| A recent study by Windmill et al. (2006) suggested that the noctuid moth, Noctua pronuba, is capable of actively tuning its membrane in order to be more sensitive to the higher echolocation frequencies used by bats. This occurs in response to high intensity auditory stimulation and is hysteretic lasting for an average of 7.5 minutes. Windmill et al. (2006) proposed that the moth is doing this in order to more accurately detect the bat should it return. The first chapter of this thesis tests Windmill's hypothesis. Linear regression analysis showed no significant change in afferent response as a function of time for Noctua pronuba, Noctua pronuba that had transected auditory afferents, Acronicta americana, Xestia dolosa, or Catocala ultronia. Amphipyra pyramidiodes showed significantly reduced sensitivity. The second chapter of this thesis used intracellular recording techniques to identify auditory afferents and additional auditory interneurons and deduce whether or not they are making direct connections with flight motorneurons. Two cells are described: (1) The possible B-cell gave an average instantaneous spike rate of 30.78 +/-1.29 Hz and closely resembled the B-cell morphology suggested in Surlykke and Miller (1982). (2) The possible motorneuron showing auditory influence was constantly spiking at an average rate of 46.75 +/- 4.91Hz. Presentation of an auditory stimulus increased firing rate to an average of 94.72 +/- 15.56Hz. |
