Dendrite-to-soma input/output function of continuous time-varying signals in hippocampal CA1 pyramidal neurons.
We examined how hippocamal CA1 neurons process complex time-varying inputs that dendrites are likely to receive in vivo. We propose a functional model of the dendrite-to-soma input/output relationship that combines temporal integration and static-gain control mechanisms. Using simultaneous dual whole cell recordings, we injected 50 s of subthreshold and suprathreshold zero-mean white-noise current into the primary dendritic trunk along the proximal 2/3 of stratum radiatum and measured the membrane potential at the soma. Applying a nonlinear system-identification analysis, we found that a cascade of a linear filter followed by an adapting static-gain term fully accounted for the nonspiking input/output relationship between the dendrite and soma. The estimated filters contained a prominent band-pass region in the 1- to 10-Hz frequency range that remained constant as a function of stimulus variance. The gain of the dendrite-to-soma input/output relationship, in contrast, varied as a function of stimulus variance. When the contribution of the voltage-dependent current I(h) was eliminated, the estimated filters lost their band-pass properties and the gain regulation was substantially altered. Our findings suggest that the dendrite-to-soma input/output relationship for proximal apical inputs to CA1 pyramidal neurons is well described as a band-pass filter in the theta frequency range followed by a gain-control nonlinearity that dynamically adapts to the statistics of the input signal.
Cook
Erik P
EP
Department of Physiology, McGill University, 3655 Sir William Osler, Montreal, QC H3G 1Y6, Canada. erik.cook@mcgill.ca
Guest
Jennifer A
JA
Liang
Yong
Y
Masse
Nicolas Y
NY
Colbert
Costa M
CM
D000200:Action Potentials / Q000502:physiology / Q000528:radiation effects; D000818:Animals; D001369:Axons / Q000502:physiology*; D003712:Dendrites / Q000502:physiology*; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation / Q000379:methods; D006624:Hippocampus / Q000166:cytology*; D066298:In Vitro Techniques; D008297:Male; D008959:Models, Neurological; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000166:cytology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors