An electrophysiological study of the visual projection to the superior colliculus of the rat

1966 ◽  
Vol 127 (4) ◽  
pp. 435-444 ◽  
Author(s):  
Robert Siminoff ◽  
Horst Otto Schwassmann ◽  
Lawrence Kruger
Keyword(s):  
Superior Colliculus ◽  
Electrophysiological Study ◽  
Visual Projection

Electrophysiological study of the posterior accessory optic tract

1960 ◽  
Vol 199 (3) ◽  
pp. 522-528 ◽  
Author(s):  
Duco Hamasaki ◽  
Elwin Marg
Keyword(s):  
Optic Nerve ◽  
Superior Colliculus ◽  
Electrophysiological Study ◽  
Optic Tract ◽  
Nerve Fibers ◽  
Medial Geniculate ◽  
Centrifugal Fiber ◽  
Ipsilateral Stimulation ◽  
Electrophysiological Methods ◽  
Stimulation Of

Electrophysiological methods were used to detect the presence of the posterior accessory optic tract—transpeduncular tract in the rabbit. Photic stimulation gave rise to mainly an ‘on’ response from the contralateral nucleus of the transpeduncular tract. Electrical stimulation of the optic nerve fibers evoked a response from this nucleus with a latency of 1–3 msec. A response could not be elicited from the nucleus of the transpeduncular tract, the lateral geniculate nucleus, or the superior colliculus by ipsilateral stimulation. Encéphale isolé preparations showed that the responses recorded under urethane anesthesia were not altered by the drug. The nucleus of the posterior accessory optic tract is situated between the optic nerve and the nucleus of the transpeduncular tract, and lies on the dorsolateral aspect of the midbrain between the superior colliculus and the medial geniculate nucleus. No centrifugal fiber responses have been found which originate from the nucleus of the transpeduncular tract and pass to the retina via the optic nerve.

Saccade-Related Spread of Activity Across Superior Colliculus May Arise From Asymmetry of Internal Connections

2006 ◽  
Vol 96 (2) ◽  
pp. 765-774 ◽  
Author(s):  
Hiroyuki Nakahara ◽  
Kenji Morita ◽  
Robert H. Wurtz ◽  
Lance M. Optican
Keyword(s):  
Superior Colliculus ◽  
Saccadic Eye Movements ◽  
Central Field ◽  
Connection Strength ◽  
Nonlinear Projection ◽  
Sensory Maps ◽  
Neuronal Connections ◽  
Visual Projection ◽  
The Brain ◽  
Global Inhibition

The superior colliculus (SC) receives a retinotopic projection of the contralateral visual field in which the representation of the central field is expanded with respect to the peripheral field. The visual projection forms a nonlinear, approximately logarithmic, map on the SC. Models of the SC commonly assume that the function defining the strength of neuronal connections within this map (the kernel) depends only on the distance between two neurons, and is thus isotropic and homogeneous. However, if the connection strength is based on the distance between two stimuli in sensory space, the kernel will be asymmetric because of the nonlinear projection onto the brain map. We show, using a model of the SC, that one consequence of these asymmetric intrinsic connections is that activity initiated at one point spreads across the map. We compare this simulated spread with the spread observed experimentally around the time of saccadic eye movements with respect to direction of spread, differing effects of local and global inhibition, and the consequences of localized inactivation on the SC map. Early studies suggested that the SC spread was caused by feedback of eye displacement during a saccade, but subsequent studies were inconsistent with this feedback hypothesis. In our new model, the spread is autonomous, resulting from intrinsic connections within the SC, and thus does not depend on eye movement feedback. Other sensory maps in the brain (e.g., visual cortex) are also nonlinear and our analysis suggests that the consequences of asymmetric connections in those areas should be considered.

Ultrastructure of developing visual cortical synapses in the cat superior colliculus

1991 ◽  
Vol 49 ◽  
pp. 156-157
Author(s):  
Caroline A. Miller ◽  
Laura L. Bruce
Keyword(s):  
Superior Colliculus ◽  
Phosphate Buffer ◽  
Receptive Fields ◽  
Visual Cortical Area ◽  
Cortical Synapses ◽  
Visual Cortical ◽  
And Function ◽  
Phosphate Buffered Saline ◽  
The Brain ◽  
Cat Superior Colliculus

The first visual cortical axons arrive in the cat superior colliculus by the time of birth. Adultlike receptive fields develop slowly over several weeks following birth. The developing cortical axons go through a sequence of changes before acquiring their adultlike morphology and function. To determine how these axons interact with neurons in the colliculus, cortico-collicular axons were labeled with biocytin (an anterograde neuronal tracer) and studied with electron microscopy.Deeply anesthetized animals received 200-500 nl injections of biocytin (Sigma; 5% in phosphate buffer) in the lateral suprasylvian visual cortical area. After a 24 hr survival time, the animals were deeply anesthetized and perfused with 0.9% phosphate buffered saline followed by fixation with a solution of 1.25% glutaraldehyde and 1.0% paraformaldehyde in 0.1M phosphate buffer. The brain was sectioned transversely on a vibratome at 50 μm. The tissue was processed immediately to visualize the biocytin.

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