Fig. 8

Morphological and electrophysiological distinctions between newly generated neurons in the upper and deeper layers. A The figure illustrates the morphological and electrophysiological differences based on neuron location. Neurons in the upper layers (left) are smaller than those in the lower layers (right). Lower layer neurons exhibit more, longer, and more complex dendrites. Additionally, their firing patterns differ, with upper layer neurons showing higher frequency firing, as indicated by the frequency recordings and frequency-current graph at the top. The central panel shows the distribution of recorded neurons from the 29–56 days post injury (dpi) and 57–90 dpi groups. Dashed lines illustrate lesion size changes over time: initially larger at 7–14 dpi (black), and progressively smaller with treatment [15–28 dpi in red, 29–56 dpi in blue, 57–90 dpi in green]. B-H Box-and-whisker plots displaying the medians (dashed lines), interquartile ranges (boxes), minimum/maximum values (whiskers) and SEM (error bars) for total surface area (B), dendrite length (C), number of total segments (D), number of terminal endings (E), rheobase (F), input resistance (G), and firing gain (H) for each group. It is remarkable that neurons in deeper layers were larger (*p = 0.036), longer (*p = 0.013), and more complex (segments, *p = 0.004; endings, *p = 0.034). They had higher rheobases (*p = 0.043) and lower firing frequencies (*p = 0.0034). Student's t-test assessed differences between groups. Asterisks (*) indicate statistically significant differences between groups, with a significance level of p ≤ 0.05