Figure 4.

Neuron-Derived Neurotrophic Factor Is a Conserved Marker for Human Layer 1 Neurogliaform Cells

(A) In situ hybridization for NDNF in human neocortex (left) and quantification of the distribution of positive neurons along cortical depth (12 slices from 2 patients). The density of NDNF-positive neurons is high in layer 1 (light gray) and drops off steeply at the border to layer 2 (dark gray) (A₁). In situ hybridization for Ndnf in mouse temporal neocortex (16 slices from 3 animals) shows a similar expression profile, indicating that Ndnf is a conserved marker for layer 1 interneurons (A₂). The image in A₁ is a montage of images assembled using Pannoramic Scan software.

(B) Whole-cell current-clamp slice recording using an Ndnf-eGFP mouse line.

(C) To determine whether Ndnf positive layer 1 interneurons correspond to one of the populations identified by unbiased clustering of the entire layer 1 interneuron population (Figure 3), we compared the distribution of action potential onset (C₁), spiking accommodation (C₂), and action potential afterhyperpolarization (C₃) in the three populations. Ndnf interneurons display robust similarity with the late-spiking cluster in all three parameters.

(D) Statistical comparison of the 10 attributes used for clustering between the three populations indicates that Ndnf interneurons and cells in the late-spiking cluster differ from the non-late-spiking cluster in the same properties, whereas no difference could be detected between the late-spiking and Ndnf populations. Error bars indicate SEM.