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I will structure my talk around two main pieces of work dealing with two sensory systems that have evolved novel ways of dealing with obstacles: my thesis work on visual responses in salamander retinas devoid of all input from photoreceptors; and my postdoctoral work on cricket auditory responses to conspecific song amid a cacophony of competing noises and hungry predators.
Bushcricket males that call to advertise their positions to females face a formidable cacophony of competing noise in the tropical rainforest. Low frequency sounds are advantageous for long-range acoustic signal transmission and for avoiding the competition, but for small animals, they constitute a challenge for signal detection and localization. We investigated the mechanical, behavioral, and neurophysiological frequency tuning of the tympana of O. uninotatus, finding unusual modifications in both its behavioral responses and its auditory system.
The behavioral responses of the females to the male call also deviates from expectation: instead of phonotaxis, the female's first response to the male call is tremulation, a form of body vibration that transmits a vibratory signal to the substrate upon which the female is seated. The female's tremulation and the male's call constitute a very rare form of multi-modal duetting.
The persistence of certain non-image-forming responses to light despite the absence of photoreceptor input in mice with macular degeneration led us to an awareness of intrinsically photosensitive retinal ganglion cells (ipRGCs). These cells have been well characterized in mammalian systems, and their activity is based on a pigment called melanopsin. We characterized the spectral sensitivity, pharmacological modulators, and the receptive fields of these cells in the salamander retina providing the first known example of ipRGC involvement in image forming circuits.
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