In vivo Positron Emission Tomography to Reveal Activity Patterns Induced by Deep Brain Stimulation in Rats

Deep brain stimulation (DBS) is an invasive neurosurgical technique based on the application of electrical pulses to brain structures involved in the patient's pathophysiology. Despite the long history of DBS, its mechanism of action and appropriate protocols remain unclear, highlighting the need for research aiming to solve these enigmas. In this sense, evaluating the in vivo effects of DBS using functional imaging techniques represents a powerful strategy to determine the impact of stimulation on brain dynamics. Here, an experimental protocol for preclinical models (Wistar rats), combined with a longitudinal study [F-18]-fluorodeoxyclucose positron emission tomography (FDG-PET), to assess the acute consequences of DBS on brain metabolism is described. First, animals underwent stereotactic surgery for bilateral implantation of electrodes into the prefrontal cortex. A post-surgical computerized tomography (CT) scan of each animal was acquired to verify electrode placement. After one week of recovery, a first static FDG-PET of each operated animal without stimulation (D1) was acquired, and two days later (D2), a second FDG-PET was acquired while animals were stimulated. For that, the electrodes were connected to an isolated stimulator after administering FDG to the animals. Thus, animals were stimulated during the FDG uptake period (45 min), recording the acute effects of DBS on brain metabolism. Given the exploratory nature of this study, FDG-PET images were analyzed by a voxel-wise approach based on a paired T-test between D1 and D2 studies. Overall, the combination of DBS and imaging studies allows describing the neuromodulation consequences on neural networks, ultimately helping to unravel the conundrums surrounding DBS.