Figure 4

Dendritic morphology and biophysical properties of CA1 pyramidal cells in naked mole rats.

(a–c) Three-dimensional quantitative morphometry (Imaris) of biocytin-filled neurons in the CA1 pyramidal layer of naked mole rats aged 4 months (a,e), 1 year (b,f) or >8 years (c,g). Black lines denote the hippocampal laminae. Pseudo-colors correspond to the length of dendrite segments (colorimetric scale from 1 μm–200 μm). Scale bars = 50 μm. (d) Morphometric parameters expressed as means ± S.D. for CA1 pyramidal cells at the age groups indicted. (e–g) Current clamp recordings with the most hyperpolarizing and depolarizing current steps depicted in black. Membrane potential traces shown in red were evoked by a depolarizing current step at evoked 2x threshold (in red). Scale bars = 150 pA. Phase diagrams of action potentials evoked at 2x threshold. The first action potential was coded red with subsequent traces progressively shaded from warm to cool colors, ending in blue. Note that the threshold potential variations (colored lines) tighten in aging animals, suggesting diminished variations.