Supralinear Ca2+ influx into dendritic tufts of layer 2/3 neocortical pyramidal neurons in vitro and in vivo.
Pyramidal neurons in layer 2/3 of the neocortex are central to cortical circuitry, but the intrinsic properties of their dendrites are poorly understood. Here we study layer 2/3 apical dendrites in parallel experiments in acute brain slices and in anesthetized rats using whole-cell recordings and Ca2+ imaging. We find that backpropagation of action potentials into the dendritic arbor is actively supported by Na+ channels both in vitro and in vivo. Single action potentials evoke substantial Ca2+ influx in the apical trunk but little or none in the dendritic tuft. Supralinear Ca2+ influx is produced in the tuft, however, when an action potential is paired with synaptic input. This dendritic supralinearity enables layer 2/3 neurons to integrate ascending sensory input from layer 4 and associative input to layer 1.
D000200:Action Potentials / Q000502:physiology; D000344:Afferent Pathways / Q000166:cytology / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology; D003712:Dendrites / Q000378:metabolism*; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D066298:In Vitro Techniques; D019579:Neocortex / Q000166:cytology / Q000502:physiology*; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D015222:Sodium Channels / Q000378:metabolism; D013003:Somatosensory Cortex / Q000166:cytology / Q000502:physiology
D015222:Sodium Channels; D002118:Calcium