Neural correlates of auditory feedback control in human

Auditory feedback plays an important role in natural speech production. We conducted a functional magnetic resonance imaging (fMRI) experiment using a transformed auditory feedback (TAF) method to delineate the neural mechanism for auditory feedback control of pitch. Twelve right-handed subjects were required to vocalize /a/ for 5 s, while hearing their own voice through headphones. In the TAF condition, the pitch of the feedback voice was randomly shifted either up or down from the original pitch two or three times in each trial. The subjects were required to hold the pitch of the feedback voice constant by changing the pitch of original voice. In non-TAF condition, the pitch of the feedback voice was not modulated and the subjects just vocalized /a/ continuously. The contrast between TAF and non-TAF conditions revealed significant activations; the supramarginal gyrus, the prefrontal area, the anterior insula, the superior temporal area and the intraparietal sulcus in the right hemisphere, but only the premotor area in the left hemisphere. This result suggests that auditory feedback control of pitch is mainly supported by the right hemispheric network.     

The effect of species-specific vocalization on the discharge of auditory cortical cells in the awake squirrel monkey (Saimiri sciureus)

Summary Action potentials of single auditory cortical neurons of the squirrel monkey were recorded in a chronic, unanesthetized preparation. The responsiveness of units was tested with various types of simple and complex acoustic stimuli in a free field situation. As simple auditory stimuli, bursts of pure tones, clicks, and white noise were utilized. Species-specific vocalizations served as complex, biologically significant stimuli.The data are based on 48 neurons which showed a discrete response to speciesspecific vocalizations. In 63% the response to calls could be predicted from the units' responses to simple stimuli. Thirty-seven percent of the neurons were classified as unpredictable with respect to their responsiveness to vocalizations. The response of most units was restricted to call stimuli which showed similarities in their frequency-time characteristics. About 7% of the 116 units responding to calls were classified as selective responders because they were not excited by any other stimulus tested. It was not possible to single out the acoustic features to which these units responded.Peter Winter died in an skiing accident in March, 1972.     

On the detection of auditory deviations: A pre-attentive activation model

The conscious perception of infrequent deviant sounds occurring in a series of frequent standard sounds may in part be based on the output of an obligatorily operating deviance detection system. This system encodes invariances inherent to the recent auditory stimulation into short-lived representations of auditory sensory memory and compares each actual input with these representations. The underlying processes may be regarded as preattentive in the sense that they do not rely on the explicit intention of a person to detect deviants and that they may be active even in the absence of attention (although they may be prone to attentional modulations). The output of this feature-specific preattentive deviance detection system fuses into an integrated mismatch signal that in turn may activate subsequent processes that result in the triggering of a motor response.     

ERP correlates of online monitoring of auditory feedback during vocalization

When speakers hear the fundamental frequency (F0) of their voice altered, they shift their F0 in the direction opposite the perturbation. The current study used ERPs to examine sensory processing of short feedback perturbations during an ongoing utterance. In one session, participants produced a vowel at an F0 of their own choosing. In another session, participants matched the F0 of a cue voice. An F0 perturbation of 0, 25, 50, 100, or 200 cents was introduced for 100 ms. A mismatch negativity (MMN) was observed. Differences between sessions were only found for 200-cent perturbations. Reduced compensation when speakers experienced the 200-cent perturbations suggests that this larger perturbation was perceived as externally generated. The presence of an MMN, and no earlier (N100) response suggests that the underlying sensory process used to identify and compensate for errors in mid-utterance may differ from feedback monitoring at utterance onset.     

