Comprehensive Morpho-Electrotonic Analysis Shows two Distinct Classes of L2 and L3 Pyramidal Neurons in Human Temporal Cortex

13 October 2017
___________________________________________The group of Idan Segev of the Hebrew University of Jerusalem and Christiaan P.J. de Kock of the Vrije Universiteit, Amsterdam, in collaboration with the Molecular Systems Section in the Simulation Neuroscience Division of the Blue Brain Project, employed feature-based statistical methods, on a rare data set of 60 3D reconstructed pyramidal neurons from L2 and L3 in the human temporal cortex (HL2/L3 PCs) removed after brain surgery.

Of these cells, 25 neurons were also characterized physiologically. Thirty-two morphological features were analyzed, 18 of which showed a significant gradual increase with depth from the pia (e.g., dendritic length and soma radius). The other features showed weak or no correlation with depth (e.g., dendritic diameter).

The basal dendritic terminals in HL2/L3 PCs are particularly elongated, enabling multiple nonlinear processing units in these dendrites. Unlike the morphological features, the active biophysical features (e.g., spike shapes and rates) and passive/cable features (e.g., somatic input resistance, membrane time constant, and dendritic cable length) appear to be depth-independent.

A novel topological descriptor for apical dendrites yielded two distinct classes, termed hereby as “slim-tufted” and “profuse-tufted” HL2/L3 PCs. The two classes also differ in their electrical properties, as the “profuse-tufted” cells tend to fire at higher rates. Therefore, two distinct morpho-electrotonic classes of HL2/L3 Pcs were identified for the first time.

Click here to read the paper published in Cerebral Cortex.

Comprehensive Morpho-Electrotonic Analysis Shows 2 Distinct Classes of L2 and L3 Pyramidal Neurons in Human Temporal Cortex
Illustration of two distinct morpho-electrotonic classes of layer 2 and layer 3 pyramidal neurons from the human temporal cortex. A rare dataset of 60 pyramidal neurons removed after brain surgery and reconstructed in 3D was analyzed. Comprehensive analysis based on various morphological features of the dendritic tree shows a gradual dependence of these features with depth from the pia. A novel topological analysis (illustrated on this figure by the density profiles) reveals two distinct morphological classes in human L2 and L3 neocortex, termed here the “slim-tufted” and “profuse-tufted” cells (representatives are shown on the figure). Importantly, these two morphological classes also differ in their electrical properties: the “profuse-tufted” cells tend to fire at higher rates than the “slim-tufted” cells.

Blue Brain Project / EPFL © 2005 – 2017.
All rights reserved