Biology subjects

Klatt, L.-I.

Publications and source records attributed to Klatt, L.-I..

13 recordsLinked to original sources

bioRxiv2026

Neural reinstatement of features in audiovisual working memory indicatesobject-based retrieval

Selective attention allows us to prioritize or retrieve task-relevant features and items from working memory. However, previous work has largely relied on unisensory paradigms, leaving open the question of how attentional mechanisms act on audiovisual working memory representations. Here, using an EEG-based audiovisual delayed-match-to-sample task, we investigate whether attention to audiovisual working memory contents operates on the level of individual unisensory features or bound cross-modal objects. On each trial, participants memorized an audiovisual item. At test, they were randomly presented with either an auditory, visual, or an audiovisual probe stimulus and indicated whether the latter matched their working memory content. Compared with recalling the entire audiovisual object, recall of unisensory visual or auditory features resulted in poorer behavioral performance and elevated midfrontal theta power. Multivariate pattern analyses (MVPA) showed that task-irrelevant feature representations were retrieved in both auditory and visual probe trials, consistent with object-based retrieval. Moreover, these results shed light on the representational structure underlying cross-modal feature storage in working memory, suggesting that audiovisual features are stored as bound objects and that attentional selection of individual object features in one modality spreads to cross-modal object features in another modality. In task conditions where such incidental recall of task-irrelevant features is detrimental to task performance, this places greater demands on cognitive control mechanisms.

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bioRxiv2025

Tracking neural representations of attended and unattended features in multisensory working memory over time

Working memory supports goal-directed behavior by maintaining task-relevant information. However, a growing number of studies shows that even task-irrelevant features are automatically encoded and can interfere with the recall of task-relevant information. While this phenomenon is well documented in unisensory contexts, it remains unclear whether and how task-irrelevant information persists in multisensory working memory. We examine the role of cross-modal binding by tracking the dynamic neural representation of audio-visual objects under varying selective attention conditions, using an EEG-based audio-visual delayed-match-to-sample task. Participants attended to either auditory or visual features (selective attention), or to both features (conjunction) of two sequential audio-visual items and subsequently compared those task-relevant features to an audio-visual probe. Further, to investigate the influence of bottom-up factors on cross-modal binding, we manipulated spatial congruency by presenting both features from either the same (i.e., in the center) or from disparate positions. Behaviorally, task-irrelevant features interfered with performance even under selective attention, consistent with automatic cross-modal binding and encoding into working memory. This interference was even stronger with spatially disparate presentation, suggesting that bottom-up attentional dynamics strengthen cross-modal bindings and their subsequent storage. Condition-level representational similarity analysis (RSA) showed that EEG activity patterns under selective attention more closely resembled those of conjunction trials than unisensory trials, indicating that task-irrelevant features were incorporated into multisensory object-level representations. This conjunction-similarity persisted in attend-visual trials, but declined over time in attend-auditory trials, reflecting partial filtering of task-irrelevant orientations. Crucially, activity patterns never shifted fully towards an auditory-only profile, indicating that irrelevant visual features were not fully excluded. In addition, feature-level RSA corroborated that both sound frequency-specific and orientation-specific information were present in EEG activity patterns, irrespective of the attended modality. Overall, these results demonstrate the persistence of task-irrelevant information in multisensory working memory and offer critical insights into how attentional processes shape its representational architecture.

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bioRxiv2024

The effect of performance contingent reward prospects flexibly adapts to more versus less specific task goals

