how are memories allocated within neurocircuits?
Although mechanisms involved in encoding, storing and retrieving memory have attracted a great deal of attention, the processes that allocate individual memories to specific neurons within a network have remained illusive.
Recent findings from our laboratory, using methods such as optogenetics -- that can track, activate and inactivate neurons -- unraveled the first insights into the mechanisms that modulate memory allocation in neuronetworks.
They showed that neurons in the lateral amygdala compete to take part in auditory fear conditioning memory traces and that the levels of the transcription factor CREB (cAMP-response element binding protein) determine the probability that a given neuron will be recruited into a given memory representation. Our electrophysiological studies showed that CREB changes the excitabilitiy of amygdala neurons, and thus affects the probability that they will be recruited into a given memory.
Key Publications:
Han, J. H., S. A. Kushner, et al. (2007). "Neuronal competition and selection during memory formation." Science 316(5823): 457-460.(PDF).
Won, J. and A. J. Silva (2008). "Molecular and cellular mechanisms of memory allocation in neuronetworks." Neurobiology of Learning and Memory 89(3): 285-292.
Silva, A. J., Y. Zhou, et al. (2009). "Molecular and cellular approaches to memory allocation in neural circuits." Science 326(5951): 391-395.(PDF)
Zhou, Y., J. Won, et al. (2009). "CREB regulates excitability and the allocation of memory to subsets of neurons in the amygdala." Nat Neurosci. (PDF)