Patterns of recurrent excitation and mutual inhibition of cat Renshaw cells

1. Patterns of convergent excitation and mutual inhibition of Renshaw cells to antidromic volleys in motor axons were investigated in cats anaesthetized with chloralose. 2. There were widely varying patterns of excitatory convergence onto individual Renshaw cells, but grouping the cells into different populations revealed the underlying positive and negative correlations between inputs from different motor nerves. 3. The greatest excitatory convergence was seen between axons supplying functionally synergistic muscles. 4. Mutual inhibition between Renshaw cell populations was most evident between antagonist motoneurones and so was inversely related to the excitatory inputs. 5. These results are discussed in relation to the control of recurrent inhibitory phenomena mediated by renshaw cells.