Composite analysis of right-sided subjects.

<p>Lateral hemispheric surface renderings of right-sided subjects (n = 4) showing recording sites where responses were significantly different for the SV versus PB conditions (filled circles) during the first 250 ms following stimulus onset. In three of the four subjects shown, a large number of STG contacts showed a statistically significant <i>decrease</i> in AEP responses during SV (panel A, filled black circles), and there were no sites where responses were increased during SV. Sites showing statistically significant differences in HGB power responses for the two conditions are shown in panel B (filled circles). In all four subjects STG sites were identified where HGB power <i>decreased</i> significantly during SV (filled black circles, panel B). With the exception of subject 175, a smaller number of recording sites show a significant reduction in HGB power compared to the number of sites showing reductions in AEP responses. In all right hemisphere subjects, sites were identified where significant <i>increases</i> in HGB power occurred during SV (red circles). These sites were observed in different STG and non-STG locations that did not conform to a consistent anatomical pattern across subjects.</p

Some sites within auditory cortex demonstrate increased HGB activity during self-vocalization compared to playback.

<p>These are four example subjects as labeled (A–D, left column) with the surface rendering of each subject's MRI with the recording site indicated (filled blue circle, right column). In each subject, these brain sites demonstrated increased averaged HGB power responses during SV (red waveforms, middle column) compared to responses obtained during PB (black waveforms, middle column). These HGB responses were ‘sustained’ throughout and beyond the duration of the utterance during SV, while the PB HGB responses were more consistent with an ‘on’ response.</p

Averaged evoked potentials recorded from subject 156 during self-vocalization and playback.

<p>(A) MRI surface rendering of the subject's left hemisphere demonstrating the location of the 96 contact recording array. Filled black circles denote contacts where the AEPs recorded during SV were attenuated (p<.01, 0–500 msec post-stimulus) compared to the AEPs recorded during the PB condition. (B) AEPs recorded from the lateral surface of the cerebral hemisphere during SV. The timing of vocalization onset is represented in each waveform panel by a vertical line. Thick gray lines represent major sulci as labeled on the lateral hemispheric surface in A. (C) AEPs obtained during PB. Two clusters of recording sites with maximal evoked activity are observed at locations along the superior temporal gyrus anterior and posterior to the transverse temporal sulcus. (LF-lateral fissure, STS-superior temporal sulcus, ITS-inferior temporal sulcus, TTS- transverse temporal sulcus).</p

Time-frequency analysis of subject 156's responses during self-vocalization and playback.

<p>(A) MRI surface rendering of the left cerebral hemisphere showing the locations of all recording contacts and major sulci. In this figure, filled black circles denote contacts where significant <i>decreases</i> (p<.01, 0–500 msec post-stimulus) in high gamma band (HGB, 70–150 Hz) power occurred during self-vocalization (SV) compared to playback (PB). Red circles indicate contacts where significant <i>increases</i> in high gamma band power were observed during SV compared to PB. (B) Broad-band time-frequency analysis (2–250 Hz) of evoked responses recorded during SV. Individual panels display the power responses for each frequency band at each recording site (−.25 sec to 1 sec post-voice onset). The largest responses are seen to occur between 70–150 Hz. Thick gray lines represent the major sulci as labeled in A. (C) Time-frequency analysis of evoked responses recorded during the PB condition (LF-lateral fissure, STS-superior temporal sulcus, ITS-inferior temporal sulcus, TTS- transverse temporal sulcus).</p

Vocalization-associated changes in auditory responses are not significantly altered by changes in PB intensity.

<p>Different intensities of the PB stimuli were tested in the three subjects shown. Each vertical column displays a recording site location (top, filled blue circle), sound stimulus envelope tracings (middle) and the evoked responses recorded from the selected recording site (bottom) for each subject. (A) Subject 146 perceived the PB stimuli to be both “softer” and “louder” than the SV stimuli despite the fact that the sound stimulus envelope was smaller at both PB intensities than those measured during SV. The AEP waveform is nearly identical for the ‘softer’ and ‘louder’ PB stimuli, and is completely attenuated during SV. The high-gamma (HGB) response shows a ‘sustained’ pattern during SV, and an ‘on’ pattern during both PB conditions, with the early HGB increase seen during PB to be attenuated during SV. Subjects 147 (B) and 149 (C) both perceived the PB stimuli to be both “softer” and “louder” than the SV stimuli yet for these subjects the measured sound stimuli envelopes were greater for both PB intensities compared to that measured during SV. Like subject 146, both subjects demonstrate attenuation of the AEP and HGB power responses during SV compared to both PB intensities, and little difference is seen in AEP and HGB power responses between the PB intensities.</p

STG evoked responses demonstrate very localized effects of vocalization on speech-sound processing.

