Hippocampal involvement in working memory encoding of changing locations: An fMRI study

Whereas the role of the hippocampus for spatial learning and long-term memory is largely undisputed, there is less evidence for a participation of hippocampal structures in spatial working memory operations. In an fMRI study (functional magnetic resonance imaging), we therefore examined the role of the hippocampus during spatial working memory performance. Nineteen healthy volunteers performed a modified version of the Corsi Block-Tapping test (CBT) during fMRI. The CBT is a neuropsychological instrument that is widely used in clinical settings. It requires the storage and subsequent reproduction of spatial target sequences. Brain activity during CBT performance has rarely been examined in the past, at least not the hemodynamic correlates. In a baseline condition, participants processed a number of subsequently presented targets as in the CBT condition. The only difference was that targets did not change their location. As compared to baseline activity, the right hippocampus showed more activation during the CBT condition. In addition, whole-brain analysis showed working memory related frontal and parietal brain activation. The results indicate that hippocampal structures contribute to serial working memory encoding of spatial locations in the human brain.

Research highlights
► Mean reaction times per single target increase as a function of sequence length.
► The hippocampus participates in encoding serial working memory information.
► Working memory encoding recruits parietal, frontal and occipital brain regions.
► Working memory is involved in almost all higher-level cognitive operations.