Differential activation in parahippocampal and prefrontal cortex during word and face encoding tasks.

Episodic encoding is the first step in the formation of a memory trace. The relation between type of stimulus material and regional brain activation is not fully understood. We measured brain activation using fMRI in 12 healthy subjects during two experiments, word and face encoding. A widespread network of common activations in both tasks was present in the bilateral frontal (BA44/45), occipital (BA17/18/19) and fusiform gyri (BA37) as well as the right hippocampal formation (BA30). A region-of-interest-analysis for the hippocampal formation and dorsolateral prefrontal cortex (DLPFC) was performed additionally. During face encoding the right dorsal and during word encoding the bilateral ventral hippocampal region was activated. In the prefrontal cortex a lateralization to the left side was present only for word encoding. During encoding, activation in the inferior frontal and hippocampal cortex is modulated by the type of stimulus material.