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Efferent projections of reuniens and rhomboid nuclei of the thalamus in the rat
Author(s) -
Vertes Robert P.,
Hoover Walter B.,
Do Valle Angela Cristina,
Sherman Alexandra,
Rodriguez J.J.
Publication year - 2006
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.21135
Subject(s) - neuroscience , subiculum , thalamus , limbic system , entorhinal cortex , biology , nucleus accumbens , anterograde tracing , hippocampus , anatomy , retrosplenial cortex , anterior olfactory nucleus , amygdala , efferent , basolateral amygdala , hippocampal formation , nucleus , olfactory tubercle , central nervous system , afferent , dentate gyrus
The nucleus reuniens (RE) is the largest of the midline nuclei of the thalamus and exerts strong excitatory actions on the hippocampus and medial prefrontal cortex. Although RE projections to the hippocampus have been well documented, no study using modern tracers has examined the totality of RE projections. With the anterograde anatomical tracer Phaseolus vulgaris leuccoagglutinin, we examined the efferent projections of RE as well as those of the rhomboid nucleus (RH) located dorsal to RE. Control injections were made in the central medial nucleus (CEM) of the thalamus. We showed that the output of RE is almost entirely directed to the hippocampus and “limbic” cortical structures. Specifically, RE projects strongly to the medial frontal polar, anterior piriform, medial and ventral orbital, anterior cingulate, prelimbic, infralimbic, insular, perirhinal, and entorhinal cortices as well as to CA1, dorsal and ventral subiculum, and parasubiculum of the hippocampus. RH distributes more widely than RE, that is, to several RE targets but also significantly to regions of motor, somatosensory, posterior parietal, retrosplenial, temporal, and occipital cortices; to nucleus accumbens; and to the basolateral nucleus of amygdala. The ventral midline thalamus is positioned to exert significant control over fairly widespread regions of the cortex (limbic, sensory, motor), hippocampus, dorsal and ventral striatum, and basal nuclei of the amygdala, possibly to coordinate limbic and sensorimotor functions. We suggest that RE/RH may represent an important conduit in the exchange of information between subcortical‐cortical and cortical‐cortical limbic structures potentially involved in the selection of appropriate responses to specific and changing sets of environmental conditions. J. Comp. Neurol. 499:768–796, 2006. © 2006 Wiley‐Liss, Inc.