The Sossin lab is interested in understand the molecular and cellular memory trace; the physical changes that occur in neurons when a memory is made and that are important for the maintaining the memory. In particular, we are exploring the hypothesis that the brain has specialized memory synapses with distinct molecular markers that are responsible for maintaining memory. How these synapses are induced, whether there are different types of memory synapses, and what are the markers that identify these synapses are questions the lab explores, both in the simple model system of Aplysia, and in rodent neurons.

The lab is also interested in how neurons regulate protein synthesis, and in particular how mRNAs are transported to synapses and then selectively produced to induce or sustain synaptic plasticity. We have shown that a major mechanism underlying this is the transport of mRNAs stalled in translation that are then reactivated to produce proteins on demand. We are exploring the molecular mechanisms underlying this process and how translation can be stalled in elongation and then reactivated.

A critical aspect of neuroscience is synaptic transmission. Using the simple model system of Aplysia, we are exploring unique aspects of transmission in the sensory neurons of this animal to learn fundamental rules for how neurotransmission works and has evolved. In particular, sensory neurons stop releasing transmitter during constant firing and this underlies behavioral habituation. This can be immediately reversed, so it is not because the sensory neuron runs out of vesicles. We believe this is due to fast changes in calcium-secretion coupling and we are exploring molecular mechanisms for this form of plasticity.