<p>(A) Surface rendered MRI of the left hemisphere of subject 147. Recording contact locations are depicted by open circles. The four colored contacts are positioned over auditory area PLST and were selected to demonstrate the spatial distribution of vocalization-induced effects on sound processing. The center-to-center distance between the contacts is 5 mm. (B) The individual trial sound stimulus envelopes (gray lines) and the average of all utterances (black line) of the utterance ‘birthday’ are displayed, with time 0 denoting onset of the first syllable. (C) Neural responses recorded from the four recording sites as labeled in A, with AEPs in the top row, and time-frequency spectrograms during SV (middle row) and PB (lower row). The most anterior of the four contacts (<i>green</i> circle) shows attenuation in the average evoked response during SV (red line) compared to PB (black line) and HGB attenuation of the onset response but a sustained increase in HGB activity during SV compared to PB. Five millimeters posteriorly, the AEP recorded from the <i>blue</i> contact is minimally affected by vocalization, and there are minimal HGB responses during either SV or PB. The largest amplitude AEP is observed at the <i>magenta</i> contact, and the initial positive deflection in this response is completely attenuated, while the later negative deflection is slightly delayed but the amplitude is preserved during SV compared to PB. Large increases in HGB power were observed in response to each of the two syllables in the stimulus during both the SV and PB conditions. The most posterior of the four contacts (<i>yellow</i>) shows AEP attenuation during SV, and minimal attenuation of the HGB response, which is only an onset response during both SV and PB, and markedly different than the responses from the neighboring contact 5 mm anterior (magenta). (LF-lateral fissure, STS-superior temporal sulcus, TTS- transverse temporal sulcus).</p

Right STG AEP and HGP Modulation.

<p>Anatomical location of contacts in subjects with right-hemisphere temporal lobe implantation that show significant AEP (left panel) and high gamma (70–150 Hz) power modulation (right panel) in response to PSS during speaking compared with playback. The graded color-coded circles at each contact site correspond to the degree of the speaking-induced enhancement (red circles) or attenuation (blue circles) of the AEP and high gamma responses, measured by the modulation index. In the left panel, the overlaid AEP traces are shown for a STG contact (black arrow) with significant speaking-induced AEP enhancement for each subject. In the right panel, the overlaid high gamma power traces along with time-frequency plots of the spectral power are shown for a STG contact (black arrow) with significant high gamma power enhancement during speaking compared with playback.</p

Left STG AEP and HGP Modulation.

<p>Anatomical location of contacts in subjects with left-hemisphere temporal lobe implantation that show significant AEP (right panel) and high gamma (70–150 Hz) power modulation (left panel) in response to PSS during speaking compared with playback. The graded color-coded circles at each contact site correspond to the degree of the speaking-induced enhancement (red circles) or attenuation (blue circles) of the AEP and high gamma responses, measured by the modulation index. In the right panel, the overlaid AEP traces are shown for a STG contact (black arrow) with significant speaking-induced AEP enhancement for each subject. In the left panel, the overlaid high gamma power traces along with time-frequency plots of the spectral power are shown for a STG contact (black arrow) with significant high gamma power enhancement during speaking compared with playback.</p

Left and Right STG High Gamma Response Patterns to PSS.

<p>Topographical maps for each subject demonstrating the consistent focus of high gamma (70–150 Hz) power increases on the posterior portion of STG in both left (a) and right (b) hemisphere subjects. Power responses are depicted as normalized values (+/−1) based on the contact for each subject demonstrating maximal high gamma power amplitude in a 0–500 ms post-pitch shift stimulus time window. In each sub-panel, the distribution maps are shown for responses to pitch-shift stimuli during speaking (left) and playback (right) conditions, separately.</p

Measures of the compensatory vocal responses to downward (−100 cents) pitch-shifts in voice auditory feedback.

<p>Measures of the compensatory vocal responses to downward (−100 cents) pitch-shifts in voice auditory feedback.</p