Biomedical subjects

I Winkler

Publications and source records attributed to I Winkler.

At least 19 recordsLinked to original sources

PubMed2001

Event-related potential correlates of sound duration: similar pattern from birth to adulthood.

The effects of sound duration on event-related potentials (ERP) were studied in newborns and adults. Increasing tone duration from 200 to 300 ms led to the enhancement of the N2 peak amplitude, whereas two peaks became distinguishable in the N2 response elicited by 400 ms long tones. The sound-duration related ERP changes most likely reflect contribution from the sustained potential, although the observed results can also be explained by assuming the elicitation of a sound-duration sensitive frontocentrally negative ERP component (duration-sensitive N2; DN2). The pattern of duration-related changes observed in newborn infants was very similar to that in adults, regardless of the structural differences between adult and infant ERPs. The results suggest that sound duration is processed already at birth in a similar way as in adulthood.

Acoustic Stimulation↗

PubMed2001

Mismatch negativity is unaffected by top-down predictive information.

The mismatch negativity (MMN) event-related brain potential is assumed to reflect a stimulus-driven change detection process. We examined whether MMN is sensitive to volitional control by testing whether MMN is affected by the subject's foreknowledge of the sound changes. Subjects were instructed to produce a sequence of button presses by pressing one button frequently and another infrequently. In the predictable condition, the frequently pressed button triggered the standard tone, the other button the deviant tone. In the unpredictable condition, each button press triggered the next tone of a prearranged standard/deviant sequence. No difference was found in the MMN amplitude, latency, or scalp distribution between the predictable and unpredictable conditions. This suggests that there is no direct top-down control over the MMN-generating process.

Acoustic Stimulation↗

PubMed2001

Common neural mechanism for processing onset-to-onset intervals and silent gaps in sound sequences.

Stimulus onset asynchrony (SOA) and inter-stimulus interval (ISI) are important factors in the perceptual organization of sound sequences. The present study tested whether these two temporal parameters are independently processed in the auditory system. Independence was studied by testing the additivity of mismatch negativity (MMN). Four conditions differing in their temporal regularities were administered: (1) constant SOA and ISI, (2) constant SOA and variable ISI, (3) constant ISI and variable SOA, and (4) variable SOA and ISI. The MMN elicited by simultaneous deviance from the constant SOA and ISI (Condition 1) was compared with an additive model calculated from the MMNs elicited in the other conditions. The amplitude of the MMN in Condition 1 was significantly larger than that of the modeled MMN, suggesting that SOA and ISI are processed by interactive or common neural mechanisms.

Acoustic Stimulation↗

PubMed2001

Organizing sound sequences in the human brain: the interplay of auditory streaming and temporal integration.

The present study examined the relationship between two of the early brain processes of sound organization: auditory streaming and the temporal window of integration (TWI). Presented at a fast stimulus delivery rate, two tones alternating in frequency are perceived as separate streams of high and low sounds. However, when two sounds are presented within a ca. 200 ms temporal window, they are often processed as a single auditory event. Both stream segregation and temporal integration occur even in the absence of focused attention as was shown by their effect on the mismatch negativity (MMN) event-related potential. The goal of the present study was to determine the precedence between these two sound organization processes by using the stimulus-omission MMN paradigm. Infrequently omitting one stimulus from a homogeneous tone sequence only elicits an MMN when the stimulus onset asynchrony separating successive tones is shorter than 170 ms. This demonstrates the effect of the TWI. Magnetic brain responses elicited by infrequent stimulus omissions appearing in a sequence of two alternating tones were recorded. The magnetic MMN was elicited by tone omission when the alternating tones formed a single stream (with no or only small frequency separation between the two tones) but not when separate high and low streams emerged in perception (large frequency separation between the two alternating tones). This result shows that auditory streaming takes precedence over the processes of temporal integration.

Acoustic Stimulation↗

PubMed2001

Changes in acoustic features and their conjunctions are processed by separate neuronal populations.

We investigated the relationship between the neuronal populations involved in detecting change in two acoustic features and their conjunction. Equivalent current dipole (ECD) models of the magnetic mismatch negativity (MMNm) generators were calculated for infrequent changes in pitch, perceived sound source location, and the conjunction of these two features. All of these three changes elicited MMNms that were generated in the vicinity of auditory cortex. The location of the ECD best describing the MMNm to the conjunction deviant was anterior to those for the MMNm responses elicited by either one of the constituent features. The present data thus suggest that at least partially separate neuronal populations are involved in detecting change in acoustic features and feature conjunctions.

