Risk Decision-Making:Insular Cortical Neuronal Encoding And Medial Prefrontal Regulation

Risk decision-making(RDM)is a psychological process in which individual makes judgments and choices with known probabilities based on their own experience.Most studies indicated that the insular cortex(IC)may be involved in RDM.However,relevant reports did not show specific details,especially the lack of evidence in neuron coding mechanism.The medial prefrontal cortex(m PFC)has abundant pathway projections with IC,but rare research explores whether this pathway control RDM by regulating the activity of IC neurons.We design a new behavior paradigm of RDM,which allowed rat to choose one from the two options.It presented a decision of balance between the choice of large reward delivered with low probability and the choice of small reward delivered with 100%probability.Astonishingly,most rats preferred to choose the option of large reward but paired with high risk.We divided all rats into risk type and safe type,detected the c-fos expression of the anterior insular cortex(AIC)which suggested that the AIC of riskpreferred rats was more active.Besides,inactivation of AIC significantly reduced the frequency of risk selection in risk type rats.We recorded 462 neurons associated with risk selection in AIC,of which 35 neurons(7.6%)increased their firing frequency 700 milliseconds before making risk choice.After optogenetic manipulation of m PFC?AIC pathway by the infecting of r AAV-Ca MKIIa-h Ch R2 and the stimulation of blue light from the fiber-optic electrodes,about 7 neurons(41.2%)encoding risk decision significantly decreased their firing activity in risk choice.Our research suggests that AIC plays a irreplaceable function of controlling risk selection in RDM and m PFC participates in regulating RDM behavior by modulating the activity of IC neurons.