Giant Bipolar Cell Synaptic Circuits in the Macaque Retina
The retina is a tissue in the back of the eye with light-sensitive rod and cone photoreceptors, which absorb light and transduce it into a neural signal. Information flows from photoreceptors to bipolar cells to retinal ganglion cells (RGCs), which transmit output to the brain. 12 types of bipolar cells have been identified in primate retinas. The giant bipolar cell (GBC) is characterized by its large axonal spread and dendritic field and is unique in receiving input from selected photoreceptors within its dendritic field.
A connectome from the inferior quadrant of parafoveal macaque retina was generated using serial blockface scanning electron microscopy and annotated with Viking software. Seven GBCs were analyzed using SBFSEM-tools in MATLAB and characterized according to distinctive morphology. Additionally, output was identified onto three wide-field RGC types in stratum 4 of the IPL: smooth monostratified, recursive monostratified (rmGCs), and parasol RGCs. Pre- and postsynaptic contacts with starburst and unidentified amacrine cells were also observed.
Parasol RGCs are important for spatial vision and motion detection. The distribution of GBC ribbon synapses is polarized, suggesting that ON parasol cells receive excitatory input from outside the classical receptive field center, potentially enhancing responses to moving stimuli. Two other GBC targets, ON smooth monostratified RGCs and rmGCs, are also sensitive to motion. Additionally, GBCs are expected to contribute to directional selectivity via reciprocal synapses with starburst amacrine cells and excitatory synapses onto rmGCs. These observations are consistent with the hypothesis that GBCs are involved in motion-sensitive circuits in the primate retina.
Senior Legacy Symposium Poster.pdf
Annelise Koch
Annelise is originally from Columbia, Illinois and will be graduating with a B.S. in Neuroscience. Following graduation, she plans to complete a research internship in St. Louis before applying to medical schools. Aside from her involvement as a member of Dr. Ogilvie’s lab, she has also served as coordinator for WHISTLe (Wellness Holistic Initiative in St. Louis) at the SLU Health Resource Center and actively volunteers with Campus Kitchen and St. Louis Children’s Hospital. Annelise is especially interested in studying neuropsychiatric disorders and hopes to one day specialize in psychiatry as a practicing physician. In her free time, she enjoys reading, creative writing, watching too many period dramas, and playing with her incredibly adorable pitbull, Tater-Tot.
Carla Hamwi
Carla Hamwi is a Neuroscience major from Syria. She moved to Missouri shortly before attending SLU, and switched into the neuroscience program during her sophomore year. Carla has a biology and psychology minor as well – she says that her favorite part of Neuroscience is its interdisciplinary nature.
Apart from research, Carla likes to travel and recently studied abroad in Madrid. In St. Louis, she volunteers as an Arabic translator for local refugees and an English tutor. Carla plans to apply to medical school this summer, and will be taking a gap year to continue research and volunteering in the meantime.
Sharon Lee
Sharon Lee is from Ballwin, Missouri, and is a graduating senior with a major in Neuroscience and minor in Psychology. After graduation, Sharon plans to take a gap year before applying to medical school. In the future, she wants to pursue a career as a physician working in pediatrics.
Swathy Karthikeyan
Swathy Karthikeyan is from Palatine, IL – a suburb of Chicago – and is majoring in neuroscience and minoring in political science. She loves learning about the brain and has loved being part of Dr. Ogilvie's lab for the past three years. At SLU, she has been involved with Camp Kesem and as a tutor for Overground Railroad.
We would like to thank Dr. Ogilvie for her continued support, guidance, and encouragement of our interests in neuroscience throughout our time as members of her lab!