Humans have the remarkably ability to integrate information from multiple memories and infer indirect relationships. But how does our brain support this important function? In the latest study from our lab, we show that rhythmic brain waves, called theta oscillations, engage and synchronize the brain regions that support the integration of memories. The results were published in the journal Current Biology.
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A key feature of Parkinson’s disease (PD) is the depletion of striatal dopamine, which is associated with the motor and non-motor symptoms of the disease. In this study, we sought to investigate the role of dopamine in spatial memory in PD patients in a cross-over medication ON/OFF design. We used a virtual reality task to assess striatal- and hippocampal-dependent spatial memory. Results show that PD patients and age-matched controls rely more on striatal cue-based spatial learning than the young adults tested in previous studies. Medication improved striatal-dependent spatial memory. The benefit of medication on hippocampal-dependent spatial memory depended on prior experience with the task. These findings shed new light on dopaminergic modulation of hippocampal-striatal functions in PD.

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Alzheimer’s patients suffer from severe memory loss and disorientation. An international research team led by Christian Doeller (Donders Institute, Radboud University, Nijmegen, The Netherlands) and Nikolai Axmacher (Ruhr-Universität Bochum, Germany) has now shown that a genetically increased risk for Alzheimer’s disease affects a brain region known as the “GPS” of the brain already in healthy young adults. The results were published in the journal “Science”.
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In a new paper in Nature Neuroscience, we show that memories of the same events co-exist at different scales in the brain. To avoid interference, the different memory scales (coarse, medium and fine) are distributed across different parts of the hippocampus, with finest scale memories at the back and the coarser memories at the front.
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In humans, bilateral hippocampal atrophy can lead to profound impairments in episodic memory. Across species, perhaps the most well established contribution of the hippocampus to memory is not to episodic memory generally but to allocentric spatial memory. However, the extent to which navigational spatial memory depends on hippocampal integrity in humans is not well documented. We investigated spatial recall using a virtual environment in two groups of patients with hippocampal damage (moderate/severe) and a normal control group.
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