Wireless Headmount Photoacoustic Tomography of the Brain in Free-moving Animals

Description

High-resolution brain imaging in free-moving animals enables monitoring neural activities in the natural state and is of great importance for identifying neural circuits, studying brain diseases, and exploring new treatment strategies in translational medicine. Especially, in the longitudinal behavioral neuroscience study, scientists need to monitor the brain activities while the animal is normally interacting with others. This motivates the development of advanced wireless head-mount photoacoustic brain imaging techniques with minimal physical constrain. Optical imaging techniques have been widely used to image the hemodynamics or neuron actions in the brain. Recently, photoacoustic tomography has been developed for brain imaging with great sensitivity to hemodynamics and oxygen saturation, high resolution, and deep penetration. However, photoacoustic imaging of neuron activities in free-moving animals is still facing tremendous challenges in the following two techniques. (1) How to minimize the head-mount imaging probe. (2) How to remove the cumbersome optical and electrical cables and allow the animals to naturally behave and socialize. Here, we propose to address these challenges via the following specific aims. (1) We will implement fully remote laser excitation and wireless signal transmission so that we can acquire photoacoustic signals from a free-moving animal without connecting any optical or electrical cables. A Galvo mirror and computer-vision-based tracking system will be developed to deliver a broad laser beam to the free-moving animal head. A radiofrequency module will be developed to wirelessly transmit the photoacoustic signal to a data acquisition system. (2) We will develop a head-mount photoacoustic tomographic system through an ergodic relay. A single-element ultrasonic transducer will be used to receive randomized photoacoustic signals at each laser shot. The transducer and the ergodic relay will be engineered to be small, light-weight, and attachable to the animal head. The head-mount probe will weigh less than 5 grams. The new wireless head-mount photoacoustic tomographic system will be demonstrated in the brain imaging of free-moving mice. The proposed research offers a new imaging technique in the deep brain of the free-moving animal.