Article Figures & Data
Figures
- Figure 1.
Experimental timelines. A, “Baseline” tail nicks were performed for blood collection Pre-PavCA, and after the rats had acquired a conditioned response (Post-PavCA). Rats were subsequently tested on the elevated plus maze (EPM) and the open field test (OFT), followed by physiological restraint, with a 10-d rest period before each. CORT response to the OFT and acute restraint was captured with time course blood sampling. B, A separate group of rats underwent five sessions of PavCA training and were subsequently euthanized to assess GR expression in the hippocampus and PrL using in situ hybridization.
- Figure 2.
Acquisition of sign-tracking and goal-tracking behavior. Sign-tracking (i.e., lever-directed, left panels) and goal-tracking (i.e., food-cup directed, right panels) behavioral measures were assessed across five PavCA sessions. Mean + SEM for probability to contact (A) the lever or (B) the food-cup; total number of contacts with (C) the lever or (D) the food-cup; and latency to contact (E) the lever or (F) the food-cup. Rats with a sign-tracking conditioned response were classified as STs (n = 32), those with a goal-tracking conditioned response as GTs (n = 11), and those that vacillated between the two conditioned responses as IRs (n = 17).
- Figure 3.
“Baseline” CORT levels before and after PavCA training. Mean + SEM for baseline plasma CORT levels before (Pre-PavCA) and following (Post-PavCA) PavCA training experience. Basal plasma CORT levels increased with Pavlovian training experience (*p = 0.001; n = 60; GT n = 10, IR = 17, ST = 32).
- Figure 4.
EPM. A, Heat map representations for the average time spent in each zone during the 5-min EPM test for each phenotype. B, Mean + SEM for the time spent in each zone of the EPM for GTs (n = 11), IRs (n = 13), and STs (n = 14). All rats spent significantly more time in the closed arms compared with the open arms and center of the maze (*p < 0.001). There was not a significant difference between GTs and STs in the amount of time spent in either the center of the arena or the open or closed arms. IRs spent significantly less time in the open arms, relative to GTs (#p < 0.05).
- Figure 5.
OFT. A, Heat map representations for the average time spent in each zone (outer edge vs center) during the 5-min OFT for each phenotype. B, Mean + SEM for time spent in the outer edge or center of the arena for GTs (n = 11), IRs (n = 13), and STs (n = 14). All rats spent significantly more time on the outer edge of the arena compared with the center. Time spent in the center of the arena is shown as an inset on a different scale for illustration purposes. There was not a significant difference between phenotypes for the amount of time spent in the center of the arena.
- Figure 6.
CORT response to the OFT and acute physiological restraint. A, Mean + SEM for plasma CORT levels 0, 20, 40, 60, and 80 min postonset of the OFT for GTs (n = 11), IRs (n = 13), and STs (n = 14). There was a significant increase in CORT induced by the OFT at 20-, 40-, 60-, and 80-min time points (*p < 0.001), but no significant difference between phenotypes. B, Mean + SEM for plasma CORT levels 0, 30, 90, and 120 min postonset of acute restraint for GTs (n = 11), IRs (n = 13), and STs (n = 12). There was a significant increase in CORT induced by restraint at 30- and 90-min time points (*p < 0.001), but no significant difference between phenotypes.
- Figure 7.
GR mRNA expression in the dorsal and ventral hippocampus. A, Coronal brain sections representing bregma coordinates used to quantify GR mRNA expression (adapted from Paxinos and Watson, 2007). B, Representative in situ images for a GT, IR, and ST rat with tracing selections of the region of interest (ROI; in red) on the right hemisphere, including hippocampal subregions demarcated as CA1, CA2, CA3, and DG. C, D, Mean + SEM optical density for GR mRNA in subregions of the (C) dorsal and (D) ventral hippocampus for GTs (n = 10), IRs (n = 10) and STs (n = 10). In the ventral hippocampus, GR mRNA varied between subregions (*p < 0.001 vs CA1, #p < 0.001 vs DG). Relative to GTs and IRs, STs show greater GR mRNA density across subregions.
- Figure 8.
