Forschungs- & Entwicklungsinformationsdienst der Gemeinschaft - CORDIS

Final Activity and Management Report Summary - FMRI IN AD (A functional neuroimaging study of face processing in early Alzheimer's disease)

Patients with Anterior temporal lobe (ATL) lesions show semantic and lexical retrieval deficits and the differential role of this area in the two processes is debated. Functional neuroimaging in healthy individuals has not clarified the matter mainly because of two reasons:
- first, semantic and lexical processes occur usually simultaneously and automatically, and cannot easily be dissociated;
- second susceptibility artifacts in ATL interfere with detection of task related Blood-oxygen-level-dependent (BOLD) signal changes.

We devised a 'functional Magnetic resonance imaging' (fMRI) paradigm, which allowed us to study the identification (i.e. association of semantic biographical information) of celebrities, with and without the ability to retrieve the proper name. Further, to reduce susceptibility artefacts in ATL, we established an optimised Echo planar imaging sequence (EPI), reaching reliable BOLD-signal sensitivity in all areas of the parietal and temporal lobes.

While semantic retrieval reliably activated the left ATL among other areas, only more posterior areas in the temporal lobe and temporo-parietal junction were modulated by naming. These results support the data from patients with ATL lesions and indicate that the anomia that they often experience is due to semantic rather than lexical retrieval impairment.

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