Ann Arbor, MI, USA. Scientists have shown how the plasticity of their brains allowed mice to restore critical functions related to learning and memory after their ability to make certain new brain cells were disrupted.

The new findings bring scientists one step closer to isolating the mechanisms by which the brain compensates for disruptions and reroutes neural functioning — which could lead to an improved understanding of how the innate body plan is implemented in humans and posit treatments for cognitive impairments (such as those caused by disease and aging.


Neurogenesis

Neurons are most actively generated during the foundational period of pre-natal development. However, the neuron population process continues throughout adulthood.

More generally stated, the regrowth or repair of cell tissues (neuroregeneration is a continuous process throughut the human life cycle.

The extent and speed of neuroregeneration can vary, depending on whether it takes place within the central nervous system (CNS) or the peripheral nervous system (PNS).

In either case, the functional mechanisms are very similar.

The discovery of such neuroplasticity eclipsed old ideas that fixed brain locations supported specific functions exclusive of other areas."It's amazing how the brain is capable of reorganizing itself in this manner," says Geoffrey Murphy, Ph.D., is the co-senior author of the study and a researcher at the Molecular and Behavioral Neuroscience Institute (MBMI) of the University of Michigan (U-M).

The mice, exhibiting neuroplasticity, were able to shift key functions associated with learning and memory. "Right now, we're still figuring out exactly how the brain accomplishes all this at the molecular level, but it's sort of comforting to know that our brains are keeping track of all of this for us."

Murphy, also an associate professor of molecular and integrative physiology at the University of Michigan Medical School, put his lab in collaboration with the Neurodevelopment and Regeneration Laboratory run by Jack Parent, M.D. to examine the effects of neurgenerative disruption. Their findings appear in the Proceedings of the National Academy of Sciences (PNAS).

In previous research, the scientists had found that restricting cell division in the hippocampuses of mice using radiation or genetic manipulation resulted in reduced functioning in a cellular mechanism important to memory formation known as long-term potentiation.

But in this study, the researchers demonstrated that the disruption is only temporary and within six weeks, the mouse brains were able to compensate for the disruption and restore plasticity, says Parent, the study's other senior co-author, a researcher with the VA Ann Arbor Healthcare System, and an associate professor of neurology at the U-M Medical School.

After halting the ongoing growth of key brain cells in adult mice, the researchers found the brain circuitry compensated for the disruption by enabling existing neurons to be more active. The existing neurons also had longer life spans than when new cells were continuously being made.

"The results suggest that the birth of brain cells in the adult, which was experimentally disrupted, must be really important — important enough for the whole system to reorganize in response to its loss," Parent says.