Nonlinear feedback models for the tuning of auditory nerve fibers

The tuning of auditory nerve (AN) fibers is generally characterized by an increase in bandwidth and, for mid- to high-frequency fibers, a downward shift in the center frequency as sound level increases. Changes in bandwidth are accompanied by changes in the phase properties of the fibers; thus the timing of neural discharges also changes as a function of sound level. This study focuses on the magnitude and phase properties of models designed to reproduce the nonlinear properties of AN fibers that were studied electrophysiologically. The forward path of each model consisted of a linear second-order resonance, and each feedback path contained a saturating nonlinearity. In model 1, the feedback path was a simple memoryless, saturating nonlinearity. In model 2, a low-pass filter was added after the feedback nonlinearity. The ability of each model to simulate aspects of the nonlinear tuning of AN fibers is discussed. Model 2 was able to simulate a wider range of nonlinear behavior for different AN fibers and thus has promise for use in simulations of populations of fibers tuned to different frequencies.     

Lability in the responses of cells in the auditory cortex of squirrel monkeys to species-specific vocalizations

Summary The activity of 28 cells located mainly in the secondary auditory cortex (A II) of awake squirrel-monkeys, was extracellularly recorded for periods of up to 6 h. Seven different species-specific vocalizations, which were repeatedly presented to the monkey, were used as auditory stimuli. Twenty-six cells responded, at least once, to one or more vocalizations; 22 cells revealed some change in their response (pattern or strength) to at least one vocalization (change in response). Twenty-one cells exhibited a change in the number and/or type of vocalization to which they responded during the recording period (change in selectivity). At some time during the recording period all the responding cells exhibited a change in response and/or a change in selectivity (change in responsiveness). A change in response of a cell to a vocalization did not necessarily exclude a change in selectivity, associated with the same vocalization, later in time and vice-versa. A change in responsiveness to one vocalization was not necessarily correlated with changes in responsiveness to other vocalizations.     

Temporal characteristics of auditory sensory memory: Neuromagnetic evidence

We investigated the temporal dependencies of N100m, the most prominent deflection of the auditory evoked response, using whole-head neuromagnetic recordings. Stimuli were presented singly or in pairs (tones in the pair were separated by 210 ms) at interstimulus intervals (ISIs) of 0.6–8.1 s. N100m to single stimuli and to the first tone of the pair had similar temporal recovery functions, plateauing at ISIs of 6 s. N100m to the second tone in the pair, which was smaller than that to the first except with short ISIs, plateaued with ISIs of about 4 s. Source analysis revealed that the N100m could be decomposed into two sources separated by about 1 cm on the supratemporal plane. The recovery function of the posterior source was not affected by stimulus presentation, whereas that of the anterior source was. Activity in the anterior area appears to reflect the effects of temporal integration. We relate these results to auditory sensory memory.     

Neural substrates of vocalizations in gulls and pigeons

Summary Vocalizations were obtained by electrically stimulating the inferior colliculus, the auditory thalamic nucleus and a medial hypothalamic nucleus of awake, unrestrained herring gulls, lesser black-backed gulls and pigeons. The significance of the involvement of auditory centres in the motor control of avian calling is discussed. The wide gammut of calls and accompanying behaviour that was elicited is described and related to the normal behaviour, typical of the species concerned. A difference between immature gulls and adult pigeons regarding this relationship is attributed to their differing hormonal states. Attention is drawn to the heterogeneity of temporal characteristics associated with the stimulus induced responses even when elicited from virtually the same site. Incorporating earlier work on the central mechanism of avian vocalizations and based on anatomical, physiological and behavioural considerations it is tentatively concluded that the neural structures involved are linearly organized into a telencephalofugal, efferent system. It is suggested that the inferior colliculus incorporates the origin of a final common pathway to medular motor centres for all vocalization generating structures.Meinem hochverehrten Lehrer Professor Dr. G. Birukow, Göttingen, zu seinem 60. Geburtstag gewidmet.     

