Retinotope Kartierung des menschlichen visuellen Kortex mit funktioneller Magnetresonanztomografie – Grundlagen, aktuelle Entwicklungen und Perspektiven für die Ophthalmologie

Zusammenfassung

Seit ihrer ursprünglichen Entwicklung Mitte der 90er-Jahre leistet die auf funktioneller Magnetresonanztomografie (fMRT) basierte retinotope Kartierung des visuellen Kortex einen fundamentalen Beitrag zum Verständnis des menschlichen Sehsystems. Multiple kortikale Repräsentationen des Gesichtsfeldes wurden nachgewiesen und so zahlreiche visuelle Areale identifiziert. Die Organisation einzelner Areale wurde im Detail beschrieben und Einflüsse pathophysiologischer Prozesse im Sehsystem auf die kortikale Organisation aufgedeckt. Diesen Ergebnissen liegen Untersuchungen mit einer Magnetfeldstärke von 3 Tesla oder weniger zugrunde. Ein Feldstärkenvergleich von 3 und 7 Tesla ergab, dass die retinotope Kartierung von einer Magnetfeldstärke von 7 Tesla profitiert und insbesondere Detailkartierungen mit einer hohen räumlichen Auflösung ermöglicht. Im Bereich der Ophthalmologie ist die Anwendung der fMRT-basierten retinotopen Kartierung insbesondere zur Untersuchung von Grundlagenfragestellungen zur Plastizität des menschlichen visuellen Kortex vielversprechend. Dies unterstreichen bisherige Studien an Patienten mit makulärer Fehlfunktion oder abnormalen Sehnervenprojektionen.

Abstract

Since its initial introduction in the mid-1990 s, retinotopic mapping of the human visual cortex, based on functional magnetic resonance imaging (fMRI), has contributed greatly to our understanding of the human visual system. Multiple cortical visual field representations have been demonstrated and thus numerous visual areas identified. The organisation of specific areas has been detailed and the impact of pathophysiologies of the visual system on the cortical organisation uncovered. These results are based on investigations at a magnetic field strength of 3 Tesla or less. In a field-strength comparison between 3 and 7 Tesla, it was demonstrated that retinotopic mapping benefits from a magnetic field strength of 7 Tesla. Specifically, the visual areas can be mapped with high spatial resolution for a detailed analysis of the visual field maps. Applications of fMRI-based retinotopic mapping in ophthalmological research hold promise to further our understanding of plasticity in the human visual cortex. This is highlighted by pioneering studies in patients with macular dysfunction or misrouted optic nerves.

Schlüsselwörter

fMRT - visueller Kortex - Plastizität - Retinotopie - Magnetfeldstärke

Key words

fMRI - visual cortex - plasticity - retinotopy - magnetic field strength

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