Optical Imaging of Motor Cortical Responses in Rats using an in vivo Approach
Location
Suwanee, GA
Start Date
17-4-2026 12:00 PM
End Date
17-4-2026 1:00 PM
Description
Introduction: Cerebellar ataxia is a disorder linked to dysfunctional signaling in the cerebello-thalamo-cortical pathway, leading to impaired coordination and balance. Transcranial electric stimulation (tES) has been shown to improve symptoms in patients with cerebellar ataxia by modulating neuronal excitability and enhancing functional connectivity in motor networks within this pathway. In this in vivo study, optical imaging was selected to detect neuronal calcium activity in the motor cortex by combining high-resolution and wide-field fluorescence (Jose et al, 2024). Visualization of the fluorescent signal of pollen grains validated the imaging capabilities of the mesoscope. Images were acquired using ThorCam software and analyzed for spatial resolution and signal uniformity.
Objective: Little is known about the cellular mechanism behind tES effects on the cerebello-thalamo-cortical pathway. To close the gap, we created an in vivo rat model that uses transverse sinus viral delivery of a genetically encoded calcium indicator and mesoscope imaging to observe neuronal population activity within this pathway. Because the mesoscope’s sensitivity to native fluorescent signals has been partially validated, its established settings can be used to ensure performance meets experimental requirements. The study aims to confirm cortical expression of the genetically encoded calcium indicator GCaMP using optical imaging.
Methods: This study follows the protocol (#A25-005) approved by the IACUC of PCOM. Neonatal Sprague-Dawley rat pups (P1) underwent transverse sinus injection of an adeno-associated viral vector (AAV9, #104487 Addgene) that expresses a calcium indicator. After a two-week expression period, optical imaging was conducted. Following a craniotomy, neuronal population activity was recorded using the mesoscope. To detect GCaMP fluorescence, excitation light at 469 nm (+/- 35 nm bandwidth) was recorded via the mesoscope camera and filtered by ThorCam (Thorlabs). Imaging data was analyzed using Fiji.
Results: The viral vector was successfully injected into the transverse sinus of rat pups (n= 21). Through the mesoscope, the surface of the motor cortex could be visualized (n= 5). Preliminary data showed a relative change in fluorescence intensity. This intensity change may represent the spontaneous neuronal activity within the motor cortex.
Future Directions: Future studies will determine how this fluorescence intensity is dependent on neuronal activity using electrophysiological recording. The effects of tES on the cerebello-thalamo-cortical pathway will be investigated. The findings from these studies may suggest how cerebellar stimulation improves motor function and support the development of more effective therapeutic stimulation for patients with cerebral ataxia.
Embargo Period
5-15-2026
Optical Imaging of Motor Cortical Responses in Rats using an in vivo Approach
Suwanee, GA
Introduction: Cerebellar ataxia is a disorder linked to dysfunctional signaling in the cerebello-thalamo-cortical pathway, leading to impaired coordination and balance. Transcranial electric stimulation (tES) has been shown to improve symptoms in patients with cerebellar ataxia by modulating neuronal excitability and enhancing functional connectivity in motor networks within this pathway. In this in vivo study, optical imaging was selected to detect neuronal calcium activity in the motor cortex by combining high-resolution and wide-field fluorescence (Jose et al, 2024). Visualization of the fluorescent signal of pollen grains validated the imaging capabilities of the mesoscope. Images were acquired using ThorCam software and analyzed for spatial resolution and signal uniformity.
Objective: Little is known about the cellular mechanism behind tES effects on the cerebello-thalamo-cortical pathway. To close the gap, we created an in vivo rat model that uses transverse sinus viral delivery of a genetically encoded calcium indicator and mesoscope imaging to observe neuronal population activity within this pathway. Because the mesoscope’s sensitivity to native fluorescent signals has been partially validated, its established settings can be used to ensure performance meets experimental requirements. The study aims to confirm cortical expression of the genetically encoded calcium indicator GCaMP using optical imaging.
Methods: This study follows the protocol (#A25-005) approved by the IACUC of PCOM. Neonatal Sprague-Dawley rat pups (P1) underwent transverse sinus injection of an adeno-associated viral vector (AAV9, #104487 Addgene) that expresses a calcium indicator. After a two-week expression period, optical imaging was conducted. Following a craniotomy, neuronal population activity was recorded using the mesoscope. To detect GCaMP fluorescence, excitation light at 469 nm (+/- 35 nm bandwidth) was recorded via the mesoscope camera and filtered by ThorCam (Thorlabs). Imaging data was analyzed using Fiji.
Results: The viral vector was successfully injected into the transverse sinus of rat pups (n= 21). Through the mesoscope, the surface of the motor cortex could be visualized (n= 5). Preliminary data showed a relative change in fluorescence intensity. This intensity change may represent the spontaneous neuronal activity within the motor cortex.
Future Directions: Future studies will determine how this fluorescence intensity is dependent on neuronal activity using electrophysiological recording. The effects of tES on the cerebello-thalamo-cortical pathway will be investigated. The findings from these studies may suggest how cerebellar stimulation improves motor function and support the development of more effective therapeutic stimulation for patients with cerebral ataxia.