Behavioral hierarchies

Tinbergen pointed out that the singleness of behavioral expression and the transitions among behaviors suggested active inhibition by a dominant behavior of subordinates. This implicit neural hypothesis has been investigated in several model systems. In no instance was choice found to be mediated by direct inhibition of one central pattern generator by another, nor through inhibition of command neurons by extrinsic inputs. Rather, changing behavioral expression was based on reconfiguring the underlying neuronal networks for alternative outputs by changing inputs from internal and external sources. Thus, where known, behavioral hierarchies and their plasticity are based on the abilities of neuronal networks to transit among multiple, metastable states of coordination.