Emerging Roles of Filopodia and Dendritic Spines in Motoneuron Plasticity during Development and Disease

Figure 2

The somatodendritic and synaptic properties of lumbar motoneurons from a newborn wild-type C57/Bl6 (P0-WT) mouse. (a) Low-power image showing a lumbar spinal cord slice in transverse plane and the location of dye-filled motoneurons (yellow cells). (b) Medium-power confocal image showing two dye-coupled motoneurons located ventrolateral to the central canal (CC), with commissural dendrites crossing the midline (dashed line) to the contralateral side of the spinal cord. (c) High-power confocal image of these two motoneurons, which displayed action potential firing upon membrane depolarization (not shown), each displaying extensive filopodia (long arrows) and spine-like processes (short arrows) present in their somatodendritic domains. (d) Excitatory postsynaptic currents (downward deflections) recorded at a holding potential of −60 mV. Fast inactivating excitatory currents may be AMPA receptor-mediated (asterisks), whereas slowly inactivating excitatory currents likely include NMDA currents alone or together with AMPA (short arrows). (e) Inhibitory postsynaptic currents (upward deflections) recorded at a holding potential of 0 mV. Fast inactivating inhibitory currents may be glycine-mediated (asterisk), whereas slowly inactivating currents likely include GABA-mediated currents (short arrows). Scale bar is 200 μm in (a), 50 μm in (b), and 10 μm in (c). Scale bars for (d and e) are 250 ms and 25 pA.

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