Patterns of convergence and divergence of retinal and cortical synaptic terminals in the cat superior colliculus

1983 ◽  
Vol 51 (1) ◽  
Author(s):  
R.R. Mize
Keyword(s):  
Superior Colliculus ◽  
Synaptic Terminals ◽  
Convergence And Divergence ◽  
Cat Superior Colliculus

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.

scholarly journals What does a neuron learn from multisensory experience?

2015 ◽  
Vol 113 (3) ◽  
pp. 883-889 ◽  
Author(s):  
Jinghong Xu ◽  
Liping Yu ◽  
Terrence R. Stanford ◽  
Benjamin A. Rowland ◽  
Barry E. Stein
Keyword(s):  
Superior Colliculus ◽  
Early Life ◽  
Life Experience ◽  
Sensory Experience ◽  
Rearing Environment ◽  
Early Life Experience ◽  
Environmental Events ◽  
Cat Superior Colliculus ◽  
Maturational Process ◽  
Multisensory Experience

The brain's ability to integrate information from different senses is acquired only after extensive sensory experience. However, whether early life experience instantiates a general integrative capacity in multisensory neurons or one limited to the particular cross-modal stimulus combinations to which one has been exposed is not known. By selectively restricting either visual-nonvisual or auditory-nonauditory experience during the first few months of life, the present study found that trisensory neurons in cat superior colliculus (as well as their bisensory counterparts) became adapted to the cross-modal stimulus combinations specific to each rearing environment. Thus, even at maturity, trisensory neurons did not integrate all cross-modal stimulus combinations to which they were capable of responding, but only those that had been linked via experience to constitute a coherent spatiotemporal event. This selective maturational process determines which environmental events will become the most effective targets for superior colliculus-mediated shifts of attention and orientation.

Glutamate-like immunoreactivity in the cat superior colliculus and visual cortex: Further evidence that glutamate is the neurotransmitter of the corticocollicular pathway

1997 ◽  
Vol 14 (1) ◽  
pp. 27-37 ◽  
Author(s):  
Chang-Jin Jeon ◽  
Michael K. Hartman ◽  
R. Ranney Mize
Keyword(s):  
Visual Cortex ◽  
Superior Colliculus ◽  
Optical Density ◽  
Retrograde Tracing ◽  
Biochemical Studies ◽  
Deep Layers ◽  
Dense Band ◽  
Cat Superior Colliculus ◽  
Made In ◽  
In Cells

AbstractBiochemical studies provide evidence that the pathway from visual cortex to the superior colliculus (SC) utilizes glutamate as a neurotransmitter. In the present study, we have used immunocytochemistry, visual cortex lesions, and retrograde tracing to show directly by anatomical methods that glutamate or a closely related analog is contained in corticocollicular neurons and terminals. A monoclonal antibody directed against gamma-L-glutamyl-L-glutamate (gamma glu glu) was used to localize glutamate-like immunoreactivity in both the superior colliculus (SC) and visual cortex (VC). Unilateral lesions of areas 17–18 were made in four cats to determine if gamma glu glu labeling was reduced in SC by this lesion. WGA-HRP was injected into the SC of 10 additional cats in order to determine if corticocollicular neurons were also labeled by the gamma glu glu antibody. A distinctive dense band of gamma glu glu immunoreactivity was found within the deep superficial gray and upper optic layers of SC where many corticotectal axons are known to terminate. Both fibers and cells were labeled within the band. Immunoreactivity was also found in cells and fibers throughout the deep layers of SC. Measures of total immunoreactivity (i.e. optical density) in the dense band were made in sections from the SC both ipsilateral to and contralateral to the lesions of areas 17–18. A consistent reduction in optical density was found in both the neuropil and in cells within the dense band of the SC ipsilateral to the lesion. A large percentage of all corticocollicular neurons that were retrogradely labeled by WGA-HRP also contained gamma glu glu. These results provide further evidence that the corticocollicular pathway in mammals is glutamatergic. The results also suggest that visual cortex ablation alters synthesis or storage of glutamate within postsynaptic SC neurons, presumably as a result of partial deafferentation.

Mechanisms of Within- and Cross-Modality Suppression in the Superior Colliculus

1997 ◽  
Vol 78 (6) ◽  
pp. 2834-2847 ◽  
Author(s):  
Daniel C. Kadunce ◽  
J. William Vaughan ◽  
Mark T. Wallace ◽  
Gyorgy Benedek ◽  
Barry E. Stein
Keyword(s):  
Superior Colliculus ◽  
Visual Stimulus ◽  
Receptive Fields ◽  
Specific Interest ◽  
Input Channel ◽  
Modality Effects ◽  
Excitatory Stimulus ◽  
Modality Specificity ◽  
Cat Superior Colliculus ◽  
Close Temporal Proximity

Kadunce, Daniel C., J. William Vaughan, Mark T. Wallace, Gyorgy Benedek, and Barry E. Stein. Mechanisms of within- and cross-modality suppression in the superior colliculus. J. Neurophysiol. 78: 2834–2847, 1997. The present studies were initiated to explore the basis for the response suppression that occurs in cat superior colliculus (SC) neurons when two spatially disparate stimuli are presented simultaneously or in close temporal proximity to one another. Of specific interest was examining the possibility that suppressive regions border the receptive fields (RFs) of unimodal and multisensory SC neurons and, when activated, degrade the neuron's responses to excitatory stimuli. Both within- and cross-modality effects were examined. An example of the former is when a response to a visual stimulus within its RF is suppressed by a second visual stimulus outside the RF. An example of the latter is when the response to a visual stimulus within the visual RF is suppressed when a stimulus from a different modality (e.g., auditory) is presented outside its (i.e., auditory) RF. Suppressive regions were found bordering visual, auditory, and somatosensory RFs. Despite significant modality-specific differences in the incidence and effectiveness of these regions, they were generally quite potent regardless of the modality. In the vast majority (85%) of cases, responses to the excitatory stimulus were degraded by ≥50% by simultaneously stimulating the suppressive region. Contrary to expectations and previous speculations, the effects of activating these suppressive regions often were quite specific. Thus powerful within-modality suppression could be demonstrated in many multisensory neurons in which cross-modality suppression could not be generated. However, the converse was not true. If an extra-RF stimulus inhibited center responses to stimuli of a different modality, it also would suppress center responses to stimuli of its own modality. Thus when cross-modality suppression was demonstrated, it was always accompanied by within-modality suppression. These observations suggest that separate mechanisms underlie within- and cross-modality suppression in the SC. Because some modality-specific tectopetal structures contain neurons with suppressive regions bordering their RFs, the within-modality suppression observed in the SC simply may reflect interactions taking place at the level of one input channel. However, the presence of modality-specific suppression at the level of one input channel would have no effect on the excitation initiated via another input channel. Given the modality-specificity of tectopetal inputs, it appears that cross-modality interactions require the convergence of two or more modality-specific inputs onto the same SC neuron and that the expression of these interactions depends on the internal circuitry of the SC. This allows a cross-modality suppressive signal to be nonspecific and to degrade any and all of the neuron's excitatory inputs.

Sign in / Sign up

Export Citation Format

Share Document