Light stimulation of brain cells can recover memories in mice with Alzheimer's disease-like memory loss, according to new research. The rescue of memories, which changed both the structure of neurons as well as the behavior of mice, was achieved using optogenetics, a method for manipulating genetically tagged cells with precise bursts of light. This finding suggests that impaired retrieval of memories, rather than poor storage or encoding, may underlie this prominent symptom of early Alzheimer's disease and points to the synaptic connectivity between memory cells as being crucial for retrieval.