title: A morphological analysis of thalamocortical axon fibers of rat posterior thalamic nuclei: a single neuron tracing study with viral vectors.
abstract: The rostral sector of the posterior thalamic nuclei (POm) is, together with the ventral posterior nuclei (VP), involved in somatosensory information processing in rodents. The POm receives inputs from the spinal cord and trigeminal nuclei and projects to the primary somatosensory (S1) cortex and other cortical areas. Although thalamocortical axons of single VP neurons are well known to innervate layer (L) 4 of the S1 cortex with distinct columnar organization, those of POm neurons have not been elucidated yet. In the present study, we investigated complete axonal and dendritic arborizations of single POm neurons in rats by visualizing the processes with Sindbis viruses expressing membrane-targeted fluorescent protein. When we divided the POm into anterior and posterior parts according to calbindin immunoreactivity, dendrites of posterior POm neurons were wider but less numerous than those of anterior neurons. More interestingly, axon fibers of anterior POm neurons were preferentially distributed in L5 of the S1 cortex, whereas those of posterior neurons were principally spread in L1 with wider and sparser arborization than those of anterior neurons. These results suggest that the POm is functionally segregated into anterior and posterior parts and that the 2 parts may play different roles in somatosensory information processing.
authors.affiliation: Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Sachi
authors.initials: S
authors.lastname: Ohno
authors.forename: Eriko
authors.initials: E
authors.lastname: Kuramoto
authors.forename: Takahiro
authors.initials: T
authors.lastname: Furuta
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Hioki
authors.forename: Yasuhiro R
authors.initials: YR
authors.lastname: Tanaka
authors.forename: Fumino
authors.initials: F
authors.lastname: Fujiyama
authors.forename: Takahiro
authors.initials: T
authors.lastname: Sonomura
authors.forename: Masanori
authors.initials: M
authors.lastname: Uemura
authors.forename: Kazuna
authors.initials: K
authors.lastname: Sugiyama
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kaneko
mesh_terms: D000818:Animals; D001369:Axons / Q000648:ultrastructure*; D002540:Cerebral Cortex / Q000648:ultrastructure*; D005822:Genetic Vectors / Q000235:genetics; D008297:Male; D009434:Neural Pathways / Q000648:ultrastructure*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012845:Sindbis Virus / Q000502:physiology; D013787:Thalamic Nuclei / Q000648:ultrastructure*; D014162:Transfection