Date of Award
Union College Only
Bachelor of Science
descending, neurons, information, receptive, stimulus
Dragonflies have been known to use a highly sophisticated visual system in the detection and capture of prey. Information about visual stimuli is sent to the wings via a number of large descending neurons in the thorax which are sensitive to specific target behaviors. By recording the signals being sent through these neurons we can determine what information the flight system receives regarding the position and velocity of the stimulus. In our experiment we took extracellular recordings of the dragonfly’s descending nerve cord using a suction electrode, which allowed us to track the responses of several target sensitive neurons at once. In order to stimulate the target response system we moved white beads of varying sizes in front of the animal in complex patterns while recording the bead’s position using two high speed cameras. This allowed us to reconstruct the precise 3-D motion of the stimulus and then coordinate this information with the electrode recordings. One of the problems we investigated with our data was whether the positional receptive fields of certain descending neurons show predictive qualities. We accomplished this by varying the delays between the stimulus and neural response in order to find the tightest receptive-field distribution. Despite problems due to sampling bias, our study discovered at least one descending neuron (MDT-4) with an optimal delay time that indicates a predictive receptive field.
Imler, Elliot J., "Using delay timing to determine the predictive qualities of descending neurons in dragonflies" (2008). Honors Theses. 1562.