Wearable 3-D Photoacoustic Tomography for Functional Brain Imaging in Behaving Rats.

Jianbo Tang,Jason E. Coleman,Xianjin Dai,Huabei Jiang

doi:10.1038/srep25470

Abstract

Understanding the relationship between brain function and behavior remains a major challenge in neuroscience. Photoacoustic tomography (PAT) is an emerging technique that allows for noninvasive in vivo brain imaging at micrometer-millisecond spatiotemporal resolution. In this article, a novel, miniaturized 3D wearable PAT (3D-wPAT) technique is described for brain imaging in behaving rats. 3D-wPAT has three layers of fully functional acoustic transducer arrays. Phantom imaging experiments revealed that the in-plane X-Y spatial resolutions were ~200 μm for each acoustic detection layer. The functional imaging capacity of 3D-wPAT was demonstrated by mapping the cerebral oxygen saturation via multi-wavelength irradiation in behaving hyperoxic rats. In addition, we demonstrated that 3D-wPAT could be used for monitoring sensory stimulus-evoked responses in behaving rats by measuring hemodynamic responses in the primary visual cortex during visual stimulation. Together, these results show the potential of 3D-wPAT for brain study in behaving rodents.

Highlights

Imaging in behaving animals is becoming an important tool in behavioral neuroscience and preclinical brain disease therapy studies
The 3D wearable PAT (3D-wearable photoacoustic tomography (wPAT)) probe contains an array of 3 × 64
We have developed a novel 3D-wPAT system that permits noninvasive brain imaging with hundred micrometer-scale spatial resolution and sub-second temporal resolution

Summary

Introduction

Imaging in behaving animals is becoming an important tool in behavioral neuroscience and preclinical brain disease therapy studies. Optical microscopic imaging techniques, such as two-photon microscopy (TPM)[9], can provide high spatial (micrometers) and temporal resolution (milliseconds), and have been used to examine brain function-behavior in behaving animals in proof-of-principle studies[10,11]. Acoustic transducer array-based photoacoustic tomography (PAT) is one implementation of photoacoustic technique that produces images by tomographically acquiring the whole ‘plane’ acoustic signal at one laser pulse[14] It is suitable for animal brain imaging since it can noninvasively image an animal’s brain at centimeter penetration with micrometer-millisecond spatiotemporal resolution[17,18,19]. We present a wearable 3D photoacoustic tomography (3D-wPAT) technique that can noninvasively image a behaving rat’s brain with high spatiotemporal resolution. To our knowledge, we show for the first time that this novel 3D-wPAT permits studies of the visual system in behaving animals by demonstrating that 3D-wPAT is capable of detecting visually evoked responses in the primary visual cortex (V1)

Methods

Results

Conclusion