Meeting Abstract
The leech Hirudo verbana sees the world through two different sets of eye cups: cephalic and sensillar. Cephalic eye cups are located on the anterior sucker, whereas sensillar eye cups are situated along the leech body. Recent studies show that shining ultraviolet radiation (UVR) on the different eye cups elicits different escape behaviors. These behaviors have yet to be characterized at a cellular level. We recorded electrical activity from the leech nerve cord to see how cephalic eye cups are encoding visual information. We also modulated light brightness to determine how leeches distinguish different UVR intensities. Lastly, to further understand the anatomical pathway of cephalic eyes and how they transmit visual information, we attempted to identify the neural pathway from the cephalic eyes to the leech headbrain. This data will be paired with behavioral assays, as well as electrophysiological recordings from sensillar eyes. We hypothesized that intensities will be encoded as follows: higher UVR intensity yields more action potentials, and each type of eye will encode UVR through a different action potential pattern. These differences may underlie the two escape behaviors. Our raw data recordings indicate that there is a difference in the firing pattern for different intensities of UVR shined on the cephalic eye cups. This work will lend insights on how H. verbana detects where light is coming from, and how the organism processes different intensities of aversive stimuli.
