Maturation of extinction behavior in infant rats: Large-scale regional interactions with medial prefrontal cortex, orbitofrontal cortex, and anteriorcingulate cortex
Hp. Nair et al., Maturation of extinction behavior in infant rats: Large-scale regional interactions with medial prefrontal cortex, orbitofrontal cortex, and anteriorcingulate cortex, J NEUROSC, 21(12), 2001, pp. 4400-4407
The ability to express a behavior during the postnatal period may be relate
d to developmental changes in the recruitment of particular neural systems.
Here, we show that developmental changes in the functional interactions in
volving three cortical regions (the medial prefrontal cortex, orbitofrontal
cortex, and anterior cingulate cortex) are associated with maturation of e
xtinction behavior in infant rats. Postnatal day 17 (P17) and P12 pups were
trained in a straight-alley runway on an alternating schedule of reward an
d nonreward [patterned single alternation (PSA)] or on a pseudorandom sched
ule of partial reinforcement (PRF); the pups were then injected with fluoro
deoxyglucose (FDG) and shifted to continuous nonreward (extinction). Handle
d control groups exposed to the same training environment but not trained o
n 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, r
evealed that functional relationships involving the three cortical regions
and large-scale systems of regions throughout the rostrocaudal extent of th
e brain changed with training in P17 pups. The cortical regions were primar
ily uncoupled in the younger group. The data suggest that functional matura
tion of the frontal cortical regions and their interactions with other brai
n systems are related to the maturational shift in behavior.