Neurocognition and PET

Summary:

Aim: In cognitive neuroscience regional cerebral blood flow (rCBF) imaging with positron-emission-tomography (PET) is a powerful tool to characterize different aspects of cognitive processes by using different data analysis approaches. By use of an n-back verbal working memory task (varied from 0- to 3-back) we present cognitive subtraction analysis as basic strategy as well as parametric and covariance analyses and discuss the results. Methods: Correlation analyses were performed using the individual performance rate as an external covariate, computing inter-regional correlations, and as network analysis applying structural equation modelling to evaluate the effective connectivity between the involved brain regions. Results: Subtraction analyses revealed a fronto-parietal neuronal network also including the anterior cingulate cortex and the cerebellum. With higher memory load the parametric analysis evidenced linear rCBF increases in prefrontal, pre-motor and inferior parietal areas including the precuneus as well as in the anterior cingulate cortex. The rCBF correlation with the individual performance as external covariate depicted negative correlations in bilateral prefrontal and inferior parietal regions, in the precuneus and the anterior cingulate cortex. The network analysis demonstrated mainly occipito-frontally directed interactions which were predominantly left-hemispheric. Additionally, strong linkages were found between extrastriate and parietal regions as well as within the parietal cortex. Conclusion: The data analysis approaches presented here contribute to an extended and more elaborated understanding of cognitive processes and their different sub-aspects.

Zusammenfassung:

Ziel, Methoden: Im Bereich der neurokognitiven Aktivierungsstudien mit Messung des regionalen zerebralen Blutflusses (rCBF) mit PET können durch Anwendung verschiedener Datenanalysestrategien unterschiedliche Aspekte eines kognitiven Prozesses charakterisiert werden. Unter Verwendung eines verbalen n-zurück-Arbeitsgedächtnis-Paradigmas (n von 0 bis 3) werden kognitive Subtraktionsanalysen als Basisauswertung, parametrische und Kovarianz-basierte Analysen vorgestellt. Letztere wurden unter Anwendung einer externen Kovariate (individuelle Rate der korrekten Antworten), mittels regionaler Interkorrelationen und als Netzwerkanalyse mit Hilfe struktureller Gleichungssysteme zur Modellierung der effektiven Konnektivität zwischen den beteiligten Hirnregionen durchgeführt. Ergebnisse: Die Subtraktionsanalysen stellten eine zunehmende Involvierung eines fronto-parietalen Netzwerkes unter Einschluss des anterioren cingulären Kortex und Kleinhirnanteilen dar. Die parametrische Analyse wies einen linear mit der Aufgabenschwierigkeit ansteigenden rCBF beidseits präfrontal, inferior parietal unter Einschluss des Präcuneus, im prä-supplementär-motorischen Kortex links und im anterior cingulären Kortex nach. Die Korrelationsanalyse mit Nutzung einer externen Kovariaten demonstrierte von dieser negativ abhängige rCBF-Veränderungen beidseits inferior parietal und im Präcuneus, bilateral präfrontal und im anterior cingulären Kortex. In der Netzwerkanalyse zur Beschreibung der effektiven Konnektivität wurden vorwiegend von okzipital nach frontal gerichtete, links-hemisphärisch dominante Interaktionen nachgewiesen. Schlussfolgerung: Die vorgestellten datenanalytischen Vorgehensweisen tragen in ihrer Gesamtheit zum umfassenden Verständnis kognitiver Prozesse und einzelner Teilaspekte bei.

Key words:

Positron emission tomography - working memory - rCBF - structural equation modeling - parametric analysis

Schlüsselwörter:

Positronenemissionstomographie - Arbeitsgedächtnis - Aktivierungsstudien - rCBF

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