Selective responses to tonic descending commands by temporal summation in a spinal motor pool.

ABSTRACT: Motor responses of varying intensities rely on descending commands to heterogeneous pools of motoneurons. In vertebrates, numerous sources of descending excitatory input provide systematically more drive to progressively less excitable spinal motoneurons. While this presumably facilitates simultaneous activation of motor pools, it is unclear how selective patterns of recruitment could emerge from inputs weighted this way. Here, using in vivo electrophysiological and imaging approaches in larval zebrafish, we find that, despite weighted excitation, more excitable motoneurons are preferentially activated by a midbrain reticulospinal nucleus by virtue of longer membrane time constants that facilitate temporal summation of tonic drive. We confirm the utility of this phenomenon by assessing the

SUBMITTER: Wang WC 

PROVIDER: S-EPMC4126198 | biostudies-literature | 2014 Aug

REPOSITORIES: biostudies-literature