Figure 4.

Organization of retrogradely labeled neurons in the piriform cortex. A, Retrogradely labeled cells in the piriform cortex (red) mapped onto a whole mouse brain reconstruction from a g-deleted rabies injection in the GCL. A, Enlargement, Gray lines corresponding to layer 2 from each coronal section. B, Correlation of injection size in GCL to number of labeled neurons in piriform cortex. C, Top, Rostral–caudal distribution of retrogradely labeled cells from A. C, Bottom, Mean rostral–caudal distribution of retrogradely labeled cells across all experiments. Error bars indicate SD. D, Laminar distribution of retrogradely labeled neurons in piriform cortex (black) compared with a Gaussian distribution centered at the layer 2 border. E, Projection (new neuron position = dark red dots, projection = red lines) of retrogradely labeled neurons (light red) onto a line (gray) through layer 2. This projection is then warped to a linear representation. F, Correlation of pairwise distances in the Euclidean space to the pairwise distances in the remapping demonstrate that local spatial relationships are preserved during remapping. G, Top, Remapping of retrogradely labeled cells in piriform to a 2D surface. G, Bottom, Density plot of retrogradely labeled neurons. Scale bar, 500 μm. H, Histogram of mean pairwise distances between neurons (black) from retrograde data and pairwise distances from randomly distributed cells (gray). Population means for the example (top) are shown. Error bar indicates SD. I, Mean pairwise distances from experiments (black) versus from random distributions (gray). J, Mean pairwise distance is not correlated with the number of retrogradely labeled neurons for either data (black, p = 0.62) or random data (gray, p = 0.32) in the piriform cortex. K, Injection of two g-deleted rabies virus constructs into the GCL (insert) and retrograde label of neurons in piriform cortex. Scale bar, 500 μm. L–N, Density of retrogradely labeled BFP (L) and GFP (M) neurons and difference in density distributions (N). Arrows correspond to clusters of feedback projecting neurons. O, Top, Outline of clusters from multiple resamples of a single experiment. O, Bottom, Outline of clusters from multiple resamples of random data for the same experiment as in O (top). P, Cluster stability as measured by correlation of cluster shape from resample to resample. Q, Number of clusters per experiment calculated from the data (black) compared with the random data (gray). R, Cumulative histogram of number of cells per cluster in the experimental data (black) compared with random data (gray). S, Mean number of cells per cluster across all experiments (black) compared with random data (gray).