Microdissection of Mouse Brain into Functionally and Anatomically Different Regions

The brain, along with the spinal cord and retina, comprise the central nervous system that executes complex behaviors, controlled by specialized, precisely positioned, and interacting cell types throughout the entire body¹. The brain is a complex organ with billions of interconnected neurons and glia with precise circuitry performing numerous functions. It is a bilateral structure with two distinct lobes and diverse cellular components². The spinal cord connects the brain to the outside world and is protected by bone, meninges, and cerebrospinal fluid and routes messages to and from the brain^2,3,4. The surface of the brain, the cerebral cortex, is uneven and has distinct folds, called gyri, and grooves, called sulci, that separate the brain into functional centers⁵. The cortex is smooth in mammals with a small brain^6,7. It is important to characterize and study the architecture of the human brain in order to understand the disorders related to the different brain regions, as well as its functional circuits. Neuroscience research has expanded in recent years and a variety of experimental methods are being used to study the structure and function of the brain. Developments in the fields of molecular and systems-level biology have ushered in a new era of exploring the complex relationship between brain structures and the functioning of molecules. Additionally, molecular biology, genetics, and epigenetics are rapidly expanding, enabling us to advance our knowledge of the underlying mechanisms involved in how systems function. These analyses can be carried out on a much more localized basis, to help target the investigation and development of more effective therapies.

The mammalian brain is structurally defined into clearly identifiable discrete regions; however, the functional and molecular complexities of these discrete structures are not yet clearly understood. The multi-dimensional and multi-layered nature of the brain tissue makes this landscape difficult to study at the functional level. In addition, the fact that multiple functions are performed by the same structure and vice versa further complicates the understanding of the brain⁸. It is vital that the experimental approach executed for the structural and functional characterization of brain regions uses precise research methodologies to achieve consistency in sampling for correlating neuroanatomical architecture with function. The complexity of brain has been recently explained using single cell sequencing^9,10 such as the temporal gyrus of the human brain which is composed of 75 distinct cell types¹¹. By comparing this data to those from an analogous region of the mouse brain, the study not only reveals similarities in their architecture and cell types but also presents the differences. To unravel the complex mechanisms, it is therefore important to study diverse regions of the brain with full precision. Conserved structures and function between a human and mouse brain enable the use of a mouse as a preliminary surrogate for elucidating human brain function and behavioral outcomes.

With the advancement of systems biology approaches, obtaining information from discrete brain regions in rodents has become a key procedure in neuroscience research.While some protocols such as laser capture microdissection¹² can be expensive, mechanical protocols are inexpensive and performed using commonly available tools^13,14. We have used multiple brain regions for transcriptomic assays¹⁵ and have developed a hands-on and rapid procedure to dissect mouse brain regions of interest in a step-by-step manner in a short time. Once dissected, these samples can be stored immediately in cold conditions to preserve the nucleic acids and proteins of these tissues. Our approach can be performed faster leading to high efficiency and permitting less chances for tissue deterioration. This ultimately, increases the chances of generating high quality, reproducible experiments using brain tissues.