Convergent projections of different limbic vocalization areas in the squirrel monkey

Summary The projections of four different sub-areas within the anterior limbic cortex, all yielding vocalization when electrically stimulated, were compared in six squirrel monkeys by the autoradiographic tracing technique.Areas of convergence of the projections from all four vocalization loci were the cortex within the anterior cingulate sulcus, a zone following the inferior thalamic peduncle from the central amygdaloid nucleus through the substantia innominata into the midline thalamus, a second zone following the periventricular fibre system from the anterior diencephalon to the caudal midbrain and dorsolateral pontine tegmentum and, finally, the tail of the caudate nucleus. Except for the latter, all of these brain structures produce vocalization when electrically stimulated. The call types elicitable from these projection areas are sometimes different from those elicitable from the anterior limbic cortex. It is hypothesized that the anterior limbic cortex controls vocalization directly, independently of the specific motivational state underlying it.Abbreviations to Figures 2 and 3 a nucl. accumbens - aa area anterior amygdalae - ab nucl. basalis accessorius amygdalae - ac nucl. centralis amygdalae - an nucl. anterior thalami - anl ansa lenticularis - aq substantia grisea centralis - ba nucl. basalis amygdalae - bc brachium conjunctivum - ca nucl. caudatus - cc corpus callosum - cent centrum medianum - ci capsula interna - cl claustrum - coa commissura anterior - coi colliculus inferior - csp tractus cortico-spinalis - gc gyrus cinguli - gl corpus geniculatum laterale - gm corpus geniculatum mediale - gp globus pallidus - gpm griseum periventriculare mesencephali - gr gyrus rectus - gts gyrus temporalis superior - h campus Foreli - ha nucl. habenularis - hip hippocampus - hy hypothalamus - lap nucl. lateralis posterior thalami - lem lemniscus medialis - m corpus mamillare - md nucl. medialis dorsalis thalami - os nucl. olivaris superior - p pedunculus cerebri - po griseum pontis - pro area praeoptica - pu nucl. pulvinaris thalami - put putamen - re formatio reticularis - s septum - sm stria medullaris - sn substantia nigra - st stria terminalis - tp cortex temporalis anterior - va nucl. ventralis anterior thalami - vpl nucl. ventralis postero-lateralis th. - vpm nucl. ventralis postero-medialis th. - III N. oculomotoriusThe study was carried out in accordance with the Guiding Principles in the Care and Use of Primates approved by the Council of the American Physiological Society.