Abstract
In decerebrate cats a train of impulses in Ia afferents may lead to a sustained increase in excitability of α-motoneurones of homonymous and heteronymous muscles. It was previously suggested that this long-lasting excitability increase reflects a maintained synaptic input to the motoneurones from excitatory interneurones. With intracellular recording from motoneurones we here demonstrate that the sustained increase of α-motoneurone activity is due to an all-or-none plateau depolarization. This plateau can be induced by a short train of excitatory synaptic potentials or a brief, intracellularly injected depolarizing current pulse and is terminated by a short train of inhibitory synaptic potentials or a hyperpolarizing current pulse. It is concluded that maintained motor unit firing triggered by a brief train of impulses in Ia afferent reflects an intrinsic bistable behaviour of α-motoneurones.
| Original language | English |
|---|---|
| Journal | Experimental Brain Research |
| Volume | 55 |
| Issue number | 2 |
| Pages (from-to) | 391-394 |
| Number of pages | 4 |
| ISSN | 0014-4819 |
| DOIs | |
| Publication status | Published - 1 Jun 1984 |
Keywords
- Bistable state
- Motoneurones
- Serotonin
- Spinal cord