Blanchette, I. | bioRxiv Science

bioRxiv2025

Valence-dependent sensory-rhythmic neural entrainment modulates cortico-subcortical dynamics, attention, and memory

Sensory rhythmic stimulation enhances executive functions by entraining oscillations in higher- order cortical networks, but its effects on subcortical structures remain unclear. We propose that stimulus valence is a key feature to enable subcortical entrainment. Using intracranial EEG in epileptic patients, we first show that visual search is supported by cortico-subcortical theta (5Hz) activity. We then show that 5 Hz negative-valence visual stimulation entrains theta oscillations in a task-related network, including the ventral visual stream, hippocampus, and dorsolateral prefrontal cortex. Finally, in a behavioral experiment in healthy individuals, we show that both neutral and negative valence 5 Hz stimulation improved visual search speed, but only negative valence stimulation enhanced target image recognition as assessed through an additional memory task. These findings highlight the role of stimulus valence in modulating subcortical brain activity and behaviors through rhythmic sensory stimulation and pave the way for further applications in clinical intervention.

neuroscience↗

bioRxiv2021

DLPFC controls the rapid neural response to visual threat: An ERP and rTMS study

Individuals are faster at detecting threatening stimuli than neutral stimuli. While generally considered a rapid bottom-up response, this threat superiority effect is also modulated by top-down mechanisms known to rely on the dorsolateral prefrontal cortex (DLPFC). What remains unclear is whether the response is modulated only at later stages of processing, or whether rapid attention to threat itself is controlled in a top-down manner. To test this, we used repetitive transcranial magnetic stimulation (rTMS) to inhibit activity in the DLPFC, and measured EEG to index the immediate neural response to threat. Participants attended two sessions where they performed a visual search task with threatening or neutral targets. Prior to this, they received 15 minutes of 1 Hz inhibitory or sham rTMS targeting the right DLPFC. We measured the impact of rTMS on the P1, a rapid visually-evoked potential that is modulated by attention. We found that threatening targets increased the amplitude of the P1 in the sham condition, but inhibition of the DLPFC abolished this increase. These results suggest that the neural signature of rapid attentional detection of threat, even at its earliest stage, is influenced in a top-down fashion by the right DLPFC.

neuroscience↗