Dissecting the Non-human Primate Brain in Stereotaxic Space
July 16th, 2009
The non-human primate is an important translational species for our understanding of the normal processing of the brain. The anatomical organization of the primate brain can provide important insights into normal and pathological conditions in humans.
This procedure starts off with a well perfused monkey head. With the calva removed, the head is then placed into the stereotaxic frame and a series of stereotaxic coronal slices are made with the manipulator arm, the brain is then removed, measured, and cryo protected. Hi, I'm Dr.Mark Burke from the Visual Neurosciences Laboratory in the School of Optometry at the University of Montreal.
I'm Dr.Shaheen Zur, also from the Visual Neurosciences Laboratory in the School of Optometry at the University of Montreal. I'm Dr.Mo Petto, director of the Visual Neuroscience Laboratory at the School of Optometry, university of Montreal. Today we will show you a procedure for blocking the non-human primate brain in stereotactic space.
We use this procedure in our laboratory to study various aspects of brain organization in normal development and in response to developmental intrusions. So Let's get started. This protocol begins following euthanasia fixation and decapitation of a vervet monkey.
Prior to brain removal, the stereotaxic frame must be prepared. First one needs to find the coordinates of the Horsley Clark Interoral plane zero or the theoretical midpoint between the ears. To measure this plane, fit the ear bars equally into the apparatus.
Then place a scalpel blade in the stereotaxic manipulator arm and measure the midpoint between the ear bars. Next, prepare the head to go into the stereotaxic frame. Use bone rgo and a scalpel to remove the lower jaw.
At this point, chip away any remaining calva throughout these steps. Be careful not to remove the temporal bones since you will need the ear canals intact to anchor the head in the stereotaxic frame. Using forceps and scissors, carefully cut away the visible dur matter from the exposed brain.
Now the skull is ready to go in the stereotaxic manipulator. To begin stereotaxic blocking the brain, place the head into the frame, adjust the eye palette and ear bars as you would for stereotaxic surgery. Place the stereotaxic manipulator in the predetermined anterior, posterior, or AP axis.
To begin blocking the brain. Position the manipulator to the far left or right side of the brain and lower the blade to make your first cut. The blade will be perpendicular to the midline of the brain cutting in the coronal plane.
Raise the blade to completely clear the brain surface. Then move medially to just overlap your first cut and lower the blade.Again. Continue to make overlapping cuts until you reach the opposite edge of the brain.
This completes the first coronal block. Move the manipulator one centimeter forward or back along the AP axis and make another series of cuts in the coronal plane parallel to your previous ones. Continue this way until you have blocked the entire brain.
Now that you have finished cutting, it is time to remove the brain from the skull. First, take the head out of the frame. Try to secure the brain by lightly coddling it in the palm of your hand to keep the brain from jiggling in the skull and becoming damaged.
Place your pinky finger across the frontal lobes to keep the peel surface of the brain from drying out. Wet a piece of gauze with PBS and drape it over the brain. Hold the head firmly by the skull and chip away the remaining occipital and temporal bones along with the spinal column.
This exposes the base and lateral aspects of the brain. Now remove the remaining dura. Lastly, remove the nasal bone and any remaining frontal bone, which will allow access to the olfactory bulbs.
It is important to remove the frontal bone. Last, because as you remove the base of the skull, the brain moves slightly and the frontal bone's. Jagged edges could damage the frontal lobes.
Remove any remaining dura matter carefully lift the front of the brain, slide the scalpel under the brain and free the brain from the skull. It will stay together like an onion sliced up the stem because the cutting blade does not reach all the way to the ventral side. There are a number of useful measurements you can make before you freeze the brain.
First, a caliper can be used to measure the AP axis of the brain. Next, find its specific density, weigh the brain. Then measure the volume as the displacement of water in a graduated cylinder.
Now you have the density mass divided by volume. Now that you have made measurements on the whole brain, it is time to release the individual blocks of tissue from where they're attached on the brain's ventral side, and prepare them for freezing. Take a tissue slicing blade and extend each cut through the ventral side of the brain releasing the blocks.
A caliper can be used to measure the medial, lateral and anterior posterior AEs. The brain blocks are now ready to be cryo protected and frozen. We've just shown you how to block a non-human primate brain in stereotaxic space.
When doing this procedure, it is important to fully retract the blade before any medial lateral movement is made with a stereotaxic manipulator. Also, when chipping away the bones from the brain, be careful not to damage a cortex with the ERs. So that's it.
Thanks for watching and good luck with your experiments.
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Overview
This article discusses the importance of non-human primates in understanding brain processing. It highlights how the anatomical organization of the primate brain can provide insights into both normal and pathological human conditions.
