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Neuromagnetic evidence for early auditory restoration of fundamental pitch.

Monahan PJ, de Souza K, Idsardi WJ - PLoS ONE (2008)

Bottom Line: We compared the M100 latencies of these tone complexes to the M100 latencies elicited by their respective pure tone (spectral pitch) counterparts.The M100 latencies for the tone complexes matched their pure sinusoid counterparts, while also replicating the M100 temporal latency response curve found in previous studies.Our findings suggest that listeners are reconstructing the inferred pitch by roughly 100 ms after stimulus onset and are consistent with previous electrophysiological research suggesting that the inferential pitch is perceived in early auditory cortex.

View Article: PubMed Central - PubMed

Affiliation: Department of Linguistics, University of Maryland, College Park, Maryland, United States of America. pmonahan@umd.edu

ABSTRACT

Background: Understanding the time course of how listeners reconstruct a missing fundamental component in an auditory stimulus remains elusive. We report MEG evidence that the missing fundamental component of a complex auditory stimulus is recovered in auditory cortex within 100 ms post stimulus onset.

Methodology: Two outside tones of four-tone complex stimuli were held constant (1200 Hz and 2400 Hz), while two inside tones were systematically modulated (between 1300 Hz and 2300 Hz), such that the restored fundamental (also knows as "virtual pitch") changed from 100 Hz to 600 Hz. Constructing the auditory stimuli in this manner controls for a number of spectral properties known to modulate the neuromagnetic signal. The tone complex stimuli only diverged on the value of the missing fundamental component.

Principal findings: We compared the M100 latencies of these tone complexes to the M100 latencies elicited by their respective pure tone (spectral pitch) counterparts. The M100 latencies for the tone complexes matched their pure sinusoid counterparts, while also replicating the M100 temporal latency response curve found in previous studies.

Conclusions: Our findings suggest that listeners are reconstructing the inferred pitch by roughly 100 ms after stimulus onset and are consistent with previous electrophysiological research suggesting that the inferential pitch is perceived in early auditory cortex.

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Comparison of the MEG waveforms to a pure sinusoid (in this case, 600 Hz) and tone complex with the corresponding inferred fundamental (in this case, 12-18-24) for a representative subject.Data is the RMS from 10 channels (five sink, five source) in the left hemisphere. The peak around 100 ms post-onset of the target (0 ms represents the onset of the target) is the M100. The peak latency of the M100 to the pure sinusoid and its corresponding tone complex were closely matched. The head-models represent the magnetic field contours for the M100. The red regions represent the source of the dipole and the blue regions represent the sink of the dipole.
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pone-0002900-g002: Comparison of the MEG waveforms to a pure sinusoid (in this case, 600 Hz) and tone complex with the corresponding inferred fundamental (in this case, 12-18-24) for a representative subject.Data is the RMS from 10 channels (five sink, five source) in the left hemisphere. The peak around 100 ms post-onset of the target (0 ms represents the onset of the target) is the M100. The peak latency of the M100 to the pure sinusoid and its corresponding tone complex were closely matched. The head-models represent the magnetic field contours for the M100. The red regions represent the source of the dipole and the blue regions represent the sink of the dipole.

Mentions: Figure 2 illustrates the RMS of a typical neuromagnetic response to both the pure sinusoid and its corresponding tone complex. Figure 3 shows mean M100 latency as a function of the fundamental frequency or missing fundamental. Statistical analyses were done using mixed-effects ANOVAs with Subject as a random effect, excluding the 12-17-19-24 complex tone to maintain a balanced design. Analysis of the latencies of the M100 responses showed main effects of frequency (F(5,88) = 11.15; p<0.0001) and signal type (pure sinusoid vs. tone complex; F(1,88) = 6.00; p = 0.016), but crucially, there was no interaction between signal type and frequency (F(5,88) = 1.02; p = 0.41). In planned post-hoc comparisons, we found no significant differences at each frequency between the M100 latency to the pure sinusoid and the M100 latency to the tone complex, though the difference between the M100 response latency to the 100 Hz sinusoid and the 100 Hz inferred pitch tone complex (12-13-23-24) was marginally significant (t(8) = 2.48; p = 0.015, n.s. due to multiple-comparisons correction, all others p>0.12). Analysis of the M100 amplitudes revealed a weakly significant main effect of frequency in which higher frequencies have larger amplitudes (F(5,88) = 2.79; p = 0.022), no main effect for signal type (F(1,88) = 0.54; p = 0.46), and a significant interaction between frequency and signal type (F(5,88) = 5.82; p<0.0001). Post-hoc comparisons (Tukey-Kramer honestly significant differences) found only one significant contrast: the amplitude of the sinusoidal 100 Hz response is significantly weaker than the amplitude of the sinusoidal 1200 Hz response. The significant interaction effect is due to a cross-over between the sinusoidal responses (which have increasing amplitudes with increasing frequency) and a generally level amplitude response to all of the tone complexes.


