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Activating the infralimbic prefrontal cortex promotes the inhibition of appetitive Pavlovian conditioning following extinction

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Activating the infralimbic prefrontal cortex promotes the inhibition of appetitive Pavlovian conditioning following extinction

Lacroix, Franca (2016) Activating the infralimbic prefrontal cortex promotes the inhibition of appetitive Pavlovian conditioning following extinction. Masters thesis, Concordia University.

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Abstract

Objectives: There is conflicting evidence about the role of the infralimbic prefrontal cortex (IL-PFC) in the extinction of appetitive Pavlovian conditioning. Here, we tested the hypothesis that IL-PFC activity mediates the inhibition of conditioned behaviour following extinction, and predicted that augmenting IL-PFC activity would reduce sucrose-induced reinstatement and spontaneous recovery of Pavlovian conditioned sucrose-seeking.
Methods: Male, Long-Evans rats (Charles River) received bilateral cannulae or unilateral microinfusions of a viral vector coding for Channelrhodopsin-2 (ChR2) and enhanced yellow fluorescent protein (eYFP), or eYFP only, and optical fiber implantation targeting the IL-PFC. During Pavlovian conditioning, presentations of an auditory conditioned stimulus (CS; 10 s, 14 trials/session, VT-140 s) were paired with a 10% w/v sucrose solution (0.2 ml; 2.8 ml/session). The same procedure was repeated during extinction and test sessions, except that sucrose was omitted during CS trials. The effect of optically stimulating (473 nm, 5 ms, 20 Hz, 30 mW) IL-PFC neurons during CS trials in spontaneous recovery tests was assessed at 24 h after a single extinction session, and also 26 days later. In two separate groups of rats, the effect of enhancing IL-PFC activity using pre-session microinfusions of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA; 0 or 0.3 nmol/µl/side) or optical stimulation during CS trials on sucrose-induced reinstatement of sucrose-seeking behaviour was assessed. The ability of optical stimulation to induce Fos expression was also measured in separate animals.
Results: Optical stimulation of IL-PFC neurons reduced spontaneous recovery after a delay of 26 days, but not 24 h. Reinstatement was reduced by both intra-IL-PFC AMPA and by optical stimulation. Optical stimulation increased Fos expression in ChR2 expressing neurons compared to eYFP controls.
Conclusions: Our results show that the IL-PFC plays a key role in maintaining the inhibition of appetitive, Pavlovian conditioned behaviour following extinction.

Divisions:Concordia University > Faculty of Arts and Science > Psychology
Item Type:Thesis (Masters)
Authors:Lacroix, Franca
Institution:Concordia University
Degree Name:M.A.
Program:Psychology
Date:5 August 2016
Thesis Supervisor(s):Chaudhri, Nadia
ID Code:981531
Deposited By: FRANCA LACROIX
Deposited On:07 Nov 2016 20:15
Last Modified:18 Jan 2018 17:53
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