GR mRNA expression in the PrL. A, Coronal brain sections representing bregma coordinates used to quantify GR mRNA expression (adapted from Paxinos and Watson, 2007). B, Representative in situ images for a GT, IR, and ST rat with tracing selections of the region of interest (ROI; in red) on the right hemisphere. C, Mean + SEM optical density for GR mRNA in the PrL for GTs (n = 10), IRs (n = 10), and STs (n = 10).
Tables
- Table 1
Results from linear mixed model analysis for sign-tracking (i.e., lever-directed) and goal-tracking (i.e., food-cup-directed) behaviors
PavCA behavior Experiment 1 Number of lever contacts Probability to contact lever Latency to contact lever Sign-tracking df1,df2 F value p value df1,df2 F value p value df1,df2 F value p value Effect of phenotype 2,54.615 38.121 p < 0.001 2,57 56.803 p < 0.001 2,55.352 40.450 p < 0.001 Effect of session 4,87.711 15.929 p < 0.001 4,57 23.654 p < 0.001 4,79.678 35.451 p < 0.001 Phenotype × session 8,87.711 8.640 p < 0.001 8,57 9.027 p < 0.001 8,79.678 11.928 p < 0.001 Number of food cup contacts Probability to contact food cup Latency to contact food cup Goal-tracking df1,df2 F value p value df1,df2 F value p value df1,df2 F value p value Effect of phenotype 2,63.287 52.264 p < 0.001 2,63.003 39.844 p < 0.001 2,60.931 45.807 p < 0.001 Effect of session 4,96.698 14.610 p < 0.001 4,155.487 10.960 p < 0.001 4,81.979 14.380 p < 0.001 Phenotype × session 8,96.698 16.953 p < 0.001 8,155.487 12.193 p < 0.001 8,87.711 17.313 p < 0.001 Experiment 2 Number of lever contacts Probability to lever Latency to contact lever Sign-tracking df1,df2 F value p value df1,df2 F value p value df1,df2 F value p value Effect of phenotype 2,25.738 73.590 p < 0.001 2,27.026 111.836 p < 0.001 2,27.037 65.914 p < 0.001 Effect of session 4,30.902 17.660 p < 0.001 4,25.527 37.054 p < 0.001 4,23.863 29.661 p < 0.001 Phenotype × session 8,30.902 10.840 p < 0.001 8,25.527 17.592 p < 0.001 8,23.885 12.406 p < 0.001 Probability to Contact food cup Number of food cup contacts Latency to contact food cup Goal-tracking df1,df2 F value p value df1,df2 F value p value df1,df2 F value p value Effect of phenotype 2,31.080 39.402 p < 0.001 2,27.941 37.563 p < 0.001 2,26.445 41.540 p < 0.001 Effect of session 4,39.514 5.3831 p = 0.002 4,47.772 6.000 p = 0.001 4,56.426 9.495 p < 0.001 Phenotype × session 8,39.631 7.976 p < 0.001 8,47.731 10.586 p < 0.001 8,56.453 12.399 p < 0.001 Effect of phenotype, session, and phenotype × session interactions were analyzed for experiment 1 (top) and experiment 2 (bottom). df1, degrees of freedom numerator; df2, degrees of freedom denominator.
