The authors would like to acknowledge Jim Knoblauch and Martin-Booth Hodges of the College of Agricultural, Consumer and Environmental Sciences Information Technology and Communication Services for their expertise in shooting, recording, and editing audio and video.

Procedures involving animal subjects have been approved by the Institutional Animal Care and Use Committee (IACUC) at the University of Illinois at Urbana-Champaign
NOTE: Prior to euthanasia, the pig was anesthetized via intramuscular injection with a combination of telazol:ketamine:xylazine (50.0 mg of tiletamine HCl plus 50.0 mg of zolazepam HCl reconstituted with 2.50 mL of ketamine HCl (100 g/L) and 2.50 mL of xylazine (100 g/L) and administered at 0.06 mg/kg BW). Once anesthetized, the pig was euthanized via intracardiac administration of sodium pentobarbital (390 mg/mL administered at 1 mL/5 kg BW). For brain dissection, it is recommended that the method of euthanasia be chosen based on the desired analytical procedure of the tissue. The method of euthanasia should cause as little damage to the brain as possible.
1. Extraction of the pig brain
<ol>
	<li>Following humane euthanasia, decapitate the pig by cutting above the nape of the neck, between the first and second vertebra (atlas and axis, respectively).</li>
	<li>Secure the head in an immobilized bench vise modified to include spikes. Ensure that the head is completely immobilized before proceeding.
	<ol>
		<li>Using a scalpel, make a sagittal cut along the midline of the skull that continues to the posterior of the head.</li>
		<li>Make a second (transverse) cut on the posterior of the head.</li>
		<li>Make a third (transverse) cut on the posterior end of the snout and in-line with the eyes. Cut the skin as far away from the skull as possible to ensure easy access to the skull.</li>
	</ol>
	</li>
	<li>Using a bone saw, make two anterior-to-posterior cuts lateral to the midline, extending from the eyes to the apex of the skull curvature. Bevel the saw towards the midline and cut just deep enough to penetrate the skull.
	<ol>
		<li>Repeat the above process on the perpendicular sides, creating a rectangular &#34;window&#34; in the skull.</li>
	</ol>
	</li>
	<li>Using a meat hook, pry the rectangular section of the skull off. Begin by placing the hook into one of the corners of the section and apply upward pressure to loosen the skull piece. Take care to place the meat hook only at the level of the skull to prevent inadvertently penetrating the brain tissue.</li>
	<li>If any meningeal layers remain on the brain, use forceps and blunt scissors (or alternatively, a scalpel) to gently remove the layers without cutting into the brain.</li>
	<li>Use a scalpel to cut away muscle and fat at the posterior portion of the head, exposing the posterior portion of the skull.
	<ol>
		<li>Make two transverse cuts along the posterior of the skull. Be sure not to cut into brain tissue.</li>
		<li>Secure the head by placing a firm hand on the snout and apply a backwards pressure to pull the posterior portion of the skull off, exposing the cerebellum.</li>
	</ol>
	</li>
	<li>Remove the head from the bench vice and place on a surgical mat.</li>
	<li>Use a long slender tool, such as the blunt end of a scalpel, to remove the brain. Invert the head and use a gentle scooping motion to coax the brain out of the skull cavity without damaging the surface of the brain. 
	&#8203;NOTE: It will be necessary to sever cranial nerves to remove the brain. Do so gently and do not attempt to forcefully pull the brain out. The brain will fall out on its own when it is properly and completely detached from the skull and spine.</li>
</ol>
2. Dissection of the pig brain
NOTE: It may be helpful to use a brain atlas or fiber dissection guide14 as a visual representation during dissection procedures. Make sure dissected tissue samples are stored properly according to project-specific needs upon removal of each sample (described in more detail below). Additionally, please note that for the purposes of this video, all brain regions shown were dissected from the right hemisphere, but this may differ per laboratory based on experimental objectives.
<ol>
	<li>To remove the brainstem (predominantly the medulla), make a coronal cut caudal to the cerebellum.</li>
	<li>To remove the cerebellum, make a coronal cut posterior to the cortex. Isolate desired regions (e.g., vermis, flocculus, etc.) of the cerebellum from this sample. Be sure not to include any portions of the brain stem in this sample.</li>
	<li>Separate the two hemispheres of the brain by making a mid-sagittal cut along the longitudinal fissure. Make this cut as a continuous motion to prevent causing damage to the cortex.</li>
	<li>To remove the midbrain, dissect a desired amount of tissue just ventral to the superior and inferior colliculi.</li>
	<li>To remove the hippocampus, place the blunt end of a scalpel in the posterior portion of the corpus callosum and gently roll the hippocampus out, using a &#34;J&#34; motion starting from the posterior portion of the corpus callosum; an entire hippocampal horn is &#39;bean-shaped&#39;.</li>
	<li>The striatum (caudate nucleus is primarily shown) is a grey and white matter-striped region just below the corpus callosum and anterior to the hippocampus. Bevel the scalpel and remove this region, revealing striated tissue upon removal.</li>
	<li>To remove the medial prefrontal cortex, dissect tissue from the frontal gyrus to the corpus callosum, removing the most medial portion of that section. The right cortex should remain after removal of the medial prefrontal cortex.</li>
	<li>To remove the thalamus, remove the bulb-like structure at the center of the midsagittal surface of the brain and rostral to the midbrain. The thalamus has a spherical shape and will look slightly darker than the surrounding tissue.</li>
</ol>
3. Post-dissection
<ol>
	<li>Upon completion of the dissection, preserve tissue samples properly for subsequent analyses. Omission of this step will result in significant autolysis and degradation within as little as 20 minutes.</li>
	<li>Leave each brain region intact at the time of dissection if structural analyses will be performed, or mince the tissues to create a homogenous tissue sample prior to preservation. Common sample preservation methods for brain tissues include cryopreservation and chemical fixation using crosslinking agents15.</li>
	<li>For standard lab assays (e.g., gene or protein expression), immerse in liquid nitrogen or solutions that stabilize genetic material prior to long-term storage at -80 &#176;C to provide convenient and cost-effective preservation methods.</li>
	<li>If maintaining tissue structure is a priority, preserve brain tissues through traditional fixation methods (e.g., using aldehyde-based fixatives to crosslink proteins), either without or with perfusion of the animal or organ of interest prior to tissue dissection.</li>
</ol>

