Associative somatodendritic interaction in layer V pyramidal neurons is not affected by the antiepileptic drug lamotrigine
Abstract
The antiepileptic drug lamotrigine was described to exert its effects on neuronal excitability via voltage-gated sodium and calcium, as well as hyperpolarization-activated conductances. In order to define the effects of lamotrigine on the excitability of layer V pyramidal cells of the rat somatosensory cortex we performed patch-clamp recordings from the soma and dendrite of this major cortical output cell type in acute slices. Voltage-clamp experiments revealed the blockade of the persistent sodium current by 50-100 micro m lamotrigine as well as by 50 micro m of the anticonvulsant drug phenytoin. In somatic current-clamp studies lamotrigine, in a therapeutic concentration range, depolarizes the membrane potential reflecting the activation of the hyperpolarization-activated current. This depolarization reduces the rheobase and increases the spiking frequency at the onset of the spike train. For long depolarizing current pulses under lamotrigine, however, a use-dependent block of sodium channels reduces spiking frequency and spike amplitude. The depolarization due to 50-100 micro m lamotrigine reduces additionally the critical frequency of back-propagating spikes necessary to elicit a dendritic calcium action potential. Ten to t...Continue Reading
References
Site independence of EPSP time course is mediated by dendritic I(h) in neocortical pyramidal neurons
Citations
Related Concepts
Related Feeds
Barrel cortex
Here is the latest research on barrel cortex, a region of somatosensory and motor corticies in the brain, which are used by animals that rely on whiskers for world exploration.