FIGURE 9.

Coupling of DS-generated electrical activity to connecting dendrite and different waveforms. (A) Cultured adult mouse hippocampal neurons were maintained for up to one week in culture, where dendrite and DS were observed under DIC (×100). Under these conditions, electrical recordings were obtained by sealing and voltage clamping one electrode in a DS (DS), while the second electrode was current clamped in the sprouting dendrite (Dendrite) a few micrometers away. (B) In the absence of ligand, neither the DS nor the sprouting dendrite showed any electrical activity. (C) In the presence of ligand in the DS-attached pipette, however, in six out of twenty six experiments, NMDA-induced electrical oscillations were observed, that back propagated to the attached dendrite. Expanded tracings are shown at the bottom. Different waveforms and polarity were observed in a single experiment, including periodic and bursts of oscillations. (D) Delay of electrical signaling between DS and dendrite. The spontaneous electrical DS signals showed a seemingly capacitive nature.