Ventral Medial Prefrontal Cortex and
Emotional Perseveration: The Memory
for Prior Extinction Training
Maria A. Morgan, Jay Schulkin, Joseph E. LeDoux
Behavioural Brain Research 146 (2003) 121-130. Online [Available] elsevier.com/locate/bbr.
Summarized by Shannon Juedes
How might mPFCv be involved in regulating
• An inhibitory association develops in
competition with the excitatory association
developed during acquisition.
• IL cortex is the crucial portion of mPFCv
involved in extinction.
• mPFCv is involved in utilizing the inhibitory
association that develops during extinction.
– Inhibitory is less stable and is dependent on the
extinction context for expression.
• mPFCvs may influence contextual conditioning
and extinction by helping to integrate
information about the internal environment
wit the external environment.
How did this study come about?
• Lesioned rats exhibited emotional
• Concluded that mPFCv plays a role in
regulating fear inhibition during the
• Medial prefrontal cortex is involved in
the extinction component of conditioned
• Morrow et al. – mPFCv lesions disrupt
extinction performance, whether lesions
were made prior to or following
• Quirk – The infralimbic cortex of the
mPFCv is important for the retention of
• Two objectives
1. To examine the impact of post-acquisition lesions
on the retention and extinction of fear responses
2. To examine the effectiveness of extinction by
determining the extent to which reacquisition of
fear responses is affected by prior extinction.
• Lesioned animals would express more fear
than controls during reacquisition, which
would indicate that prior extinction trials
were less effective in guiding their behavior.
• Male Sprague-Dawley rats
– Housed in pairs upon arrival for 9 days
– Unlimited assess to rat food and water
– 12-h light:12-h dark cycles
– 6 days later received 1 day context habituation and
2 days acquisition training
• Rats in cages for 20-55 min
• CS: sound
• US: shock
– Freezing response was the measure of conditioned
emotional responding (fear acquisition).
– Surgery day after
• 2 groups—mPFCv (prelimbic/infralimbic cortical regions) and
– 14-day recovery period
– Extinction trials
• 2 consecutive days of 5 s or fewer spent freezing
– 2-3min later ―reinstating US‖
• Ineffective in reinstating a CR to a CS for both control and
– Extinction trials day after
– Reacquisition training next day
• 4 groups
– Control-delay (6) and mPFCv-delay (8)
– Control-no-delay (7) and mPFC-no-delay (9)
– Reextinction trials to criterion
• When lesioned following acquisition training,
mPFCv-lesioned animals responded less to the
context than did controls.
• L animals extinguished their response at the
same rate as controls to the context.
• L animals responded significantly more than
control animals to both the context and CS
• L animals showed resistance to extinction
during reextinction relative to their own
performance during the initial extinction
• Changes in mPFCv may predispose one
to develop fear responses that are
difficult to extinguish or otherwise treat.
• Functional activity in the mPFC and
amygdala are inversely related.