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Modulating brain oscillations has strong therapeutic potential. However, commonly used non-invasive interventions such as transcranial magnetic or direct current stimulation have limited effects on deeper cortical structures like the medial temporal lobe. Repetitive audio-visual stimulation, or sensory flicker, modulates such structures in mice but little is known about its effects in humans. Using high spatiotemporal resolution, we mapped and quantified the neurophysiological effects of sensory flicker in human subjects undergoing presurgical intracranial seizure monitoring. We found that flicker modulates both local field potential and single neurons in higher cognitive regions, including the medial temporal lobe and prefrontal cortex, and that local field potential modulation is likely mediated via resonance of involved circuits. We then assessed how flicker affects pathological neural activity, specifically interictal epileptiform discharges, a biomarker of epilepsy also implicated in Alzheimer's and other diseases. In our patient population with focal seizure onsets, sensory flicker decreased the rate interictal epileptiform discharges. Our findings support the use of sensory flicker to modulate deeper cortical structures and mitigate pathological activity in humans.
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http://dx.doi.org/10.1101/2023.03.14.23286691 | DOI Listing |
bioRxiv
August 2025
Coulter Department of Biomedical Engineering, Georgia Institute of Technology & Emory University, Atlanta, GA.
Gamma oscillations (30-100 Hz) have long been theorized to play a key role in sensory processing and attention by coordinating neural firing across distributed neurons. Gamma oscillations can be generated internally by neural circuits during attention or exogenously by stimuli that turn on and off at gamma frequencies. However, it remains unknown if driving gamma activity via exogenous sensory stimulation affects attention.
View Article and Find Full Text PDFCortex
August 2025
Experimental Psychology, Division of Psychology and Language Sciences, University College London, London, UK; Institute of Ophthalmology, University College London, London, UK.
Visual hallucinations occur across many clinical conditions, but can also be induced experimentally in healthy individuals, using high-frequency flicker (Ganzflicker) and sensory deprivation (Ganzfeld). It is unclear how hallucinatory proneness changes across the lifespan, with prior questionnaire-based studies showing mixed results. As factors such as multi-sensory acuity loss and relatively increased reliance on prior knowledge may increase as we age, and these are considered risk factors for hallucination proneness, we hypothesised that reported decreases in hallucinations might reflect underreporting due to stigma.
View Article and Find Full Text PDFBiomed Phys Eng Express
September 2025
Department of Psychology, LMU Munich, Leopoldstr. 13, 80802 Munich, Germany.
. Combining Transcranial Electrical Stimulation and Visual Stimulation at the gamma frequency of 40 Hz holds scientific and clinical potential, but requires concurrent electrophysiological measurement to quantify neuronal effects. This poses substantial methodological challenges: electrical stimulation artifacts largely overshadow EEG signals; gamma signals' amplitude is particularly low; and oculo-muscular confounds overlap in frequency.
View Article and Find Full Text PDFImaging Neurosci (Camb)
May 2025
Neurocomputation and Neuroimaging Unit, Department of Education and Psychology, Freie Universität Berlin, Berlin, Germany.
Neuroscientific research has shown that perceptual decision-making occurs in brain regions that are associated with the required motor response. Recent functional magnetic resonance imaging (fMRI) studies that dissociated decisions from coinciding processes, such as the motor response, partly challenge this, indicating that perceptual decisions are represented in an abstract or sensory-specific manner that might vary across sensory modalities. However, comparisons across sensory modalities have been difficult since most task designs differ not only in modality but also in effectors, motor response, and level of abstraction.
View Article and Find Full Text PDFImaging Neurosci (Camb)
October 2024
Experimental Psychology and Methods, Faculty of Life Sciences, Wilhelm-Wundt Institute for Psychology, Universität Leipzig, Leipzig, Germany.
Spatial attention is a key function enabling the selection of relevantinformation and meaningful behavioral responses and is likely implemented bydifferent neural mechanisms. In previous work, attention led to robust butuncorrelated modulations of Steady-State-Visual-Evoked-Potentials (SSVEPs) as amarker of early sensory gain and visual as well as motor alpha-band activity. Weprobed the behavioral relevance of attention-modulated trial-by-trialfluctuations of these measures.
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