Study On The Whole-brain Transsynaptic Input Pattern In The Nucleus Accumbens

Nucleus accumbens(NAc),located in the ventral striatum,is an important part of the basal ganglia,which is composed of core and shell.NAc plays an important role in action selection,cognition,reward-related processes,drug addiction and other brain functions in mice.NAc is also closely associated with a variety of neuropsychiatric diseases,such as Alzheimer's disease,depression,Parkinson's disease,etc.Inhibition of AMPA(?-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor)and NMDA(N-methyl-D-aspartic acid receptor)in NAc core significantly reduced the response of mice to reward related stimuli,while inhibition of corresponding receptors in NAc shell significantly increased the response of mice to non reward related stimuli.Previous studies have shown that the medial prefrontal cortex(m PFC),basolateral amygdala nucleus(BL)and hippocampus(HPC)are the three brain regions with more input to NAc.The neural circuits formed by m PFC and NAc are closely related to brain functions such as decision-making,memory and social behavior;the neural circuits formed by BL and NAc are closely related to the regulation of conditional reward seeking behavior;the neural circuits formed by HPC and NAc are closely related to the regulation of aggressive behavior.However,the whole brain input received by these neural circuits is not clear.Therefore,it is necessary to quantitatively analyze and compare the whole brain input received by the above neural circuits,so as to provide some reference information for the analysis of complex NAc functions.In our study,we systematically analyzed the whole brain input patterns of m PFC,BL and HPC neurons projecting to different NAc subregions via using TRIO(tracing the relationship between input and output)labeling strategy.The results of this study show that:(1)The upstream input patterns between m PFC-core and m PFC-shell neurons,BL-core and BL-shell neurons,HPC-core and HPC-shell neurons were similar.However,m PFC and BL neurons projecting to different NAc subregions receive a wide range of inputs,while HPC neurons projecting to different NAc subregions receive more concentrated inputs,of which local(HPC)inputs account for more than half.(2)Our studies have shown that the entorhinal cortex(Ent),piriform cortex(Pir)and HPC project a large number to different NAc subregions.We found that m PFC,BL and HPC project to different NAc subregions also receive a large number of projections from Ent,Pir and HPC.It is proved that Ent,Pir and HPC may regulate the activity of NAc neurons directly or indirectly through m PFC,BL and HPC.In summary,the whole brain input patterns of m PFC,BL and HPC neurons projecting to different NAc subregions were revealed,which laid a solid foundation for further analysis of complex NAc functional mechanisms in the future.