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Author Mellott, Jeffrey Garrett ♦ Schofield, Brett R. ♦ Motts, Susan Diane
Source Directory of Open Access Journals (DOAJ)
Content type Text
Publisher Frontiers Media S.A.
File Format HTM / HTML
Date Created 2014-09-16
Copyright Year ©2014
Language English
Subject Domain (in LCC) RC321-571 ♦ QM1-695
Subject Keyword Biological psychiatry ♦ Neurosciences ♦ Human anatomy ♦ Medial geniculate nucleus ♦ Binaural ♦ Internal medicine ♦ Lateral lemniscus ♦ Medicine ♦ Neuropsychiatry ♦ Parallel pathways ♦ Science ♦ Brain evolution ♦ Reticular Formation
Abstract Experiments in several species have identified direct projections to the medial geniculate nucleus (MG) from cells in subcollicular auditory nuclei. Moreover, many cochlear nucleus cells that project to the MG send collateral projections to the inferior colliculus (IC) (Schofield et al., 2014, Front. Neuroanat. 8:10). We conducted 3 experiments to characterize projections to the MG from the superior olivary and the lateral lemniscal regions in guinea pigs. For experiment 1, we made large injections of retrograde tracer into the MG. Labeled cells were most numerous in the superior paraolivary nucleus, ventral nucleus of the trapezoid body, lateral superior olivary nucleus, ventral nucleus of the lateral lemniscus, ventrolateral tegmental nucleus, paralemniscal region and sagulum. Additional sources include other periolivary nuclei and the medial superior olivary nucleus. The projections are bilateral with an ipsilateral dominance (66%). For experiment 2, we injected tracer into individual MG subdivisions. The results show that the subcollicular projections terminate primarily in the medial MG, with the dorsal MG a secondary target. The variety of projecting nuclei suggest a range of functions, including monaural and binaural aspects of hearing. These direct projections could provide the thalamus with some of the earliest (i.e., fastest) information regarding acoustic stimuli.For experiment 3, we made large injections of different retrograde tracers into one MG and the homolateral IC to identify cells that project to both targets. Such cells were numerous and distributed across many of the nuclei listed above, mostly ipsilateral to the injections. The prominence of the collateral projections suggests that the same information is delivered to both the IC and the MG, or perhaps that a common signal is being delivered as a preparatory indicator or temporal reference point. The results are discussed from functional and evolutionary perspectives.
ISSN 16625129
Age Range 18 to 22 years ♦ above 22 year
Educational Use Research
Education Level UG and PG ♦ Career/Technical Study
Learning Resource Type Article
Publisher Date 2014-07-01
e-ISSN 16625129
Journal Frontiers in Neuroanatomy
Volume Number 8

Source: Directory of Open Access Journals (DOAJ)