Optical coherence tomography guided neurosurgical procedures in small rodents.

The delivery of therapeutic agents directly to targets deep within the brain is becoming an important tool in the treatment of a variety of neurological disorders. Currently, the standard method to accomplish this is by using stereotactic procedures. While this existing method is adequate for many experimental situations, it is essentially a blind procedure that cannot provide real-time feedback on whether the actual location deviated from the intended location or whether the therapeutic agent was actually delivered. Here we describe an optical guidance technique that is designed to work in conjunction with existing stereotactic procedures to provide the needed real-time feedback for therapeutic delivery in live animals. This real-time feedback is enabled by a technology called catheter-based optical coherence tomography (OCT). In this study we show that OCT can provide real-time position feedback based on microanatomic landmarks from the live rodent brain. We show that OCT can provide the necessary guidance to perform microsurgery such as the selective transection of the Schaffer collateral inputs to the CA1 region of the hippocampus with minimal perturbation of overlying structures. We also show that OCT allows visual monitoring of the successful delivery of viral vectors to specific subregions of the hippocampus.