New Discovery in Brain Network Science

The hippocampus, located underneath the cortex, plays important roles in memory and navigation. Alzheimer’s disease and other forms of dementia have been proven to have affected and damaged this area of the brain, resulting in early symptoms including short-term memory loss and disorientation. People with hippocampal damage may lose the ability to form and retain new memories. It is also closely related to other diseases such as epilepsy, schizophrenia, transient global amnesia and posttraumatic stress disorder.

However, the role of hippocampus in complex brain networks, particularly its influence on brain-wide functional connectivity, is not well understood by scientists. Functional connectivity refers to the functional integration between spatially separated brain regions.

A research team has made major breakthrough in unveiling the mysteries of the brain to reveal functions of an important region, hippocampus, not known to scientists before in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS).

Link to full-text original article: New functions of the Hippocampus

Rodent experiments revealed that low-frequency activities in the hippocampus can drive brain-wide functional connectivity in the cerebral cortex and enhance sensory responses. The cerebral cortex is the largest region of the mammalian brain and plays a key role in memory, attention, perception, cognition, awareness, thought, language, and consciousness. In other words, low-frequency activities of the hippocampus can drive the functional integration between different regions of the cerebral cortex and enhance the responsiveness of vision, hearing and touch. These results indicated that hippocampus can be considered as the heart of the brain, a breakthrough in our knowledge of how the brain works.

Furthermore, these results also suggest that low-frequency activities in the hippocampus can enhance learning and memory since low-frequency activities usually occur during slow-wave sleep which has been associated with learning and memory. Slow-wave sleep, often referred as deep sleep, is a state that we usually enter several times each night and is necessary for survival. Alzheimer’s disease is a chronic neurodegenerative disease that usually starts slowly and worsens over time, and the most common early symptom is memory loss. These results may also have potential therapeutic implications of hippocampal neuromodulation in Alzheimer’s disease.

These current findings are a major step in furthering our fundamental understanding of the origins and roles of brain-wide functional connectivity. These findings also signify the potentials of rsfMRI and neuromodulation for early diagnosis and enhanced treatment of brain diseases including Alzheimer’s disease, dementia, epilepsy, schizophrenia, transient global amnesia, and posttraumatic stress disorder.

Their earlier revelation that the thalamus, another region connecting to the cortex, is not just a relay or passive brain region as initially thought, but can initiate brain-wide neural interactions at different frequencies, had been published in the December 2016 edition of PNAS.