Encoding of Conditioned Taste Aversion in Cortico-Amygdala Circuits Karen Lavi, Gilad A. Jacobson, Kobi Rosenblum, Andreas Lüthi  Cell Reports  Volume 24, Issue 2, Pages 278-283 (July 2018) DOI: 10.1016/j.celrep.2018.06.053 Copyright © 2018 The Authors Terms and Conditions

Cell Reports 2018 24, 278-283DOI: (10.1016/j.celrep.2018.06.053) Copyright © 2018 The Authors Terms and Conditions

Figure 1 Imaging Taste Responses of Identified GC Neurons upon CTA (A) Two-pipette preference assays with water versus gustatory stimulus: sodium saccharin (0.5%) (Sacc), sodium chloride (0.4%) (NaCl), and quinine (0.04%) (Quin). Following pre-exposure to gustatory stimuli, mice have high preference to Sacc over water (n = 12; mean, 75 ± 5.4%; p = 0.0008, one-sample t test) and NaCl over water (n = 12; mean, 64 ± 5.9%; p = 0.0337, one-sample t test), and aversion to Quin relative to water (n = 10; mean, 9.4 ± 2.3%; p < 0.0001, one-sample t test). Data are presented as preference to gustatory stimulus: (tastant consumption)/(total consumption)∗100 ± SEM. The dotted line represents no preference between the tastant and water. (B) Two-pipette preference assay with water versus conditioned or non-conditioned tastant. Left, CTA-Sacc mice exhibited aversion to Sacc and preference to NaCl (n = 6; preference median, 86.3% to NaCl over water and 16.5% to Sacc over water; p = 0.001, Mann-Whitney-Wilcoxon [MWW] test). Right, CTA-NaCl mice exhibited aversion to NaCl and preference to Sacc (n = 6; preference median, 31.4% to NaCl over water and 94.0% to Sacc over water; p = 0.001, MWW test). (C) Post-fixation coronal slice following retrograde labeling using injection of CAV2-Cre into the BLA of hCAR::tdTomato mice. BLA-projecting neurons were located throughout layer 2/3 and to some extent in layer 5 of the granular part of the GC. (D–F) Data from a representative CTA-Sacc animal. (D) Example of an in vivo two-photon imaging field of GC neurons. Green: GCaMP6s; red: tdTomato-labeled BLA-projecting GC cells. (E) Ca2+ traces from five cells expressing both GCaMP6s and tdTomato. Colored rectangle: gustatory stimulus window. (F) Ca2+ traces of all identified BLA-projecting cells from that animal. Each row represents a single cell’s activity, averaged across trials, and time relative to stimulus delivery is represented along the x axis (white dashed vertical lines depict taste delivery, 0–10 s). Cells are sorted according to the magnitude of response to the first stimulus (Sacc). Cell Reports 2018 24, 278-283DOI: (10.1016/j.celrep.2018.06.053) Copyright © 2018 The Authors Terms and Conditions

Figure 2 CTA Shifts Neuronal Population Coding in BLA-Projecting GC Neurons (A) Conditioned aversive gustatory stimuli activated a higher fraction of BLA-projecting neurons than non-conditioned stimuli (N = 8 [89 responding cells]; mean of differences, 38.57 ± 13.31%; p = 0.036, paired t test). No significant difference was found when comparing responses to conditioned aversive and non-conditioned stimuli in non-labeled GC cells (N = 8 [914 responding cells]; mean of differences, 0.69 ± 5.6%; p = 0.47, paired t test). (B) BLA-projecting neurons exhibited larger evoked responses to the conditioned aversive stimuli (N = 8; mean of differences, 6.7 ± 2.5%; p = 0.02, paired t test). No differences were found between the responses to conditioned aversive and non-conditioned responses in non-labeled GC cells (N = 8; mean of differences, 2.6 ± 2.71%; p = 0.38, paired t test). (C) Correlation coefficient of population responses to the different tastants (conditioned aversive, CTA; non-conditioned appetitive, non-CTA; innately aversive). Within the BLA-projecting population, pattern correlation between conditioned aversive and innately aversive stimuli (dark gray; r = 0.25) was significantly higher than the correlation between non-conditioned appetitive and innately aversive tastants (r = −0.32; mean differences, 0.45; two-way repeated-measures ANOVA, F(2,34) = 6.092, p = 0.0055, followed by Tukey’s multiple-comparison test, p = 0.0017). Differences were not significant in the non-labeled GC cells (mean of differences, 0.1042; p = 0.6330). (D) Correlation matrices for the non-labeled GC cells (left) and the BLA-projecting population (right). (E) Conditioned aversive gustatory stimuli activated a higher fraction of BLA-projecting neurons than innately aversive stimulus (N = 8 [76 responding cells]; mean of differences, 50.28 ± 14.18%; p = 0.019, paired t test). No significant difference was found when comparing responses of conditioned aversive and non-conditioned stimuli in non-labeled GC cells (N = 8 [875 responding cells]; mean of differences, 3.5 ± 4.1%; p = 0.185, paired t test). (F) Response amplitude of BLA-projecting neurons was significantly higher to the conditioned aversive stimuli compared to the innately aversive stimulus (N = 8; mean of differences, 4% ± 2%; p = 0.036, paired t test). No significant difference was found within the non-labeled GC cells (N = 8; mean of differences, 2% ± 1%; p = 0.065, paired t test). Box-whisker plots indicate median, interquartile range, and 10th to 90th percentiles of the distribution; crosses indicate means. ∗p < 0.05, ∗∗p < 0.01 Cell Reports 2018 24, 278-283DOI: (10.1016/j.celrep.2018.06.053) Copyright © 2018 The Authors Terms and Conditions