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Hyperpolarization-Activated Current IhDisconnects Somaticand Dendritic SpikeInitiation Zones inLayer V PyramidalNeurons Thomas K. BergerWalter SennHans‐R. Lüscher2003 год

Hyperpolarization-Activated Current Ih Disconnects Somatic and Dendritic Spike Initiation Zones in Layer V Pyramidal Neurons
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Аннотация: Layer V pyramidal cells of the somatosensory cortex operate with two spike initiation zones. Subthreshold depolarizations are strongly attenuated along the apical dendrite linking the somatic and distal dendritic spike initiation zones. Sodium action potentials, on the other hand, are actively back-propagating from the axon hillock into the apical tuft. There they can interact with local excitatory input leading to the generation of calcium action potentials. We investigated if and how back-propagating sodium action potentials alone, without concomitant excitatory dendritic input, can initiate calcium action potentials in the distal dendrite. In acute slices of the rat somatosensory cortex, layer V pyramidal cells were studied under current-clamp with simultaneous recordings from the soma and the apical dendrite. A train of four somatic action potentials had to reach high frequencies to induce calcium action potentials in the dendrite (“critical frequency,” CF ∼100 Hz). Depolarization in the dendrite reduced the CF, while hyperpolarization increased it. The CF depended on the presence of the hyperpolarization-activated current I h : blockade with 20 μM 4-( N-ethyl- N-phenylamino)-1,2-dimethyl-6-(methylamino) pyridinium chloride (ZD7288) reduced the CF to 68% of control. If the neurons were stimulated with noisy current injections, leading to in-vivo-like irregular spiking, no calcium action potentials were induced in the dendrite. However, after I h channel blockade, calcium action potentials were frequently seen. These data suggest that I h prevents initiation of the dendritic calcium action potential by proximal input alone. Dendritic calcium action potentials may therefore represent a unique signature for coincident somatic and dendritic activation.
Год издания: 2003
Авторы: Thomas K. Berger, Walter Senn, Hans‐R. Lüscher
Издательство: American Physiological Society
Источник: Journal of Neurophysiology
Ключевые слова: Neural dynamics and brain function, Neuroscience and Neuropharmacology Research, Neuroscience and Neural Engineering
Другие ссылки: Journal of Neurophysiology (HTML)
PubMed (HTML)