Biology subjects

Ten Oever, S.

Publications and source records attributed to Ten Oever, S..

5 recordsLinked to original sources

bioRxiv2026

Item-specific clustering of high gamma-band activity on theta phase during speech categorization

Theta-gamma phase-amplitude coupling (PAC) has been proposed as a mechanism for separating neural representations in time. Although item-specific PAC has been reported, its role in perception remains unclear. Notably, previous work has shown that theta phase can bias perception, raising the question whether such biases are linked to phase-specific gamma activity. Here, we investigated whether phase-dependent perceptual biases are accompanied by item-specific theta-gamma PAC. We presented ambiguous speech sounds that could be interpreted as either /da/ or /ga/ in patients with epilepsy implanted with intracranial electrocorticography. We found that pre-stimulus theta phase predicted both the neural and perceptual response, with /da/ and /ga/ tuned channels exhibiting gamma activity clustering at distinct theta phases. These findings suggest that neural and perceptual biases stem from phase-specific pre-activation of item-specific neural representations. They demonstrate the generalizability of the theta-gamma code, shaping behavior and enhancing representational capacity.

neuroscience↗

bioRxiv2026

Theta-Phase Targeted Encoding Gates Memory Sensitivity

Theta phase has been proposed to play an important role in memory. It may gate encoding and retrieval, such that certain phases are more favorable for memory processing than others, or become part of the memory representation, such that reinstating the encoding phase benefits retrieval. To test and distinguish these competing accounts, we used a closed-loop EEG system, allowing us to control the phase at which items were presented at encoding and retrieval. In an associative memory task, visual targets were presented at predefined phases of the ongoing mid-frontal theta rhythm, thereby pairing individual memory items with specific encoding phases. During retrieval, targets appeared either at the same phase as during encoding or at an alternative phase. We show that theta phase during encoding predicted subsequent memory sensitivity, while finding no evidence that retrieval phase nor the match between encoding and retrieval phases influenced performance. Therefore, our findings are consistent with a gating account, in which the rhythmic state at the moment of encoding influences the efficacy of memory formation.

neuroscience↗

bioRxiv2023

Phase-dependent word perception emerges from region-specific sensitivity to the statistics of language

Neural oscillations reflect fluctuations in excitability, which biases the percept of ambiguous sensory input. Why this bias occurs is still not fully understood. We hypothesized that neural populations representing likely events are more sensitive, and thereby become active on earlier oscillatory phases, when the ensemble itself is less excitable. Perception of ambiguous input presented during less-excitable phases should therefore be biased towards frequent or predictable stimuli that have lower activation thresholds. Here, we show with computational modelling, psychophysics, and magnetoencephalography such a frequency bias in spoken word recognition; a computational model matched the double dissociation found with MEG, where the phase of oscillations in the superior temporal gyrus (STG) and medial temporal gyrus (MTG) biased word-identification behavior based on phoneme and lexical frequencies, respectively. These results demonstrate that oscillations provide a temporal ordering of neural activity based on the sensitivity of separable neural populations.

neuroscience↗

bioRxiv2021

Information redundancy across spatial scales modulates early visual cortical processing

Visual images contain redundant information across spatial scales where low spatial frequency contrast is informative towards the location and likely content of high spatial frequency detail. Previous research suggests that the visual system makes use of those redundancies to facilitate efficient processing. In this framework, a fast, initial analysis of low-spatial frequency (LSF) information guides the slower and later processing of high spatial frequency (HSF) detail. Here, we used multivariate classification as well as time-frequency analysis of MEG responses to the viewing of intact and phase scrambled images of human faces to demonstrate that the availability of redundant LSF information, as found in broadband intact images, correlates with a reduction in HSF representational dominance in both early and higher-level visual areas as well as a reduction of gamma-band power in early visual cortex. Our results indicate that the cross spatial frequency information redundancy that can be found in all natural images might be a driving factor in the efficient integration of fine image details.

neuroscience↗

bioRxiv2020

Linguistic constraints modulate speech timing in an oscillating neural network

Neuronal oscillations putatively track speech in order to optimize sensory processing. However, it is unclear how isochronous brain oscillations can track pseudo-rhythmic speech input. Here we propose that oscillations can track pseudo-rhythmic speech when considering that speech time is dependent on predictions flowing from internal language models. We show that the temporal dynamics of speech are dependent on the predictability of words in a sentence. A computational model including oscillations, feedback, and inhibition is able to track the natural pseudo-rhythmic speech input. As the model processes, it generates temporal phase codes, which are a candidate mechanism for carrying information forward in time. The model is optimally sensitive to the natural temporal speech dynamics and can explain empirical data on temporal speech illusions. Our results reveal that speech tracking does not only rely on the input acoustics but instead entails an interaction between oscillations and constraints flowing from internal language models.

neuroscience↗