Negative feedback control of neuronal activity by microglia

Badimon A, Strasburger HJ, Ayata P, Chen X, Nair A, Ikegami A, Hwang P, Chan AT, Graves SM, Uweru JO, Ledderose C, Kutlu MG, Wheeler MA, Kahan A, Ishikawa M, Wang Y-C, Loh Y-WE, Jiang JX, Surmeier DJ, Robson SC, Junger WG, Sebra R, Calipari ES, Kenny PJ, Eyo UB, Colonna M, Quintana FJ, Wake H, Gradinaru V and Schaefer A

Nature, 2020

Summary:

Microglia have been shown to be important in suppression of neuronal activity in a highly region-specific fashion.  In this paper, the authors suggest that microglia operate similarly to inhibitory neurons using a negative feedback mechanism which is essential to protect the brain.    

The primary neurons were cultured in Axion multiwell MEA (microelectrode array) plates (full description of culture protocol is available in the methods sections of the paper).  After 12 days of culture the the microglia were added and co-cultured with the neurons.  The baseline recording were performed 2 days later and analyzed using the neural module software.  Two hours after baseline recording the treatments were applied to the co-culture.  One hour later, the final recordings were taken.  

The MEA plates allowed for continuous electric field recordings.  Microglia were shown to suppress neuronal activity in response to glutamate-induced activation with a decreased percentage change in mean firing rate.