Biology subjects

Leticevscaia, O.

Publications and source records attributed to Leticevscaia, O..

3 recordsLinked to original sources

bioRxiv2026

The behaviour bends, the code holds: working-memory category information in the multiple-demand network across graded interruption

Protecting working memory (WM) from interference is essential for goal-directed behaviour, yet its neural mechanisms remain unclear. The multiple-demand (MD) network - a set of frontoparietal regions recruited by diverse cognitive demands - is a candidate system for maintaining WM content under interference. We examined how the MD network represents a memorandum when an unrelated task interrupts maintenance. Participants memorised an image of a tool or animal and, during the delay, performed a digit task whose difficulty was parametrically varied (passive, easy, hard), allowing us to test how task engagement and associated cognitive demands affected concurrently maintained information. Using fMRI and multivariate pattern analysis, we decoded the maintained category (tool vs. animal) from 13 MD regions and early visual cortex. Behaviourally, interruption reduced recall accuracy, while the most demanding interrupter slowed responses. Neurally, category information was present during the delay, most strongly in visual cortex and bilateral intraparietal sulcus. This information was unaffected by task engagement (active vs. passive), consistently across decoding accuracy and cross-validated Mahalanobis (crossnobis) distance, with Bayesian evidence supporting the null effect. Increasing the demand of the active interrupter, however, produced a modest, network-wide reduction in crossnobis distance that was not detectable in decoding accuracy. Together, these findings reveal a dissociation between the behavioural costs of interruption and the neural representation of maintained category information. Although interruption impaired recall, engaging in an interrupter did not measurably alter category-level information in the MD network or visual cortex. Increasing the demand of the interrupter produced only a modest, network-wide reduction in representational distance, without affecting decoding accuracy, suggesting that the behavioural costs of interruption may not be fully explained by changes in the categorical representation of the memorandum.

neuroscience↗

bioRxiv2024

Scene context and attention independently facilitate MEG decoding of object category

Many of the objects we encounter in our everyday environments would be hard to recognize without any expectations about these objects. For example, a distant silhouette may be perceived as a car because we expect objects of that size, positioned on a road, to be cars. Reflecting the influence of such expectations on visual processing, neuroimaging studies have shown that when objects are poorly visible, expectations derived from scene context facilitate the representations of these objects in visual cortex from around 300 ms after scene onset. The current magnetoencephalography (MEG) study tested whether this facilitation occurs independently of attention and task relevance. Participants viewed degraded objects alone or within their original scene context while they either attended the scenes (attended condition) or the fixation cross (unattended condition), temporally directing attention away from the scenes. Results showed that at 300 ms after stimulus onset, multivariate classifiers trained to distinguish clearly visible animate vs inanimate objects generalized to distinguish degraded objects in scenes better than degraded objects alone, despite the added clutter of the scene background. Attention also modulated object representations at this latency, with better category decoding in the attended than the unattended condition. The modulatory effects of context and attention were independent of each other. Finally, data from the current study and a previous study were combined (N=51) to provide a more detailed temporal characterization of contextual facilitation. These results extend previous work by showing that facilitatory scene-object interactions are independent of the specific task performed on the visual input.

neuroscience↗

bioRxiv2019

Auditory and semantic cues facilitate decoding of visual object category in MEG

Sounds (e.g., barking) help us to visually identify objects (e.g., a dog) that are distant or ambiguous. While neuroimaging studies have revealed neuroanatomical sites of audiovisual interactions, little is known about the time-course by which sounds facilitate visual object processing. Here we used magnetoencephalography (MEG) to reveal the time-course of the facilitatory influence of natural sounds (e.g., barking) on visual object processing, and compared this to the facilitatory influence of spoken words (e.g., \"dog\"). Participants viewed images of blurred objects preceded by a task-irrelevant natural sound, a spoken word, or uninformative noise. A classifier was trained to discriminate multivariate sensor patterns evoked by animate and inanimate intact objects with no sounds, presented in a separate experiment, and tested on sensor patterns evoked by the blurred objects in the three auditory conditions. Results revealed that both sounds and words, relative to uninformative noise, significantly facilitated visual object category decoding between 300-500 ms after visual onset. We found no evidence for earlier facilitation by sounds than by words. These findings provide evidence for a semantic route of facilitation by both natural sounds and spoken words, whereby the auditory input first activates semantic object representations, which then modulate the visual processing of objects.

neuroscience↗