| Division of Developmental Psychobiology - NYSPI @ Columbia University |  |
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Formation and Influence of Early Social Relationships |
Dr.
Shair's interest is in determining how the early environment, pre- or
postnatal, contributes to ontogenetic course of the growing organism.
Much of his work has focused on the influence of the parent-infant interaction
on postnatal development. His most recent work has addressed the mechanisms
by which the earliest social bonds are formed (see Social potentiation,
below). While never ignoring the primary importance of behavior, Dr.
Shair also investigates the physiological mechanisms underlying behavior
in studies of the cardiovascular system, respiratory regulation, and
sleep/wake states. Other areas of research have included the impact
of early denervations, malnutrition, and genetic interactions with environmental
effects. Collaborations within the department have been with Dr. Hofer
(see Processes of attachment and regulation of development), Dr. Brunelli
(see Genetic basis of separation anxiety), and Dr. Myers (see Developmental
physiology and behavior). When mammalian infants are separated from their caretakers, most respond with a series of behaviors that include vocalization and increased activity. In rat pups, the vocal portion of the response has a frequency of 40-50 kHz. Thus, these cries have been called ultrasonic vocalizations (USV). USV are known to elicit and hasten retrieval of isolated pups by their dams. Maternal potentiation of USV represents an augmentation of the separation response caused by a recent social interaction. As originally described, when a pup isolated in a novel environment for 3min is then exposed briefly to maternal contact with an anesthetized dam, in the ensuing 3min isolation, the USV rate is greatly increased (potentiated). Contact with a group of litter mates or a pile of home cage shavings does not alter USV rate in a subsequent isolation. Contact with an adult male rat suppresses USV for several minutes thereafter. Adult males are known to be predators of infant rats. Maternal potentiation does not affect all aspects of the separation response, only the vocal behavior. Thus, it is not part of a generalized increase in arousal and ongoing studies investigate what factors regulate its occurrence. It has been shown that there are two forms of potentiation, active and passive, which have different ontogenetic patterns, sensory eliciting stimuli, and neurochemical controls. Active potentiation occurs after a brief interaction with an awake, unanesthetized dam; passive potentiation after a brief reunion with an anesthetized dam.
The results of studies on the effects of altered early experience raise
the possibility that USV potentiation is a marker for a social bond.
Pups reared with both dam and sire in the nest cage demonstrate equal
USV potentiation to either adult. Normally reared pups exposed to adult
males typically show a fear-related suppression of behavior that continues
even after the male is removed. Thus, some facet of early experience
with an adult male alters the pup's response to the male from fear-like
to distress-reducing. Our laboratory is investigating the mechanisms
for that altered reaction, with the hypothesis that the results will
inform us about how secondary attachments are formed. Similarly, studying
how 'paternal' potentiation develops will provide clues to the formation
of the primary relationship to the dam.
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