A Large Lateral Craniotomy Procedure for Mesoscale Wide-field Optical Imaging of Brain Activity

Abstract

The craniotomy is a commonly performed procedure to expose the brain for in vivo experiments. In mouse research, most labs utilize a small craniotomy, typically 3 mm x 3 mm. This protocol introduces a method for creating a substantially larger 7 mm x 6 mm cranial window exposing most of a cerebral hemisphere over the mouse temporal and parietal cortices (e.g., bregma 2.5 - 4.5 mm, lateral 0 - 6 mm). To perform this surgery, the head must be tilted approximately 30° and much of the temporal muscle must be retracted. Due to the large amount of bone removal, this procedure is intended only for acute experiments with the animal anesthetized throughout the surgery and experiment. The main advantage of this innovative large lateral cranial window is to provide simultaneous access to both medial and lateral areas of the cortex. This large unilateral cranial window can be used to study the neural dynamics between cells, as well as between different cortical areas by combining multi-electrode electrophysiological recordings, imaging of neuronal activity (e.g., intrinsic or extrinsic imaging), and optogenetic stimulation. Additionally, this large craniotomy also exposes a large area of cortical blood vessels, allowing for direct manipulation of the lateral cortical vasculature.

High-performance, inexpensive setup for simultaneous multisite recording of electrophysiological signals and mesoscale voltage imaging in the mouse cortex

“…The plastic headplate (inner diameter 8 mm) was attached to the bone with dental cement 43 . An ∼8-mm-diameter single cranial window was made over both cortical hemispheres (2.5 to 5.5 mm, anterior-posterior and 0 to 4 mm laterally from bregma) using a high-speed dental drill 44 . To keep the brain cool, the drilling was done intermittently and the skull was moistened with artificial CSF composed of NaCl (3.94g), KCl (0.2 g), MgCl2 6normalH2O (0.102 g), CaCl2 2normalH2O (0.132 g), and Na HEPES (0.651 g) in 500 ml of ultrapure Milli-Q water.…”

“…Caution was taken to keep the dura intact when removing the bone. Once the bone was removed, dura mater was also carefully removed as described previously 44 . For each hour under anesthesia, the mouse was given 10 ml/kg of 20 mM glucose in brain buffer IP to maintain hydration.…”

Prenatal Stress Dysregulates Resting-State Functional Connectivity and Sensory Motifs

“…For imaging the neocortex, an acute craniotomy was performed for the PS (n=6) and control (n=12) offspring at age 2-3 months. Mice were given an acute 7×6mm unilateral craniotomy and the dura was removed (bregma +2.5 to -4.5mm, lateral to the midline 0 to 6mm for VSD imaging experiments as previously described (Kyweriga et al, 2017)). Isoflurane (1.0–1.5%) was used to anesthetize mice both for induction and during surgery.…”

A High Performance, Inexpensive Setup for Simultaneous Multisite Recording of Electrophysiological Signals and Wide-Field Optical Imaging in the Mouse Cortex

“…A ~8mm diameter single cranial window was made over both mouse cortical hemispheres (2.5-5.5 mm, anterior-posterior and 0-4 mm laterally from bregma) using a high-speed dental drill (Kyweriga et al 2017). To keep the brain cool, the drilling was done intermittently and the skull was moistened with brain buffer.…”