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Intrinsic membrane properties causing a bistable behaviour of α-motoneurones

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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.

OriginalsprogEngelsk
TidsskriftExperimental Brain Research
Vol/bind55
Udgave nummer2
Sider (fra-til)391-394
Antal sider4
ISSN0014-4819
DOI
StatusUdgivet - 1 jun. 1984

ID: 194981226