Subkomponenten des Arbeitsgedächtnisses

Zusammenfassung

Die funktionelle Magnetresonanztomographie (fMRT) ermöglicht die Untersuchung kognitiv induzierter Hirnaktivierungen im Rahmen von Arbeitsgedächtnisfunktionen in vivo. Das Arbeitsgedächtnis dient der vorübergehenden Speicherung und Manipulation von Informationen im Kurzzeitspeicher und steht damit im Dienste von strategischem Denken und Problemlösungsverhalten. Mit der ereigniskorrelierten funktionellen Magnetresonanztomographie (erfMRT) können einzelne Subkomponenten von Arbeitsgedächtnisprozessen wie das Einprägen (»Encoding«), das Behalten (»Maintenance«) und der Abruf (»Retrieval«) von Informationen voneinander abgegrenzt werden. Zusätzlich sind unterschiedliche Ebenen von Arbeitsgedächtnisanforderungen und hinzutretenden exekutiven Komponenten systematisch variierbar und auswertbar. Vorliegende Untersuchungen mit dieser Methodik belegen eine funktionelle Dissoziation des präfrontalen Kortex mit einer vorrangigen Beteiligung des ventrolateralen präfrontalen Kortex im Rahmen einfacher Behaltensleistungen und einer zusätzlichen Rekrutierung des dorsolateralen präfrontalen Kortex im Rahmen von exekutiven Anforderungen. Schizophrene Patienten zeigen Defizite vorrangig während exekutiver Leistungen als Hinweis der zugrunde liegenden kortikalen Ineffizienz.

Summary

Functional magnetic resonance imaging (fMRI) allows for the study of working memory related cognitive brain activation patterns in vivo. Working memory is subserving the temporary storage of data and the manipulation of this information while kept in storage. It is, therefore, the basis for strategic reasoning and problem solving. Using event related functional magnetic resonance imaging (erfMRI) subcomponents of working memory such as encoding to, maintenance in and retrieval from working memory can be differentiated. Additionally, varying levels of executive demand can be systematically investigated. Previous studies employing this method are demonstrating a functional dissociation of the prefrontal cortex with predominant involvement of the ventrolateral prefrontal cortex for the maintenance of information and the dorsolateral prefrontal cortex for additional executive demand. Schizophrenic patients are exhibiting impaired activation patterns during executive task components related to an existing cortical inefficiency.

Schlüsselwörter

Kognition - ereigniskorrelierte fMRT - Arbeitsgedächtnis - exekutive Funktionen - Schizophrenie

Keywords

Cognition - event related fMRI - working memory - executive functions - schizophrenia

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