the complex tones were chosen so that the spectral melody had an inverse contour when compared with the virtual one. Evoked magnetic fields were recorded contralaterally to the ear of stimulation from both hemispheres. After a base line measurement, the subjects were exposed repeatedly to the experimental stimuli for 1 hour a day. All subjects reported a sudden change in the perceived melody, indicating possible reorganization of the cortical processes involved in the virtual pitch formation. After this switch in perception, a second measurement was performed. Cortical sources of the evoked gamma-band activity were significantly stronger and located more medially after a switch in perception. Independent Component Analysis revealed enhanced synchronization in the gamma-band frequency range. Comparing the gamma-band activation of both hemispheres, no laterality effects were observed. The results indicate that the primary auditory cortices are involved in the process of virtual pitch perception and that their function is modifiable by laboratory manipulation.

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