Biomedical subjects

Sonja Lattner

Publications and source records attributed to Sonja Lattner.

6 recordsLinked to original sources

PubMed2006

Phonemic restoration in a sentence context: evidence from early and late ERP effects.

When a particular speech sound is obliterated and replaced by a non-speech sound in continuous speech the listener may not notice any disturbance in speech or have difficulties in understanding the word. The present study examined for the first time neurophysiological correlates of the perception of words with an obliterated initial phoneme. Behavioral responses and event-related potentials (ERPs) were measured while participants listened to naturally spoken sentences which had a highly or less expected final word. Half of the sentences were manipulated to have a cough replacing the beginning of the final word, thus, reducing the initial phonetic information available for the word recognition. An N1-P2 complex indicated an automatic registration of the cough's onset. An early negativity to less expected relative to highly expected words was observed for phonetically intact words but not for manipulated words. Although the N400 effect to manipulated words was elicited later than to intact words, after the fragment onset, its amplitude was not enhanced. Further, no significant enhancement of the N400 was found for the manipulated highly expected words. This finding, together with behavioral results, indicated an easier integration of the manipulated highly expected words with the sentence context than of intact but less expected words. Taken together, the study demonstrates an efficient usage of both a context-driven expectancy of the suitable word as well as a stimulus-driven processing of the phonetic information during online perception of speech. The present ERP results support the earlier behavioral research in showing that phonemic restoration is not a bottom-up phenomenon but rather reflects a top-down repair process.

Acoustic Stimulation↗

PubMed2005

Voice perception: Sex, pitch, and the right hemisphere.

The present functional magnetic resonance imaging (fMRI) study examined the neurophysiological processing of voice information. The impact of the major acoustic parameters as well as the role of the listener's and the speaker's gender were investigated. Male and female, natural, and manipulated voices were presented to 16 young adults who were asked to judge the naturalness of each voice. The hemodynamic responses were acquired by a 3T Bruker scanner utilizing an event-related design. The activation was generally stronger in response to female voices as well as to manipulated voice signals, and there was no interaction with the listener's gender. Most importantly, the results suggest a functional segregation of the right superior temporal cortex for the processing of different voice parameters, whereby (1) voice pitch is processed in regions close and anterior to Heschl's Gyrus, (2) voice spectral information is processed in posterior parts of the superior temporal gyrus (STG) and areas surrounding the planum parietale (PP) bilaterally, and (3) information about prototypicality is predominately processed in anterior parts of the right STG. Generally, by identifying distinct functional regions in the right STG, our study supports the notion of a fundamental role of the right hemisphere in spoken language comprehension.

Acoustic Stimulation↗

PubMed2004

Pre-attentive auditory processing of lexicality.

The effects of lexicality on auditory change detection based on auditory sensory memory representations were investigated by presenting oddball sequences of repeatedly presented stimuli, while participants ignored the auditory stimuli. In a cross-linguistic study of Hungarian and German participants, stimulus sequences were composed of words that were language-familiar, lexical, meaningful in Hungarian but language-unfamiliar, not lexical, meaningless in German, and words with the opposite characteristics. The roles of frequently presented stimuli (Standards) and infrequently presented one (Deviants) were fully crossed. Language-familiar and language-unfamiliar Deviants elicited the Mismatch Negativity component of the event-related brain potential. We found differences in processes of change detection depending on whether the Standard was language-familiar, or not. Whereas, the lexicality of the Deviant had no effect on the processes of change detection. Also, language-familiar Standards processed differently than language-unfamiliar ones. We suggest that pre-attentive (default) tuning to meaningful words sets up language-specific preparatory processes that affect change detection in speech sequences.

Adolescent↗

PubMed2003

Talker's voice and gender stereotype in human auditory sentence processing--evidence from event-related brain potentials.

The present study investigated the influence of implicit speaker information on the sentence interpretation. We auditorily presented sentences that comprised of either stereotypically male or stereotypically female self-referent utterances. In the congruent conditions, these utterances were produced by speakers whose gender matched the semantic content. In the incongruent condition, stereotypically male utterances were produced by female speakers and vice versa. The event-related brain potentials (ERP) of 32 listeners exhibited a late positivity (P600) for the incongruent condition. No significant differences were observed between male and female listeners. In the absence of any ERP effect in the earlier time range, it was concluded that the access of the semantic information as such is independent of the speaker's voice, but that speaker property, semantic content and stereotypical knowledge are integrated in a later processing stage.

Adult↗

PubMed2003

Dissociation of human and computer voices in the brain: evidence for a preattentive gestalt-like perception.

We investigated the early ("preattentive") cortical processing of voice information, using the so-called "mismatch response". This brain potential allows inferences to be made about the sensory short-term store. Most importantly, the mismatch potential also provides information about the organization of long-term memory traces in the auditory system. Such traces have reliably been reported for phonemes. However, it is unclear whether they also exist for human voice information. To explore this issue, 10 healthy subjects were presented with a single word stimulus uttered by voices of different prototypicality (natural, manipulated, synthetic) in a mismatch experiment (stimulus duration 380 msec, onset-to-onset interval 900 msec). The event-related magnetic fields were recorded by a 148-channel whole-head magnetometer and a source current density modeling of the magnetic field data was performed using a minimum-norm estimate. Each deviating voice signal in a series of standard-voice stimuli evoked a mismatch response that was localized in temporal brain regions bilaterally. Increased mismatch related magnetic flux was observed in response to decreased prototypicality of a presented voice signal, but did not correspond to the acoustic similarity of standard voice and deviant voices. We, therefore, conclude that the mismatch activation predominantly reflects the ecological validity of the voice signals. We further demonstrate that the findings cannot be explained by mere acoustic feature processing, but rather point towards a holistic mapping of the incoming voice signal onto long-term representations in the auditory memory.

Acoustic Stimulation↗

PubMed2002

Early parallel processing of auditory word and voice information.

The present study investigates the relationship of linguistic (phonetic) and extralinguistic (voice) information in preattentive auditory processing. We provide neurophysiological data, which show for the first time that both kinds of information are processed in parallel at an early preattentive stage. In order to establish the temporal and spatial organization of the underlying neuronal processes, we studied the conjunction of voice and word deviations in a mismatch negativity experiment, whereby the listener's brain responses were collected using magnetoencephalography. The stimuli consisted of single spoken words, whereby the deviants manifested a change of the word, of the voice, or both word and voice simultaneously (combined). First, we identified the N100m (overlain by mismatch field, MMF) and localized its generators, analyzing N100 m/MMF latency, dipole localization, and dipole strength. While the responses evoked by deviant stimuli were more anterior than the standard, localization differences between the deviants could not be shown. The dipole strength was larger for deviants than the standard stimulus, but again, no differences between the deviants could be established. There was no difference in the hemispheric lateralization of the responses. However, a difference between the deviants was observed in the latencies. The N100 m/MMF revealed a significantly shorter and less variant latency for the combined stimulus compared to all other experimental conditions. The data suggest an integral parallel processing model, which describes the early extraction of phonetic and voice information from the speech signal as parallel and contingent processes.

Adult↗