Presentation Title

Super-Resolution Imaging of Synapse Loss Following Traumatic Brain Injury

Faculty Mentor

Terrance Kummer

Start Date

17-11-2018 3:00 PM

End Date

17-11-2018 5:00 PM

Location

CREVELING 66

Session

POSTER 3

Type of Presentation

Poster

Subject Area

behavioral_social_sciences

Abstract

Traumatic brain injury (TBI) is a leading cause of neurological disability and a precursor to various neurodegenerative diseases including Alzheimer’s Disease. Impairment is the result of neural circuit dysfunction, but the loci of this dysfunction are inadequately characterized. To better understand these injuries, we are developing a super-resolution microscopy approach, called AirySynapse, to analyze synaptic density in the mouse and human brain. AirySynapse utilizes the super-resolution ZEISS LSM 880 Airyscan Microscope and custom image analysis. Several parameters of this analysis pipeline require optimization followed by validation. I systematically tested the effects of altering the levels of several post-imaging analysis parameters: namely the Airyscan reprocessing filter strength (the Wiener deconvolution parameter) and the method of background subtraction. These parameters were subsequently tested on control c57bl/6 mice and those that underwent modCHIMERA TBI. modCHIMERA is a novel, reliable, non-invasive TBI model that avoids the large focal lesions characteristic of many other models, permitting careful analysis of gray matter circuits. The resulting data show a decrease in synaptic density following injury across all time points through 30 days post injury, supporting the notion that AirySynapse is able to detect synaptic changes due to neurodegradation. Moreover, the AirySynapse technique has a broad array of potential applications and permits analysis of several endpoints that would be challenging with other techniques. For example, different molecular subsets of synapses can be imaged with AirySynapse, and the technique can be expanded to large regions of brain sections.

Summary of research results to be presented

Two of the parameters that were tested were the method of background subtraction and the Weiner deconvolution strength. While background subtraction had no discernible advantageous effect, an increase in the Wiener parameter of 1 from the system’s automatically-determined filter strength was shown to increase total colocalizations of 88% across injured mice, 35% across control mice, and 55% across all mice. Additionally, the metric of noise, determined as the ratio of random colocalizations to intact synapses, was calculated to be 7%, which fell below the predetermined threshold of 10%. The optimized AirySynapse parameters were subsequently utilized to identify synaptic changes between injured and control c57bl/6 mice at 4 different time points. Mice were injured using the modCHIMERA device, set at 10psi. Deficits in synaptic density of 7%, 16%, 40%, 25% were observed in injured mice at 1, 3, 7, and 30 days post-injury. These results suggest that neurodegeneration due to TBI peaks at some time between 3 and 30 days post-injury, with a substantial level of regeneration occurring between 7 and 30 days post-injury. Consistency with current knowledge regarding the timeline of neurodegeneration following TBI suggests that AirySynapse can be a powerful method for both synaptic quantification and detecting changes in synaptic density.

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Nov 17th, 3:00 PM Nov 17th, 5:00 PM

Super-Resolution Imaging of Synapse Loss Following Traumatic Brain Injury

CREVELING 66

Traumatic brain injury (TBI) is a leading cause of neurological disability and a precursor to various neurodegenerative diseases including Alzheimer’s Disease. Impairment is the result of neural circuit dysfunction, but the loci of this dysfunction are inadequately characterized. To better understand these injuries, we are developing a super-resolution microscopy approach, called AirySynapse, to analyze synaptic density in the mouse and human brain. AirySynapse utilizes the super-resolution ZEISS LSM 880 Airyscan Microscope and custom image analysis. Several parameters of this analysis pipeline require optimization followed by validation. I systematically tested the effects of altering the levels of several post-imaging analysis parameters: namely the Airyscan reprocessing filter strength (the Wiener deconvolution parameter) and the method of background subtraction. These parameters were subsequently tested on control c57bl/6 mice and those that underwent modCHIMERA TBI. modCHIMERA is a novel, reliable, non-invasive TBI model that avoids the large focal lesions characteristic of many other models, permitting careful analysis of gray matter circuits. The resulting data show a decrease in synaptic density following injury across all time points through 30 days post injury, supporting the notion that AirySynapse is able to detect synaptic changes due to neurodegradation. Moreover, the AirySynapse technique has a broad array of potential applications and permits analysis of several endpoints that would be challenging with other techniques. For example, different molecular subsets of synapses can be imaged with AirySynapse, and the technique can be expanded to large regions of brain sections.