Influences of cortico-tectal and intertectal connections on visual responses in the cat's superior colliculus

1971 ◽  
Vol 12 (2) ◽  
Author(s):  
K.P. Hoffmann ◽  
M. Straschill
Keyword(s):  
Superior Colliculus ◽  
Visual Responses ◽  
Intertectal Connections

Visual responses of pulvinar and collicular neurons during eye movements of awake, trained macaques

1991 ◽  
Vol 66 (2) ◽  
pp. 485-496 ◽  
Author(s):  
D. L. Robinson ◽  
J. W. McClurkin ◽  
C. Kertzman ◽  
S. E. Petersen
Keyword(s):  
Eye Movements ◽  
Superior Colliculus ◽  
Visual Stimulation ◽  
Receptive Fields ◽  
Visual Responses ◽  
Stimulus Motion ◽  
Stimulus Movement ◽  
Pursuit Eye Movements ◽  
Extraretinal Signal ◽  
Wide Range

1. We recorded from single neurons in awake, trained rhesus monkeys in a lighted environment and compared responses to stimulus movement during periods of fixation with those to motion caused by saccadic or pursuit eye movements. Neurons in the inferior pulvinar (PI), lateral pulvinar (PL), and superior colliculus were tested. 2. Cells in PI and PL respond to stimulus movement over a wide range of speeds. Some of these cells do not respond to comparable stimulus motion, or discharge only weakly, when it is generated by saccadic or pursuit eye movements. Other neurons respond equivalently to both types of motion. Cells in the superficial layers of the superior colliculus have similar properties to those in PI and PL. 3. When tested in the dark to reduce visual stimulation from the background, cells in PI and PL still do not respond to motion generated by eye movements. Some of these cells have a suppression of activity after saccadic eye movements made in total darkness. These data suggest that an extraretinal signal suppresses responses to visual stimuli during eye movements. 4. The suppression of responses to stimuli during eye movements is not an absolute effect. Images brighter than 2.0 log units above background illumination evoke responses from cells in PI and PL. The suppression appears stronger in the superior colliculus than in PI and PL. 5. These experiments demonstrate that many cells in PI and PL have a suppression of their responses to stimuli that cross their receptive fields during eye movements. These cells are probably suppressed by an extraretinal signal. Comparable effects are present in the superficial layers of the superior colliculus. These properties in PI and PL may reflect the function of the ascending tectopulvinar system.

The functional influence of nicotinic cholinergic receptors on the visual responses of neurones in the superficial superior colliculus

2000 ◽  
Vol 17 (2) ◽  
pp. 283-289 ◽  
Author(s):  
K.E. BINNS ◽  
T.E. SALT
Keyword(s):  
Superior Colliculus ◽  
Nicotinic Receptors ◽  
Visual Stimulation ◽  
Glutamate Release ◽  
Drug Application ◽  
Receptor Activation ◽  
Visual Input ◽  
Visual Response ◽  
Visual Responses ◽  
Parabigeminal Nucleus

In the rat, the superficial gray layer (SGS) of the superior colliculus receives glutamatergic projections from the contralateral retina and from the visual cortex. A few fibers from the ipsilateral retina also directly innervate the SGS, but most of the ipsilateral visual input is provided by cholinergic afferents from the opposing parabigeminal nucleus (PBG). Thus, visual input carried by cholinergic afferents may have a functional influence on the responses of SGS neurones. When single neuronal extracellular recording and iontophoretic drug application were employed to examine this possibility, cholinergic agonists were found to depress responses to visual stimulation. Lobeline and 1-acetyl-4-methylpiperazine both depressed visually evoked activity and had a tendency to reduce the background firing rate of the neurones. Carbachol depressed the visual responses without any significant effect on the ongoing activity, while the muscarinic receptor selective agonist methacholine increased the background activity of the neurones and reduced their visual responses. Lobeline was chosen for further studies on the role of nicotinic receptors in SGS. Given that nicotinic receptors are associated with retinal terminals in SGS, and that the activation of presynaptic nicotinic receptors normally facilitates transmitter release (in this case glutamate release), the depressant effects of nicotinic agonists are intriguing. However, many retinal afferents contact inhibitory neurones in SGS; thus it is possible that the increase in glutamate release in turn facilitates the liberation of GABA which goes on to inhibit the visual responses. We therefore attempted to reverse the effects of lobeline with GABA receptor antagonists. The depressant effects of lobeline on the visual response could not be reversed by the GABAA antagonist bicuculline, but the GABAB antagonist CGP 35348 reduced the effects of lobeline. We hypothesize that cholinergic drive from the parabigeminal nucleus may activate presynaptic nicotinic receptors on retinal terminals, thereby facilitating the release of glutamate onto inhibitory neurones. Consequently GABA is released, activating GABAB receptors, and thus the ultimate effect of nicotinic receptor activation is to depress visual responses.