Adult↗

PubMed2001

The role of large-scale memory organization in the mismatch negativity event-related brain potential.

The mismatch negativity (MMN) component of event-related brain potentials is elicited by infrequent changes in regular acoustic sequences even if the participant is not actively listening to the sound sequence. Therefore, the MMN is assumed to result from a preattentive process in which an incoming sound is checked against the automatically detected regularities of the auditory sequence and is found to violate them. For example, presenting a discriminably different (deviant) sound within the sequence of a repetitive (standard) sound elicits the MMN. In the present article, we tested whether the memory organization of the auditory sequence can affect the preattentive change detection indexed by the MMN. In Experiment 1, trains of six standard tones were presented with a short, 0.5-sec stimulus onset asynchrony (SOA) between tones in the train. This was followed by a variable SOA between the last standard and the deviant tone (the "irregular presentation" condition). Of 12 participants displaying an MMN at the 0.5-sec predeviant SOA, it was elicited by 11 with the 2-sec predeviant SOA, in 5 participants with the 7-sec SOA, and in none with the 10-sec SOA. In Experiment 2, we repeated the 7-sec irregular predeviant SOA condition, along with a "regular presentation" condition in which the SOA between any two tones was 7 sec. MMN was elicited in about half of the participants (9 out of 16) in the irregular presentation condition, whereas in the regular presentation condition, MMN was elicited in all participants. These results cannot be explained on the basis of memory-strength decay but can be interpreted in terms of automatic, auditory preperceptual grouping principles. In the irregular presentation condition, the close grouping of standards may cause them to become irrelevant to the mismatch process when the deviant tone is presented after a long silent break. Because the MMN indexes preattentive auditory processing, the present results provide evidence that large-scale preperceptual organization of auditory events occurs despite attention being directed away from the auditory stimuli.

Acoustic Stimulation↗

PubMed2001

"Primitive intelligence" in the auditory cortex.

The everyday auditory environment consists of multiple simultaneously active sources with overlapping temporal and spectral acoustic properties. Despite the seemingly chaotic composite signal impinging on our ears, the resulting perception is of an orderly "auditory scene" that is organized according to sources and auditory events, allowing us to select messages easily, recognize familiar sound patterns, and distinguish deviant or novel ones. Recent data suggest that these perceptual achievements are mainly based on processes of a cognitive nature ("sensory intelligence") in the auditory cortex. Even higher cognitive processes than previously thought, such as those that organize the auditory input, extract the common invariant patterns shared by a number of acoustically varying sounds, or anticipate the auditory events of the immediate future, occur at the level of sensory cortex (even when attention is not directed towards the sensory input).

Auditory Cortex↗

PubMed2001

Auditory stream segregation processes operate similarly in school-aged children and adults.

Our previous research with adults suggests that pre-attentive (bottom-up) brain processes govern auditory stream segregation [Sussman et al., 1998. Brain Res. 789, 130--138; Sussman et al., 1999. Psychophysiology 36, 22--34; Winkler et al., submitted for publication]. We investigated whether the pre-attentive mechanisms underlying auditory stream segregation operate similarly in school-aged (7--10 years of age) children and adults. We used an electrophysiological index of auditory change detection that does not require the experimental participant to focus on the sounds to be evoked. In Experiment 1, children were presented with mixtures of high and low frequency tones in different conditions and were instructed to watch a silent video and ignore the sounds. In Experiment 2, children were asked to listen to the same sets of sounds as presented in Experiment 1 and tell whether they heard one or two auditory streams. The pre-attentive processing of the mixture of sounds as one or two auditory streams (Experiment 1), matched with the perception of the sounds as one or two distinct streams (Experiment 2). Our results demonstrate that the mechanisms for auditory stream segregation operate similarly in school-aged children and adults when frequency proximity is the cue for segregation.

Acoustic Stimulation↗

PubMed2001

Simultaneously active pre-attentive representations of local and global rules for sound sequences in the human brain.

