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The work described in this dissertation explores how the internal state of the praying mantis plays an integral role in both the central brain processing of relevant sensory stimuli as well as towards the external predatory behavior observed after measured experimental manipulations of the praying mantis’s satiety state. The aim is to better elucidate the underlying principles and connections between the animal’s internal and external environments. In the introductory chapter, I discuss the scientific literature pertinent to the praying mantis, predatory hunting behavior, central nervous system anatomy and physiology and satiety’s effect on invertebrate metabolism.In Chapter 2, both food consumption and insulin injection are shown to be sufficient to significantly decrease both sensory and motor aspects of the predatory behavior in freely hunting female Chinese praying mantises, Tenodera sinensis. We observed that prey consumption reduced the distance of attention and the angular range in azimuth that evoked an appetitive head turn compared to 5-day starved adult females. We also demonstrated that the number of steps taken towards prey during pursuit significantly decreased with increased consumption. Next, we showed that insulin injection was sufficient to cause these same significant decreases in starved animals and that this occurred along a concentration-dependent axis. Lastly, using computer-generated virtual prey, we learned that abdominal insulin injection significantly reduced the praying mantis’ rate of attention towards small-field prey stimuli compared to a saline control. These conclusions support our hypothesis that release of a neurohormone regulator of internal state modify behavioral responses to prey-like visual stimuli.In Chapter 3, we bring the question to the neural level by performing tetrode recordings in the central brain of freely-walking praying mantises and observing insulin’s effects on populations of CNS cells as the animal was free to hunt computer-generated virtual prey or live cockroach nymphs. Taken together, this work expounds on the known information on the interactions between animal physiology and metabolism. Specifically, that metabotrophic indicators of internal state, like insulin, adjust the ‘gain’ of CNS cell populations to cause significant changes in their firing frequency towards small ‘prey-like’ stimuli. These changes, in turn, reflect those seen in the animal’s predatory behavior. |
