Biomedical subjects

István Winkler

Publications and source records attributed to István Winkler.

At least 19 recordsLinked to original sources

PubMed2006

Object representation in the human auditory system.

One important principle of object processing is exclusive allocation. Any part of the sensory input, including the border between two objects, can only belong to one object at a time. We tested whether tones forming a spectro-temporal border between two sound patterns can belong to both patterns at the same time. Sequences were composed of low-, intermediate- and high-pitched tones. Tones were delivered with short onset-to-onset intervals causing the high and low tones to automatically form separate low and high sound streams. The intermediate-pitch tones could be perceived as part of either one or the other stream, but not both streams at the same time. Thus these tones formed a pitch 'border' between the two streams. The tones were presented in a fixed, cyclically repeating order. Linking the intermediate-pitch tones with the high or the low tones resulted in the perception of two different repeating tonal patterns. Participants were instructed to maintain perception of one of the two tone patterns throughout the stimulus sequences. Occasional changes violated either the selected or the alternative tone pattern, but not both at the same time. We found that only violations of the selected pattern elicited the mismatch negativity event-related potential, indicating that only this pattern was represented in the auditory system. This result suggests that individual sounds are processed as part of only one auditory pattern at a time. Thus tones forming a spectro-temporal border are exclusively assigned to one sound object at any given time, as are spatio-temporal borders in vision.

Acoustic Stimulation↗

PubMed2006

Association between dopamine D4 receptor (DRD4) gene polymorphisms and novelty-elicited auditory event-related potentials in preschool children.

We investigated associations of the exon III repeat and the -521 C/T polymorphisms of the DRD4 gene with novelty-elicited auditory ERP components and behavioral resistance to distraction in 57 healthy, typically developing 6-year-old children. Dopamine-related gene polymorphisms have previously been linked to processes directing focused attention. We did not find associations between the 7-repeat allele or the T.7 haplotype and the early ERP responses suggesting that DRD4 polymorphisms did not affect the detection of novelty. However, the same polymorphisms affected the late negative components (LN1 and LN2). Late negativities elicited by deviant and novel sounds have been regarded as reflecting reorientation after distraction or additional processing of new information. Children carrying the T.7 haplotype had significantly smaller LN1 and LN2 amplitudes. The presence of the T.7 haplotype also significantly enhanced behavioral resistance to distraction. We suggest that less distraction in T.7 carriers led to less reorienting activity (reflected by the LN components). We also speculate that activation of less sensitive and fewer D4 receptors (as with the T.7 haplotype) is less effective in modulating GABAergic inhibitory signaling, which in turn is reflected in smaller LN amplitudes.

Acoustic Stimulation↗

PubMed2006

Visual temporal window of integration as revealed by the visual mismatch negativity event-related potential to stimulus omissions.

We studied whether, similarly to the auditory modality, short-period temporal integration processes occur in vision. Event-related potentials (ERP) were recorded for occasional stimulus omissions from sequences of patterned visual stimuli. A posterior negative component emerged only when the constant stimulus onset asynchrony (SOA) was shorter than 150 ms. This upper limit is comparable with the duration of the temporal window of integration observed in the auditory modality (including experiments studying the effects of stimulus omissions). Parameters of the posterior negativity were highly similar irrespective of whether the stimuli were task-relevant or not (Experiment 1). Thus, we identified this potential as the visual mismatch negativity (vMMN) component, which reflects task-independent detection of violating regularities of the stimulation. vMMN was followed by an anterior positivity (the P3a), indicating attentional shifts induced by the stimulus omissions. In Experiment 2, a posterior negativity similar to that observed in Experiment 1 emerged after the termination of short trains of stimuli, again only when the SOA was shorter than 150 ms. These results support the notion of a temporal integration window in the visual modality, the duration of which is between 150 and 180 ms.

Adult↗

PubMed2006

The temporal window of integration in elderly and young adults.

Integration of information across time is an essential part of auditory processing. Evidence from a variety of experiments support the notion of an approximately 200-ms long time window following the onset of a sound, during which a unitary sound representation is formed (the temporal window of integration, TWI). The temporal resolution in the auditory system is assumed to decrease with aging suggesting that the duration of the TWI may be longer in elderly than young adults. The TWI duration was assessed in young and elderly adults using the oddball paradigm in which a regular auditory event (standard) is occasionally exchanged for a different event (deviant). Previous studies showed that when the stimulus onset asynchrony (SOA) exceeds the duration of the TWI, two successive deviations occurring infrequently in a repetitive sound sequence elicit two separate mismatch negativity (MMN) event-related brain potentials. However, only one MMN is elicited when the SOA is shorter than the TWI. Experiment 1 tested MMN elicitation for the second of two successive deviant sounds as a function of the SOA. Experiment 2 used the sound omission paradigm, in which MMN is only elicited by omissions when the SOA is shorter than the TWI. Again, MMN elicitation was tested by infrequent tone omissions as a function of the SOA. Results showed no significant differences between elderly and younger participants as a function of SOA. This suggests that the duration of the TWI is approximately between 200 and 250 ms in both groups of subjects. On the other hand, the lower MMN amplitudes elicited by frequency deviation in the elderly compared with the younger participants suggest that the specificity of frequency representation deteriorates with aging.

