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Different cortical projections from three subdivisions of the rat lateral posterior thalamic nucleus: a single‐neuron tracing study with viral vectors
Author(s) -
Nakamura Hisashi,
Hioki Hiroyuki,
Furuta Takahiro,
Kaneko Takeshi
Publication year - 2015
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.12882
Subject(s) - neuroscience , neuron , visual cortex , thalamus , retinotopy , axon , retrograde tracing , axoplasmic transport , biology , nucleus
The lateral posterior thalamic nucleus ( LP ) is one of the components of the extrageniculate pathway in the rat visual system, and is cytoarchitecturally divided into three subdivisions – lateral (LPl), rostromedial (LPrm), and caudomedial (LPcm) portions. To clarify the differences in the dendritic fields and axonal arborisations among the three subdivisions, we applied a single‐neuron labeling technique with viral vectors to LP neurons. The proximal dendrites of LP l neurons were more numerous than those of LP rm and LP cm neurons, and LP rm neurons tended to have wider dendritic fields than LP l neurons. We then analysed the axonal arborisations of LP neurons by reconstructing the axon fibers in the cortex. The LP l, LP rm and LP cm were different from one another in terms of the projection targets – the main target cortical regions of LP l and LP rm neurons were the secondary and primary visual areas, whereas those of LP cm neurons were the postrhinal and temporal association areas. Furthermore, the principal target cortical layers of LP l neurons in the visual areas were middle layers, but that of LP rm neurons was layer 1. This indicates that LP l and LP rm neurons can be categorised into the core and matrix types of thalamic neurons, respectively, in the visual areas. In addition, LP l neurons formed multiple axonal clusters within the visual areas, whereas the fibers of LP rm neurons were widely and diffusely distributed. It is therefore presumed that these two types of neurons play different roles in visual information processing by dual thalamocortical innervation of the visual areas.