The Journal of Neuroscience, June 15, 2001, 21(12):4400-4407
Maturation of Extinction Behavior in Infant Rats:
Large-Scale Regional Interactions with Medial Prefrontal Cortex,
Orbitofrontal Cortex, and Anterior Cingulate Cortex
Hemanth P.
Nair,
Jason D.
Berndt,
Douglas
Barrett, and
F.
Gonzalez-Lima
Institute for Neuroscience and Department of Psychology, University
of Texas at Austin, Austin, Texas 78712
The ability to express a behavior during the postnatal period may
be related to developmental changes in the recruitment of particular
neural systems. Here, we show that developmental changes in the
functional interactions involving three cortical regions (the medial
prefrontal cortex, orbitofrontal cortex, and anterior cingulate cortex)
are associated with maturation of extinction behavior in infant rats.
Postnatal day 17 (P17) and P12 pups were trained in a straight-alley
runway on an alternating schedule of reward and nonreward [patterned
single alternation (PSA)] or on a pseudorandom schedule of partial
reinforcement (PRF); the pups were then injected with
fluorodeoxyglucose (FDG) and shifted to continuous nonreward
(extinction). Handled control groups exposed to the same
training environment but not trained on a particular schedule were
included. Among P17 pups, extinction proceeded faster in PSA pups
relative to PRF pups. No differences were found between P12 groups. FDG
uptake, an index of acute changes in functional activity, was
quantified in the three cortical regions and 27 other brain regions of
interest. A multivariate covariance analysis, seed partial least
squares, revealed that functional relationships involving the
three cortical regions and large-scale systems of regions throughout
the rostrocaudal extent of the brain changed with training in P17 pups.
The cortical regions were primarily uncoupled in the younger group. The
data suggest that functional maturation of the frontal cortical regions
and their interactions with other brain systems are related to the
maturational shift in behavior.
Key words:
brain imaging; frontal cortex; covariance; extinction; development; rat
Copyright © 2001 Society for Neuroscience 0270-6474/01/21124400-08$05.00/0