Neuromagnetic evidence for early auditory restoration of fundamental pitch.

Monahan PJ, de Souza K, Idsardi WJ - PLoS ONE (2008)

Comparison of the MEG waveforms to a pure sinusoid (in this case, 600 Hz) and tone complex with the corresponding inferred fundamental (in this case, 12-18-24) for a representative subject.Data is the RMS from 10 channels (five sink, five source) in the left hemisphere. The peak around 100 ms post-onset of the target (0 ms represents the onset of the target) is the M100. The peak latency of the M100 to the pure sinusoid and its corresponding tone complex were closely matched. The head-models represent the magnetic field contours for the M100. The red regions represent the source of the dipole and the blue regions represent the sink of the dipole.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2483422&req=5

pone-0002900-g002: Comparison of the MEG waveforms to a pure sinusoid (in this case, 600 Hz) and tone complex with the corresponding inferred fundamental (in this case, 12-18-24) for a representative subject.Data is the RMS from 10 channels (five sink, five source) in the left hemisphere. The peak around 100 ms post-onset of the target (0 ms represents the onset of the target) is the M100. The peak latency of the M100 to the pure sinusoid and its corresponding tone complex were closely matched. The head-models represent the magnetic field contours for the M100. The red regions represent the source of the dipole and the blue regions represent the sink of the dipole.
Mentions: Figure 2 illustrates the RMS of a typical neuromagnetic response to both the pure sinusoid and its corresponding tone complex. Figure 3 shows mean M100 latency as a function of the fundamental frequency or missing fundamental. Statistical analyses were done using mixed-effects ANOVAs with Subject as a random effect, excluding the 12-17-19-24 complex tone to maintain a balanced design. Analysis of the latencies of the M100 responses showed main effects of frequency (F(5,88) = 11.15; p<0.0001) and signal type (pure sinusoid vs. tone complex; F(1,88) = 6.00; p = 0.016), but crucially, there was no interaction between signal type and frequency (F(5,88) = 1.02; p = 0.41). In planned post-hoc comparisons, we found no significant differences at each frequency between the M100 latency to the pure sinusoid and the M100 latency to the tone complex, though the difference between the M100 response latency to the 100 Hz sinusoid and the 100 Hz inferred pitch tone complex (12-13-23-24) was marginally significant (t(8) = 2.48; p = 0.015, n.s. due to multiple-comparisons correction, all others p>0.12). Analysis of the M100 amplitudes revealed a weakly significant main effect of frequency in which higher frequencies have larger amplitudes (F(5,88) = 2.79; p = 0.022), no main effect for signal type (F(1,88) = 0.54; p = 0.46), and a significant interaction between frequency and signal type (F(5,88) = 5.82; p<0.0001). Post-hoc comparisons (Tukey-Kramer honestly significant differences) found only one significant contrast: the amplitude of the sinusoidal 100 Hz response is significantly weaker than the amplitude of the sinusoidal 1200 Hz response. The significant interaction effect is due to a cross-over between the sinusoidal responses (which have increasing amplitudes with increasing frequency) and a generally level amplitude response to all of the tone complexes.

Bottom Line: We compared the M100 latencies of these tone complexes to the M100 latencies elicited by their respective pure tone (spectral pitch) counterparts.The M100 latencies for the tone complexes matched their pure sinusoid counterparts, while also replicating the M100 temporal latency response curve found in previous studies.Our findings suggest that listeners are reconstructing the inferred pitch by roughly 100 ms after stimulus onset and are consistent with previous electrophysiological research suggesting that the inferential pitch is perceived in early auditory cortex.

View Article: PubMed Central - PubMed

Affiliation: Department of Linguistics, University of Maryland, College Park, Maryland, United States of America. pmonahan@umd.edu

ABSTRACT

Background: Understanding the time course of how listeners reconstruct a missing fundamental component in an auditory stimulus remains elusive. We report MEG evidence that the missing fundamental component of a complex auditory stimulus is recovered in auditory cortex within 100 ms post stimulus onset.

Methodology: Two outside tones of four-tone complex stimuli were held constant (1200 Hz and 2400 Hz), while two inside tones were systematically modulated (between 1300 Hz and 2300 Hz), such that the restored fundamental (also knows as "virtual pitch") changed from 100 Hz to 600 Hz. Constructing the auditory stimuli in this manner controls for a number of spectral properties known to modulate the neuromagnetic signal. The tone complex stimuli only diverged on the value of the missing fundamental component.

Principal findings: We compared the M100 latencies of these tone complexes to the M100 latencies elicited by their respective pure tone (spectral pitch) counterparts. The M100 latencies for the tone complexes matched their pure sinusoid counterparts, while also replicating the M100 temporal latency response curve found in previous studies.

Conclusions: Our findings suggest that listeners are reconstructing the inferred pitch by roughly 100 ms after stimulus onset and are consistent with previous electrophysiological research suggesting that the inferential pitch is perceived in early auditory cortex.

Show MeSH