Somatic translocation: a novel mechanism of granule cell dendritic dysmorphogenesis and dispersion.

Pronounced neuronal remodeling is a hallmark of temporal lobe epilepsy. Here, we use real-time confocal imaging of tissue from mouse brain to demonstrate that remodeling can involve fully differentiated granule cells following translocation of the soma into an existing apical dendrite. Somatic translocation converts dendritic branches into primary dendrites and shifts adjacent apical dendrites to the basal pole of the cell. Moreover, somatic translocation contributes to the dispersion of the granule cell body layer in vitro, and when granule cell dispersion is induced in vivo, the dispersed cells exhibit virtually identical derangements of their dendritic structures. Together, these findings identify novel forms of neuronal plasticity that contribute to granule cell dysmorphogenesis in the epileptic brain.