Dissection Of Long Range Onputs To Three Types Of GABAergic Neurons In Medial Prefrontal Cortex Of Mouse

The medial prefrontal cortex(m PFC)served as a high order cortical area and played an important role in regulating memory,emotions,decision making and social behaviors.There are two groups of neurons in m PFC: the excitatory glutamatergic long range projection neurons and inhibitory GABAergic interneurons.The inhibitory GABAergic interneurons receive inputs from other cortical areas and subcortical nuclei and regulate the excitatory-inhibitory balance to maintain the normal functions of m PFC.Based on the biomarkers,the GABAergic neurons in m PFC can be divided into three types: the parvabumin(PV)positive neurons,the somatostatin(SST)positive neurons and the vasoactive intestinal peptide(VIP)positive neurons.Previous studies have indicated that these three types of GABAergic neurons in m PFC are involved in different neural circuits and execute different functions.Their distinct functions rely on integrating information from local and long range inputs onto different types of neurons.Previous physiological studies have resolved the local inputs to three types of GABAergic neurons in m PFC,however,their long range inputs remained unclear.In the present study,we employed modified rabies virus tracing in several Cre driver line mice that target specific GABAergic neurons,in combination with our in-house fluorescence micro-optical sectioning tomography(f MOST)system to investigate the long range inputs to PV+,SST+ and VIP+ neurons in the m PFC.We quantified the distribution of long range input neurons to three types of GABAergic neurons in m PFC and compared the long range input patterns among three types of GABAergic neurons.We found that different GABAergic neurons in m PFC receive inputs from same brain areas but with with quantitative differences in some brain areas.These quantitative differences indicated that different GABAergic neurons in m PFC may involve in different neural circuits.By applying immunochemical staining and physiological studies,we found that three types of GABAergic neurons in m PFC are regulated by multiple neural modulators,such as PV+ projection neurons and cholinergic neurons in basal forebrain,serotoninergic neurons in raphe nuclei,dopaminergic neurons in ventral tegmental area.Specially,we found that cholinergic neurons in basal forebrain and serotoninergic neurons in raphe nuclei can release glutamate to activate GABAergic neurons in m PFC.Taking advantage of our precise whole brain imaging system,we reconstructed the single neuron projectome of the input neurons that target three types of GABAergic neurons in m PFC.By analyzing the full morphology of the input neurons,we discovered novel neural circuits involved in GABAergic neurons in m PFC and their upstream input neurons.Furthermore,we identified several new neuron types in neocortex and hippocampus that regulate the GABAergic neurons in m PFC.Finally,we applied our atlas to study the functions of hippocampus-m PFC circuits.We found that hippocampus can transfer social memory to m PFC.Inhibition of hippocampus will impair social memory and locomotion.While activation of PV+ neurons in m PFC but not SST+ neurons can rescue social memory and locomotion impairment.Activation of VIP+ neurons in m PFC can further impair locomotion.By applying fiber photometry,we found that Inhibition of hippocampus disrupt the activity of PV+ neurons in m PFC.In the present study,we provided the most comprehensive whole brain atlas of direct long-range inputs to different GABAergic neurons in the m PFC,which will lead to deep insights into the structural and functional organization of the m PFC.