Absence of cross-modal reorganization in the primary auditory cortex of congenitally deaf cats

To investigate possible cross-modal reorganization of the primary auditory cortex (field A1) in congenitally deaf cats, after years of auditory deprivation, multiunit activity and local field potentials were recorded in lightly anesthetized animals and compared with responses obtained in hearing cats. Local field potentials were also used for current source-density analyses. For visual stimulation, phase-reversal gratings of three to five different spatial frequencies and three to five different orientations were presented at the point of central vision. Peripheral visual field was tested using hand-held stimuli (light bar-shaped stimulus of different orientations, moved in different directions and flashed) typically used for neurophysiological characterization of visual fields. From 200 multiunit recordings, no response to visual stimuli could be found in A1 of any of the investigated animals. Using the current source-density analysis of local field potentials, no local generators of field potentials could be found within A1, despite of the presence of small local field potentials. No multiunit responses to somatosensory stimulation (whiskers, face, pinna, head, neck, all paws, back, tail) could be obtained. In conclusion, there were no indications for a cross-modal reorganization (visual, somatosensory) of area A1 in congenitally deaf cats.     

Vocal analysis related to changes in frequency of pure tone auditory feedback

Purpose

Many studies have shown that subjects show a change of vocal fundamental frequency (F0) when phonating subjects hear their vocal pitch feedback shifted upward or downward. This study was performed to demonstrate whether vocal parameters [F0, intensity, jitter, shimmer, and noise to harmonic ratio (NHR)] in normal males respond to changes in frequency of pure tone masking.

Materials and Methods

Twenty healthy male subjects participated in this study. Subjects vocalized /a/ vowel sounds while listening to a pitch-shift pure tone through headphones (upward pitch-shift in succession: 1kHz to 2 kHz and 1 kHz to 4 kHz at 50 dB or 80 dB, respectively, downward pitch-shift in succession: 1 kHz to 250 Hz and 1 kH to 500 Hz at 50 dB or 80 dB, respectively).

Results

Vocal intensity, F0, was increased, whereas jitter was decreased as the pitch of pure tone was shifted upward. However, there was no correlation between shimmer and NHR with pitch-shift feedback for pure tones. Unlike vocal pitch-shift feedback in other studies, upward pitch-shift feedback of pure tones caused the vocal F0 and intensity to change in the same direction as pitch-shift.

Conclusion

The results of this study demonstrated that auditory kinesthetic feedback is affected by pitch-shift in pure tone.     

Interactions between auditory and somatosensory feedback for voice <Emphasis Type="Italic">F</Emphasis><Subscript>0</Subscript> control

Previous studies have demonstrated the importance of both kinesthetic and auditory feedback for control of voice fundamental frequency (F ₀). In the present study, a possible interaction between auditory feedback and kinesthetic feedback for control of voice F ₀ was tested by administering local anesthetic to the vocal folds in the presence of perturbations in voice pitch feedback. Responses to pitch-shifted voice feedback were larger when the vocal fold mucosa was anesthetized than during normal kinesthesia. A mathematical model incorporating a linear combination of kinesthesia and pitch feedback simulated the main aspects of our experimental results. This model indicates that a feasible explanation for the increase in response magnitude with vocal fold anesthesia is that the vocal motor system uses both pitch and kinesthesia to stabilize voice F ₀ shortly after a perturbation of voice pitch feedback has been perceived.     

ERP correlates of auditory processing during automatic correction of unexpected perturbations in voice auditory feedback

Auditory sensory processing is an important element of the neural mechanisms controlling human vocalization. We evaluated which components of Event Related Potentials (ERP) elicited by the unexpected shift of fundamental frequency in a subject's own voice might correlate with his/her ability to process auditory information. A significant negative correlation between the latency of the N1 component of the ERP and the Montreal Battery of Evaluation of Amusia scores for Melodic organization was found. A possible functional role of neuronal activity underling the N1 component in voice control mechanisms is discussed.     