<ol>
	<li>Hughes, H. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Swine+in+cardiovascular+research.">Swine in cardiovascular research.</a> Laboratory Animal Science. 36 (4), 348-350 (1986).</li><li>Yen, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anatomy+of+the+Digestive+System+and+Nutritional+Physiology.">Anatomy of the Digestive System and Nutritional Physiology.</a> Biology of the Domestic Pig. , 31-63 (2001).</li><li>Pond, W. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Of+Pigs+and+People.">Of Pigs and People.</a> Swine Nutrition. , 3-24 (2001).</li><li>Odle, J., Lin, X., Jacobi, S. K., Kim, S. W., Stahl, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Suckling+Piglet+as+an+Agrimedical+Model+for+the+Study+of+Pediatric+Nutrition+and+Metabolism.">The Suckling Piglet as an Agrimedical Model for the Study of Pediatric Nutrition and Metabolism.</a> Annual Review of Animal Biosciences. 2 (1), 419-444 (2014).</li><li>Larsen, M. O., Rolin, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+the+G&#246;ttingen+minipig+as+a+model+of+diabetes,+with+special+focus+on+type+1+diabetes+research.">Use of the G&#246;ttingen minipig as a model of diabetes, with special focus on type 1 diabetes research.</a> ILAR Journal. 45 (3), 303-313 (2004).</li><li>Lehmann, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+minipig+in+general+toxicology.">The minipig in general toxicology.</a> Scandinavian Journal of Laboratory Animal Science. 25, 59-62 (1998).</li><li>Richer, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sacrococcygeal+and+transsacral+epidural+anesthesia+in+the+laboratory+pig.">Sacrococcygeal and transsacral epidural anesthesia in the laboratory pig.</a> Surgical Radiologic Anatomy. 20, 431-435 (1998).</li><li>Lind, N. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+pigs+in+neuroscience:+Modeling+brain+disorders.">The use of pigs in neuroscience: Modeling brain disorders.</a> Neuroscience and Biobehavioral Reviews. 31 (5), 728-751 (2007).</li><li>Sauleau, P., Lapouble, E., Val-Laillet, D., Malbert, C. -. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+pig+model+in+brain+imaging+and+neurosurgery.">The pig model in brain imaging and neurosurgery.</a> Animal. 3 (8), 1138-1151 (2009).</li><li>Dobbing, J., Sands, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+aspects+of+the+brain+growth+spurt.">Comparative aspects of the brain growth spurt.</a> Early Human Development. 311, 79-83 (1979).</li><li>Aurich, L. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microsurgical+training+model+with+nonliving+swine+head.+Alternative+for+neurosurgical+education.">Microsurgical training model with nonliving swine head. Alternative for neurosurgical education.</a> Acta Cirurgica Brasileira. 29 (6), 405-409 (2014).</li><li>Bassi, T., Rohrs, E., Fernandez, K., Ornowska, M., Reynolds, C. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+brain+excision:+An+easier+method+to+harvest+the+pig's+brain.">Direct brain excision: An easier method to harvest the pig's brain.</a> Interdisciplinary Neurosurgery. 14, 37-38 (2018).</li><li>Bjarkam, C. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exposure+of+the+pig+CNS+for+histological+analysis:+A+manual+for+decapitation,+skull+opening,+and+brain+removal.">Exposure of the pig CNS for histological analysis: A manual for decapitation, skull opening, and brain removal.</a> Journal of Visualized Experiments. 122, e55511 (2017).</li><li>Pascalau, R., Szabo, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fibre+dissection+and+sectional+study+of+the+major+porcine+cerebral+white+matter+tracts.">Fibre dissection and sectional study of the major porcine cerebral white matter tracts.</a> Anatomia, Histologia, Embryologia. 46, 378-390 (2017).</li><li>McFadden, W. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perfusion+fixation+in+brain+banking:+a+systematic+review.">Perfusion fixation in brain banking: a systematic review.</a> Acta Neuropathologica Communications. 7, 146 (2019).</li><li>F&#233;lix, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stereotaxic+atlas+of+the+pig+brain.">Stereotaxic atlas of the pig brain.</a> Brain Research Bulletin. 49, 1 (1999).</li></ol>

