Physiology & Behavior, Vol. 38, pp. 629-640. Copyright i Pergamon Journals Ltd., 1986. Printed in the U.S.A.
Provided by Cognitive Sciences ePrint Archive
THE medial preoptic area (MPO), which lies immediately
rostral to the anterior hypothalamus, is the brain region that
is most strongly implicated in the control of maternal behav-
ior (see [40] for review). Although a unified theory of the role
of the MPO in maternal behavior has not yet emerged, its
involvement has been demonstrated in numerous studies.
The MPO appears to be important in the gradual induction of
maternal behavior produced by extensive exposure to stim-
uli emanating from rat pups, such as that produced in virgin
‘ rats by housing them with pups. It also appears to be the
locus at which steroid hormones act to intensify the effect of
exteroceptive stimuli to the point of inducing maternal be-
havior almost immediately upon exposure to pups, such as
that evident at delivery [15, 17, 19,20,24,38,39,41,44,61].
The lateral preoptic area, more specifically the fibers
coursing through it, may also be implicated in the control of
maternal behavior. ParasagittaI knife cuts placed between the
medial and lateral preoptic areas produce disruptions in ma-
ternal behavior that are similar to those produced by MFO
lesions; the lateral connections of the MPO appear to be
critical for maternal behavior produced by pup exposure
alone, as well as that facilitated by hormonal manipulations
[29-31, 39, 41, 42, 54, 57, 60].
Although many of the neuroanatomical sites from which
the MPO receives lateral afferent projections, and to which
the MPO sends lateral efferent projections, have been de-
scribed, the specific pathways critical for maternal behavior
have not yet been delineated. Studies on efferent projections
have shown that fibers travel laterally out of the MPO
through the lateral preoptic area and substantia.innominata
to the medial amygdala, laterally through the supraoptic
commissure of Meynert (located just above the optic tract)
into the amygdala, or dorsolaterally through the stria termi-
nalis to the medial amygdala. Descending axons travel later-
ally out of the MPO through the medial portion of the medial
forebrain bundle (MFB), through which they descend to
terminate in the median eminence, arcuate nucleus, medial
hypothalamus (paraventricular, dorsomedial, and ven-
tromedial nuclei), lateral hypothalamus, ventral premammil-
Iary and Supramammillary nuclei, central gray of the
'Current address: Department of Psychology. St. Andrews Presbyterian College, Laurinburg, NC 28352.
2Requests for reprints should be addressed to Mark B. Kristal, Department of Psychology, Park Hall, SUNY-Buffalo. Buffalo. NY 14260.
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