Characterization of state dependent differences in central complex activity and its influence on motor control in the praying mantis (Tenodera sinensis)

点击翻译按钮获取中文摘要

When an animal navigates through its natural environment, it must constantly deal with barriers as it seeks out targets or avoids predation. This requires a rich interplay between local control reflexes, pattern generators, and higher brain centers. Basic locomotor patterns that are generated at the spinal or nerve chord level will in most cases not provide the agility necessary to allow the animal to navigate all complex terrain. To guide movements and place them in the context of immediately existing internal and external conditions (e.g. illumination, temperature or hunger) animals rely on sophisticated sensory systems. Clearly this requires a level of multi-sensory integration that must occur somewhere in the central nervous system. A considerable body of neurogenetic and electrophysiological data suggests that in insects these functions reside largely in the central complex (CX), a highly structured group of interconnected midline neuropils in the protocerebrum of all arthropods. The CX receives massive amounts of sensory information regarding the insects surroundings and its own physiological state. Multi-channel tetrode wires implanted in the CX of tethered or freely walking cockroaches demonstrated clear correlations between activity in individual neural units and navigational decisions. A recent meta-analysis of genetic, behavioral and physiological data strongly suggested that the CX is homologous to the mammalian basal ganglia which are primarily involved in behavioral choice and selection. However, despite intense research from many laboratories, the behavioral role of the CX has not been conclusively determined. Therefore I will examine how the activity in CX circuits influences specific behaviors as an insect experiences changes in its immediate surroundings or internal state. To accomplish this goal, I propose to examine multi-channel tetrode recordings in the brain of the praying mantis, using techniques that were developed for cockroach CX but have now been adapted for use in the closely related mantis brain. The use of a predatory insect like the praying mantis enables me to predict exactly where the insect would move to prior to experimental manipulation or relate patterns of neural activity to precise directional movements. It also affords the opportunity to test a hypothesis that neuromodulators associated with hunger and satiety alter stalking behavior through changes in CX circuitry. I will combine multi-channel tetrode recordings with high speed video analysis to examine patterns of neural activity in regions of the central complex associated with stalking and striking movements. I believe that these studies and the resulting neural based models will provide important insights in the functionality of state dependent control.