Neuropsychology Talk

14.07.2026

Pre-stimulus Occipital High-Frequency Bursts Regulate Attentional Efficiency via Local Synchronization and Prefrontal Communication

Speaker:
Prof. Dr. Qi Chen (South China Normal University, Guangzhou)

Venue:
IB 4/115 or online: https://ruhr-uni-bochum.zoom.us/j/99038888420?pwd=c1d0blhPWE5ldWZTMW1haTJzUlg4Zz09

Starting time:
4:00 pm

Abstract:
Selective attention depends not only on stimulus-evoked processing but also on the neural state preceding stimulus onset. However, how prestimulus cortical excitability and transient network communication jointly shape attentional efficiency remains poorly understood. Here, we investigated this question using intracranial EEG (iEEG) recordings from 45 epilepsy patients performing an audiovisual cross-modal Stroop task. Participants alternated between attending visual color patches or auditory color words while ignoring conflicting information from the other modality, enabling dissociation of modality-specific attentional preparation from post-stimulus conflict processing.

Behaviorally, auditory attention produced slower responses and larger cross-modal interference than visual attention. At the neural level, stimulus-evoked high-frequency broadband (HFB, 70–180 Hz) activity exhibited distinct temporal dynamics across auditory cortex, visual cortex, and prefrontal cortex, with sensory cortices responding earlier than prefrontal regions. Importantly, prestimulus occipital HFB power consistently predicted subsequent behavioral performance. Elevated prestimulus occipital HFB was associated with slower reaction times and reduced stimulus-evoked HFB responses, suggesting that excessive baseline excitability limits subsequent sensory processing efficiency. Similar relationships were observed in auditory cortex during auditory attention, although with distinct modality-dependent characteristics.

To determine whether these effects reflected transient neural events, we quantified HFB bursts and their coupling to low-frequency oscillations. Prestimulus HFB burst density closely tracked HFB power, indicating that baseline HFB modulation primarily arose from burst dynamics. Within sensory cortices, stronger burst-locked phase consistency predicted slower responses, suggesting that excessive local synchronization constrains processing flexibility. In contrast, during visual attention, stronger beta-band phase locking in prefrontal cortex time-locked to occipital HFB bursts predicted faster responses, indicating that efficient attentional performance depends on rapid long-range communication rather than enhanced local synchrony alone. Moreover, stronger prestimulus burst-phase coupling predicted earlier stimulus-evoked responses, linking prestimulus network organization to subsequent sensory processing efficiency.

Together, these findings demonstrate that prestimulus occipital HFB activity regulates attentional efficiency through two complementary mechanisms: local HFB synchronization reflects cortical excitability that can hinder efficient processing when excessive, whereas rapid inter-regional communication between occipital and prefrontal cortex facilitates effective attentional selection. These results provide intracranial evidence that transient prestimulus high-frequency dynamics establish network states that determine the efficiency of subsequent sensory processing and cognitive control.