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Abstract:
Tasks to measure visual memory usually require motor
functions involved in the response process. During fMRI these
affordances are circumvented by requiring a recognition process to
measure behavioral results. We designed both, a novel task and
response procedure allowing free recall of abstract visual designs
during functional MRI. Subjects (n=8) were asked to memorize 10
Figures each presented for 5 seconds during a learning phase.
Subsequently, free recall was measured. Functional MRI was
performed with a 1.5 Tesla Siemens Magnetom Vision scanner with
EPI-booster (16 slices, 5 mm thickness, 1 mm gap). For anatomical
reference, T2w SE-images were obtained at identical positions. Data
analysis was peformed by means of Statistical Parametric Mapping
(Welcome Institute of Neurology, London). Overall we observed
significant brain activation mainly located in lateral visual areas
as well as posterior midline structures. Additional activation was
to observe in superior parietal and in frontal regions. Activation
of the posterior areas was mainly bilateral whereas parietal and
frontal activations were mostly located in the right hemisphere.
During the two phases of learning and free recall no significant
difference of activation could be observed. We conclude that this
newly designed test allows investigation of free recall visual
memory under conditions of fMRI. The locations of significant
activations during the task support previous studies with PET and
fMRI.
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