Ascending projections emanating from the median raphe (MR) are implicated in numerous brain functions but the cortical control of the raphe complex is largely unexplored. A main cortical input of the MR is the prefrontal cortex, a key region on top of the brain’s action network. The anterior cingulate–one subregion of the PFC formation–specifically plays role in the fromation of contextual fear, error detection and evaluation of effort/reward cost. Spatial memory supported by ACC-hippocampus (HC) communication is essential for executing these behaviours. The MR can be a key link between the PFC (ACC) and hippocampus. We used retrograde AAV tracers injected to the MR to label MR-projecting ACC cells. We have observed an abundant MR-targeting principal cell population. These cells could be optogenetically tagged and recorded simultaneously with MR neurons in head-fixed, awake mice. We have observed MR-projecting ACC neurons tuned to aversive and / or rewarding stimuli.To further evaluate the ACC-MR-HC loop, we constructed a fully automated modified T-maze system, where freely moving mice solve an alternation task to receive water reward. After the succesful learning phase, animals get aversive stimuli on interchangeable locations, so they need to shift spatial strategies. For the next phase of the study, we have implanted silicone probes in both the ACC and hippocampus to register correlated activity of MR-targeting ACC and hippocampal neurons during the above detailed behavior.Based on our preliminary results, we will test the hypothesis that MR-projecting ACC neurons would be key for readjusting behavior during threatening events.