Posters

1) Tinnitus is robustly characterized by aberrant auditory prediction patterns

Lisa Reisinger¹

¹University of Salzburg, Austria

Phantom perceptions occur without any identifiable environmental or bodily source. The mechanisms and key drivers behind phantom perceptions like tinnitus are not well understood. The dominant framework suggesting that tinnitus results from neural hyperactivity in the auditory pathway following hearing damage, has been difficult to investigate in humans and has reached explanatory limits. As a result, researchers have tried to explain perceptual and potential neural aberrations in tinnitus within a more parsimonious predictive-coding framework. In two independent magnetoencephalography (MEG) studies, participants passively listened to sequences of pure tones with varying levels of regularity (i.e. predictability) ranging from random or ordered. Next to being a replication of the first study, the pre-registered second study ensured rigorous matching of hearing status, as well as age, sex, and hearing loss between individuals with and without tinnitus. Despite some changes in the details of the paradigm, using multivariate pattern analysis approaches, both studies revealed an analogous group difference prior to target sound onset. Our results make a strong case that individuals with tinnitus engage differently anticipatory auditory predictions as compared to controls. While the effect is robust and generalizable, the precise neurocognitive mechanism underlying this group difference needs to be further elucidated. Furthermore, future longitudinal studies need to determine whether dysregulated predictive processes are a consequence of tinnitus or rather pose a risk factor for developing this condition.

2) Won't get fooled again: EEG does not reflect the manifestation of cognition, but action

Tzvetan Popov¹

¹University of Zurich, Switzerland

EEG components such event induced potentials and oscillations are consistently and continuously linked to cognitive constructs. Among these constructs, arguably the most fundamental are socio-affective perception and emotion. The N170, the late positive potential (LPP), and the power reduction of alpha oscillations are consistently and unequivocally interpreted as the 'neural underpinnings' of these hypothetical constructs to the extent that the N170 measure is now the first psychiatric biomarker for social impairment accepted in the FDA Biomarker Qualification Program.

Evidence from two experiments (N= 50 each) is presented demonstrating that this conclusion is premature. Neither component directly links to the studied phenomenon. The P1-N170 latency of approximately 100 ms is indicative of the well-established 100 ms saccade reaction time necessary for the vector code neural operation observed in the superior colliculus, visual parietal, and frontal cortex. Conversely, the LPP and the sustained reduction of alpha oscillation indicate the continuous ongoing exploration of the presented stimulus. These results have been consistently replicated, even in images generated by DALL-E, where participants reported 100% confidence in detecting the artificial nature of the images. In such cases, automatic, evolutionary preserved socio-affective cortical responses do not provide a plausible explanation.

Instead, the consistency of experimental design across labs worldwide, which typically includes a baseline fixation period preceding the actual stimulus presentation, provides a common ground for the conjecture that EEG components in psychophysiological experiments relate to cognition indirectly through their actual relationship with oculomotor action: a requirement in all cognitive experiments.

3) Effects of a novel combination training on reading and visual exploration in simulated hemianopia

Inara Makhkamova¹, Thomas Schenk¹

¹Ludwig-Maximilians-Universität in Munich, Germany

Homonymous hemianopia often results in significant impairments in reading and visual exploration. Patients typically do not utilize effective strategies to compensate for their functional deficits, rendering appropriate training or therapy necessary. While compensatory therapy approaches are supported by evidence and are most effective in treating hemianopia, it remains unclear whether such approaches facilitate a transfer between improvements in visual exploration and reading skills. The current study introduces a novel combination training and examines its effectiveness in enhancing both skills in healthy participants with simulated right-sided hemianopia. The training combined visual exploration and reading elements, while exploration training without a reading component served as the control condition. Additionally, the effect of training duration was assessed in both training groups by offering training on three consecutive days and testing reading and visual exploration abilities at the end of each day. Results indicate that both training types lead to improvements in reading and visual exploration. However, the combination training results in more significant improvements in reading skills, positively impacting both reading speed and accuracy. Additionally, it leads to further reading improvements after the second day of training. On the other hand, the exploration training does not improve reading accuracy, nor does it result in further reading improvements with longer training duration. Overall, combination training appears to be more effective than exploration training alone, warranting further evaluation in hemianopic patients.

