EM connectomics reveals axonal target variation in a sequence-generating network
- Max Planck Institute of Neurobiology, Germany
- New York University Langone Medical Center, United States
- New York University, United States
- Max Planck Institute for Biological Cybernetics, Germany
- Bernstein Center for Computational Neuroscience, Germany
- Center of Advanced European Studies and Research, Germany
Figures
Figure 1 with 4 supplements
Analysis of synaptic inputs onto HVC(RA) dendrites.
(a) A schematic of the songbird brain showing HVC and its two main downstream targets, RA and Area X. (b) A backlabeled HVC(RA) neuron (red) during juxtacellular filling (pipette shown in white) …
Figure 1—figure supplement 1
Sample preparation for LM and EM.
(a,b) For LM, HVC(RA) neurons are retrogradely labeled by injecting a fluorescent dextran (fluoro-Ruby) into RA (a), and a single labeled neuron is targeted and filled with Neurobiotin under the …
Figure 1—figure supplement 2
Synaptic boutons on HVC(RA) axon collaterals.
(a) An LM reconstruction of HVC(RA) axon collaterals of one neuron with the HVC border indicated by dashed lines. Locations of all synaptic boutons are marked by grey spheres. (b) Bouton density of …
Figure 1—figure supplement 3
Ultrastructural classification of synapses.
(a) An asymmetric synapse onto a BDA-labeled HVC(RA) dendrite whose morphology is partially obscured by the label. Red arrows indicate the synaptic cleft. (b to d) Other synapses made by the same …
Figure 1—figure supplement 4
The BDA label is inefficient and incomplete.
(a) All cells within our SBEM dataset are represented by spheres at the location of the cell body. Known HVC(RA) neurons, which were labeled with BDA, were colored red. Also shown are putative HVC(RA…
Figure 2 with 1 supplement
Classification of postsynaptic targets.
(a) A BDA-labeled axon with four synaptic boutons (boxes). One bouton and its postsynaptic structure labeled in red and blue, respectively: In cross section (top right) and as a surface …
Figure 2—figure supplement 1
Morphological markers of interneurons.
(a) Ultrastructural and morphological differences of the somata of an HVC interneuron (left, blue shade) and an HVC(RA) neuron (right, red shade). Compared with HVC(RA) neurons, interneurons had …
Figure 3 with 3 supplements
Spatial variation of postsynaptic cell type.
(a) SBEM-based reconstructions and synaptic targets for two orphaned axon segments. Colored spheres mark the locations and types of synapses. (b) Axon collaterals (LM-based reconstruction) of an HVC(…
Figure 3—figure supplement 1
Synaptic properties of HVC(RA) axons, using a Bayesian approach to estimate distance from soma.
(a) Total synaptic strength (summated active zone area/pathlength) onto excitatory neurons vs. estimated distance of the presynaptic axon from the soma (p<0.05, Pearson's correlation). (b) The ratio …
Figure 3—figure supplement 2
A SBEM-based reconstruction and synaptic targets for an orphaned axon with high branch density.
Small spheres mark the location of synapses, with the color indicating the target type. Note the higher frequency of inhibitory targets (blue) along the length of the reconstruction compared with …
Figure 3—figure supplement 3
A small population of RA neurons project to HVC.
(a) The borders of RA were traced across nine sequential 100 µm thick sagittal sections, and the location of each retrogradely labeled HVC-projecting RA neuron is marked with a dot. (b) DiI …
Videos
Video 1
Video shifting through a z-stack of a sagittal section within HVC, containing a Neurobiotin-filled HVC(RA) neuron stained with DAB.
Number of z-sections shown is 144. Voxel size is 92 × 92 × 500 nm.
Video 2
Video of a subregion of the acquired SBEM dataset, showing the original data resolution (lossy compression).
Number of z-sections shown is 100, translating to 2.9 µm.
Video 3
Video of a subregion of the acquired SBEM dataset, showing a larger field of view with a BDA-labeled HVC(RA) soma (lossy compression).
Number of z-sections shown is 200, translating to 5.8 µm.
Video 4
Video of a z-stack of 18 consecutive images (100 × 100 pixels) showing a symmetric synapse.
Voxel dimensions: 11 × 11 × 29.
Video 5
Video of a z-stack of 18 consecutive images (100 × 100 pixels) showing an asymmetric synapse.
Voxel dimensions: 11 × 11 × 29.