Regular sequences of sounds (i.e., non-random) can usually be described by several, equally valid rules. Rules allowing extrapolation from one sound to the next are termed local rules, those that define relations between temporally non-adjacent sounds are termed global rules. The aim of the present study was to determine whether both local and global rules can be simultaneously extracted from a sound sequence even when attention is directed away from the auditory stimuli. The pre-attentive representation of a sequence of two alternating tones (differing only in frequency) was investigated using the mismatch negativity (MMN) auditory event-related potential. Both local- and global-rule violations of tone alternation elicited the MMN component while subjects ignored the auditory stimuli. This finding suggests that (a) pre-attentive auditory processes can extract both local and global rules from sound sequences, and (b) that several regularity representations of a sound sequence are simultaneously maintained during the pre-attentive phase of auditory stimulus processing.

Acoustic Stimulation↗

PubMed2001

Dynamic sensory updating in the auditory system.

Typically, in everyday situations, auditory input is constantly changing. Change is an important cue for the auditory system, which can signal the start of new sources of information or that some action may be required. Using an event-related brain potential that can be elicited whether or not attention is focused on the sounds (the mismatch negativity, MMN) we measured the time course of the effects of contextual changes on the brain's response to the same stimulus event. The onset or cessation of a sound in a stimulus block brought about context changes. The effect of the context was observed through changes in the MMN response to a deviant event that was present throughout the sound sequence. These results suggest the existence of a dynamic system of change detection, which updates its model of the sensory input on-line as the changes occur.

Acoustic Stimulation↗

PubMed2001

[Who, What, How much, Where? - an analysis of publications by German authors on sociopsychiatric issues in scientific journals].

OBJECTIVE: Stimulated by Finzen's critical appraisal of the actual situation of social psychiatric research in Germany an analysis of recent publications of German authors on social psychiatric topics was carried out. METHOD: Covering the years 1998 - 2000, 70 scientific journals from psychiatry and related disciplines were systematically analysed. RESULTS: A substantial proportion of research in social psychiatry is concentrated on a small number of research institutions. In German journals of general psychiatry papers dealing with social psychiatric topics are rarely found. By contrast in international, particularly in European journals the proportion of papers on social psychiatric topics originating from German authors is quite high as compared to papers on other topics. Applied research, especially research on mental health services, dominates the field. By contrast, basic research on social psychiatric issues is underrepresented. Studies using qualitative methods are almost missing. While, as traditionally, the research interest is still particularly focussed on schizophrenia, there are a number of papers dealing with other disorders, mainly with substance abuse disorders and affective disorders. DISCUSSION: The critique raised by Finzen is to a large extent supported by the results of our study. However, we still hesitate to agree with his pessimistic prognosis for the future of social psychiatric research in Germany.

Authorship↗

PubMed2001

Preattentive processing of spectral, temporal, and structural characteristics of acoustic regularities: a mismatch negativity study.

In the present study we investigated the relationship between detecting violations of structural regularities of tone sequences and detecting deviations from temporal regularities or repetitive spectral auditory stimulus features. Twelve subjects were presented with randomized sequences of two tones (differing both in frequency and intensity) delivered alternately to the left and right ears at a constant stimulus onset asynchrony (SOA). In separate blocks, occasional deviant stimuli broke one, two, or three of the following regularities: spatial alternation, the constancy of SOA, or the dominant frequency-intensity conjunctions. Unlike the mismatch negativity (MMN) elicited by alternation-plus-SOA deviants, the MMN elicited by alternation-plus-conjunction deviants was approximately equal to the sum of the two corresponding single-deviant MMNs. These results suggest that the preattentive change-detection system processes infrequent violations of the structural regularities of sound sequences together with changes in temporal regularities, but separately from changes in repetitive spectral sound features. The MMN elicited by the triple-deviant stimuli corroborated these conclusions.

Adult↗

PubMed2001

Preattentive extraction of abstract feature conjunctions from auditory stimulation as reflected by the mismatch negativity (MMN).

