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Inter-individual variability

Individual animals exhibit variability in behavior and/or variability in circuit properties. It is important to understand the implications of these differences.  Sea slugs offer a great opportunity for studying such inter-individual variability because the neurons in neural circuits are individually identifiable.  So, we can examine how particular neurons and particular synapses differ between individuals. Furthermore, we can perturb those neurons and synapses to make them more or less similar to each other using techniques like dynamic clamp or expression of exogenous genes.

We found that individual Pleurobranchaea differ in their propensity to swim on any given day and that the number of flexion cycles that they produced was correlated with the extent of serotonergic neuromodulation of a particular synapse in the central pattern generator (CPG) circuit underlying swimming (Lillvis and Katz, 2013). We are currently investigating whether individuals differ in their expression of serotonin receptors in particular neurons.

We previously found that when a commissure connecting the two halves of the brain in Tritonia is cut, swimming is impaired (Sakurai and Katz, 2009). Recently, we discovered that not all animals are equally susceptible to the injury.  Although the behavior was similar before the cut, some animals had fewer flexion cycles after the cut than others.  Our evidence suggest that this is correlated with the strength of a particular synapse in the swim CPG (Sakurai, Tamvacakis, and Katz, 2014). We showed that there are individual differences in recovery from the lesion (Sakurai et al, 2016).
This work is supported by a grant from the March of Dimes of Foundation.