4) Neural signatures of contingency awareness

Yuri Pavlov¹

¹University of Tübingen, Germany

The recognition of the conditioned-unconditioned stimulus (CS-US) association in human fear conditioning is referred to as contingency awareness. A common view is that such simple forms of associative learning are independent of awareness. We challenge this view in an experiment where only some participants learned the association between CS and US. In this preregistered study (https://osf.io/vywq7), the participants heard words paired with tactile stimulation followed by either a neutral sound (CS-) or unpleasant loud noise (CS+). The condition depended on the word+vibration side compound. The participants were only instructed to listen carefully. Based on structured interviews, the participants were divided into aware (N=50) and unaware (N=31) groups. Questionnaires were administered to explore potential predictors of contingency awareness. Only the aware group showed signs of learning as expressed in a larger CS+/CS- difference in stimulus preceding negativity developing shortly before the US. In terms of oscillatory brain activity, the aware group showed stronger alpha-beta suppression before and in response to the vibration. Moreover, the aware group scored higher on the intolerance to uncertainty scale and had a narrower distribution of trait anxiety. These findings support the notion that associative learning cannot occur without contingency awareness. We conclude that contingency awareness is indexed by generally amplified neural patterns reflecting expectation of an aversive event and informative cues, as well as violation and confirmation of the expectation.

5) Social expectation formation in the dog temporal lobe

Magdalena Boch¹, Christoph Völter², Rogier B. Mars³, Ludwig Huber², Claus Lamm¹

¹University of Vienna, Austria, ²University of Veterinary Medicine Vienna, Austria, ³University of Oxford, United Kingdom

One reason for humans’ advanced social interaction skills is their capacity to continuously make predictions about the state of mind of others. Predictions (or expectations) about one’s social environment can be formed based on the perception of others’ actions, knowledge, and beliefs. A key region for this complex social ability in humans is the temporoparietal junction, and recent evidence suggests that the evolutionary origin of this area was already present in their close primate ancestors. Like humans, dogs are also sensitive to others' actions or intentions, but the neural mechanisms supporting this complex social ability remain unstudied. To close this research gap, we used a series of functional MRI tasks with awake and unrestrained pet dogs (N = 22-28). Preliminary results indicate that observing social interactions recruits a complex occipital-temporal-parietal network in dogs similar to humans. The network includes face- and body-responsive brain areas and areas sensitive to dynamic aspects of social cues and action features in the dog suprasylvian and sylvian temporal cortex. Unlike observations in humans and non-human primates, the temporal lobe was predominant in supporting social cognition for dogs. Our findings further show how the dog's temporal lobe responds to observing social interactions that take unexpected turns (e.g., interruption by another event) and that they elicit a social prediction error analogous to observations in humans and non-human primates. We provide new insights into the neural mechanisms supporting dogs’ complex social abilities and show whether social behaviours arise similarly in these species.

6) Dynamic alpha power modulations and slow negative potentials track spatio-temporal attention

Charline Peylo¹, Carola Romberg-Taylor², Larissa Behnke¹, Paul Sauseng¹

¹University of Zurich, Switzerland, ²Ludwig-Maximilians-Universität in Munich, Germany

Alpha power modulations and slow negative potentials have previously been associated with anticipatory processes in spatial and temporal top-down attention. In typical experimental designs, however, neural responses triggered by transient stimulus onsets can interfere with attention-driven activity patterns and our interpretation of such. Here, we investigated these signatures of spatio-temporal attention in a dynamic paradigm free from potentially confounding stimulus-driven activity using electroencephalography. Participants attended the cued side of a bilateral stimulus rotation and mentally counted how often one of two remembered sample orientations (i.e., the target) was displayed while ignoring the uncued side and non-target orientation. Afterwards, participants performed a delayed match-to-sample task, in which they indicated if the orientation of a probe stimulus matched the corresponding sample orientation (previously target or non-target). We observed dynamic alpha power reductions and slow negative waves around task-relevant points in space and time (i.e., onset of the target orientation in the cued hemifield) over posterior electrodes contralateral to the locus of attention. In contrast to static alpha power lateralization, these dynamic signatures correlated with subsequent memory performance (primarily detriments for matching probes of the non-target orientation), suggesting a preferential allocation of attention to task-relevant locations and time points at the expense of reduced resources and impaired performance for information outside the current focus of attention. Our findings suggest that humans can naturally and dynamically focus their attention at relevant points in space and time and that such spatio-temporal attention shifts can be reflected by dynamic alpha power modulations and slow negative potentials.

7) Analysis of the EEG signal complexity in the antisaccade task for various age groups

Julia Klaudia Byrska^1,2

¹University of Warsaw, Poland, ²University of Trento, Italy

The study was performed to examine and compare the complexity of electroencephalographic (EEG) data obtained from younger and older participants during the performance of an antisaccade task. The purpose of applying different complexity measures, such as multiscale entropy (MSE) and detrended fluctuation analysis (DFA), to the analysis of EEG signals was to

indicate significant differences in signal complexity correlated with age. Specifically, it was proposed that the analysis should focus on the precise time interval and brain region during the antisaccade task to capture and explore the inhibitory control mechanism. This targeted approach revealed noticeable differences between the younger and older groups, suggesting that differences in the complexity of the EEG data may reflect changes in cognitive function

associated with aging. Moreover, the detection of significant correlations between MSE and DFA highlighted their effectiveness in capturing complementary aspects of EEG signal complexity. These findings support the hypothesis that EEG complexity indices may act as biomarkers of aging-related changes in cognitive function.