The authors declare that they have no competing financial interests.

The techniques described herein were designed for pigs approximately 4 weeks of age. It is critical to perform these steps immediately after the pig has been humanely euthanized to ensure the integrity of brain tissue structure is maintained, especially when considering subsequent biochemical assays. It is helpful to use an atlas or fiber16 dissection guides when first learning the techniques. It is recommended that the experimenter practice several brain extractions and dissections prior to obtai...

The pig has been well documented and accepted as a translatable animal model for research in cardiovascular systems1, gastrointestinal systems2, nutrition3,4, diabetes5, toxicology6, and surgical techniques7. Use of the pig in neuroscience is beginning to increase, as PubMed searches for the keywords &#34;swine brain animal model&#34; result in four-times more results from 1996-2005 than the preceding 10 year period8, and even more results at present. A primary reason that the popularity of the pig model is expanding is due to its similarities in growth, structure, and function of the brain when compared with humans. In comparison to the human brain, the pig brain exhibits similar gyral patterning, vascularization and distribution of gray and white matter9. Moreover, the pig brain has been used in neuroimaging procedures, evoked potential recording, and in establishing neurosurgery techniques8,9. Unlike other animal models, however, the pig and human experience perinatal brain growth spurts, as opposed to pre- or post-natal growth spurts. At birth, the human and pig brain weigh approximately 27 and 25 percent of their adult brain weight, respectively, compared to the rat brain that weighs 12 percent of its adult brain weight and the rhesus monkey brain at 76 percent of adult weight10.
One reason the pig has been only slowly adopted as an animal model for neuroscience is because many researchers are unfamiliar with the animal in this context. Researchers may not be aware of its potential uses in the field or may not know the proper techniques required to use such a model. As use of the pig as a biomedical and preclinical model gains attention and use in neuroscience, it is necessary to establish standardized procedures of tissue removal to ensure accurate comparison of data across studies. Although dissection and surgical techniques involving the pig brain have been published elsewhere11,12,13, there is a need for simple and standardized protocols to collect pig brain tissue, especially for use in biochemical assays. As such, the aim of this video is to provide the knowledge necessary to allow researchers to perform a standardized brain extraction and dissection. This video illustrates one proper technique to remove the pig brain while keeping the cortex and brainstem intact, and subsequently review methods to dissect several key brain regions.

