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MECHANISMS REGULATING
AUDITORY COMMUNICATION IN PRIMATES
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John D. Newman, PhD, Head, Unit on
Developmental Neuroethology Michelle Becker, PhD, Postdoctoral
Fellow Deborah Bernhards, BS,
Biological Technician Maria Rakhovskaya, BA, BS, Technical Training Fellow |
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Understanding the mechanisms
underlying the expression and perception of auditory communication in
nonhuman primates provides important insights into the neural systems that
mediate nonverbal auditory communication in humans. Our research focuses on
the changes in vocal behavior that are associated with maturation and social
experience as well as on the neural systems implicated in these developmental
changes. Infants are highly vocal during brief periods of separation from
their caregiver, and we take advantage of this behavior to collect and analyze
temporal and acoustic patterns at different ages and under different social
environments. We identify and study in detail the neural substrates that
mediate vocal production in order to understand the genetic and experiential
influences that guide the neural circuitry underlying such behavior. Crying
is a compelling stimulus to caregivers, and we study the acoustic attributes
that promote positive caregiver responses to crying infants. Of particular
interest is the nature of the mechanisms underlying cry perception, which we
study by using a variety of methodologies. Functional imaging of
brain areas responsive to infant cries in humans Newman; in
collaboration with Kose, Lorberbaum Following two earlier studies
with fewer subjects and an unfamiliar cry as the stimulus, the present study
involved 40 mothers and a cry sequence from their own infant, recorded in the
home when the infant was five to eight weeks of age. We computed differences
between brain oxygen level changes in reaction to own infant or unfamiliar
infant and mapped them onto MRI scans from each subject. Areas with increased
activity in response to own infant included the medial preoptic area,
midbrain, thalamus, ventral striatum, septum, amygdala, cingulate cortex,
mesial prefrontal area, insula, and temporal pole. Subsequently, we recruited
10 fathers of the same set of infants for the fMRI study. In striking
contrast to the mothers, fathers showed very limited differential brain
activation to the cry stimuli, mainly in neocortex and cerebellum (also
activated in the mothers). The results suggest that fathers and mothers use
different brain circuitry in processing infant cry sounds. Newman JD. Infant cry and
colic: what lies beneath. Behav Brain
Sci, in press. Vocal responses to isolation calls in squirrel monkeys Newman, Becker,
Bernhards, Rakhovskaya; in collaboration with Soltis Squirrel monkeys are highly
social and exhibit a rich vocal repertoire; their brains have undergone
extensive study in the context of brain-behavior relationships. The species
is of additional interest in the context of our research in that the monkeys
continue to make vocalizations acoustically and functionally similar to their
infant cries (“isolation calls”) into adulthood. In this study,
we examined vocal responses of listeners hearing the cries of distant
animals. We tested groups of two species for possible differential responses
to calls from their own species. We observed no significant differences in
response to a stimulus call from the same or another species. The results
confirm our anecdotal observations and suggest that squirrel monkeys may
exhibit a type of altruistic or empathic vocal behavior. Newman, JD. Motherese by any
other name: mother-infant communication in non-hominin mammals. Behav Brain Sci, in press. Newman, JD. The primate
isolation call: a comparison with precocial birds and nonprimate mammals. In:
Newman, JD. Vocal
communication and the triune brain. Physiol
Behav 2003;79:495-502. Immunocytochemical
studies of primate brains Newman, Becker,
Bernhards, Rakhovskaya Studies of the distribution of
the protein products of gene expression have not been extensively reported in
primates, particularly in the species that we study. We are therefore
conducting two studies in this area. In the first, we are studying the
distribution of Fos (c-fos gene
product) in squirrel monkeys and marmosets after separating the individual
for 20 minutes to encourage production of isolation calls. To date, we have
processed and examined brain sections from six adult squirrel monkeys and
eight adult marmosets. Results from the most robust vocalizers of both
species show extensive label (marking the presence of Fos) in the anterior
cingulate gyrus, preoptic area, hypothalamus, and periaqueductal gray of the
midbrain, regions all implicated in vocal production in other studies. In
addition, we found label in auditory cortex (activated as a result of
auditory feedback from the vocalizing animal) and parts of the hippocampus.
In the second study, we are examining the distribution of three
calcium-binding proteins, calbindin, calretinin, and parvalbumin, with results
pending. Lorberbaum JP, Newman JD, Horwitz AR, Dubno JR, Lydiard RB, Hamner MB, Bohning DE, George MS. A potential role for thalamocingulate circuitry in human maternal behavior. Biol Psychiatry 2002;51:431-445. COLLABORATORS Samet Kose, MD, Medical Jeffrey
Lorberbaum, MD, Medical Joseph Soltis,
PhD, Disney’s Animal Kingdom, For further
information, contact newmanj@mail.nih.gov |
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