In some situations, e.g., when we expect to gain a reward in case of good performance, goal-driven top-down attention is particularly strong. Little is known about the task specificity of such increases of top-down attention due to environmental factors. To understand to what extent performance-contingent reward prospects can result in specific and unspecific changes in cognitive processing, we here investigate reward effects under different levels of task specification. Thirty-two participants performed a visual or an auditory discrimination task cued by two consecutive visual stimuli: First, a reward cue indicated if good performance was rewarded. Second, a task cue announced either which of the two tasks would follow (precise cue) or that both tasks would follow equally likely (imprecise cue). Reward and task cue preciseness both significantly improved performance. Moreover, the response time difference between precisely and imprecisely cued trials was significantly stronger in rewarded than in unrewarded trials. These effects were reflected in ERP slow wave amplitudes: Reward and preciseness both significantly enhanced the contingent negative variation (CNV) prior to the task stimulus. In an early CNV time interval, both factors also showed an interaction. A negative slow wave prior to the task cue was also significantly enhanced for rewarded trials. This effect correlated with the reward difference in response times. These results indicate that reward prospects trigger task-specific changes in preparatory top-down attention which can flexibly adapt over time and across different task requirements. This highlights that a reward-induced increase of cognitive control can occur on different specificity levels.

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bioRxiv2024

Behavior and alpha-band oscillations reveal cross-modal interactions between chemosensory and auditory processing

The ventriloquism effect, where sounds are mislocalized towards a spatially disparate but temporally synchronous visual stimulus, is well established. Liang et al. (2022) provided first evidence that chemosensory cues can similarly bias sound localization. This study, conducted in 2023, replicates and extends their behavioral findings, using diffusion modeling and EEG to identify underling computational and neural mechanisms. Participants localized (left vs. right) each sound in eight-item sequences, with trigeminally-potent odorants presented concurrently with the first four sounds (left, right, or both nostrils). Unbeknownst to participants, some sounds originated from the center. For central sounds, the proportion of right-ward responses increased with right-nostril stimulation but decreased with left-nostril stimulation (relative to controls). This bias was strongest in the second half of the sequence and disappeared at larger sound eccentricity. Diffusion modeling showed the bias was best explained by changes in drift rate (perceptual evidence accumulation), not in starting point (decision bias). EEG alpha-band activity lateralized towards the chosen side for central sounds, consistent with attentional orienting towards the perceived location, and was diminished at large eccentricities with incongruent chemosensory stimulation. The findings corroborate an odorant-sound spatial ventriloquism effect and provide novel insights into the cognitive and attentional processes involved. Public significance statementOur findings reveal that trigeminally potent odors can subtly influence sound localization judgments, even when those odors are irrelevant to the task at hand. This influence is strongest when sound information is uncertain (i.e., when unbeknownst to participants, a sound that had to be localized as coming from the left or right side, originated from a central location), suggesting that trigeminal stimulation can act as a spatial cue under ambiguous conditions. In addition, concurrent EEG cording revealed that the influence of odorant stimulation was also reflected in neural correlates of auditory spatial attention. Critically, diffusion modeling showed that the observed cross-modal bias occurs at a perceptual level. These findings highlight that the human brain integrates information from the chemical sense and hearing more deeply than previously assumed, revealing that even task-irrelevant odors can shape spatial perception in other senses.

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bioRxiv2024

The Interplay Between Multisensory Processing and Attention in Working Memory: Behavioral and Neural Indices of Audio-Visual Object Storage

Although real-life events are multisensory, how audio-visual objects are stored in working memory is an open question. At a perceptual level, evidence shows that both top-down and bottom-up attentional processes can play a role in multisensory interactions. To understand how attention and multisensory processes interact in working memory, we designed an audio-visual delayed match-to-sample task in which participants were presented with one or two audio-visual memory items, followed by an audio-visual probe. In three different blocks, participants were instructed to either (a) attend to the auditory features, (b) attend to the visual features, or (c) attend to both auditory and visual features. Participants were instructed to indicate whether the task-relevant features of the probe matched one of the task-relevant feature(s) or objects in working memory. Behavioral results showed interference from task-irrelevant features, suggesting bottom-up integration of audio-visual features and their automatic encoding into working memory, irrespective of their task relevance. Yet, ERP analyses revealed no evidence for active maintenance of these task-irrelevant features, while they clearly taxed greater attentional resources during recall. Notably, alpha oscillatory activity revealed that linking information between auditory and visual modalities required more attentional demands at retrieval. Overall, these results offer critical insights into how and at which processing stage multisensory interactions occur in working memory. Public Significance StatementCurrent working memory research is dominated by investigations of the visual domain. Yet, understanding how more complex representations, e.g., based on multisensory inputs, are formed, stored, and recalled is crucial to obtaining a more realistic understanding of working memory function. The present study shows that when confronted with audio-visual inputs at the same time and location, features from both modalities are combined into a working memory representation, irrespective of their task relevance. During maintenance, alpha oscillations serve to flexibly gate information flow in the cortex, allowing for the re-distribution of attentional resources between modalities depending on their task-relevance. Notably, when the task instructions explicitly involve the storage of audio-visual objects as a whole, recall requires more attentional resources.