A multimodal brain-based feedback and communication system

The Thought Translation Device (TTD) is a brain-computer interface based on the self-regulation of slow cortical potentials (SCPs) and enables completely paralyzed patients to communicate using their brain potentials. Here, an extended version of the TTD is presented that has an auditory and a combined visual and auditory feedback modality added to the standard visual feedback. This feature is necessary for locked-in patients who are no longer able to focus their gaze. In order to test performance of physiological regulation with auditory feedback 54 healthy participants were randomly assigned to visual, auditory or combined visual-auditory feedback of slow cortical potentials. The training consisted of three sessions with 500 trials per session with random assignment of required cortical positivity or negativity in half of the trials. The data show that physiological regulation of SCPs can be learned with auditory and combined auditory and visual feedback although the performance of auditory feedback alone was significantly worse than with visual feedback alone.This study was supported by the Deutsche Forschungsgemeinschaft (DFG) SFB 550/B5, and the National Institute of Health (NIH)     

The contribution of general and specific motor inhibitory sets to the so-called auditory inhibition of return

The detection of sounds that come from a region of space recently exposed to acoustic stimulation is often slower than the detection of sounds coming from regions of space previously unexposed to acoustic stimulation. The relative increase in reaction time (RT) to targets in recently stimulated locations is generally termed "inhibition of return" (IOR). This term alludes to the possibility that spatial attention is biased against returning to recently visited locations, thus favoring the sampling of new sources of information. However, auditory IOR effects found in paradigms where subjects have to detect a first sound (cue) without making an overt response to it, and then respond as fast as possible to a second sound (target), may be due to a purely motor inhibition carried over from cue to target. Such motor inhibition has been shown to be maximal when cue and target belong to the same category, such as when they occupy the same spatial position. We have assessed the possible contribution of this motor inhibition to auditory IOR effects by having subjects respond to both cues and targets randomly presented in a right location and a left location. Reaction time to targets preceded by cues at the same location was longer than reaction times to targets preceded by cues at the opposite location (IOR effect). Compared to a condition in which subjects responded only to targets, the IOR effect was smaller, but still significant, in the double response condition, suggesting that such an effect depends on both motor inhibition and other factors, possibly related to covert spatial orienting and oculomotor control. A second experiment indicated that the IOR effect component independent of motor inhibition was slightly but significantly greater when space was relevant to the task because subjects had to report the positions of both cues and targets, compared to when space was irrelevant to the task because subjects were not required to report stimulus positions.     

Sensory interactions in the anterior ectosylvian cortex of cats

Sensory interactions, namely, the responses of single cells to stimulations originating from the two sides of the body or from the two visual fields, or from more than one sensory modality (namely, visual, auditory and somatosensory), were evaluated within the anterior ectosylvian cortex (AEC) of cats. Results showed that responses of single neurons to a stimulus of one modality can be enhanced or inhibited by the presentation of another stimulus of either the same or another modality. This facilitatory or inhibitory modulation seems to depend upon temporal and/or spatial relationships between the stimuli. These results, taken together with those previously obtained in our laboratory and by others, suggest that neurons in the AEC may be involved in integrating inputs from various modalities and possibly linking sensory input with action.     

咽鼓管区薄层断层解剖学研究

目的 :研究咽鼓管及其周围结构的断面形态及相互解剖关系 ,为临床影像学诊断提供解剖学依据。方法 :利用生物塑化技术 ,将 9侧咽鼓管区及相邻结构制成三个方位 (横断、冠状位及矢状位 )的薄层断层标本 ,观察咽鼓管及周围结构在各方位上的解剖关系。结果 :咽鼓管由骨部和软骨部构成 ,是中耳与鼻咽之间的通道。纤维软骨位于咽鼓管后内侧 ,其上缘向外弯曲形成软骨部的顶。咽鼓管咽筋膜封闭咽鼓管前外侧并向下延伸构成咽鼓管的下壁。腭帆张肌位于咽鼓管前外侧 ,腭帆提肌位于其外后下方。粘膜下筋膜位于腭帆提肌的内侧 ,咽颅底筋膜走行于腭帆张肌和腭帆提肌之间 ,Weber Liel筋膜位于腭帆张肌外侧。结论 :咽鼓管及其周围肌肉、筋膜构成鼻咽的外侧壁 ,可防止肿瘤向外扩展。在横、冠状塑化薄层断面上可较好显示咽鼓管的正常解剖结构及毗邻关系 ,对鼻咽区病变的影像诊断具有重要参考价值     