Key Study Components
Area of Science
- Neuroscience
- Translational research
- Primate anatomy
Background
- Non-human primates serve as a critical model for studying brain function.
- Their brain structure is similar to humans, making them valuable for research.
- Understanding their brain can lead to advancements in medical science.
- Research in this area can help address neurological disorders.
Purpose of Study
- To demonstrate a procedure for blocking the non-human primate brain in stereotactic space.
- To provide insights into the anatomical organization of the primate brain.
- To enhance understanding of brain processing relevant to human health.
Methods Used
- Preparation of a well-perfused monkey head.
- Removal of the calva and placement into a stereotaxic frame.
- Creation of stereotaxic coronal slices using a manipulator arm.
- Measurement and cryo-protection of the brain.
Main Results
- The procedure effectively prepares the primate brain for further study.
- Insights gained can inform both normal brain function and pathology.
- Demonstrates the utility of non-human primates in neuroscience research.
- Provides a foundation for future studies on brain processing.
Conclusions
- Non-human primates are essential for understanding complex brain functions.
- The anatomical similarities to humans make them invaluable in research.
- Procedures developed can aid in the study of neurological conditions.
Frequently Asked Questions
Executive Industry Relevance
Blocking non-human primate brains in stereotaxic space enables standardized tissue preparation for neurobiological studies, supporting target validation in CNS drug discovery. This method enhances predictive confidence by providing reproducible, anatomically defined tissue blocks for downstream analysis, reducing mechanistic ambiguity in early discovery. It facilitates translational continuity from discovery through preclinical research by ensuring consistent sectioning and cryoprotection workflows.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Enables interrogation of therapeutic hypotheses through anatomically precise coronal sectioning of primate brain tissue.
- Operational Value: Supports biological de-risking by clarifying brain organization in a translationally relevant model.
- Predictive Value: Enhances target confidence by allowing consistent sampling across subjects and experimental conditions.
Screening & Assay Development
- Scientific Value: Prepares validated biological systems for downstream workflows by generating uniform 1cm tissue blocks.
- Operational Value: Addresses assay standardization and reproducibility through stereotaxically guided blocking in the coronal plane.
- Scalability: Enables reliable compound evaluation by producing manageable-sized blocks suitable for cryoprotection and sectioning on standard cryostats.
Translational & Preclinical Research
- Translational Continuity: Supports disease-relevant system use by maintaining anatomical alignment from discovery through preclinical validation.
- Risk-Adjusted Advancement: Facilitates penetration of sucrose for cryoprotection, preserving tissue integrity for longitudinal studies.
- Mechanistic De-risking: Enables delineation of areas of interest through standardized coronal sectioning, reducing variability in regional analysis.
Pipeline & Workflow Integration
The method integrates into the discovery continuum by enabling standardized tissue preparation from early discovery through preclinical stages, supporting hypothesis testing and pathway clarification in primate models of neurological function.
- Discovery Biology: Supports hypothesis testing and biological de-risking by providing stereotaxically defined brain blocks for regional analysis.
- Screening: Enhances assay readiness through reproducible blocking that minimizes partial sections and ensures consistent tissue thickness.
- Analytics: Enables quantitative measurements such as AP axis length, brain mass, and volume displacement for comparative condition analysis.
- Translational Research: Connects discovery to preclinical continuity by preserving tissue structure through cryoprotection and standardized block sizing.
- Enterprise Reuse: Establishes a reusable capability for neuroanatomy workflows across multiple studies and model systems.
Operational & Enterprise Impact
- Scientific Value: Predictive confidence through anatomically standardized tissue preparation and reduction of sectioning variability.
- Operational Value: Standardization, reproducibility, and scalability via stereotaxic guidance and 1cm block sizing.
- Strategic Value: Better go/no-go decisions by reducing late-stage biological risk through early mechanistic clarity.
- Portfolio Impact: Risk-adjusted prioritization via reliable tissue preparation supporting consistent biomarker and target engagement readouts.
Implementation Considerations
- Requires expertise in neuroanatomy and stereotaxic instrumentation for precise coordinate identification and manipulator control.
- Dependent on stereotaxic frame, manipulator arm, and scalpel or blade for coronal sectioning in the intact skull.
- Necessitates cross-team standardization of blocking parameters (e.g., 1cm intervals, coronal plane alignment) for multi-site reproducibility.
- Requires adaptation considerations when applying to different primate species or brain sizes while maintaining stereotaxic fidelity.
- Practical limitations include the need for intact temporal bones to anchor the head and careful dura removal to avoid cortical damage during brain extraction.
