Abstract
To navigate complex environments, animals must generate highly robust, yet flexible, locomotor behaviors. For example, walking speed must be tailored to the needs of a particular environment: Not only must animals choose the correct speed and gait, they must also rapidly adapt to changing conditions, and respond to sudden and surprising new stimuli. Neuromodulators, particularly the small biogenic amine neurotransmitters, allow motor circuits to rapidly alter their output by changing their functional connectivity. Here we show that the serotonergic system in the vinegar fly, Drosophilamelanogaster, can modulate walking speed in a variety of contexts and in response to sudden changes in the environment. These multifaceted roles of serotonin in locomotion are differentially mediated by a family of serotonergic receptors with distinct activities and expression patterns.