Phenotype comparisons Experiment 1 Sign-tracking Goal-tracking Number of lever contacts Number of food cup contacts 1 2 3 4 5 1 2 3 4 5 GT vs IR p = 0.090 p = 0.152 p = 0.083 p = 0.001* p < 0.001* p = 1.000 p = 0.820 p = 1.000 p < 0.001* p < 0.001* GT vs ST p = 0.024* p < 0.001* p < 0.001* p < 0.001* p < 0.001* p = 1.000 p = 0.072 p < 0.001* p < 0.001* p < 0.001* ST vs IR p = 1.000 p = 0.007* p < 0.001* p < 0.001* p < 0.001* p = 1.000 p < 0.001* p < 0.001* p < 0.001* p < 0.001* Probability to contact lever Probability to contact food cup 1 2 3 4 5 1 2 3 4 5 GT vs IR p = 0.074 p = 0.018* p < 0.001* p < 0.001* p < 0.001* p = 1.000 p = 0.542 p = 1.000 p = 0.226 p = 0.051 GT vs ST p = 0.004* p < 0.001* p < 0.001* p < 0.001* p < 0.001* p = 1.000 p = 0.382 p < 0.001* p < 0.001* p < 0.001* ST vs IR p = 0.930 p = 0.012* p < 0.001* p < 0.001* p = 0.001* p = 1.000 p = 0.002* p < 0.001* p < 0.001* p < 0.001* Latency to contact lever Latency to contact food cup 1 2 3 4 5 1 2 3 4 5 GT vs IR p = 0.092 p = 0.057 p = 0.006* p < 0.001* p < 0.001* p = 1.000 p = 1.000 p < 0.001* p < 0.001* p < 0.001* GT vs ST p = 0.011* p < 0.001* p < 0.001* p < 0.001* p < 0.001* p = 1.000 p = 0.081 p < 0.001* p < 0.001* p < 0.001* ST vs IR p = 1.000 p = 0.047* p < 0.001* p < 0.001* p = 0.001* p = 1.000 p = 0.003* p < 0.001* p < 0.001* p < 0.001* Sign-tracking Goal-tracking Number of lever contacts Number of food cup contacts Experiment 2 1 2 3 4 5 1 2 3 4 5 GT vs IR p = 0.852 p = 0.005* p = 0.016* p = 0.001* p < 0.001* p = 0.959 p = 1.000 p = 0.063 p < 0.001* p < 0.001* GT vs ST p = 0.001* p < 0.001* p < 0.001* p < 0.001* p < 0.001* p = 0.073 p = 0.052 p < 0.001* p < 0.001* p < 0.001* ST vs IR p = 0.010* p < 0.001* p < 0.001* p < 0.001* p < 0.001* p = 0.547 p = 0.217 p = 0.001* p < 0.001* p = 0.003* Probability to contact lever Probability to contact food cup 1 2 3 4 5 1 2 3 4 5 GT vs IR p = 0.211 p < 0.001* p < 0.001* p < 0.001* p < 0.001* p = 1.000 p = 1.000 p = 0.820 p = 0.093 p = 0.005* GT vs ST p < 0.001* p < 0.001* p < 0.001* p < 0.001* p < 0.001* p = 0.163 p = 0.138 p < 0.001* p < 0.001* p < 0.001* ST vs IR p = 0.018* p < 0.001* p = 0.004* p = 0.003* p = 0.003* p = 0.331 p = 0.359 p < 0.001* p < 0.001* p < 0.001* Latency to contact lever Latency to contact food cup 1 2 3 4 5 1 2 3 4 5 GT vs IR p = 0.649 p = 0.005* p < 0.001* p < 0.001* p < 0.001* p = 1.000 p = 1.000 p = 0.072 p < 0.001* p < 0.001* GT vs ST p < 0.001* p < 0.001* p < 0.001* p < 0.001* p < 0.001* p = 0.285 p = 0.096 p < 0.001* p < 0.001* p < 0.001* ST vs IR p = 0.013* p = 0.001* p < 0.001* p < 0.001* p = 0.002* p = 0.420 p = 0.408 p = 0.006* p < 0.001* p < 0.001* Sign-tracking (i.e., lever-directed) and goal-tracking (i.e., food-cup-directed) behaviors are included for experiment 1 (top) and experiment 2 (bottom). *p < 0.005.
- Table 3
Results of Pearson correlation analysis between the change in the PavCA index from session 1 to session 5 (Δ PavCA index) and baseline CORT profiles (Pre-PavCA, Post-PavCA, and the change in baseline values, Δ CORT) for the entire population (i.e., all) and for each phenotype separately
CORT and behavior correlations Pre-PavCA
CORT levelsPost-PavCA
CORT levelsPre- to Post-PavCA
CORT level Difference
“Δ CORT”n = r-value p-value n = r-value p-value n = r-value p-value “Δ PavCA Index” All 56 0.262 0.051 53 0.290 0.035* 50 0.121 0.402 GTs 9 0.667 0.045* 8 0.023 0.957 7 –0.301 0.512 IRs 16 0.422 0.103 17 0.151 0.563 16 −0.058 0.830 STs 31 0.058 0.768 28 0.437 0.020* 27 0.470 0.013* *p < 0.005
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