Figure 6

Dendritic morphology and biophysical properties of dentate granule cells in naked mole rats.

(a,b,c) Three-dimensional quantitative morphometry (Imaris) of biocytin-filled neurons in the dentate gyrus of naked mole rats aged 4 months (a,e), 1 year (b,f) or >8 years (c,g). Dashed black lines denote the boundaries of the granule and molecular layers in the dentate gyrus (upper saber). Pseudo-colors correspond to the length of dendrite segments (colorimetric scale from 1 μm −200 μm). Scale bars = 50 μm (a), 25 μm (b,c). Note that higher resistances (R_m) correlate with cells deeper in the granule layer and indicate immature neurons. (d) Morphometric parameters expressed as means ± S.D. for dentate granule cells at the age groups indicted. (e–g) Current clamp recordings of the reconstructed granule cells with the most hyperpolarizing and depolarizing current steps depicted in black. Membrane potential traces shown in red evoked by a depolarizing current step at 2x threshold (in red). Scale bars = 150 pA. Phase diagrams of the action potentials evoked at 2x threshold. The first action potential phase diagram was colored red with subsequent traces progressively shaded from warm to cool colors, ending in blue.