Afferent and efferent connections of the ventrolateral tegmental area in the rat

Abstract

The present study examined the organization of afferent and efferent connections of the rat ventrolateral tegmental area (VLTg) by employing the retrograde and anterograde axonal transport of Fluorogold and Phaseolus vulgaris-leucoagglutinin, respectively. Our interest was focused on whether the anatomical connections of the VLTg would provide evidence as to the involvement of this reticular area in audiomotor behavior. Our retrograde experiments revealed that minor inputs to the VLTg arise in various telencephalic structures, including the cerebral cortex. Stronger projections originate in the lateral preoptic area, the zona incerta, the nucleus of the posterior commissure and some other thalamic areas, the lateral substantia nigra, the deep layers of the superior colliculus, the dorsal and lateral central gray, the deep mesencephalic nucleus, the paralemniscal zone, the intercollicular nucleus, the external cortex of the inferior colliculus, the oral and caudal pontine reticular nucleus, the deep cerebellar nuclei, the gigantocellular and lateral paragigantocellular reticular nuclei, the prepositus hypoglossal nucleus, the spinal trigeminal nuclei, and the intermediate layers of the spinal cord. Most importantly, we disclosed strong auditory afferents arising in the dorsal and ventral cochlear nuclei and in the cochlear root nucleus. The efferent projections of the VLTg were found to be less widespread. Telencephalic structures do not receive any input from the VLTg. Moderate projections were seen to diencephalic reticular areas, the zona incerta, the nucleus of the posterior commissure, and to various other thalamic areas. The major VLTg projections terminate in the deep layers of the superior colliculus, the deep mesencephalic nucleus, the intercollicular nucleus and external cortex of the inferior colliculus, the oral and caudal pontine reticular nucleus, the gigantocellular and lateral paragigantocellular reticular nuclei, and in the medial column of the facial nucleus. From our data, we conclude that the VLTg might play a role in sensorimotor behavior.

Neuroanatomical Projections of the Species-Specific Tyrosine Hydroxylase-Immunoreactive Cells of the Male Prairie Vole Bed Nucleus of the Stria Terminalis and Medial Amygdala

“…For example, the MPO has connections with both the cell bodies and targets of the extra-hypothalamic argininevasopressin system [Anderson and Shen, 1980;Chiba and Murata, 1985;Grove, 1988a, b;Finn et al, 1993;Staiger and Nurnberger, 1991;Coolen and Wood, 1998;Varoqueaux and Poulain, 1999;Wood and Swann, 2005], and through its connections with the ACB or VTA [Groenewegen and Russchen, 1984;Chiba and Murata, 1985;Fahrbach et al, 1986] may alter communication among multiple catecholaminergic networks. In addition, we found TH-ir input from the VTA to the BSTpr and MEApd, which has not been reported in other rodents [Herbert et al, 1997;Coolen and Wood, 1998;Wood and Swann, 2005], and may link motivational information with olfactory information to promote social interactions in this highly gregarious species.…”

KCNQ4, a K + channel mutated in a form of dominant deafness, is expressed in the inner ear and the central auditory pathway

“…4C). Not all neurons expressing KCNQ4 are involved in processing auditory information, but it is interesting that also the ventral tegmental area receives significant input from the cochlear nucleus (33), that some cells in the substantia nigra are connected to the inferior colliculus (34,35) as are cells from several nuclei of the raphe and the locus coeruleus (36,37). Neurons in these regions are also labeled for KCNQ4 (Fig.…”

Integrating Optogenetic and Pharmacological Approaches to Study Neural Circuit Function: Current Applications and Future Directions

“…One caveat to the optogenetic projection targeting techniques arises because afferent fibers exiting a structure are frequently bundled together, and stimulating terminals in one region may also stimulate fibers of passage that may also be expressing opsins. For example, DA afferents from the VTA projecting to the PFC travel through the NAc (Beckstead et al, 1979;Herbert et al, 1997), and stimulation of DA terminals in the NAc will likely also stimulate PFC-projecting fibers. Another limitation to this method is the possibility of back-propagating action potentials.…”