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bioRxiv2022

Cross-modal interactions at the audiovisual cocktail-party revealed by behavior, ERPs, and neural oscillations

Theories of attention argue that objects are the units of attentional selection. In real-word environments such objects can contain visual and auditory features. To understand how mechanisms of selective attention operate in multisensory environments, we created an audiovisual cocktail-party situation, in which two speakers (left and right of fixation) simultaneously articulated brief numerals. In three separate blocks, informative auditory speech was presented (a) alone or paired with (b) congruent or (c) uninformative visual speech. In all blocks, subjects localized a pre-defined numeral. While audiovisual-congruent and uninformative speech improved response times and speed of information uptake according to diffusion modeling, an ERP analysis revealed that this did not coincide with enhanced attentional engagement. Yet, consistent with object-based attentional selection, the deployment of auditory spatial attention (N2ac) was accompanied by visuo-spatial attentional orienting (N2pc) irrespective of the informational content of visual speech. Notably, an N2pc component was absent in the auditory-only condition, demonstrating that a sound-induced shift of visuo-spatial attention relies on the availability of audio-visual features evolving coherently in time. Additional analyses revealed cross-modal interactions in working memory and modulations of cognitive control. The preregistered methods and hypotheses of this study can be found at https://osf.io/vh38g.

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bioRxiv2022

Age influences audiovisual speech processing in multi-talker scenarios - Evidence from cortical oscillations

Age-related differences in the processing of audiovisual speech in a multi-talker environment were investigated analyzing event-related spectral perturbations (ERSPs), focusing on theta, alpha, and beta oscillations that are assumed to reflect conflict processing, multisensory integration, and attentional mechanisms, respectively. Eighteen older and 21 younger healthy adults completed a two-alternative forced-choice word discrimination task, responding to audiovisual speech stimuli. In a cocktail-party scenario with two competing talkers (located at-15{degrees} and 15{degrees} azimuth), target words (/yes/ or /no/) appeared at a pre-defined (attended) position, distractor words at the other position. In two audiovisual conditions, acoustic speech was combined either with congruent or uninformative visual speech. While a behavioral benefit for congruent audiovisual speech occurred for both age groups, differences between audiovisual conditions in the theta and beta band were only present for older adults. A stronger increase in theta perturbations for stimuli containing uninformative visual speech could be associated with early conflict processing, while a stronger suppression in beta perturbations for congruent audiovisual speech could be associated to audiovisual integration. Compared to the younger group, the older group showed generally stronger beta perturbations. No condition differences in the alpha band were found. Overall, the findings suggest age-related differences in audiovisual speech integration in a multi-talker environment. While the behavioral benefit of congruent audiovisual speech was unaffected by age, older adults had a stronger need for cognitive control when processing conflicting audiovisual speech input. Furthermore, mechanisms of audiovisual integration are differently activated depending on the informational content of the visual information.

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bioRxiv2022

Preparing for the unknown: How working memory provides a link between perception and anticipated action

