The basolateral amygdala complex and perirhinal cortex represent focal and peripheral states of information processing in rats
- School of Psychology, University of New South Wales, Australia
Figures
Figure 1
The neural substrates of the mediated S2-shock and direct S1-shock associations that form in stage 2 of sensory preconditioning are doubly dissociable at the level of N-methyl-D-aspartate receptor (NMDAR)-activation in the perirhinal cortex (PRh) and basolateral amygdala complex (BLA).
(A, C) Schematics of the protocols used to assess the involvement of NMDAR in acquisition of freezing to S2 and S1 in the PRh (Experiment 1A) and BLA (Experiment 1B). The protocols differed only in whether rats received an infusion of the NMDAR antagonist, DAP5, into the PRh (in A) or BLA (in C). (B) Test results showing that a stage 2 infusion of DAP5 into the PRh disrupts freezing to S2 without affecting freezing to S1. (D) Test results showing that a stage 2 infusion of DAP5 into the BLA disrupts freezing to S1 without affecting freezing to S2. The bars in each histogram show the mean level of freezing in each group across repeated presentations of S2 or S1 under conditions of extinction. The error bars show the standard error of the mean, and the overlaid data points represent the mean level of freezing for individual rats. The final group sizes were n=10 for Group VEH and n=11 for Group DAP5 in Experiment 1A, and n=15 for Group VEH and n=13 for Group DAP5 in Experiment 1B.
Figure 2
Combining the S2-S1 and S1-shock pairings into S2-S1-shock sequences alters the substrates of conditioning to the S2 in the perirhinal cortex (PRh) and basolateral amygdala complex (BLA).
(A, C) Schematics of the protocols used to assess when N-methyl-D-aspartate receptor (NMDAR) is involved in acquisition of freezing to S2 and S1 in the PRh (Experiment 2A) and BLA (Experiment 2B). The protocols differed only in whether rats received an infusion of the NMDAR antagonist, DAP5, into the PRh (in A) or BLA (in C). (B) Test results showing that a stage 2 infusion of DAP5 into the PRh has no effect on levels of freezing to either S2 or S1. (D) Test results showing that a stage 2 infusion of DAP5 into the BLA disrupts levels of freezing to both the S2 and S1. The final group sizes were n=8 for Group VEH and n=9 for Group DAP5 in Experiment 2A, and n=8 for Group VEH and n=9 for Group DAP5 in Experiment 2B.
Figure 3
Pre-exposing rats to S2-S1 pairings prior to a session of S2-S1-shock sequences re-engages N-methyl-D-aspartate receptor (NMDAR) in the perirhinal cortex (PRh) for conditioning of the S2.
(A, C) Schematics of the protocols used to assess when NMDARs are involved in acquisition of freezing to S2 and S1 in the PRh (Experiment 3A) and basolateral amygdala complex (BLA) (Experiment 3B). The protocols differed only in whether rats received an infusion of the NMDAR antagonist, DAP5, into the PRh (in A) or BLA (in C). (B) Test results showing that a stage 2 infusion of DAP5 into the PRh disrupts freezing to S2 without affecting freezing to S1. (D) Test results showing that a stage 2 infusion of DAP5 into the BLA disrupts freezing to S1 without affecting freezing to S2. The final group sizes were n=12 for Group VEH and n=12 for Group DAP5 in Experiment 3A, and n=10 for Group VEH and n=10 for Group DAP5 in Experiment 3B.
Figure 4
Pre-exposing rats to S2-S1 pairings prior to a session of S2-[trace]-shock pairings re-engages N-methyl-D-aspartate receptor (NMDAR) in the basolateral amygdala complex (BLA) for conditioning of the S2.
(A, C) Schematics of the protocols used to assess when NMDARs are involved in acquisition of freezing to S2 and S1 in the perirhinal cortex (PRh) (Experiment 4A) and BLA (Experiment 4B). (B, D) Test results showing that a stage 2 infusion of DAP5 has no effect on the level of freezing to S2 when injected into the PRh (in B) but disrupts the level of freezing to S2 when injected into the BLA (in D). The final group sizes were n=14 for Group VEH and n=15 for Group DAP5 in Experiment 3A, and n=12 for Group VEH and n=14 for Group DAP5 in Experiment 3B.
Figure 5
Cannula placements in the perirhinal cortex (PRh) for rats in Experiments 1B, 2B, 3B, and 4B.
The most ventral portion of the cannulas is marked on coronal sections based on the atlas of Paxinos and Watson, 2007.
Figure 6
Cannula placements in the perirhinal cortex (PRh) for rats in Experiments 1A, 2A, 3A, and 4A.
The most ventral portion of the cannulas is marked on coronal sections based on the atlas of Paxinos and Watson, 2007.
Tables
Table 1
Designs and predictions for each experiment in the series.
| Experiment | Training | Predictions | ||
|---|---|---|---|---|
| Stage 1 | Stage 2 | For S2 | For S1 | |
| 1A | S2-S1 |  S1-shock | Disrupted | Intact |
| 1B | S2-S1 |  S1-shock | Intact | Disrupted |
| 2A | … |  S2-S1-shock | Intact | Intact |
| 2B | … |  S2-S1-shock | Disrupted | Disrupted |
| 3A | S2-S1 |  S2-S1-shock | Disrupted | Intact |
| 3B | S2-S1 |  S2-S1-shock | Intact | Disrupted |
| 4A | S2-S1 |  S2-[trace]-shock | Intact |  |
| 4B | S2-S1 |  S2-[trace]-shock | Disrupted |  |
-
Notes.
=PRh infusion of DAP5; 
=BLA infusion of DAP5. In Experiments 1A, 1B, 3A, and 3B, S2 is familiar and indirectly paired with shock, whereas S1 is familiar and directly paired with shock. In Experiments 2A and 2B, S2 is novel and indirectly paired with shock, whereas S1 is novel and directly paired with shock. In Experiments 4A and 4B, S2 is familiar and more directly paired with shock (compared to Experiments 3A and 3B).
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The basolateral amygdala complex and perirhinal cortex represent focal and peripheral states of information processing in rats
eLife 14:RP107943.
https://doi.org/10.7554/eLife.107943.3
