Fotos: Guido Kollmeier, Rechte: Universität zu Lübeck.
Fotos: Guido Kollmeier, Rechte: Universität zu Lübeck.
Wöstmann, Alavash and Obleser demonstrate that alpha oscillations in the human brain implement distractor suppression independent of target selection.
In theory, the ability to selectively focus on relevant objects in our environment bases on selection of targets and suppression of distraction. As it is unclear whether target selection and distractor suppression are independent, we designed an Electroencephalography (EEG) study to directly contrast these two processes.
Participants performed a pitch discrimination task on a tone sequence presented at one loudspeaker location while a distracting tone sequence was presented at another location. When the distractor was fixed in the front, attention to upcoming targets on the left versus right side induced hemispheric lateralisation of alpha power with relatively higher power ipsi- versus contralateral to the side of attention.
Critically, when the target was fixed in front, suppression of upcoming distractors reversed the pattern of alpha lateralisation, that is, alpha power increased contralateral to the distractor and decreased ipsilaterally. Since the two lateralized alpha responses were uncorrelated across participants, they can be considered largely independent cognitive mechanisms.
This was further supported by the fact that alpha lateralisation in response to distractor suppression originated in more anterior, frontal cortical regions compared with target selection (see figure).
The paper is also available as preprint here.
We welcome Dr. Sebastian Puschmann as a new postdoc in the Obleser/Auditory Cognition lab!
Sebastian has a background in Physics. He received his training in auditory cognitive neuroscience at the University of Oldenburg and the Montreal Neurological Institute. In Lübeck, Sebastian will push forward studies on the neural mechanics and neural changes in hearing loss.
Congratulations to our currently ERC-funded lab member and postdoc Mohsen Alavash who has just secured 3‑year funding (~380,000 €) by the Deutsche Forschungsgemeinschaft (DFG) for an ambitious project: Mohsen wants to get closer to a network/graph-theoretical description of how spatial attention in the listening brain is organised. In a later stage of the project, Mohsen also plans on studying how the network organisation of spatial attention may be altered in hearing-impaired listeners.
We are glad that Mohsen plans on running this project within the Obleser lab, here at the University of Lübeck.
Also, make sure to check out Mohsen’s latest publication on the topic.
Im Februar hatte ich die Ehre, für die Kind Hörstiftung auf deren 2019er Symposium in Berlin unsere Arbeiten zur Vorhersage des Hörerfolgs exemplarisch anhand einiger unserer Studien allgemeinverständlich zu beleuchten. Ein 25-minütiges Video dieses Vortrags ist jetzt online.
(In February, I had the honour of presenting some of our recent work on predicting individuals’ listening success at the symposium of the Kind Hearing Foundation. A video in German is now available.)
Jonas and the lab are happy and thankful to announce a new research project funded by Sivantos, Erlangen. We are looking very much forward to a renewed collaboration with the audiological science team around Ronny Hannemann, beginning in October 2019.
The three-year project will look into the psychological and neurobiological challenges of attending and ignoring for normal-hearing and hearing-impaired listeners in complex acoustic scenes.
In this three-year project, we will use the auditory modality as a test case to investigate how the suppression of distracting information (i.e., “filtering”) is neurally implemented. While it is known that the attentional sampling of targets (a) is rhythmic, (b) can be entrained, and © is modulated by top-down predictions, the existence and neural implementation of these mechanisms for the suppression of distractors is at present unclear. To test this, we will use adaptations of established behavioural paradigms of distractor suppression and recordings of human electrophysiological signals in the Magento-/ Electroencephalogram (M/EEG).
Background: Goal-directed behaviour in temporally dynamic environments requires to focus on relevant information and to not get distracted by irrelevant information. To achieve this, two cognitive processes are necessary: On the one hand, attentional sampling of target stimuli has been focus of extensive research. On the other hand, it is less well known how the human neural system exploits temporal information in the stimulus to filter out distraction. In the present project, we use the auditory modality as a test case to study the temporal dynamics of attentional filtering and its neural implementation.
Approach and general hypothesis: In three variants of the “Irrelevant-Sound Task” we will manipulate temporal aspects of auditory distractors. Behavioural recall of target stimuli despite distraction and responses in the electroencephalogram (EEG) will reflect the integrity and neural implementation of the attentional filter. In line with preliminary research, our general hypothesis is that attentional filtering bases on similar but sign-reversed mechanisms as attentional sampling: For instance, while attention to rhythmic stimuli increases neural sensitivity at time points of expected target occurrence, filtering of distractors should instead decrease neural sensitivity at the time of expected distraction.
Work programme: In each one of three Work Packages (WPs), we will take as a model an established neural mechanism of attentional sampling and test the existence and neural implementation of a similar mechanism for attentional filtering. This way, we will investigate whether attentional filtering follows an intrinsic rhythm (WP1), whether rhythmic distractors can entrain attentional filtering (WP2), and whether foreknowledge about the time of distraction induces top-down tuning of the attentional filter in frontal cortex regions (WP3).
Objectives and relevance: The primary objective of this research is to contribute to the foundational science on human selective attention, which requires a comprehensive understanding of how the neural system achieves the task of filtering out distraction. Furthermore, hearing difficulties often base on distraction by salient but irrelevant sound. Results of this research will translate to the development of hearing aids that take into account neuro-cognitive mechanisms to filter out distraction more efficiently.
Wöstmann, Schmitt and Obleser demonstrate that closing the eyes enhances the attentional modulation of neural alpha power but does not affect behavioural performance in two listening tasks
Does closing the eyes enhance our ability to listen attentively? In fact, many of us tend to close their eyes when listening conditions become challenging, for example on the phone. It is thus surprising that there is no published work on the behavioural or neural consequences of closing the eyes during attentive listening. In the present study, we demonstrate that eye closure does not only increase the overall level of absolute alpha power but also the degree to which auditory attention modulates alpha power over time in synchrony with attending to versus ignoring speech. However, our behavioural results provide evidence for the absence of any difference in listening performance with closed versus open eyes. The likely reason for this is that the impact of eye closure on neural oscillatory dynamics does not match alpha power modulations associated with listening performance precisely enough (see figure).
The paper is available as preprint here.