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extraction and dissection of the domesticated pig brain

Use of the pig as a preclinical and translatable animal model has been well-documented and accepted by research fields investigating cardiovascular systems, gastrointestinal systems, and nutrition, and the pig is increasingly being used as a large animal model in neuroscience. Furthermore, the pig is an accepted model to study neurodevelopment as it displays brain growth and development patterns similar to what occurs in humans. As a less common animal model in neuroscience, surgical and dissection procedures on pigs may not be as familiar or well-practiced among researchers. Therefore, a standardized visual protocol detailing consistent extraction and dissection methods may prove valuable for researchers working with the pig. The following video showcases a technique to remove the pig brain while keeping the cortex and brainstem intact and reviews methods to dissect several commonly investigated brain regions including the brainstem, cerebellum, midbrain, hippocampus, striatum, thalamus, and medial prefrontal cortex. The purpose of this video is to provide researchers with the tools and knowledge necessary to consistently perform a brain extraction and dissection on the four-week-old pig.

This section describes examples of results obtained after correct extraction and dissection of a 4-week-old pig brain. Figure 1 outlines the shape of each brain region for use as a guide during dissection. Part of the brainstem may remain in the skull after removal of the cerebellum (Figure 1B). This can be removed while isolating the desired region of the cerebellum. Table 1 displays the average weight (mean &#177; standard error of the mean) f...

Watch this Scientific Journal Video about Extraction and Dissection of the Domesticated Pig Brain at JoVE.com

Extraction and Dissection of the Domesticated Pig Brain

This protocol details the technique for removal of the pig brain in its entirety and dissection of several brain regions commonly studied in neuroscience.

Use of the pig as a preclinical and translatable animal model has been well-documented and accepted by research fields investigating cardiovascular ...

extraction-and-dissection-of-the-domesticated-pig-brain

Research

JoVE Journal

Neuroscience

20.1K Views.  University of Illinois at Urbana-Champaign. This protocol details the technique for removal of the pig brain in its entirety and dissection of several brain regions commonly studied in neuroscience. 

Video: Extraction and Dissection of the Domesticated Pig Brain

Biomarkers in an Animal Model for Revealing Neural, Hematologic, and Behavioral Correlates of PTSD

Identification of biomarkers representing the evolution of the pathophysiology of Post Traumatic Stress Disorder (PTSD) is vitally important, not only for objective diagnosis but also for the evaluation of therapeutic efficacy and resilience to trauma. Ongoing research is directed at identifying molecular biomarkers for PTSD, including traumatic stress induced proteins, transcriptomes, genomic variances and genetic modulators, using biologic samples from subjects' blood, saliva, urine, and postmortem brain tissues. However, the correlation of these biomarker molecules in peripheral or postmortem samples to altered brain functions associated with psychiatric symptoms in PTSD remains unresolved. Here, we present an animal model of PTSD in which both peripheral blood and central brain biomarkers, as well as behavioral phenotype, can be collected and measured, thus providing the needed correlation of the central biomarkers of PTSD, which are mechanistic and pathognomonic but cannot be collected from people, with the peripheral biomarkers and behavioral phenotypes, which can.
Our animal model of PTSD employs restraint and tail shocks repeated for three continuous days - the inescapable tail-shock model (ITS) in rats. This ITS model mimics the pathophysiology of PTSD 17, 7, 4, 10. We and others have verified that the ITS model induces behavioral and neurobiological alterations similar to those found in PTSD subjects 17, 7, 10, 9. Specifically, these stressed rats exhibit (1) a delayed and exaggerated startle response appearing several days after stressor cessation, which given the compressed time scale of the rat's life compared to a humans, corresponds to the one to three months delay of symptoms in PTSD patients (DSM-IV-TR PTSD Criterian D/E 13), (2) enhanced plasma corticosterone (CORT) for several days, indicating compromise of the hypothalamopituitary axis (HPA), and (3) retarded body weight gain after stressor cessation, indicating dysfunction of metabolic regulation.
The experimental paradigms employed for this model are: (1) a learned helplessness paradigm in the rat assayed by measurement of acoustic startle response (ASR) and a charting of body mass; (2) microdissection of the rat brain into regions and nuclei; (3) enzyme-linked immunosorbent assay (ELISA) for blood levels of CORT; (4) a gene expression microarray plus related bioinformatics tools 18. This microarray, dubbed rMNChip, focuses on mitochondrial and mitochondria-related nuclear genes in the rat so as to specifically address the neuronal bioenergetics hypothesized to be involved in PTSD.

