Clocking the conduction velocity of the visual pathway with optically pumped magnetometers

Projektinformationen

OptiVision

ID Finanzhilfevereinbarung: 101138983

DOI

10.3030/101138983

Projekt abgeschlossen

EK-Unterschriftsdatum 9 Oktober 2023

Startdatum 1 Januar 2024

Enddatum 30 Juni 2026

Finanziert unter

• European Research Council (ERC)

Gesamtkosten

Keine Daten

EU-Beitrag

€ 150 000,00

Koordiniert durch

AARHUS UNIVERSITET
Denmark

Periodic Reporting for period 1 - OptiVision (Clocking the conduction velocity of the visual pathway with optically pumped magnetometers)

Berichtszeitraum: 2024-01-01 bis 2026-06-30

Zusammenfassung vom Kontext und den Gesamtzielen des Projekts

The visual pathway provides an important window into the health of the central nervous system. Retinocortical conduction time (RCT), the time required for signals to travel from the retina to the visual cortex, has long been proposed as a potential biomarker for neurological disorders. However, current approaches rely on relatively slow electrophysiological responses, and important questions remain regarding how visual pathway conduction can be measured accurately and non-invasively.
The OptiVision project was motivated by findings from the ERC-funded OscillatoryVision programme that suggested the potential for estimating RCT from earlier neural responses than those traditionally used. To pursue this objective, the project focused on developing the methodological, technical, and anatomical foundations required for future studies.

A major component of the project involved advancing the use of optically pumped magnetometers (OPMs) for measurements of visual system activity. This included substantial efforts to improve the magnetic measurement environment, reduce environmental noise, optimize experimental procedures, and establish workflows capable of supporting challenging high-frequency recordings.

In parallel, the project investigated anatomical factors relevant to visual pathway conduction. In particular, it examined the relationship between head size and visual pathway length, providing evidence on how inter-individual anatomical variability may influence conduction delays. Understanding these anatomical determinants is essential for interpreting future RCT measurements and for developing biomarkers that can distinguish normal biological variation from disease-related changes.

The expected impact of the project is therefore twofold. First, it has established technical capabilities and measurement methodologies that strengthen the foundation for future OPM-based studies of visual system function. Second, it has improved our understanding of anatomical factors that influence visual pathway conduction, providing critical groundwork for the future development of more accurate biomarkers of visual pathway integrity. In the longer term, such biomarkers could contribute to improved assessment and monitoring of neurological disorders.

Arbeit, die ab Beginn des Projekts bis zum Ende des durch den Bericht erfassten Berichtszeitraums geleistet wurde, und die wichtigsten bis dahin erzielten Ergebnisse

The project focused on establishing the technical and scientific foundations required for improved measurement of visual pathway conduction. This comprised development of magnetic field compensation for OPM measurements and the investigation of anatomical factors that may influence conduction delays.

A major achievement of the project was the development of a magnetic field compensation algorithm to automatically tune biplanar coils for arbitrary OPM sensor configurations. This reduces background noise and improves tolerance to movements and vibrations. These advances strengthened the laboratory’s capability to perform high-sensitivity OPM recordings and provide a foundation for future studies.

The project also investigated the relationship between head size and visual pathway length. The results demonstrated that anatomical variability can influence the distance over which visual signals travel and therefore represents an important factor to consider when interpreting conduction measurements across individuals.

Despite the improvement of OPM signal quality that was achieved, detection of retinal high-frequency responses remained difficult. To address the main neuroscientific aim, the experiment was redesigned with conventional MEG and ERG to ensure measurement of high-frequency signals. Analysis for the expected effects on retinocortical conduction time estimation remains ongoing.

Overall, the project delivered valuable technical knowledge and improvements for OPM measurements and new insights into anatomical determinants of visual pathway conduction. These outcomes reduce technical barriers for future studies and advance the long-term goal of developing improved biomarkers of visual pathway function.

Fortschritte, die über den aktuellen Stand der Technik hinausgehen und voraussichtliche potenzielle Auswirkungen (einschließlich der bis dato erzielten sozioökonomischen Auswirkungen und weiter gefassten gesellschaftlichen Auswirkungen des Projekts)

The project advanced the methodological foundations for studying visual pathway conduction using emerging OPM technology. In particular, it improved the measurement environment, recording procedures, and analysis workflows required for high-sensitivity neuromagnetic recordings, providing a platform that can benefit from future improvements in high-frequency signal-to-noise ratio.

Although OPM-based detection of the targeted high-frequency retinal responses proved more challenging than anticipated, the underlying high-frequency retinocortical conduction time (RCT) concept was successfully demonstrated using conventional MEG and ERG recordings. These results support the feasibility of measuring visual pathway conduction from early neural responses.

The project therefore delivered both technical advances for future OPM-based implementations and scientific validation of the high-frequency RCT approach. Building on these results, clinical collaborations have been established to evaluate the sensitivity of high-frequency RCT measures in neurological and neuropsychiatric populations.
The key outcomes of the project are an improved OPM measurement infrastructure, enhanced expertise in low-noise magnetic recordings, new insights into anatomical variability in visual pathway length, and ongoing validation of the high-frequency RCT concept as a promising candidate biomarker of visual pathway function.