Areal specializations in the morpho-electric and transcriptomic properties of primate layer 5 extratelencephalic projection neurons.

Large-scale analysis of single-cell gene expression has revealed transcriptomically defined cell subclasses present throughout the primate neocortex with gene expression profiles that differ depending upon neocortical region. Here, we test whether the interareal differences in gene expression translate to regional specializations in the physiology and morphology of infragranular glutamatergic neurons by performing Patch-seq experiments in brain slices from the temporal cortex (TCx) and motor cortex (MCx) of the macaque. We confirm that transcriptomically defined extratelencephalically projecting neurons of layer 5 (L5 ET neurons) include retrogradely labeled corticospinal neurons in the MCx and find multiple physiological properties and ion channel genes that distinguish L5 ET from non-ET neurons in both areas. Additionally, while infragranular ET and non-ET neurons retain distinct neuronal properties across multiple regions, there are regional morpho-electric and gene expression specializations in the L5 ET subclass, providing mechanistic insights into the specialized functional architecture of the primate neocortex.

Microscale visualization of cellular features in adult macaque visual cortex.

Expansion microscopy and light sheet imaging enable fine-scale resolution of intracellular features that comprise neural circuits. Most current techniques visualize sparsely distributed features across whole brains or densely distributed features within individual brain regions. Here, we visualize dense distributions of immunolabeled proteins across early visual cortical areas in adult macaque monkeys. This process may be combined with multiphoton or magnetic resonance imaging to produce multimodal atlases in large, gyrencephalic brains.

2-Cyano-anilinium iodide.

The solid-state structure of the title salt, C7H7N2 (+.)I(-), consists of cation-anion sheets lying parallel to (110), with the components linked by N-H⋯I hydrogen bonds.

4-Cyano-anilinium bromide.

In the crystal structure of the title compound, C(7)H(7)N(2) (+)·Br(-), the cations are associated into inversion dimers through weak pairwise C-H⋯N hydrogen bonds. The dimers further form stepped sheets via weak pairwise C-H⋯N hydrogen bonds. In the sheets, the spacing between the mean planes of the laterally displaced aromatic rings in adjacent dimers is 1.124 (6) Å. Three N-H⋯Br inter-actions and two weak C-H⋯Br inter-actions per cation tie the sheets together.

4-Cyano-anilinium iodide.

In the title compound, C(7)H(7)N(2) (+)·I(-), the cation is located on a site of 4mm symmetry and is thus disordered about the fourfold axis so that there are two perpendicular orientations of the six-membered ring and four rotational orientations of the {-NH(3) (+)} group. In the crystal, there are two layers perpendicular to the c axis, each containing iodide ions and the {-NH(3) (+)} portions of the cations, with the remainder of the cations extending outwards from these layers.

2-Cyano-1-methyl-pyridinium nitrate.

In the title compound, C(7)H(7)N(2) (+)·NO(3) (-), all atoms except the methyl H atoms lie on a crystallographic mirror plane. The inter-layer distance, including that between aligned N atoms from alternating cations and anions in adjacent layers, is exceptionally short at 3.055 (1) Å. Two-dimensional C-H⋯O hydrogen-bonded networks link cations to anions, while C-H⋯N inter-actions link cations within each layer. Anion-π inter-actions with the cations assist in binding the layers together.