Role of the mesoamygdaloid dopamine projection in emotional learning.
BACKGROUND
Amygdala dopamine is crucially involved in the acquisition of Pavlovian associations, as measured via conditioned approach to the location of the unconditioned stimulus (US). However, learning begins before skeletomotor output, so this study assessed whether amygdala dopamine is also involved in earlier 'emotional' learning.


OBJECTIVE
A variant of the conditioned reinforcement (CR) procedure was validated where training was restricted to curtail the development of selective conditioned approach to the US location, and effects of amygdala dopamine manipulations before training or later CR testing assessed.


METHODS
Experiment 1a presented a light paired (CS+ group) or unpaired (CS- group) with a US. There were 1, 2 or 10 sessions, 4 trials per session. Then, the US was removed, and two novel levers presented. One lever (CR+) presented the light, and lever pressing was recorded. Experiment 1b also included a tone stimulus. Experiment 2 applied intra-amygdala R(+) 7-OH-DPAT (10 nmol/1.0 microl/side) before two training sessions (Experiment 2a) or a CR session (Experiment 2b).


RESULTS
For Experiments 1a and 1b, the CS+ group preferred the CR+ lever across all sessions. Conditioned alcove approach during 1 or 2 training sessions or associated CR tests was low and nonspecific. In Experiment 2a, R(+) 7-OH-DPAT before training greatly diminished lever pressing during a subsequent CR test, preferentially on the CR+ lever. For Experiment 2b, R(+) 7-OH-DPAT infusions before the CR test also reduced lever pressing.


CONCLUSIONS
Manipulations of amygdala dopamine impact the earliest stage of learning in which emotional reactions may be most prevalent.
Phillips
Gavin D
GD
Department of Psychology, University of York, Heslington, York, YO10 5DD, UK. g.phillips@psych.york.ac.uk
Salussolia
Emily
E
Hitchcott
Paul K
PK
D000679:Amygdala / Q000502:physiology*; D000818:Animals; D001245:Association Learning / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology; D004298:Dopamine / Q000502:physiology*; D004644:Emotions / Q000502:physiology*; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D051381:Rats; D012055:Reinforcement Schedule; D012054:Reinforcement, Psychology
D004298:Dopamine
Psychopharmacology (Berl). 1980;69(2):219-22
6256791
Psychopharmacology (Berl). 2009 Mar;203(1):161-73
18949458
Adv Anat Embryol Cell Biol. 1998;142:1-118
9586282
Learn Behav. 2008 Aug;36(3):253-65
18683469
Brain Res. 2001 Apr 6;897(1-2):150-6
11282368
Ann N Y Acad Sci. 1999 Jun 29;877:412-38
10415662
Science. 2000 Jan 14;287(5451):248-51
10634773
Brain Res. 2001 Apr 27;899(1-2):218-26
11311883
Proc Natl Acad Sci U S A. 1994 Nov 8;91(23):11271-5
7972046
Psychopharmacology (Berl). 2007 Apr;191(3):433-7
16977476
Arzneimittelforschung. 1992 Feb;42(2A):224-30
1586393
Neuroscience. 2003;117(3):741-53
12617978
Psychopharmacology (Berl). 1998 Dec;140(4):458-69
9888622
Front Integr Neurosci. 2007 Nov 02;1:2
18958230
Psychopharmacology (Berl). 1998 Dec;140(3):310-8
9877011
Annu Rev Psychol. 2003;54:25-53
12185211
Q J Exp Psychol B. 2005 Jan;58(1):19-30
15844375
Psychopharmacology (Berl). 1998 Dec;140(3):300-9
9877010
J Neurosci. 2001 Nov 15;21(22):9018-26
11698612
Psychopharmacology (Berl). 1997 Aug;132(3):237-46
9292623
Prog Brain Res. 2006;156:3-29
17015072
Philos Trans R Soc Lond B Biol Sci. 2008 Oct 12;363(1507):3137-46
18640920
Brain Res. 1994 Jan 7;633(1-2):243-52
7511034
J Exp Anal Behav. 1962 Oct;5:529-30
13945507
Psychopharmacology (Berl). 1998 Dec;140(3):354-64
9877015
Neuropharmacology. 1998 Apr-May;37(4-5):461-9
9704987
Psychopharmacology (Berl). 1983;80(3):226-30
6412266
Psychopharmacology (Berl). 1984;84(2):158-62
6438674
Psychopharmacology (Berl). 1990;101(3):338-43
2163539
Neuroscience. 1999 Apr;90(1):119-30
10188939
Physiol Behav. 2002 Dec;77(4-5):489-93
12526988
Prog Neurobiol. 1980;14(2-3):69-97
6999537
Psychopharmacology (Berl). 1994 Mar;114(2):345-59
7838928
Psychopharmacology (Berl). 1997 Oct;133(3):240-8
9361329
Physiol Behav. 2002 Aug;76(4-5):677-84
12127008
Nature. 2002 May 16;417(6886):282-7
12015602
Brain Res Brain Res Rev. 1998 May;26(2-3):136-47
9651506
J Neurosci. 2002 Jan 1;22(1):324-37
11756516
Integr Physiol Behav Sci. 1994 Apr-Jun;29(2):109-33
7947327
Neuroscience. 2003;117(3):755-67
12617979
Nat Neurosci. 2005 Nov;8(11):1481-9
16251991
Eur J Neurosci. 2004 Jul;20(1):240-8
15245496
J Neurochem. 1995 Jun;64(6):2581-9
7760038
Eur J Neurosci. 2000 Jan;12(1):405-13
10651899
Psychopharmacology (Berl). 1984;84(3):405-12
6440188
Behav Brain Res. 2002 Aug 21;134(1-2):249-57
12191811
Psychopharmacology (Berl). 1997 Aug;132(3):247-54
9292624
J Neurosci. 2003 Aug 20;23(20):7702-9
12930810
Synapse. 1992 Jun;11(2):146-54
1385664
Philos Trans R Soc Lond B Biol Sci. 2006 Jul 29;361(1471):1149-58
16874930
Neurobiol Learn Mem. 2002 Mar;77(2):125-84
11848717
Neuron. 2002 Oct 10;36(2):241-63
12383780