Fig. 6.

Zebrafish blood and skin extract elicit highly similar neural activity in the dorsal olfactory bulb. Olfactory bulb responses to zebrafish blood, zebrafish skin extract, food odor, bile acid, and saline control (artificial cerebrospinal fluid) were measured using two-photon calcium imaging in adult zebrafish brain explants (n = 4 fish; see the “Methods” section). a Calcium signals representing the odor responses averaged across all optical planes in a representative fish. Warm colors represent stronger neural activity. b Three-dimensional reconstructions of olfactory bulb responses to all odors in the same fish as in a. Each circle represents an individual neuron. The spatial orientation and scale bars are indicated on the left graph and are the same for all representations. c Odor responses of the three individual neurons selective for skin extract and blood indicated in a. d Correlation matrix representing the average pairwise similarity between multi-neuronal odor representations (n = 4 fish). e Representation of all odors with the first three principal components of the neural responses (PC, see the “Methods” section). The percentage of variance explained by each PC is indicated between brackets. Gray lines indicate the distance of each odor to the saline control (filled black dot). f Representation of the same odors with the first three principal components of the behavioral responses (adapted from Fig. 5c). The data used in this figure are provided in Additional file 11: Data S3