Normalization of Ca2+ signals by small oblique dendrites of CA1 pyramidal neurons.
Oblique dendrites of CA1 pyramidal neurons predominate in stratum radiatum and receive approximately 80% of the synaptic input from Schaffer collaterals. Despite this fact, most of our understanding of dendritic signal processing in these neurons comes from studies of the main apical dendrite. Using a combination of Ca2+ imaging and whole-cell recording techniques in rat hippocampal slices, we found that the properties of the oblique dendrites differ markedly from those of the main dendrites. These different properties tend to equalize the Ca2+ rise from single action potentials as they backpropagate into the oblique dendrites from the main trunk. Evidence suggests that this normalization of Ca2+ signals results from a higher density of a transient, A-type K+ current [I(K(A))] in the oblique versus the main dendrites. The higher density of I(K(A)) may have important implications for our understanding of synaptic integration and plasticity in these structures.
Frick
Andreas
A
Division of Neuroscience, Baylor College of Medicine, Houston, Texas 77030, USA.
Magee
Jeffrey
J
Koester
Helmut J
HJ
Migliore
Michele
M
Johnston
Daniel
D
D015761:4-Aminopyridine / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D003712:Dendrites / Q000145:classification / Q000187:drug effects / Q000378:metabolism*; D004558:Electric Stimulation; D005456:Fluorescent Dyes; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D017966:Pyramidal Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism; D013779:Tetrodotoxin / Q000494:pharmacology
D002121:Calcium Channel Blockers; D005456:Fluorescent Dyes; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D015222:Sodium Channels; D013779:Tetrodotoxin; D015761:4-Aminopyridine; D002118:Calcium