Kierstyn Folgers, “Methodology of Dendritic Spine Density Analysis of Retrosplenial Secondary Basilar Dendrites”
Mentor: James Moyer, Psychology
Poster #61
There are many different methods used to visualize a neuron isolated from the brain’s vast interconnected network. Distinct morphological components like dendritic spines can also be observed. Spines are small protrusions on a dendrite that vary in shape and size. They play an integral role in intercellular communication by receiving and emitting signals. Literature eludes that spine density may be proportional to the efficiency of electrical signals. Proficient signaling is crucial for many regions of the brain including that of the retrosplenial cortex, which plays a role in decision making, memory consolidation, and spatial navigation. Literature also supports the notion that as neurons age there shows a decrease in spine density which may disrupt synaptic connectivity. Cognitive deficits and overall neuronal function may change as density declines. Using the following methodology spines of young and aged neurons can be observed and their densities analyzed. While working in the Moyer lab, I have been able to learn and apply techniques that align with this specific topic. The region of the retrosplenial cortex was isolated using a vibratome and a cryostat. Fluorescent tagging was used to fill neurons and the waves that emit from light are visualized under a confocal microscope. Additionally, the confocal microscope was used to take images in ‘slices’ to create a 3D stack of fluorescent neurons. The tissue slices are 400µm thick and a laser on the microscope allows for deep tissue visualization of these neurons. The addition of oil emersion on the 40x objective lens revealed an intricate display of spines on the surface of the dendrites. 3D reconstruction of the entire neuron, using Nurolucida 360, provided information obtained from Scholl analysis such as dendrite length and thickness. These variables could be utilized as parameters for the neurons analyzed for further study. Using Neurolucida 360, spine density and classification can also be obtained. Imaging using fluorescence with the confocal microscope along with Neurolucida 360 for spine data is a method that has not been done before in our lab. The retrosplenial cortex and its spine density is an unexplored area in research that this new methodology could investigate. Retrosplenial secondary basilar dendrites in young and old neurons more specifically are being analyzed using this new methodology in hopes for further application in synaptic function and aging.