What mechanisms underlie the transfer of a working memory representation into a higher-level code for guiding future actions? Electrophysiological correlates of attentional selection and motor preparation processes within working memory were investigated in two retrospective cuing tasks. In the first experiment, participants stored the orientation and location of a grating. Subsequent feature cues (selective vs. neutral) indicated which feature would be the target for later report. The oscillatory response in the mu and beta frequency range with an estimated source in the sensorimotor cortex contralateral to the responding hand was used as correlate of motor preparation. Mu/beta suppression was stronger following the selective feature cues compared to the neutral cue, demonstrating that purely feature-based selection is sufficient to form a prospective motor plan. In the second experiment, another retrospective cue was included to study whether knowledge of the task at hand is necessary to initiate motor preparation. Following the feature cue, participants were cued to either compare the stored feature(s) to a probe stimulus (recognition task) or to adjust the memory probe to match the target feature (continuous report task). An analogous suppression of mu oscillations was observed following a selective feature cue, even ahead of task specification. Further, a subsequent selective task cue again elicited a mu/beta suppression, which was stronger after a continuous report task cue. This indicates that working memory is able to flexibly store different types of information in higher-level mental codes to provide optimal prerequisites for all required action possibilities. Highlights* Selectively cueing features results in an overall performance benefit * Feature-based attention is sufficient to form a prospective motor plan * Prospective motor preparation can be initiated ahead of task specification * Retro-active task specification leads to forming of higher-level action codes * Different tasks requirements result in different prospective action plans

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bioRxiv2021

Attentional Modulations of Alpha Power Are Sensitive to the Task-relevance of Auditory Spatial Information

The topographical distribution of oscillatory power in the alpha band is known to vary depending on the current focus of spatial attention. Here, we investigated to what extend univariate and multivariate measures of post-stimulus alpha power are sensitive to the required spatial specificity of a task. To this end, we varied the perceptual load and the spatial demand in an auditory search paradigm. A centrally presented sound at the beginning of each trial indicated the to-be-localized target sound. This spatially unspecific pre-cue was followed by a sound array, containing either two (low perceptual load) or four (high perceptual load) simultaneously presented lateralized sound stimuli. In separate task blocks, participants were instructed either to report whether the target was located on the left or the right side of the sound array (low spatial demand) or to indicate the exact target location (high spatial demand). Univariate alpha lateralization magnitude was neither affected by perceptual load nor by spatial demand. However, an analysis of onset latencies revealed that alpha lateralization emerged earlier in low (vs. high) perceptual load trials as well as in low (vs. high) spatial demand trials. Finally, we trained a classifier to decode the specific target location based on the multivariate alpha power scalp topography. A comparison of decoding accuracy in the low and high spatial demand conditions suggests that the amount of spatial information present in the scalp distribution of alpha-band power increases as the task demands a higher degree of spatial specificity. Altogether, the results offer new insights into how the dynamic adaption of alpha-band oscillations in response to changing task demands is associated with post-stimulus attentional processing.

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bioRxiv2020

Congruent lip movements facilitate speech processing in a dynamic audiovisual multi-talker scenario: An ERP study with older and younger adults

In natural conversations, visible mouth and lip movements play an important role in speech comprehension. There is evidence that visual speech information improves speech comprehension, especially for older adults and under difficult listening conditions. However, the neurocognitive basis is still poorly understood. The present EEG experiment investigated the benefits of audiovisual speech in a dynamic cocktail-party scenario with 22 (aged 20 to 34 years) younger and 20 (aged 55 to 74 years) older participants. We presented three simultaneously talking faces with a varying amount of visual speech input (still faces, visually unspecific and audiovisually congruent). In a two-alternative forced-choice task, participants had to discriminate target words ("yes" or "no") among two distractors (one-digit number words). In half of the experimental blocks, the target was always presented from a central position, in the other half, occasional switches to a lateral position could occur. We investigated behavioral and electrophysiological modulations due to age, location switches and the content of visual information, analyzing response times and accuracy as well as the P1, N1, P2, N2 event-related potentials (ERPs) and the contingent negative variation (CNV) in the EEG. We found that audiovisually congruent speech information improved performance and modulated ERP amplitudes in both age groups, suggesting enhanced preparation and integration of the subsequent auditory input. In the older group, larger amplitude measures were found in early phases of processing (P1-N1). Here, amplitude measures were reduced in response to audiovisually congruent stimuli. In later processing phases (P2-N2) we found decreased amplitude measures in the older group, while an amplitude reduction for audiovisually congruent compared to visually unspecific stimuli was still observable. However, these benefits were only observed as long as no location switches occurred, leading to enhanced amplitude measures in later processing phases (P2-N2). To conclude, meaningful visual information in a multi-talker setting, when presented from the expected location, is shown to be beneficial for both younger and older adults.

