In Vivo Wide-Field and Two-Photon Calcium Imaging from a Mouse Using a Large Cranial Window
August 4th, 2022
8.7K views
The present protocol describes making a large (6 x 3 mm2) cranial window using food wrap, transparent silicone, and cover glass. This cranial window allows in vivo wide-field and two-photon calcium imaging experiments in the same mouse.
Overview
This study presents a protocol for creating a large cranial window in mice using food wrap, transparent silicone, and cover glass. This window facilitates both wide-field and two-photon calcium imaging to examine neural and glial activity during behavior, offering insights into cortical dynamics and sensorimotor integration.
Key Study Components
Area of Science
- Neuroscience
- Calcium imaging
- In vivo imaging techniques
Background
- Measuring neural activity is crucial for understanding brain function.
- Cranial windows allow for chronic imaging in live subjects.
- The proposed method is cost-effective and scalable.
- Prior techniques may not accommodate large imaging areas.
Purpose of Study
- To develop a reliable method for creating large cranial windows.
- To facilitate the observation of neuronal and glial activities in real-time.
- To enable the study of behavior-response relationships in mice.
Methods Used
- Large cranial windows were created using food wrap, silicone, and cover glass.
- The model involved transgenic mice expressing genetically encoded calcium indicators.
- Detailing of the window preparation, including surgical steps and materials.
- The technique included careful handling to prevent brain damage.
- Calcium imaging was performed two to four weeks post-surgery.
Main Results
- The large window allowed observation of cortical activity induced by sensory stimulation.
- Fluorescence changes were noted, indicating neural responses across different cortical areas.
- Eight of ten mice maintained functional windows for up to ten weeks.
- Initial trials suggested starting with smaller windows for improved chances of success.
Conclusions
- This protocol enables in-depth studies of brain activity in behaving mice.
- The method has potential applications in various neuroscience research areas.
- Insights gained can advance understanding of neural plasticity and behavioral neuroscience.
Frequently Asked Questions
What are the advantages of using a large cranial window?
A large cranial window allows for the imaging of extensive cortical regions simultaneously, enabling comprehensive studies of neural activity.
How is the cranial window created?
The protocol involves surgical preparation to remove bone and dura mater, followed by applying food wrap and securing it with silicone and cover glass.
What types of imaging data can be obtained?
The protocol enables wide-field and two-photon imaging, providing insights into both macroscopic and single-cell neuronal activities.
In what contexts can this method be applied?
It can be used to study behavior in mice, exploring relationships between neural activity and tasks such as decision-making and sensory responses.
What are key considerations when making the cranial window?
Care must be taken to avoid damaging the brain during surgery, and careful monitoring is essential for window integrity post-operation.
How frequently should the condition of the window and mice be monitored?
It is recommended to check the condition every 2 to 4 weeks to ensure long-term viability of the cranial window and the health of the mice.
What impact does this method have on future neuroscience studies?
The ability to image large areas of the cortex during live behavior enhances our understanding of functional connectivity and neural dynamics in health and disease.
Executive Industry Relevance
Large cranial window preparation in mice enables simultaneous wide-field and two-photon calcium imaging, supporting multi-scale interrogation of neural and glial dynamics during behavior. This capability advances predictive confidence in preclinical neuroscience models by linking macroscopic circuit activity with single-cell resolution. The method's cost-effectiveness and stability facilitate scalable, reproducible studies relevant to early discovery and translational research pipelines.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables direct observation of neural and glial activity in response to behavioral stimuli.
- Supports mechanistic de-risking by correlating circuit-level and cellular responses.
- Facilitates functional target validation in disease-relevant neural systems.
Screening & Assay Development
- Provides a validated in vivo platform for quantitative calcium imaging readouts.
- Supports assay reproducibility and standardization across multiple cortical regions.
- Enables screening of genetic or pharmacological interventions with high spatial resolution.
Translational & Preclinical Research
- Aligns preclinical models with disease-relevant neural circuit dynamics.
- Enables longitudinal studies of neural plasticity and injury models.
- Supports risk-adjusted advancement decisions by linking behavior to neural activity.
Pipeline & Workflow Integration
This method bridges early discovery, lead identification, and preclinical validation by enabling multi-scale imaging in behaving mice.
- Discovery Biology: Supports hypothesis testing on neural circuit function and glial interactions.
- Screening: Delivers reproducible, quantitative imaging outputs for compound or genetic screening.
- Analytics: Provides high-content data for comparing neural responses across conditions and timepoints.
- Translational Research: Facilitates continuity from basic discovery to disease modeling and biomarker exploration.
- Enterprise Reuse: Offers a scalable, cost-effective platform adaptable to diverse neuroscience R&D programs.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence and reduces mechanistic ambiguity in neural target studies.
- Operational Value: Standardizes in vivo imaging workflows and supports reproducibility across studies.
- Strategic Value: Improves go/no-go decisions and capital efficiency by enabling robust, multi-scale data collection.
- Portfolio Impact: Supports risk-adjusted prioritization of neuroscience assets and translational models.
Implementation Considerations
- Requires expertise in microsurgery and in vivo imaging techniques.
- Needs access to wide-field and two-photon microscopy infrastructure.
- Demands cross-team standardization for window preparation and imaging protocols.
- Adaptable to various transgenic or viral labeling strategies for neural and glial targets.
- Careful surgical technique is essential to avoid brain damage and ensure long-term window integrity.
Biopharma FAQs
Why does null hypothesis testing matter for wide-field calcium imaging?
Null hypothesis testing in wide-field calcium imaging enables objective evaluation of whether observed cortical activity changes are statistically significant, supporting robust target validation and reducing false positives in early discovery.
How does independent variable isolation fit two-photon imaging workflows?
Isolating independent variables, such as specific sensory stimuli or genetic manipulations, allows two-photon imaging to attribute single-cell calcium responses directly to defined experimental conditions, increasing mechanistic clarity in neural circuit studies.
What do quantitative dependent variable measurements enable in this protocol?
Quantitative measurements of fluorescence changes enable precise comparison of neural and glial activity across cortical regions and timepoints, supporting data-driven decisions in screening and translational research.
Why are replication requirements critical for cross-functional imaging studies?
Replication ensures that observed neural activity patterns are reproducible across animals and experimental runs, facilitating cross-team collaboration and increasing confidence in preclinical findings.
What statistical analysis capabilities are required before implementing large cranial window imaging?
Robust statistical analysis is needed to interpret fluorescence data, assess variability, and validate the significance of observed neural responses, ensuring reliable integration into enterprise R&D workflows.
