Oscillatory neural networks underlying rhythmic behaviors such as locomotion, chewing, and respiration, are flexible to enable organisms to successfully adapt. This flexibility extends to which neurons participate in a network. Neuromodulatory inputs (sensory, “higher-order” inputs) can shift neuronal participation from one network to another, or from single- to dual-network activity, even if the networks operate at distinct frequencies, such as those for locomotion and respiration. 

The Blitz lab uses a set of small, well-described motor networks involved in food-processing behaviors in the crab, Cancer borealis, to investigate the cellular and synaptic mechanisms underlying switches in neuronal participation. Using identified modulatory neurons, network neurons, and target muscles, the lab determined that modulation of intrinsic neuronal properties, and unmasking of previously non-functional chemical synapses collectively enable 1) a neuron to switch from single- to dual-network participation, and 2) coordinate related food processing behaviors. Additionally, properties of electrical synapses, which are not modulated, are essential for a neuron to both periodically “escape” from, yet still participate in its “home” network. Following the activity to the periphery, the lab found that different target muscles are differentially sensitive to dual-network activity, highlighting the importance of investigating the consequences of network modulation across levels of a motor system. This dual-network activity can play important roles in coordinating rhythmic behaviors, whether crab chewing and filtering of food, or talking and eating without choking, and in larger sensory and cognitive network flexibility.