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bioRxiv2019

A dual mechanism underlying retroactive shifts of auditory spatial attention: dissociating target- and distractor-related modulations of alpha lateralization

Attention can be allocated to mental representations to select information from working memory. To date, it remains ambiguous whether such retroactive shifts of attention involve the inhibition of irrelevant information or the prioritization of relevant information. Investigating asymmetries in posterior alpha-band oscillations during an auditory retroactive cueing task, we aimed at differentiating those mechanisms. Participants were cued to attend two out of three sounds in an upcoming sound array. Importantly, the resulting working memory representation contained one laterally and one centrally presented item. A centrally presented retro-cue then indicated the lateral, the central, or both items as further relevant for the task (comparing the cued item(s) to a memory probe). Time-frequency analysis revealed opposing patterns of alpha lateralization depending on target eccentricity: A contralateral decrease in alpha power in target lateral trials indicated the involvement of target prioritization. A contralateral increase in alpha power when the central item remained relevant (distractor lateral trials) suggested the de-prioritization of irrelevant information. No lateralization was observed when both items remained relevant, supporting the notion that auditory alpha lateralization is restricted to situations in which spatial information is task-relevant. Altogether, the data demonstrate that retroactive attentional deployment involves excitatory and inhibitory control mechanisms.

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bioRxiv2019

The role of working memory for bridging the gap between perception and goal-directed actions - Evidence by mu and beta oscillations in sensorimotor cortex

What mechanisms are at work when transferring a visual representation in working memory into a higher-level code for guiding future actions? We investigated the underlying attentional and motor selection processes in working memory by means of oscillatory EEG parameters. Participants stored two, three or four objects in working memory and subsequent retroactive cues indicated one or two items as task-relevant. The oscillatory response in mu (10-14 Hz) and beta (15-25 Hz) frequencies with an estimated source in sensorimotor cortex contralateral to response side was used as a correlate of motor planning. There was a stronger suppression of oscillatory power when only one item was cued. Importantly, this effect appeared although the required response could not be anticipated at this point in time. This suggests that working memory can store multiple item-specific motor plans and the selection of a stored visual item leads to an automatic updating of associated response alternatives.

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bioRxiv2019

Unraveling the relation between EEG-correlates of attentional orienting and sound localization performance: a diffusion model approach

Understanding the contribution of cognitive processes and their underlying neurophysiological signals to behavioral phenomena has been a key objective in recent neuroscience research. Using a diffusion-model framework, we investigated to what extent well-established correlates of spatial attention in the electro-encephalogram contribute to behavioral performance in an auditory free-field sound-localization task. Younger and older participants were instructed to indicate the horizontal position of a pre-defined target among three simultaneously presented distractors. The central question of interest was whether posterior alpha lateralization and amplitudes of the anterior contralateral N2 subcomponent (N2ac) predict sound localization performance (accuracy, mean reaction time) and/or diffusion model parameters (drift rate, boundary separation, non-decision time). Two age groups were compared to explore whether in older adults, who struggle with multi-speaker environments, the brain-behavior relationship would differ from younger adults. Regression analyses revealed that N2ac amplitudes predicted drift rate and accuracy, whereas alpha lateralization was not related to behavioral or diffusion modeling parameters. This was true irrespective of age. The results indicate that a more efficient attentional filtering and selection of information within an auditory scene, reflected by increased N2ac amplitudes, was associated with a higher speed of information uptake (drift rate) and better localization performance (accuracy), while the underlying response criteria (threshold separation), mean reaction times, and non-decisional processes remained unaffected. The lack of a behavioral correlate of post-stimulus alpha power lateralization constrast the well-established notion that pre-stimulus alpha power reflects a functionally relevant attentional mechanism. This highlights the importance of distinguishing anticipatory from post-stimulus alpha power modulations.

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