| Program#/Poster#: |
860.15/JJJ10 |
| Title: |
Effects of medial amygdala lesions on Pavlovian conditioning, Sidman avoidance and aversive Pavlovian-instrumental transfer |
| Location: |
Halls B-H |
| Presentation Time: |
Wednesday, Nov 13, 2013, 3:00 PM - 4:00 PM |
| Authors: |
M. MCCUE1, J. E. LEDOUX1,2, *C. K. CAIN1,2;
1Emotional Brain Inst., Nathan Kline Inst. For Psychiatric Res., Orangeburg, NY; 2Ctr. for Neural Sci., New York Univ., New York, NY |
| Abstract: |
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Pavlovian conditioned stimuli (CSs) play an important role in the reinforcement and motivation of instrumental active avoidance (AA). Threatening Pavlovian CSs can also invigorate ongoing AA responding (Pavlovian-instrumental transfer or PIT). The neural circuits mediating Pavlovian-instrumental interactions are poorly understood, although lesion studies suggest that lateral, basal and central amygdala nuclei (Choi et al, 2010; Lázaro-Muñoz et al, 2010), as well as infralimbic prefrontal cortex (Moscarello & LeDoux, 2013), make key contributions. We recently completed an extensive analysis of brain c-Fos expression in good vs. poor avoiders following an AA test. In addition to the brain regions listed above, this analysis identified medial amygdala (ME) as a potentially important region for mediating competition between Pavlovian reactions and instrumental actions. ME is known to contribute to innate defensive responding and social behaviors, but its contribution to aversive Pavlovian-instrumental interactions is unknown. We evaluated the effect of electrolytic ME lesions on Pavlovian conditioning, Sidman two-way AA conditioning (shuttling) and aversive PIT in adult, male rats. Mild footshocks served as the unconditioned stimulus in all conditioning phases. Pretraining ME lesions had no effect on AA but selectively impaired Pavlovian responses in the AA context; conditioned freezing and 22 kHz ultrasonic vocalizations during AA training were sharply reduced compared to sham-operated controls. ME lesions also blocked the expression of aversive PIT. Interestingly, ME lesions failed to affect Pavlovian context- or cue-elicited freezing when assessed outside of the AA chamber. This latter finding differentiates ME from central amygdala, as central amygdala lesions abolish Pavlovian freezing inside and outside of the AA context. Taken together, these results suggest that ME is not required for Pavlovian or AA conditioning, but plays a selective role in mediating aversive Pavlovian-instrumental interactions.
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| Support: |
Sevier Laboratories |
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