8) Ultra-high frequency visual stimulation can induce hippocampal ripple oscillations

Julian Keil¹, Victor Hernandez-Urbina², Liam Doherty², Fabian Queisner², Markus Müschenich²

¹University of Potsdam, Germany, ²Ababax Health GmbH, Berlin, Germany

Flickering visual stimulation can evoke steady-state visual evoked potentials (SSVEPs), which can potentially influence ongoing brain activity. Recent experimental evidence indicates that Gamma-band (40 Hz) SSVEPs do not propagate beyond visual cortical areas. However, electrophysiological recordings of ripple oscillations (80-180 Hz) showed that ripple oscillations occur in the neocortex and the hippocampus, that they phase-synchronize across long distances, and that neocortical ripples often precede hippocampal ripples during wakefulness. Thus, it may be possible for ultra-high frequency neocortical oscillations to propagate beyond sensory areas and influence ongoing brain activity in subcortical areas. To test this hypothesis, we conducted one MEG experiment (N=10) and one ECoG experiment (N=4) in humans, using a recently developed ultra-high frequency visual stimulation paradigm to evoke neocortical ripple oscillations. While hippocampal sharp-wave ripples (SWRs) mostly occur during quiet rest periods or slow-wave-sleep, we aimed to increase their abundance during visual stimulation. In the MEG experiment, we used beamformer source analyses to create virtual hippocampal channels, in the ECoG experiment, we examined direct hippocampal recordings. In both experiments, we observed a higher number of SWRs during periods of stimulation compared to a resting state baseline. This indicates that ultra-high frequency visual stimulation can be used as a noninvasive tool to influence hippocampal oscillations.

9) The ‘Ocular Response Function’ for encoding and decoding oculomotor related neural activity

Juliane Schubert¹, Quirin Gehmacher², Aaron Kaltenmaier², Nathan Weisz¹, Clare Press²

¹University of Salzburg, Austria, ²University College London, University of London, United Kingdom

In recent years, oculomotor related signals in neuroimaging have evolved from a mere confound towards a variable of interest when investigating cognitive processes across various areas in neuroscience. From attention to memory, eye movements provide an easily accessible window into important aspects of human cognition. However, their role and contribution with regards to underlying neural processes is largely unknown due to anatomical and temporal overlap with concurrent stimulation. We thus aimed to develop a method to understand the role of eye movements in links between experimental variables and neural processes. Here, we use simultaneous human magnetoencephalographic (MEG) and eye tracking recordings in combination with temporal response functions during the resting state to establish transfer functions from oculomotion to neural codes. We use these source-projected ‘Ocular Response Functions (ORF)’ to reliably predict eye movement behaviour from MEG recordings. Afterwards, we show that ORFs can also be used to predict oculomotor related neural activity (and underlying sources) during experimental tasks. ‘Generic ORFs’ (i.e. averaged across participants) are then applied to open-source datasets to replicate oculomotor effects based on brain data and vice versa. We consider the insights into cognitive processes that could be gleaned with this method and hope to provide a useful new tool for understanding the complex role of oculomotor related signals in human cognition.

10) Impact of Aging on Theta-Phase Gamma-Amplitude Coupling During Learning: A Multivariate Analysis

Dawid Strzelczyk¹, Nicolas Langer¹

¹University of Zurich, Switzerland

Aging is associated with cognitive decline and memory impairment, but the underlying neural mechanisms remain unclear. Phase-amplitude coupling (PAC) between theta (5 Hz) and gamma (>50 Hz) oscillations is a proposed marker for parallel storage of multiple items in working memory. However, research has mainly focused on young individuals and epilepsy patients, with only a few studies on aging populations. Moreover, these studies have relied on univariate PAC methods, which can be flawed by potential spurious or biased PAC estimates due to non-stationarity of EEG signal.

To address these gaps, we employed multivariate PAC (mPAC) through generalized eigendecomposition (GED) analysis, which avoids the pitfalls of non-sinusoidal oscillations. Over 100 young and 100 older healthy participants engaged in a sequence learning paradigm, in which they learned a fixed sequence of visual stimuli over repeated observations, allowing us to track the mPAC during the incremental process of learning.

Behavioral results revealed that younger participants learned significantly faster than older participants. Neurophysiological data showed that mPAC increased over the course of learning in both age groups and could significantly predict fast and slow learners. However, older participants exhibited lower mPAC compared to younger counterparts, which suggest compromised parallel storage of items in working memory in older age. These findings shed light on the age-related differences in memory formation processes and may guide interventions to enhance memory performance in older adults.