Acoustic Stimulation↗

PubMed2006

ERPs and deviance detection: visual mismatch negativity to repeated visual stimuli.

Previous studies showed a visual analogue of the mismatch negativity (MMN) event-related potential (ERP), which is elicited by violating some sensory regularity. Separating physical change from violating a regularity, here we show that the visual MMN (vMMN) is elicited by regularity violations that do not involve physical stimulus change. Adult participants were presented with a series of red-black and green-black checkerboard patterns delivered regularly in an RRGGRRGG ... order. Infrequently (p=0.1) this regularity was broken by repeating a stimulus one additional time (e.g. RRGGRRR). ERPs elicited by irregular stimulus repetitions were negatively displaced compared to those elicited both by regular repetition and regular change in two latency ranges: 100-140 ms and 220-260 ms. Whereas the first of these two negative ERP differences appears to be sensitive to stimulus repetition per se, the second difference can be identified as a vMMN response to violating the sequential regularity. Thus, similarly to its auditory counterpart, vMMN reflects deviance-(regularity-violation) rather than change-detection processes.

Adult↗

PubMed2006

Loudness summation and the mismatch negativity event-related brain potential in humans.

Abstract Infrequently omitting a sound from a repetitive sequence elicits the mismatch negativity (MMN) ERP response when the stimulus onset asynchrony (SOA) is less than 200 ms. We contrasted two alternative explanations of omission MMN. (1) Each sound starts a separate temporal integration process. Omissions violate the constancy of the temporal structure within the integration window. (2) Sounds preceding an omission are perceived to be louder than those followed by a sound within the integration period, because omissions allow the full stimulus aftereffect to be included in perceived loudness. We varied the SOA between 117 and 217 ms. For this case, the temporal structure explanation predicts that no MMN will be elicited, whereas the loudness summation explanation predicts that MMN will be elicited. MMN was elicited by tone omissions with random SOA, suggesting that loudness summation plays an important role in the elicitation of omission MMN.

Acoustic Stimulation↗

PubMed2005

Effects of temporal grouping on the memory representation of inter-tone relationships.

The length of silence between successive sounds is a dominant cue for temporal grouping of sounds. The present study tested whether the sensory memory representation of inter-tone relationships is dependent on the grouping of tones within a single stream of sound. Subjects were presented with sequences of two alternating tones that differed from each other in frequency. Perception of a sequence made up of tone-pairs was promoted by alternating a short and a long inter-tone interval. Occasional tone repetitions fell either within one tone-pair or across two pairs. We found that detecting tone repetitions was slower for across- than within-pair repetitions (Experiment 1). Also the amplitude of the mismatch negativity (MMN) event-related potential was lower for across-pair repetitions compared with that measured in the control isochronous sequences (Experiment 2). This attenuation of the MMN-amplitude could not be explained by the inter-tone interval differences that existed between the paired and the isochronous conditions (Experiment 3). These results demonstrate that temporal grouping affects the sensory memory representation of inter-tone relationships within a single sound stream.

Adult↗

PubMed2005

Disruption of immediate memory and brain processes: an auditory ERP protocol.

An event-related potential (ERP) protocol is described that can be used to investigate those sound-evoked neural processes that may be implicated in disrupting immediate memory. Conventional electroencephalogram (EEG) is recorded during the performance of a task that involves ignoring irrelevant sounds while trying to hold in memory lists of numbers. Specific bioelectric measures are made to prevent the contamination of recordings by the movements of articulators. An approach is also outlined which controls the timing of ERP components to sounds with different envelopes. Using this approach, it has been shown that the neural processes involved in the elicitation of the auditory N1 ERP response may be involved in the disruption of memory for serial order produced by irrelevant sound.

Acoustic Stimulation↗

PubMed2005

Preattentive representation of feature conjunctions for concurrent spatially distributed auditory objects.

