Flipping a “Light Switch” Recovers Memories in Mice with Alzheimer’s

Researchers are making progress in the fight against the memory stealing effects of Alzheimer's disease by reconnecting memories in mice with Alzheimer’s-like memory loss.

Researchers from the RIKEN-MIT Center for Neural Circuit Genetics have found that light stimulation of brain cells can recover memories in mice with Alzheimer's disease-like memory loss.

Researchers were effectively able to rescue memories using optogenetics, a method for manipulating genetically tagged cells with precise bursts of light.

According to Riken, the finding suggests that impaired retrieval of memories, rather than poor storage or encoding, may be behind the hallmark memory loss associated with early Alzheimer's disease, and points to the synaptic connectivity between memory cells as being crucial for the retrieval of memories.

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“We have shown for the first time that increasing synaptic connectivity within engram cell circuits can be used to treat memory loss in mouse models of early Alzheimer’s disease,” said lead author Dheeraj Roy in a release.

Using mice genetically engineered to develop Alzheimer’s-like symptoms, a group of researchers led by RIKEN Brain Science Institute and RIKEN-MIT Center Director Susumu Tonegawa showed that spines — small knobs on brain-cell dendrites through which synaptic connections are formed — were essential for memory retrieval in these mice. Moreover, fiber-optic light stimulation can re-grow lost spines and help mice remember a previous experience. The work was recently published in the journal Nature.

“The successful retrieval of memories in AD mice by increasing the number of spines for normal memory processing only in the memory cells, rather than in a broad population of cells, highlights the importance of highly-targeted manipulation of neurons and their circuits for future therapies,” said Tonegawa in a statement. “This level of specificity has not yet been accomplished in current deep brain stimulation therapies.”