Fixation of Ultrasound Transducers for Spinal Cord Neuromodulation in Mice

Focused ultrasound (FUS) has emerged as an innovative non-invasive neuromodulation technology demonstrating significant potential for spinal cord neural regulation. However, achieving stable transducer fixation along the spinal column presents notable technical challenges. Existing immobilization methods often require prolonged animal anesthesia or demonstrate inadequate adhesion reliability. These critical constraints underscore the urgent need for developing a novel fixation paradigm that ensures both operational stability and physiological compatibility. This protocol introduces an innovative ultrasound transducer fixation system for stimulation of the spinal cord in awake, freely moving mice. Establishing a reliable method for precise ultrasound transducer placement on the vertebral column is key for neurostimulation experiments. This method integrates three phases: surgical exposure of the T13 vertebral body, precision grinding of the spinous process to create a planar contact interface, and secure adhesive bonding of the metal base and collimator to the vertebral column using denture base material and adhesive mixture. It allows natural motor behaviors through unrestricted movement and ensures stable positioning with minimal spatial variation between sessions, facilitating investigation of ultrasound-mediated spinal cord interventions in conscious animal models. It is particularly relevant to studies requiring behavioral assessments in spinal injury repair, blood-spinal cord barrier modulation, and chronic pain mechanisms. By addressing a critical technical challenge in awake-animal neuromodulation research, this protocol offers a stable transducer-spinal interface without movement restriction, paving the way for more accurate and reliable experimental outcomes.