Target Selection for Saccadic Eye Movements: Direction-Selective Visual Responses in the Superior Colliculus

2001 ◽  
Vol 86 (5) ◽  
pp. 2527-2542 ◽  
Author(s):  
Gregory D. Horwitz ◽  
William T. Newsome
Keyword(s):  
Superior Colliculus ◽  
Eye Movement ◽  
Discrimination Task ◽  
Visual Motion ◽  
Target Selection ◽  
Small Population ◽  
Saccade Target ◽  
Visual Responses ◽  
Direction Discrimination ◽  
Deep Layers

We investigated the role of the superior colliculus (SC) in saccade target selection in rhesus monkeys who were trained to perform a direction-discrimination task. In this task, the monkey discriminated between opposed directions of visual motion and indicated its judgment by making a saccadic eye movement to one of two visual targets that were spatially aligned with the two possible directions of motion in the display. Thus the neural circuits that implement target selection in this task are likely to receive directionally selective visual inputs and be closely linked to the saccadic system. We therefore studied prelude neurons in the intermediate and deep layers of the SC that can discharge up to several seconds before an impending saccade, indicating a relatively high-level role in saccade planning. We used the direction-discrimination task to identify neurons whose prelude activity “predicted” the impending perceptual report several seconds before the animal actually executed the operant eye movement; these “choice predicting” cells comprised ∼30% of the neurons we encountered in the intermediate and deep layers of the SC. Surprisingly, about half of these prelude cells yielded direction-selective responses to our motion stimulus during a passive fixation task. In general, these neurons responded to motion stimuli in many locations around the visual field including the center of gaze where the visual discriminanda were positioned during the direction-discrimination task. Preferred directions generally pointed toward the location of the movement field of the SC neuron in accordance with the sensorimotor demands of the discrimination task. Control experiments indicate that the directional responses do not simply reflect covertly planned saccades. Our results indicate that a small population of SC prelude neurons exhibits properties appropriate for linking stimulus cues to saccade target selection in the context of a visual discrimination task.

Synchronization of visual responses in the superior colliculus of awake cats

Neuroreport ◽  
2001 ◽  
Vol 12 (1) ◽  
pp. 43-47 ◽  
Author(s):  
Michael Breche ◽  
Rainer Goebel ◽  
Wolf Singer ◽  
Andreas K. Engel
Keyword(s):  
Superior Colliculus ◽  
Visual Responses ◽  
Awake Cats

scholarly journals A neural locus for spatial-frequency specific saccadic suppression in visual-motor neurons of the primate superior colliculus

2017 ◽  
Vol 117 (4) ◽  
pp. 1657-1673 ◽  
Author(s):  
Chih-Yang Chen ◽  
Ziad M. Hafed
Keyword(s):  
Spatial Frequency ◽  
Superior Colliculus ◽  
Motor Neurons ◽  
Motor Command ◽  
Visual Sensitivity ◽  
Saccadic Suppression ◽  
Behavioral Measure ◽  
Visual Responses ◽  
Spatial Frequencies ◽  
Visual Motor

Saccades cause rapid retinal-image shifts that go perceptually unnoticed several times per second. The mechanisms for saccadic suppression have been controversial, in part because of sparse understanding of neural substrates. In this study we uncovered an unexpectedly specific neural locus for spatial frequency-specific saccadic suppression in the superior colliculus (SC). We first developed a sensitive behavioral measure of suppression in two macaque monkeys, demonstrating selectivity to low spatial frequencies similar to that observed in earlier behavioral studies. We then investigated visual responses in either purely visual SC neurons or anatomically deeper visual motor neurons, which are also involved in saccade generation commands. Surprisingly, visual motor neurons showed the strongest visual suppression, and the suppression was dependent on spatial frequency, as in behavior. Most importantly, suppression selectivity for spatial frequency in visual motor neurons was highly predictive of behavioral suppression effects in each individual animal, with our recorded population explaining up to ~74% of behavioral variance even on completely different experimental sessions. Visual SC neurons had mild suppression, which was unselective for spatial frequency and thus only explained up to ~48% of behavioral variance. In terms of spatial frequency-specific saccadic suppression, our results run contrary to predictions that may be associated with a hypothesized SC saccadic suppression mechanism, in which a motor command in the visual motor and motor neurons is first relayed to the more superficial purely visual neurons, to suppress them and to then potentially be fed back to cortex. Instead, an extraretinal modulatory signal mediating spatial-frequency-specific suppression may already be established in visual motor neurons. NEW & NOTEWORTHY Saccades, which repeatedly realign the line of sight, introduce spurious signals in retinal images that normally go unnoticed. In part, this happens because of perisaccadic suppression of visual sensitivity, which is known to depend on spatial frequency. We discovered that a specific subtype of superior colliculus (SC) neurons demonstrates spatial-frequency-dependent suppression. Curiously, it is the neurons that help mediate the saccadic command itself that exhibit such suppression, and not the purely visual ones.