We describe a rat model of post traumatic stress disorder (PTSD) that reveals the persistent alterations in neuroendocrine function and the delayed long-term, exaggerated fear response, characteristic of PTSD patients. The animal model and methods described here are useful for correlating biomarkers in brain nuclei, which are mechanistic but cannot be measured in patients, with biomarkers in peripheral white blood cells, which can.

Identification of biomarkers representing the evolution of the pathophysiology of Post Traumatic Stress Disorder (PTSD) is vitally important, not only for ...

Medicine

Exposure of the Pig CNS for Histological Analysis: A Manual for Decapitation, Skull Opening, and Brain Removal

Pigs have become increasingly popular in large-animal translational neuroscience research as an economically and ethically feasible substitute to non-human primates. The large brain size of the pig allows the use of conventional clinical brain imagers and the direct use and testing of neurosurgical procedures and equipment from the human clinic. Further macroscopic and histological analysis, however, requires postmortem exposure of the pig central nervous system (CNS) and subsequent brain removal. This is not an easy task, as the pig CNS is encapsulated by a thick, bony skull and spinal column. The goal of this paper and instructional video is to describe how to expose and remove the postmortem pig brain and the pituitary gland in an intact state, suitable for subsequent macroscopic and histological analysis.

The goal of this paper and instructional video is to describe how to expose and remove the postmortem pig brain and pituitary gland in an intact state, suitable for subsequent macroscopic and histological analysis.

Pigs have become increasingly popular in large-animal translational neuroscience research as an economically and ethically feasible substitute to ...

Use of a Piglet Model for the Study of Anesthetic-induced Developmental Neurotoxicity (AIDN): A Translational Neuroscience Approach

Anesthesia cannot be avoided in many cases when surgery is required, particularly in children. Recent investigations in animals have raised concerns that anesthesia exposure may lead to neuronal apoptosis, known as anesthesia-induced developmental neurotoxicity (AIDN). Furthermore, some clinical studies in children have suggested that anesthesia exposure may lead to neurodevelopmental deficits later in life. Nonetheless, an ideal animal model for preclinical study has yet to be developed. The neonatal piglet represents a valuable model for preclinical study, as they share a striking number of developmental similarities with humans.
The anatomy and physiology of piglets allow for implementation of rigorous human perioperative conditions in both survival and non-survival procedures. Femoral artery catheterization allows for close monitoring, thus enabling prompt correction of any deviation of the piglet's vital signs and chemistries. In addition, there are multiple developmental similarities between piglets and human neonates. The techniques required to use piglets for experimentation will require experience to master. A pediatric anesthesiologist is a critical member of the investigative team. We describe, in a general sense, the appropriate use of a piglet model for neurodevelopmental study.

Use of a Piglet Model for the Study of Anesthetic-induced Developmental Neurotoxicity AIDN: A Translational Neuroscience Approach

Anesthesia-induced developmental neurotoxicity (AIDN) research has focused on rodents, which are not broadly applicable to humans. Non-human primate models are more relevant, but are cost-prohibitive and difficult to use for experimentation. The piglet, in contrast, is a clinically relevant, practical animal model ideal for the study of anesthetic neurotoxicity.

Anesthesia cannot be avoided in many cases when surgery is required, particularly in children.  Recent investigations in animals have raised concerns that ...

Visualization of Cortical Modules in Flattened Mammalian Cortices

The cortex of mammalian brains is parcellated into distinct substructures or modules. Cortical modules typically lie parallel to the cortical sheet, and can be delineated by certain histochemical and immunohistochemical methods. In this study, we highlight a method to isolate the cortex from mammalian brains and flatten them to obtain sections parallel to the cortical sheet. We further highlight selected histochemical and immunohistochemical methods to process these flattened tangential sections to visualize cortical modules. In the somatosensory cortex of various mammals, we perform cytochrome oxidase histochemistry to reveal body maps or cortical modules representing different parts of the body of the animal. In the medial entorhinal cortex, an area where grid cells are generated, we utilize immunohistochemical methods to highlight modules of genetically determined neurons which are arranged in a grid-pattern in the cortical sheet across several species. Overall, we provide a framework to isolate and prepare layer-wise flattened cortical sections, and visualize cortical modules using histochemical and immunohistochemical methods in a wide variety of mammalian brains.