Gastric saline infusion reduces ultrasonic vocalizations and brown fat activity in suckling rat pups

Under standard conditions involving isolation and cooling, it has been documented that intraoral infusion of milk and injection of the intestinal peptide cholecystokinin (CCK) result in an attenuation in ultrasonic vocalizations (USV) emitted by infant rat pups. One of the most effective stimuli in inhibiting ingestion in suckling rat pups is gastric distension, but the effect of gastric distension on USV production has not been reported. In this experiment, we subjected infant rats to intragastric infusion of isotonic saline (2% body weight) to produce a natural level of gastric distension and hydration. We found that this stimulus resulted in a powerful reduction in USV emissions in isolated 10-day-old rats. In a subsequent experiment, we found that gastric saline infusion also diminished brown adipose tissue (BAT) thermogenesis. There were different time courses of the gastric saline infusion effects on BAT thermogenesis and on USV emissions, however, suggesting that these processes may be independently regulated. We hypothesize that this stimulus induces a transient activation of the parasympathetic nervous system, which overrides the sympathetic control of BAT and USV production.     

Early APV chronic blocked alters experience-dependent plasticity of auditory spatial representation in rat auditory cortical neurons

Development of auditory function can be affected by environment and experience. In this study, we investigated whether the NMDA receptor mediates the plasticity of auditory spatial representation during development of the rat auditory cortex. We found that early auditory experience significantly increased the auditory spatial sensitivity of A1 neurons and induced training-dependent plasticity. Implantation of Elvax-APV in the auditory cortex gradually reduced the auditory spatial sensitivity of A1 neurons and blocked the auditory spatial plasticity induced by early auditory experience. These results indicate that the NMDA receptor has a key role in experience-dependent plasticity of auditory cortical circuits immediately after birth.     

The role of amygdala during auditory verbal imagery of derogatory appraisals by others

We tend to simulate or recall others’ appraisals through auditory verbal imagery (AVI) process to react appropriately. In particular, the ability to imagine derogatory appraisals by others may be critically important for social survival. In this study, we investigated the neural correlates implicated in the processing of unpleasant emotion related to derogatory remark and its self-directedness during AVI process. Twenty-three right-handed healthy human subjects participated in our study. We asked each subject to imagine hearing one’s own or another person’s voice saying derogatory or non-derogatory neutral remarks during the scanning of functional magnetic imaging. A test of the interaction between derogatory emotion and its self-directedness revealed significant activation of the amygdala. Additionally, we observed decreased neural activity in the anterior cingulate cortex (ACC) during imagery of derogatory remarks compared to neutral remarks. Our findings indicate an important role of the amygdala in the processing of unpleasant emotion or self-relevance of information in the real world may also be expanded to the processing of self-directedness of unpleasant emotion in the imagined world, and thereby contribute to human higher social cognitive process. This study also suggests that deactivation of ACC may enable us to enact vivid affective responses, and thereby contribute to an effective simulation of social interaction.     

Fine-tuning of auditory cortex during speech production

The cortex suppresses sensory information when it is the result of a self-produced motor act, including the motor act of speaking. The specificity of the auditory cortical suppression to self-produced speech, a prediction derived from the posited operation of a precise forward model system, has not been established. We examined the auditory N100 component of the event-related brain potential elicited during speech production. While subjects uttered a vowel, they heard real-time feedback of their unaltered voice, their pitch-shifted voice, or an alien voice substituted for their own. The subjects' own unaltered voice feedback elicited a dampened auditory N100 response relative to the N100 elicited by altered or alien auditory feedback. This is consistent with the operation of a precise forward model modulating the auditory cortical response to self-generated speech and allowing immediate distinction of self and externally generated auditory stimuli.