scholarly journals What the Brain Stem Tells the Frontal Cortex. I. Oculomotor Signals Sent From Superior Colliculus to Frontal Eye Field Via Mediodorsal Thalamus

2004 ◽  
Vol 91 (3) ◽  
pp. 1381-1402 ◽  
Author(s):  
Marc A. Sommer ◽  
Robert H. Wurtz
Keyword(s):  
Superior Colliculus ◽  
Frontal Cortex ◽  
Brain Stem ◽  
Signal Transmission ◽  
Frontal Eye Field ◽  
Visual Responses ◽  
Mediodorsal Thalamus ◽  
Visual Activity ◽  
Eye Field ◽  
The Brain

Neuronal processing in cerebral cortex and signal transmission from cortex to brain stem have been studied extensively, but little is known about the numerous feedback pathways that ascend from brain stem to cortex. In this study, we characterized the signals conveyed through an ascending pathway coursing from the superior colliculus (SC) to the frontal eye field (FEF) via mediodorsal thalamus (MD). Using antidromic and orthodromic stimulation, we identified SC source neurons, MD relay neurons, and FEF recipient neurons of the pathway in Macaca mulatta. The monkeys performed oculomotor tasks, including delayed-saccade tasks, that permitted analysis of signals such as visual activity, delay activity, and presaccadic activity. We found that the SC sends all of these signals into the pathway with no output selectivity, i.e., the signals leaving the SC resembled those found generally within the SC. Visual activity arrived in FEF too late to contribute to short-latency visual responses there, and delay activity was largely filtered out in MD. Presaccadic activity, however, seemed critical because it traveled essentially unchanged from SC to FEF. Signal transmission in the pathway was fast (∼2 ms from SC to FEF) and topographically organized (SC neurons drove MD and FEF neurons having similarly eccentric visual and movement fields). Our analysis of identified neurons in one pathway from brain stem to frontal cortex thus demonstrates that multiple signals are sent from SC to FEF with presaccadic activity being prominent. We hypothesize that a major signal conveyed by the pathway is corollary discharge information about the vector of impending saccades.

scholarly journals Effect of methylphenidate on visual responses in the superior colliculus in the anaesthetised rat: Role of cortical activation

2017 ◽  
Vol 31 (10) ◽  
pp. 1347-1361 ◽  
Author(s):  
L Hetherington ◽  
EJ Dommett ◽  
AC Turner ◽  
TB Riley ◽  
JX Haensel ◽  
...  
Keyword(s):  
Superior Colliculus ◽  
Cortical Activation ◽  
Cortical Arousal ◽  
Visual Responses ◽  
Hyperactivity Disorder ◽  
Anaesthetised Rats ◽  
Anaesthetised Rat ◽  
Light Flashes ◽  
Stimulation Of

The mechanism of action of psychostimulant drugs in the treatment of Attention Deficit Hyperactivity Disorder is still largely unknown, although recent evidence suggests one possibility is that the drugs affect the superior colliculus (SC). We have previously demonstrated that systemically administered d-amphetamine attenuates/abolishes visual responses to wholefield light flashes in the superficial layers of the SC in anaesthetised rats, and the present study sought to extend this work to methylphenidate (MPH). Anaesthetised rats were administered MPH at a range of doses (or saline) and subjected to monocular wholefield light flashes at two intensities, juxta-threshold and super-threshold. In contrast to d-amphetamine, systemic MPH produced an enhancement of visual activity at both intensities. Methylphenidate was also found to produce activation of the cortical EEG in anaesthetised rats. Furthermore, cortical activation induced by electrical stimulation of the pons was found to enhance visual responses in superficial layers of the SC, and when MPH was paired with pontine-induced cortical activation, the response-enhancing effects of MPH were substantially attenuated. Taken together, the results suggest that the enhancement of visual responses in the superficial layers of the SC by MPH in the anaesthetised rat is an artefact of the drug’s interaction with cortical arousal.

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