The role of attention in conjoining features of an object has been a topic of much debate. Studies using the mismatch negativity (MMN), an index of detecting acoustic deviance, suggested that the conjunctions of auditory features are preattentively represented in the brain. These studies, however, used sequentially presented sounds and thus are not directly comparable with visual studies of feature integration. Therefore, the current study presented an array of spatially distributed sounds to determine whether the auditory features of concurrent sounds are correctly conjoined without focal attention directed to the sounds. Two types of sounds differing from each other in timbre and pitch were repeatedly presented together while subjects were engaged in a visual n-back working-memory task and ignored the sounds. Occasional reversals of the frequent pitch-timbre combinations elicited MMNs of a very similar amplitude and latency irrespective of the task load. This result suggested preattentive integration of auditory features. However, performance in a subsequent target-search task with the same stimuli indicated the occurrence of illusory conjunctions. The discrepancy between the results obtained with and without focal attention suggests that illusory conjunctions may occur during voluntary access to the preattentively encoded object representations.

Acoustic Stimulation↗

PubMed2005

Event-related brain potentials reveal multiple stages in the perceptual organization of sound.

Auditory stream segregation has been suggested to include two distinct processing stages: (1) forming representations for alternative organizations of the acoustic input and (2) choosing one organization for perception after weighing the evidence that supports the different alternatives. The current study tested the possibility that auditory event-related potentials (ERP) could be used to index both stages of the stream-segregation process. Sequences of tones that could be perceived either as a single coherent auditory stream (integrated organization) or as two separate streams of sounds (segregated organization) were presented to subjects. The stimulus configuration encouraged perception to fluctuate between these alternative organizations. Subjects were instructed to continuously indicate whether they perceived one or the other organization of the tone sequence. Occasionally, a tone was omitted from the otherwise regular sequence. This deviance was expected to be processed differently depending on the perceptual organization of the sequence at the time of the omission. We found an early ERP response to omission, which was fully determined by parameters of the stimulation and was not sensitive to the perceived sound organization. In contrast, modulation of two ERP components elicited by the regular tone patterns as well as later responses elicited by deviants correlated with the perceived sound organization. These results suggest that sound organization goes through at least two distinct stages, the first being fully stimulus driven, whereas the second is partly under top-down control.

Adult↗

PubMed2005

From sensory to long-term memory: evidence from auditory memory reactivation studies.

Everyday experience tells us that some types of auditory sensory information are retained for long periods of time. For example, we are able to recognize friends by their voice alone or identify the source of familiar noises even years after we last heard the sounds. It is thus somewhat surprising that the results of most studies of auditory sensory memory show that acoustic details, such as the pitch of a tone, fade from memory in ca. 10-15 s. One should, therefore, ask (1) what types of acoustic information can be retained for a longer term, (2) what circumstances allow or help the formation of durable memory records for acoustic details, and (3) how such memory records can be accessed. The present review discusses the results of experiments that used a model of auditory recognition, the auditory memory reactivation paradigm. Results obtained with this paradigm suggest that the brain stores features of individual sounds embedded within representations of acoustic regularities that have been detected for the sound patterns and sequences in which the sounds appeared. Thus, sounds closely linked with their auditory context are more likely to be remembered. The representations of acoustic regularities are automatically activated by matching sounds, enabling object recognition.

Adolescent↗

PubMed2005

Memory-based or afferent processes in mismatch negativity (MMN): a review of the evidence.

The mismatch negativity (MMN) is an electromagnetic response to any discriminable change in regular auditory input. This response is usually interpreted as being generated by an automatic cortical change-detection process in which a difference is found between the current input and the representation of the regular aspects of the preceding auditory input. Recently, this interpretation was questioned by Jääskeläinen et al. (2004) who proposed that the MMN is a product of an N1 (N1a) difference wave emerging in the subtraction procedure used to visualize and quantify the MMN. We now evaluate this "adaptation hypothesis" of the MMN in the light of the available data. It is shown that the MMN cannot be accounted for by differential activation of the afferent N1 transient detectors by repetitive ("standard") stimuli and deviant ("novel") stimuli and that the presence of a memory representation of the standard is required for the elicitation of MMN.

Acoustic Stimulation↗

PubMed2005

Preattentive binding of auditory and visual stimulus features.

We investigated the role of attention in feature binding in the auditory and the visual modality. One auditory and one visual experiment used the mismatch negativity (MMN and vMMN, respectively) event-related potential to index the memory representations created from stimulus sequences, which were either task-relevant and, therefore, attended or task-irrelevant and ignored. In the latter case, the primary task was a continuous demanding within-modality task. The test sequences were composed of two frequently occurring stimuli, which differed from each other in two stimulus features (standard stimuli) and two infrequently occurring stimuli (deviants), which combined one feature from one standard stimulus with the other feature of the other standard stimulus. Deviant stimuli elicited MMN responses of similar parameters across the different attentional conditions. These results suggest that the memory representations involved in the MMN deviance detection response encoded the frequently occurring feature combinations whether or not the test sequences were attended. A possible alternative to the memory-based interpretation of the visual results, the elicitation of the McCollough color-contingent aftereffect, was ruled out by the results of our third experiment. The current results are compared with those supporting the attentive feature integration theory. We conclude that (1) with comparable stimulus paradigms, similar results have been obtained in the two modalities, (2) there exist preattentive processes of feature binding, however, (3) conjoining features within rich arrays of objects under time pressure and/or longterm retention of the feature-conjoined memory representations may require attentive processes.

