The Hippocampus At The Crossroads Of Learning And Memory

By artificially manipulating the activity of specific brain regions in rodents, scientists in Hong Kong have demonstrated that the hippocampus integrates brain signals to enable learning and memory.

AsianScientist (Oct. 9, 2017) – Researchers in Hong Kong have discovered that the hippocampus is responsible for integrating signals from other brain regions, making it more important to learning and memory than previously thought. They report their findings in the journal the Proceedings of the National Academy of Sciences.

The hippocampus, located underneath the cortex, plays important roles in memory and navigation. Patients with Alzheimer’s disease and other forms of dementia exhibit abnormalities in this area of the brain which result in short-term memory loss and disorientation. People with hippocampal damage may also lose the ability to form and retain new memories.

Despite these observations, the role of the hippocampus in brain-wide functional connectivity is not well understood by scientists. Functional connectivity refers to the functional integration between spatially separated brain regions.

In this study, a research team led by Professor Ed X. Wu of the Department of Electrical and Electronic Engineering at the University of Hong Kong used optogenetics and drugs to alter the activity of specific brain regions in rodents. Coupled with functional magnetic resonance imaging (fMRI), the researchers demonstrated that low-frequency activities in the hippocampus can drive brain-wide functional connectivity in the cerebral cortex and enhance sensory responses, such as vision, hearing and touch.

The findings also suggest that low-frequency activities in the hippocampus can enhance learning and memory; low-frequency brain activities usually occur during slow-wave sleep and have been shown to be critical for memory formation. Because the most common early symptom of Alzheimer’s disease is memory loss, these results indicate that hippocampal neuromodulation might also be useful in treating Alzheimer’s disease.

These findings are a major step in furthering our fundamental understanding of the origins and roles of brain-wide functional connectivity. They also highlight the immense potential of fMRI and neuromodulation for the early diagnosis and enhanced treatment of brain diseases, including Alzheimer’s disease, dementia, epilepsy, schizophrenia, transient global amnesia and post-traumatic stress disorder.

The article can be found at: Chan et al. (2017) Low-frequency Hippocampal–cortical Activity Drives Brain-wide Resting-state Functional MRI Connectivity.


Source: University of Hong Kong.
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