Brain mechanisms extracting invariant information from varying auditory inputs were studied using the mismatch-negativity (MMN) brain response. We wished to determine whether the preattentive sound-analysis mechanisms, reflected by MMN, are capable of extracting invariant relationships based on abstract conjunctions between two sound features. The standard stimuli varied over a large range in frequency and intensity dimensions following the rule that the higher the frequency, the louder the intensity. The occasional deviant stimuli violated this frequency-intensity relationship and elicited an MMN. The results demonstrate that preattentive processing of auditory stimuli extends to unexpectedly complex relationships between the stimulus features.

Acoustic Stimulation↗

PubMed1999

Event-related brain potentials reveal covert distractibility in closed head injuries.

Event-related brain potentials (ERPs) to auditory stimuli were recorded from 11 closed head injured (CHI) and 10 age-matched healthy adults. Auditory stimuli consisted of sequences of repetitive standard tones (600 Hz), occasionally replaced by deviant tones (660 Hz) or by natural novel sounds. Subjects were instructed to ignore auditory stimuli while concentrating on a demanding visuo-motor tracking task. CHI patients showed, in comparison to control subjects, significantly enhanced late P3a component in the ERPs to novel sounds. This suggests that novel stimuli cause greater distraction in CHI patients than in controls, demonstrating that ERPs provide a powerful tool to determine the physiological basis of attentional deficits in CHI patients.

Acoustic Stimulation↗

PubMed1999

Independent processing of changes in auditory single features and feature conjunctions in humans as indexed by the mismatch negativity.

The mismatch negativity (MMN), an event-related potential component of the EEG, is elicited by violations of auditory regularities In the present study, the stimulus blocks contained two types of standard tones, differing from each other in frequency and intensity. MMNs were recorded to three different types of deviant stimuli: (a) feature deviants, differing from standards in their perceived locus of origin; (b) conjunction deviants, having the frequency of one of the standards and the intensity of the other; (c) double deviants, differing from standards in both (a) and (b). The MMN to double deviants was similar to the sum of the MMNs to feature and conjunction deviants. This result indicates that changes in simple stimulus features and conjunction of features are processed independently by the automatic sound change detection system indexed by MMN.

Adult↗

PubMed1999

Neuronal populations in the human brain extracting invariant relationships from acoustic variance.

The ability to extract invariant relationships from physically varying stimulation is critical for example to categorical perception of complex auditory information such as speech and music. Human subjects were presented with tone pairs randomly varying over a wide frequency range, there being no physically constant tone pair at all. Instead, the invariant feature was either the direction of the tone pairs (ascending: the second tone was higher in frequency than the first tone) or the frequency ratio (musical interval) of the two tones. The subjects ignored the tone pairs, and instead attended a silent video. Occasional deviant pairs (either descending in direction or having a different frequency ratio) elicited the mismatch negativity (MMN) of the event-related potential, demonstrating the existence of neuronal populations which automatically (independently of attention) extract invariant relationships from acoustical variance.

Acoustic Stimulation↗

PubMed1999

Temporal integration of auditory stimulus deviance as reflected by the mismatch negativity.

We recorded event-related brain potentials (ERPs) to two different infrequent deviant tones presented successively within the repetitive sequence of a standard tone. A separate mismatch negativity (MMN) component was elicited by each of the two deviants when the interval separating their onsets was 300 ms. However, only a single MMN component was elicited when the temporal separation between the onsets of the two deviants was 150 ms. Previous studies obtained similar results using two temporally separated deviations carried by a single sound. Taken together, these results support the notion of a general temporal integration mechanism in the formation of auditory events with ca. 200 ms long window.

Acoustic Stimulation↗

PubMed1999

Pre-attentive detection of vowel contrasts utilizes both phonetic and auditory memory representations.

Event-related brain potentials (ERP) were recorded to infrequent changes of a synthesized vowel (standard) to another vowel (deviant) in speakers of Hungarian and Finnish language, which are remotely related to each other with rather similar vowel systems. Both language groups were presented with identical stimuli. One standard-deviant pair represented an across-vowel category contrast in Hungarian, but a within-category contrast in Finnish, with the other pair having the reversed role in the two languages. Both within- and across-category contrasts elicited the mismatch negativity (MMN) ERP component in the native speakers of either language. The MMN amplitude was larger in across- than within-category contrasts in both language groups. These results suggest that the pre-attentive change-detection process generating the MMN utilized both auditory (sensory) and phonetic (categorical) representations of the test vowels.

Acoustic Stimulation↗