This article describes a detailed methodology to obtain flattened tangential sections from mammalian cortices and visualize cortical modules using histochemical and immunohistochemical methods.

The cortex of mammalian brains is parcellated into distinct substructures or modules. Cortical modules typically lie parallel to the cortical sheet, and ...

Subdural Soft Electrocorticography (ECoG) Array Implantation and Long-Term Cortical Recording in Minipigs

Neurological impairments and diseases can be diagnosed or treated using electrocorticography (ECoG) arrays. In drug-resistant epilepsy, these help delineate the epileptic region to resect. In long-term applications such as brain-computer interfaces, these epicortical electrodes are used to record the movement intention of the brain, to control the robotic limbs of paralyzed patients. However, current stiff electrode grids do not answer the need for high-resolution brain recordings and long-term biointegration. Recently, conformable electrode arrays have been proposed to achieve long-term implant stability with high performance. However, preclinical studies for these new implant technologies are needed to validate their long-term functionality and safety profile for their translation to human patients. In this context, porcine models are routinely employed in developing medical devices due to their large organ sizes and easy animal handling. However, only a few brain applications are described in the literature, mostly due to surgery limitations and integration of the implant system on a living animal.
Here, we report the method for long-term implantation (6 months) and evaluation of soft ECoG arrays in the minipig model. The study first presents the implant system, consisting of a soft microfabricated electrode array integrated with a magnetic resonance imaging (MRI)-compatible polymeric transdermal port that houses instrumentation connectors for electrophysiology recordings. Then, the study describes the surgical procedure, from subdural implantation to animal recovery. We focus on the auditory cortex as an example target area where evoked potentials are induced by acoustic stimulation. We finally describe a data acquisition sequence that includes MRI of the whole brain, implant electrochemical characterization, intraoperative and freely moving electrophysiology, and immunohistochemistry staining of the extracted brains.
This model can be used to investigate the safety and function of novel design of cortical prostheses; mandatory preclinical study to envision translation to human patients.

Subdural Soft Electrocorticography ECoG Array Implantation and Long-Term Cortical Recording in Minipigs

Here, we present a method for the long-term performance and safety assessment of soft subdural electrode arrays in a minipig model, describing surgical method and tools, postoperative magnetic resonance imaging, electrophysiology of the auditory cortex, electrochemical properties of the implant, and postmortem immunochemistry.

Neurological impairments and diseases can be diagnosed or treated using electrocorticography (ECoG) arrays. In drug-resistant epilepsy, these help ...

Bioengineering

Microdissection of Mouse Brain into Functionally and Anatomically Different Regions

The brain is the command center for the mammalian nervous system and an organ with enormous structural complexity. Protected within the skull, the brain consists of an outer covering of grey matter over the hemispheres known as the cerebral cortex. Underneath this layer reside many other specialized structures that are essential for multiple phenomenon important for existence. Acquiring samples of specific gross brain regions requires quick and precise dissection steps.&#160;It is understood that at the microscopic level, many sub-regions exist and likely cross the arbitrary regional boundaries that we impose for the purpose of this dissection.
Mouse models are routinely used to study human brain functions and diseases. Changes in gene expression patterns may be confined to specific brain areas targeting a particular phenotype depending on the diseased state. Thus, it is of great importance to study regulation of transcription with respect to its well-defined structural organization. A complete understanding of the brain requires studying distinct brain regions, defining connections, and identifying key differences in the activities of each of these brain regions. A more comprehensive understanding of each of these distinct regions may pave the way for new and improved treatments in the field of neuroscience. Herein, we discuss a step-by-step methodology for dissecting the mouse brain into sixteen distinct regions. In this procedure, we have focused on male mouse C57Bl/6J (6-8 week old) brain removal and dissection into multiple regions using neuroanatomical landmarks to identify and sample discrete functionally-relevant and behaviorally-relevant&#160;brain regions. This work will help lay a strong foundation in the field of neuroscience, leading to more focused approaches in the deeper understanding of brain function.

