Extracellular matrix and development of lamination in the dorsal lateral geniculate nucleus in the tree shrew ( Tupaia belangeri )

This study investigated the organization of the dorsal lateral geniculate nucleus (LGN) of the tree shrew (Tupaia glis) using both microelectrode recording and anatomical techniques. The tree shrew LGN contains approximately 100,000 cells, of which 20% are in layers 2 and 6. These two layers receive input from the ipsilateral eye. The topography of the tree shrew LGN was delineated by taking systematic penetrations through the structure. Examination of the organization of the LGN laminae showed the following: in layer 1 (the lamina next to the optic tract) a mixture of on-center, off-center and on-off center cells was found; the majority of these cells responded transiently to visual stimuli and they had slightly longer conduction latencies than did cells in the other laminae. On-center and off-center cells in laminae 2-6 were sharply segregated: layers 2, 3, and 4 contained off-center cells and layers 5 and 6 contained on-center cells. Most of the cells in laminae 2-6 responded in a sustained manner to visual stimuli. These results suggest that one function of the LGN lamina is to group cells into various classes. Such grouping has now been shown to occur partially or completely for 1) eye of origin, 2) cell types characterized as on-center and off-center, and 3) cell types characterized as producing transient and sustained responses. The nature and degree of laminar specificity, however, varies considerably from species to species.

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Laminar organization and ultrastructure of GABA-immunoreactive neurons and processes in the dorsal lateral geniculate nucleus of the tree shrew (Tupaia belangeri)

Visual Neuroscience ◽

10.1017/s0952523800001462 ◽

1988 ◽

Vol 1 (2) ◽

pp. 189-204 ◽

Cited By ~ 15

Author(s):

Robert N. Holdefer ◽

Thomas T. Norton ◽

Ranney Mize R.

Keyword(s):

Lateral Geniculate Nucleus ◽

Functional Organization ◽

Tree Shrew ◽

Visual Signals ◽

Dorsal Lateral Geniculate Nucleus ◽

Gamma Aminobutyric Acid ◽

Cross Sectional ◽

Axon Terminals ◽

Tupaia Belangeri ◽

Lateral Geniculate

AbstractThe distribution and ultrastructure of neurons and neuropil labeled by an antiserum to gamma-aminobutyric acid (GABA) were examined in the lateral geniculate nucleus (LGN) of the tree shrew (Tupaia belangeri). The LGN of this species segregates center type and cell class into three distinct pairs of laminae: a medial pair (laminae 1 and 2) containing ON-center cells, a more lateral pair (4, 5) containing OFF-center cells, and 2 laminae (3, 6) containing W-like cells. The relationship between this laminar segregation and the distribution of GABA immunoreactivity was investigated in the present study. GABA-immunoreactive neurons and neuropil were present in all six of the laminae. However, both the density of labeled cells (adjusted for neuronal density across laminae) and the density of labeled neuropil showed a medial-to-lateral gradient. The adjusted density of labeled cells was higher laterally than medially, and the density of labeled neuropil was significantly greater in the more lateral OFF-center laminae and W-like laminae than in the medial two ON-center laminae. Thus, inhibitory, GABAergic influences may modulate to different degrees the visual signals in the ON, OFF, and W pathways. Labeled cells had a mean cross-sectional area (107 μm2) approximately one-half that of unlabeled cells (216 μm2). They constitute 16–34% of the neurons in the LGN. At the electron microscope level, three different kinds of labeled profile were observed. Vesicle containing profiles like the F2 profiles of cat were postsynaptic to retinal terminals and presynaptic to conventional dendrites. Fl axon terminals with dense clusters of vesicles were also labeled as were some myelinated axons. Another labeled profile, which we suggest should be called an F3 process, was a large dendrite of irregular caliber with punctate groups of vesicles near the synapse. Our results suggest that GABAergic circuitry is an important part of the functional organization in the LGN of the tree shrew.

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Decision letter for "Heterochrony of postnatal accumulation of non-phosphorylated heavy-chain neurofilament by neurons of the cat dorsal lateral geniculate nucleus"

10.1002/cne.25028/v1/decision1 ◽

2020 ◽

Keyword(s):

Lateral Geniculate Nucleus ◽

Heavy Chain ◽

Dorsal Lateral Geniculate Nucleus ◽

Lateral Geniculate ◽

Dorsal Lateral Geniculate

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