Acoustic Stimulation↗

PubMed2005

Familiarity affects the processing of task-irrelevant auditory deviance.

The effects of familiarity on auditory change detection on the basis of auditory sensory memory representations were investigated by presenting oddball sequences of sounds while participants ignored the auditory stimuli. Stimulus sequences were composed of sounds that were familiar and sounds that were made unfamiliar by playing the same sounds backward. The roles of frequently presented stimuli (standards) and infrequently presented ones (deviants) were fully crossed. Deviants elicited the mismatch negativity component of the event-related brain potential. We found an enhancement in detecting changes when deviant sounds appeared among familiar standard sounds compared when they were delivered among unfamiliar standards. Familiarity with the deviant sounds also enhanced the change-detection process. We suggest that tuning to familiar items sets up preparatory processes that affect change detection in familiar sound sequences.

Acoustic Stimulation↗

PubMed2004

Auditory organization of sound sequences by a temporal or numerical regularity--a mismatch negativity study comparing musicians and non-musicians.

The human auditory system can encode regularities in the acoustic environment without the requirement of attention. We investigated whether the auditory system of musicians is more sensitive than that of non-musicians in encoding complex regularities. We presented tone sequences containing either a temporal or a numerical regularity. The sequence with the temporal regularity could be divided into segments of a constant duration while the segments contained a varying number of tones. The sequence with the numerical regularity, on the other hand, could be divided into segments containing a constant number of tones while the segments varied in duration. Auditory encoding of the regularity was determined by measuring whether an occasional segment lengthening, either in time or by number elicited the mismatch negativity (MMN). In both musicians and non-musicians, an MMN was elicited when the temporal regularity was violated. In contrast, only in musicians an MMN was elicited to violations of the numerical regularity. The results show that temporal processing is of general importance in audition since at an involuntary auditory processing stage a complex temporal regularity can be encoded irrespective of musical expertise. Furthermore, the auditory system of professional musicians can encode a numerical regularity without attention being required reflecting the functional importance of beat tracking in the perceptual organization of music.

Adult↗

PubMed2004

How the human auditory system treats repetition amongst change.

Occasional repetitions embedded in a sequence of ever-changing sounds elicit a frontally negative event-related potential peaking between 100 and 200 ms from the onset of sound repetition (repetition negativity, RN). Three interpretations have been suggested for the emergence of RN: (1) RN is a mismatch negativity (MMN) response elicited because the auditory system detected sound change as a regular feature of the stimulus sequence, which is violated by repetitions. (2) RN reflects short-term sensitization of the auditory system to the specific acoustic parameters of each sound, a process subserving the formation of durable memory traces. (3) The difference between responses elicited by repetition and change reflects differential refractoriness of the P2 component. In order to distinguish between the MMN-based and the other two explanations of RN, we varied the global sequential probability of tone-repetitions (at 5, 20, and 50%) in sequences composed of tones of five different frequencies. Whereas all three explanations of the RN predict a local repetition-probability effect on the RN amplitude, MMN should also be affected by the global repetition-probability, because MMN is sensitive to the global deviant-probability, independently of local deviant-probability. To eliminate differences in local repetition-probabilities, we compared the responses elicited by tones that followed the same micro-sequence (change-change-repetition) across the three different global-probability conditions. Global repetition probability had a significant effect on RN: it was only elicited with 5%, but not with the two higher repetition-probabilities. This result supports the MMN interpretation of the RN.

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↗

PubMed2004

Grouping of sequential sounds--an event-related potential study comparing musicians and nonmusicians.

It is believed that auditory processes governing grouping and segmentation of sounds are automatic and represent universal aspects of music perception (e.g., they are independent of the listener's musical skill). The present study challenges this view by showing that musicians and nonmusicians differ in their ability to preattentively group consecutive sounds. We measured event-related potentials (ERPs) from professional musicians and nonmusicians who were presented with isochronous tone sequences that they ignored. Four consecutive tones in a sequence could be grouped according to either pitch similarity or good continuation of pitch. Occasionally, the tone-group length was violated by a deviant tone. The mismatch negativity (MMN) was elicited to the deviants in both subject groups when the sounds could be grouped based on pitch similarity. In contrast, MMN was only elicited in musicians when the sounds could be grouped according to good continuation of pitch. These results suggest that some forms of auditory grouping depend on musical skill and that not all aspects of auditory grouping are universal.

Acoustic Stimulation↗