The ability to image the neuroadaptations induced by drug abuse/addiction in small animal brains noninvasively offers the opportunity to evaluate pathologic progression in a fast time frame with an improved resolution. Photoacoustic imaging (PAI) is an emerging technology to image one of the optical properties>absorption>while maintaining high resolutions in regions up to 5 cm deep. PAI has been successfully applied on noninvasively visualizing the structures of a number of different biological tissues with satisfactory sensitivity and spatial resolution. The objective of current research is to apply PAI to detect the activation of the brain due to drug abuse in in vivo small animal experiments. The long term goal is to develop PAI as a convenient, low cost, noninvasive alternative imaging method to assess brain alternations due to drug abuse/addiction, as well as to provide complementing information to fMRI and PET in some cases. Specifically, in this proposal, we will employ PAI to detect brain function alternation caused by cocaine in small animals. The specific aims of this study include (1) develop and optimize a PAI system suitable for small animal whole brain imaging;(2) perform experiments to detect small animal brain function alternations due to the cocaine use, and compare PAI images with fMRI images. During this research, both the feasibility and the reliability of PAI on the detection of small animal brain functional alternations will be explored. PUBLIC HEALTH RELEVANCE: In this study, we apply the novel photoacoustic imaging (PAI) to the detection of brain functional alternations induced by drug abuse/addiction. A whole brain PAI system will be built and optimized for this purpose. The success of this project will provide an alternative, optical-contrast-based imaging modality to investigators in the field of drug abuse/addiction at significantly lower cost than fMRI and PET.