Spinal neural networks generate locomotion. An adjustment of the locomotion speed entails a precise order of recruitment of excitatory interneurons (e.g., V2a interneurons) within these networks. We show (pp. E3631-E3639), using the adult zebrafish spinal cord, that the recruitment order of V2a interneurons is not topographic and does not conform to input resistance. The incremental recruitment of these interneurons is determined by scaling the excitatory drive with input resistance. We also

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... w that locomotor networks are composed of multiple microcircuits recruited in a continuum. Thus, we provide insights into the recruitment mechanisms of spinal microcircuits that ensure optimal execution of locomotor movements. Successful social interaction depends on the ability to recognize others, evaluate their mental states (e.g. intentions, desires, and beliefs), and "read" their emotional states. Here, we show that, in monkeys, damage to the amygdala, a brain structure that is central to the expression of emotion, significantly disrupts the processing of emotional facial expression in high-level visual cortical areas involved in face recognition. These findings (pp. E3640-E3648) suggest that the projections of the amygdala to visual cortical areas likely enhance the sensory processing of biologically important signals, including those related to potential environmental threats and social contexts.