The locus coeruleus influences behavior by coordinating effective integration of fear memories and sensory input
Fig 4
Contribution ofβ-norepinephrine receptors to dmPFC neuronal responses and freezing levels.
(A) Experimental paradigm for examining inputs to dmPFC using injection of retrobeads in dmPFC (left) and visualization of retrobeads in the auditory cortex (right). A1, primary auditory cortex; AuV, auditory cortex; TeA, temporal association cortex. Scale bar, 200 μm. (B) Responses (z-score) of T-neurons and S-neurons to opto-activation of TeA inputs (0.9 Hz, 250 ms). T-neurons, n = 20 units/5 mice; S-neurons, n = 12 units/5 mice. rAAV2/9-CaMKII-ChR2-mCherry viruses were injected in TeA and optical fiber implanted in the TeA to activate TeA neurons. (C) Injection of rAAV2/9-CaMKII-ChR2-mCherry virus in the TeA (Left). Representative EPSC trace in the dmPFC neurons to opto-stimulation of TeA inputs (Right). Bar indicates blue light illumination. Scale bars, 200 pA and 25 ms. (D) Experimental procedure for examining intra-cerebroventricular injection of propranolol or saline on neuronal responses and freezing levels. (E) Freezing levels during retrieval with (Prop) or without (Saline) propranolol injection in conditioned mice. Two-tailed paired t test, Prop vs. Saline, P < 0.05; N = 6 mice. (F) Effect of intra-cerebroventricular injection of Prop on spike rates in the S-neurons. Two-tailed paired t test, Prop vs. Saline, P < 0.05. N = 9 units/6 mice. (G) Effect of intra-cerebroventricular injection of Prop on spike rates in the T-neurons. N = 22 units/6 mice. (H) (Top) Representative sEPSCs traces in the S-neurons during bath application of Isop (50 μM). Scale bars, 20 pA and 50 ms. (Bottom) Effects of Isop on sEPSC frequency (Two-tailed paired t test, t = 4.246, df = 10, Pre-Isop vs. Isop, P < 0.01; n = 11 cells/4 mice), and sEPSC amplitude in the S-neurons (Two-tailed paired t test, t = 0.976, df = 20, Pre-Isop vs. Isop, P > 0.05; n = 11 cells/4 mice). (I) (Top) Representative sIPSCs traces in S-neurons during bath application of Isop. Scale bars, 50 pA and 50 ms. (Bottom) Effects of Isop on sIPSC frequency (Two-tailed paired t test, t = 4.961, df = 7, Pre-Isop vs. Isop, P < 0.01; n = 8 cells/3 mice) and sIPSC amplitude in the S-neurons (Two-tailed paired t test, t = 2.088, df = 7, Pre-Isop vs. Isop, P > 0.05; n = 8 cells/3 mice). (J) (Top) Representative action potential traces in the S-neurons before and after bath application of Isop. Scale bars, 20 mV and 200 ms. (Lower left) Effects of Isop on the resting membrane potential (RMP) in the S-neurons (Two-tailed paired t test, t = 6.143, df = 9, Pre-Isop vs. Isop, P < 0.01; n = 10 cells/4 mice) and intrinsic excitability of S-neurons (Two-way RM ANOVA, F (15, 288) = 2.294, Bonferroni’s posttest, P < 0.01; Pre-Isop vs. Isop, P < 0.01; n = 12 cells/3 mice). (K) Effects of Isop on sEPSC frequency (Two-tailed paired t test, t = 2.333, df = 9, Pre-Isop vs. Isop, P < 0.05; n = 10 cells/4 mice) and sEPSC amplitude in the T-neurons (Two-tailed paired t test, t = 1.758, df = 9, Pre-Isop vs. Isop, P < 0.05; n = 10 cells/4 mice). (L) Effects of Isop on sIPSC frequency (Two-tailed paired t test, t = 1.265, df = 7, Pre-Isop vs. Isop, P > 0.05; n = 8 cells/3 mice) and sIPSC amplitude in the T-neurons (Two-tailed paired t test, t = 1.778, df = 7, Pre-Isop vs. Isop, P > 0.05; n = 8 cells/3 mice). (M) Effects of Isop on RMP (Two-tailed paired t test, Pre-Isop vs. Isop, P > 0.05; n = 8 cells/3 mice) and intrinsic excitability of T-neurons (Two-way RM ANOVA, F (15, 336) = 0.4195, Bonferroni’s posttest, P > 0.05; Pre-Isop vs. Isop, P > 0.05; n = 12 cells/3 mice). Numerical data can be found in S1 Data.