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This image shows an isolated B8 motor neuron from an Aplysia californica buccal ganglion. This neuron controls a muscle involved in food grasping and intake during feeding.

 

How can memories last for days, years, or a lifetime? Proposed mechanisms for maintaining synaptic potentiation and memory.

 

Non synaptic memory mechanisms.

 

The synapse between sensory and motor neurons in Aplysia californica is a crucial site for learning and memory.  Confocal microscopy was used to demonstrate in naive animals that the number of synapses is proportional to synaptic strength.  Sensory neuron processes (red) can be observed in close proximity to those from motor neurons (green).  In projections through stacks of optical sections, areas of overlap appear yellow, but subsequent analysis demonstrates that only a few such areas are actually in close contact.

 

Phase-plane projections of the dynamic activity of a modeled bursting neuron.  Loops represent the attractors associated with each of seven stable modes of electrical activity.  A transient synaptic input can perturb the cell from one stable attractor to another and hence cause a permanent change in the electrical activity of the neuron.