We present a hands-on, step-by-step, rapid protocol for mouse brain removal and dissection of discrete regions from fresh brain tissue. Obtaining brain regions for molecular analysis has become routine in many neuroscience labs. These brain regions are immediately frozen to obtain high quality transcriptomic data for system level analysis.

The brain is the command center for the mammalian nervous system and an organ with enormous structural complexity. Protected within the skull, the brain ...

Direct Cannula Implantation in the Cisterna Magna of Pigs

The glymphatic system is a waste clearance system in the brain that relies on the flow of cerebrospinal fluid (CSF) in astrocyte-bound perivascular spaces and has been implicated in the clearance of neurotoxic peptides such as amyloid-beta. Impaired glymphatic function exacerbates disease pathology in animal models of neurodegenerative diseases, such as Alzheimer's, which highlights the importance of understanding this clearance system. The glymphatic system is often studied by cisterna magna cannulations (CMc), where tracers are delivered directly into the cerebrospinal fluid (CSF). Most studies, however, have been carried out in rodents. Here, we demonstrate an adaptation of the CMc technique in pigs. Using CMc in pigs, the glymphatic system can be studied at a high optical resolution in gyrencephalic brains and in doing so bridges the knowledge gap between rodent and human glymphatics.

This article presents a step-by-step protocol for the direct cannula implantation in the cisterna magna of pigs.

The glymphatic system is a waste clearance system in the brain that relies on the flow of cerebrospinal fluid (CSF) in astrocyte-bound perivascular spaces ...

An Efficient High-Speed Pneumatic Drill Craniectomy to Access the Porcine Brain

Accessing the Porcine Brain via High-Speed Pneumatic Drill Craniectomy

The use of pigs as an experimental animal model is especially relevant in neuroscience research, as the porcine and human central nervous systems (CNS) share many important functional and architectural properties. Consequently, pigs are expected to have an increasingly important role in future research on various neurological diseases. Here, a method to perform an anterior craniectomy through the porcine frontal bone is described. After a midline incision and subsequent exposure of the porcine frontal bone, anatomical landmarks are used to ensure the optimal location of the craniectomy. By careful and gradual thinning of the frontal bone with a rounded drill, a rectangular opening to the dura mater and underlying cerebral hemispheres is achieved. The presented method requires certain surgical materials, including a pneumatic high-speed drill, and some degree of surgical experience. Potential complications include unintended lesions of the dura mater or dorsal sagittal sinus. However, the method is simple, time-efficient, and offers a high degree of reproducibility for researchers. If performed correctly, the technique exposes a large portion of the unaffected pig brain for various neuromonitoring or analyses.

Author Spotlight: A Reproducible and Efficient Method for Accessing Porcine Brain via Craniectomy

This protocol describes performing a craniectomy using a high-speed pneumatic drill on a 3-month-old Danish Landrace pig. The access is made through the frontal bone and reveals the ventral dura mater and underlying cerebral hemispheres. This procedure allows for access to a large portion of the pig brain.

The use of pigs as an experimental animal model is especially relevant in neuroscience research, as the porcine and human central nervous systems (CNS) ...

Preparation of Organotypic Slice Cultures from a Rat Pup&#39;s Hippocampus

Source: Mosa, A. J. et al., <a href="https://app.jove.com/v/52353">Organotypic Slice Cultures for Studies of Postnatal Neurogenesis.</a> J. Vis. Exp. (2015).
This video demonstrates a method for preparing organotypic hippocampal slice cultures from the brain of a rat pup. It outlines the steps involved in the dissection of the hippocampus, slicing, and culture conditions required to promote cell viability and growth in the hippocampal slices, ultimately generating organotypic slice cultures.

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.
1. ...

JoVE Encyclopedia of Experiments

Neuronal Culture Techniques

Advanced Neuronal Models

Formation and Expansion of Neurospheres from a Hippocampal Tissue

Source: Soares, R. et al., <a href="https://app.jove.com/v/60822">Isolation and Expansion of Neurospheres from Postnatal (P1&#8722;3) Mouse Neurogenic Niches.</a>&#160;J. Vis. Exp. (2020).
This video demonstrates the process of neurosphere formation and their expansion from hippocampal tissue. Neural stem and progenitor cells from the postnatal mouse dentate gyrus tissue proliferate and form primary neurospheres, which are then reseeded to form secondary neurospheres.

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.
1. Basic ...