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Superior olivary complex organization and cytoarchitecture may be correlated with function and catarrhine primate phylogeny.

Hilbig H, Beil B, Hilbig H, Call J, Bidmon HJ - Brain Struct Funct (2009)

Bottom Line: As recency of common ancestry with human beings increases, primates have improved low-frequency sensitivity and reduced sensitivity to higher frequencies.Here, Nissl-stained sections of the superior olivary complex of man (Homo sapiens), bonobo (Pan paniscus), chimpanzee (Pan troglodytes), gorilla (Gorilla gorilla), orangutan (Pongo pygmaeus), gibbon (Hylobates lar), and macaque (Macaca fascicularis) were compared to reveal differences and coincidences.From chimpanzees to humans, the size of the LSO decreased, and the MNTB as a compact nucleus nearly disappears.

View Article: PubMed Central - PubMed

Affiliation: Institute of Anatomy, Leipzig University, Liebigstr. 13, 04103, Leipzig, Germany. hilbigh@medizin.uni-leipzig.de

ABSTRACT
In the mammalian auditory system, the medial nucleus of the trapezoid body and the lateral superior olive (MNTB-LSO system) contribute to binaural intensity processing and lateralization. Localization precision varies with the sound frequencies. As recency of common ancestry with human beings increases, primates have improved low-frequency sensitivity and reduced sensitivity to higher frequencies. The medial part of the MNTB is devoted to higher frequency processing. Thus, its high-frequency-dependent function is nearly lost in humans and its role in binaural processing as part of the contralateral pathway to the LSO remains questionable. Here, Nissl-stained sections of the superior olivary complex of man (Homo sapiens), bonobo (Pan paniscus), chimpanzee (Pan troglodytes), gorilla (Gorilla gorilla), orangutan (Pongo pygmaeus), gibbon (Hylobates lar), and macaque (Macaca fascicularis) were compared to reveal differences and coincidences. From chimpanzees to humans, the size of the LSO decreased, and the MNTB as a compact nucleus nearly disappears. From chimpanzees to humans, the LSO/MNTB ratio increases dramatically too, whereas the LSO/MSO ratio remains 1.1; a finding that probably corresponds to the phylogenetic proximity between the species.

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Dorsal aspects of 3-D reconstructions of the SOC (MNTB red, MSO black, LSO blue) revealing the lateral distance of the MNTB from the median line of the auditory brainstem (line at left) and the rostro-caudal extension of the SOC
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Fig4: Dorsal aspects of 3-D reconstructions of the SOC (MNTB red, MSO black, LSO blue) revealing the lateral distance of the MNTB from the median line of the auditory brainstem (line at left) and the rostro-caudal extension of the SOC

Mentions: Within the Hominidae (i.e. the African apes: gorillas, chimpanzees, and bonobos; and humans), there is a successive loss of the MNTB from gorilla to man in correlation with decreasing extensions of the LSO. The LSO decreased more slowly than the MNTB, which was almost lost (Figs.  2, 3, 4, 5, 6, 7; Table 1), since only very few widely dispersed neurons were detectable.Fig. 3


Superior olivary complex organization and cytoarchitecture may be correlated with function and catarrhine primate phylogeny.

Hilbig H, Beil B, Hilbig H, Call J, Bidmon HJ - Brain Struct Funct (2009)

Dorsal aspects of 3-D reconstructions of the SOC (MNTB red, MSO black, LSO blue) revealing the lateral distance of the MNTB from the median line of the auditory brainstem (line at left) and the rostro-caudal extension of the SOC
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2737112&req=5

Fig4: Dorsal aspects of 3-D reconstructions of the SOC (MNTB red, MSO black, LSO blue) revealing the lateral distance of the MNTB from the median line of the auditory brainstem (line at left) and the rostro-caudal extension of the SOC
Mentions: Within the Hominidae (i.e. the African apes: gorillas, chimpanzees, and bonobos; and humans), there is a successive loss of the MNTB from gorilla to man in correlation with decreasing extensions of the LSO. The LSO decreased more slowly than the MNTB, which was almost lost (Figs.  2, 3, 4, 5, 6, 7; Table 1), since only very few widely dispersed neurons were detectable.Fig. 3

Bottom Line: As recency of common ancestry with human beings increases, primates have improved low-frequency sensitivity and reduced sensitivity to higher frequencies.Here, Nissl-stained sections of the superior olivary complex of man (Homo sapiens), bonobo (Pan paniscus), chimpanzee (Pan troglodytes), gorilla (Gorilla gorilla), orangutan (Pongo pygmaeus), gibbon (Hylobates lar), and macaque (Macaca fascicularis) were compared to reveal differences and coincidences.From chimpanzees to humans, the size of the LSO decreased, and the MNTB as a compact nucleus nearly disappears.

View Article: PubMed Central - PubMed

Affiliation: Institute of Anatomy, Leipzig University, Liebigstr. 13, 04103, Leipzig, Germany. hilbigh@medizin.uni-leipzig.de

ABSTRACT
In the mammalian auditory system, the medial nucleus of the trapezoid body and the lateral superior olive (MNTB-LSO system) contribute to binaural intensity processing and lateralization. Localization precision varies with the sound frequencies. As recency of common ancestry with human beings increases, primates have improved low-frequency sensitivity and reduced sensitivity to higher frequencies. The medial part of the MNTB is devoted to higher frequency processing. Thus, its high-frequency-dependent function is nearly lost in humans and its role in binaural processing as part of the contralateral pathway to the LSO remains questionable. Here, Nissl-stained sections of the superior olivary complex of man (Homo sapiens), bonobo (Pan paniscus), chimpanzee (Pan troglodytes), gorilla (Gorilla gorilla), orangutan (Pongo pygmaeus), gibbon (Hylobates lar), and macaque (Macaca fascicularis) were compared to reveal differences and coincidences. From chimpanzees to humans, the size of the LSO decreased, and the MNTB as a compact nucleus nearly disappears. From chimpanzees to humans, the LSO/MNTB ratio increases dramatically too, whereas the LSO/MSO ratio remains 1.1; a finding that probably corresponds to the phylogenetic proximity between the species.

Show MeSH
Related in: MedlinePlus