Fig. 5. EMG recordings during phonotaxis. (A) Alternating six-chirp sequences from the left and right were related to right front extensor tibiae EMG traces while animals were acoustically orienting on a trackball. In single trace EMG recordings the step pattern was the dominant modulation in motor unit activity. (B) Averaging EMG activity with respect to the start of the contralateral sound pattern revealed the auditory input to tibial motoneurons. SETi spike rate increased in response to ipsilateral (right) sound, and FFTi spike rate was modulated by contralateral (left) sound. SFTi activity was unaffected. The spike rate of FETi was too low to reveal any auditory activation and is not presented.