Interlaminar connections of the superior colliculus in the tree shrew. I. The superficial gray layer

1993 ◽  
Vol 332 (2) ◽  
pp. 213-223 ◽  
Author(s):  
William C. Hall ◽  
Psyche Lee
Keyword(s):  
Superior Colliculus ◽  
Tree Shrew ◽  
Interlaminar Connections

Interlaminar connections of the superior colliculus in the tree shrew. III: The optic layer

1997 ◽  
Vol 14 (4) ◽  
pp. 647-661 ◽  
Author(s):  
William C. Hall ◽  
Psyche Lee
Keyword(s):  
Superior Colliculus ◽  
Tree Shrew ◽  
Brain Slices ◽  
Intermediate Layers ◽  
Interlaminar Connections ◽  
Dendritic Fields ◽  
Descending Projections ◽  
Apical Dendrites ◽  
The Brain ◽  
Selection Of

AbstractThese experiments were designed to test the idea that the optic layer in the tree shrew, Tupaia belongeri, is functionally distinct and provides a link between the visuosensory superficial and the premotor intermediate layers of the superior colliculus. First, cells in the optic layer were intracellularly labeled with biocytin in living brain slices. Compared to cells in the adjacent lower part of the superficial gray layer, which have apical dendrites that ascend toward the tectal surface, optic layer cells have dendritic fields that are restricted for the most part to the optic layer itself. The differences in dendritic-field location imply that superficial gray and optic layer cells have different patterns of input. The axons of optic layer cells terminate densely within the optic layer and, in addition, project in a horizontally restricted fashion to the overlying superficial gray and subjacent intermediate gray layers. This pattern also is different from the predominantly descending interlaminar projections of lower superficial gray layer cells. Next cells in the intermediate gray layer were labeled in order to examine the relationships between optic layer cells and these subjacent neurons that project from the superior colliculus to oculomotor centers of the brain stem Neurons in the upper part of the intermediate gray layer send apical dendrites into the optic layer and therefore can receive signals from the superficial gray layer either directly, from descending axons of lower superficial gray layer cells, or indirectly, through intervening optic layer cells. In contrast, lower intermediate gray layer cells have more radiate dendritic fields that are restricted to the intermediate gray layer. Thus, these lower cells must depend on descending projections from optic or upper intermediate gray layer cells for signals from the superficial gray layer. Together, these results support the idea that the optic layer is a distinct lamina that provides a link between the superficial and intermediate gray layers. They also are consistent with the traditional view that descending intracollicular projections play a role in the selection of visual targets for saccades.

Local Excitatory Circuits in the Intermediate Gray Layer of the Superior Colliculus

1999 ◽  
Vol 81 (3) ◽  
pp. 1424-1427 ◽  
Author(s):  
Diana L. Pettit ◽  
Matthew C. Helms ◽  
Psyche Lee ◽  
George J. Augustine ◽  
William C. Hall
Keyword(s):  
Superior Colliculus ◽  
Intermediate Layer ◽  
Tree Shrew ◽  
Patch Clamp Recording ◽  
Inward Current ◽  
Whole Cell Patch Clamp ◽  
Synaptic Interactions ◽  
Layer Neuron ◽  
Inward Currents ◽  
Synaptic Responses

Local excitatory circuits in the intermediate gray layer of the superior colliculus. We have used photostimulation and whole cell patch-clamp recording techniques to examine local synaptic interactions in slices from the superior colliculus of the tree shrew. Uncaging glutamate 10–75 μm from the somata of neurons in the intermediate gray layer elicited a long-lasting inward current, due to direct activation of glutamate receptors on these neurons, and brief inward currents caused by activation of presynaptic neurons. The synaptic responses occurred as individual currents or as clusters that lasted up to several hundred milliseconds. Excitatory synaptic responses, which reversed at membrane potentials near 0 mV, could be evoked by uncaging glutamate anywhere within 75 μm of an intermediate layer neuron. Our results indicate the presence of extensive local excitatory circuits in the intermediate layer of the superior colliculus and support the hypothesis that such intrinsic circuitry contributes to the development of presaccadic command bursts.

Interlaminar connections of tree shrew visual cortex

1979 ◽  
Vol 11 (2) ◽  
pp. 107-110 ◽  
Author(s):  
Albert B. Butler ◽  
John A. Jane ◽  
Paula Falk
Keyword(s):  
Visual Cortex ◽  
Tree Shrew ◽  
Interlaminar Connections

Superior Colliculus of the Tree Shrew: A Structural and Functional Subdivision into Superficial and Deep Layers

Science ◽  
1972 ◽  
Vol 177 (4047) ◽  
pp. 444-447 ◽  
Author(s):  
V. A. Casagrande ◽  
J. K. Harting ◽  
W. C. Hall ◽  
I. T. Diamond ◽  
G. F. Martin
Keyword(s):  
Superior Colliculus ◽  
Tree Shrew ◽  
Deep Layers
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