Limited Spatial Spread Explains the Dependence of Visual Response Adaptation on Stimulus Size in Rat Superior Colliculus Neurons

Neuroscience ◽  
2020 ◽  
Vol 451 ◽  
pp. 60-78
Author(s):  
Gytis Baranauskas
Keyword(s):  
Superior Colliculus ◽  
Stimulus Size ◽  
Visual Response ◽  
Spatial Spread ◽  
Superior Colliculus Neurons

Dark rearing reveals the mechanism underlying stimulus size tuning of superior colliculus neurons

2006 ◽  
Vol 23 (5) ◽  
pp. 741-748 ◽  
Author(s):  
KHALEEL A. RAZAK ◽  
SARAH L. PALLAS
Keyword(s):  
Superior Colliculus ◽  
Visual Stimuli ◽  
Stimulus Size ◽  
Size Selectivity ◽  
Small Stimulus ◽  
Inhibitory Circuitry ◽  
Classical Receptive Field ◽  
Superior Colliculus Neurons ◽  
Retinal Afferents ◽  
Dark Rearing

Neurons in the superficial layers of the midbrain superior colliculus (SC) exhibit distinct tuning properties for visual stimuli, but, unlike neurons in the geniculocortical visual pathway, most respond best to visual stimuli that are smaller than the classical receptive field (RF). The mechanism underlying this size selectivity may depend on the number and pattern of feedforward retinal inputs and/or the balance between inhibition and excitation within the RF. We have previously shown that chronic blockade of NMDA receptors (NMDA-R), which increases the convergence of retinal afferents onto SC neurons, does not alter size selectivity in the SC. This suggests that the number of retinal inputs does not determine size selectivity. Here we show, using single unit extracellular recordings from the SC of normal hamsters, that size selectivity in neurons selective for small stimulus size is correlated with the strength of inhibition within the RF. We also show that dark rearing causes concomitant reductions in both inhibition and size selectivity. In addition, dark rearing increases the percentage of neurons non-selective for stimulus size. Finally, we show that chronic blockade of NMDA-R, a procedure that does not alter size tuning, also does not change the strength of inhibition within the RF. Taken together, these results argue that inhibition within the RF underlies selectivity for small stimulus size and that inhibition must be intact for size tuning to be preserved after developmental manipulations of activity. In addition, these results suggest that regulation of the balance between excitation and inhibition within the RF does not require NMDA-R activity but does depend on visual experience. These results suggest that developmental experience influences neural response properties through an alteration of inhibitory circuitry.

scholarly journals Symbolic Cue-Driven Activity in Superior Colliculus Neurons in a Peripheral Visual Choice Task

2006 ◽  
Vol 95 (6) ◽  
pp. 3585-3595 ◽  
Author(s):  
Kyoung-Min Lee ◽  
Edward L. Keller
Keyword(s):  
Superior Colliculus ◽  
Target Selection ◽  
Saccadic Eye Movements ◽  
Spatial Location ◽  
Choice Response ◽  
Visual Response ◽  
Superior Colliculus Neurons ◽  
Response Task ◽  
And Control

Recent evidence implicates the superior colliculus (SC) in cognitive processes, such as target selection and control of spatial attention, in addition to the execution of saccadic eye movements. We report here the presence of a cognitive response in some cells in the SC in a task that requires the long-term association of spatial location with an arbitrary color. In this study, using a visual choice response task, we demonstrate that visuomotor neurons in the SC were activated by the appearance of a central symbolic cue delivered outside of the visual response fields of the recorded neurons. This procedure ensures that cognitively generated activity in these SC cells is not confounded with modulation of activity from previous visual stimuli that appeared in the response field of the neurons. The experiments suggest that cognitive signals can activate SC cells by themselves instead of only being able to modulate activities already evoked by visual events. Furthermore, a substantial fraction of these cells accurately reflected cue-aligned target selection in advance of saccade initiation. Our results add further support to other studies that have demonstrated that internally generated signals exist in SC cells.

Dependence of Saccade-Related Activity in the Primate Superior Colliculus on Visual Target Presence

2001 ◽  
Vol 86 (2) ◽  
pp. 676-691 ◽  
Author(s):  
Jay A. Edelman ◽  
Michael E. Goldberg
Keyword(s):  
Superior Colliculus ◽  
Visual Target ◽  
Visual Response ◽  
Target Presence ◽  
Related Activity ◽  
Intermediate Layers ◽  
Saccade Velocity ◽  
Trial Basis ◽  
Visual Targets ◽  
Extracellular Activity

Neurons in the intermediate layers of the superior colliculus respond to visual targets and/or discharge immediately before and during saccades. These visual and motor responses have generally been considered independent, with the visual response dependent on the nature of the stimulus, and the saccade-related activity related to the attributes of the saccade, but not to how the saccade was elicited. In these experiments we asked whether saccade-related discharge in the superior colliculus depended on whether the saccade was directed to a visual target. We recorded extracellular activity of neurons in the intermediate layers of the superior colliculus of three rhesus monkeys during saccades in tasks in which we varied the presence or absence of a visual target and the temporal delays between the appearance and disappearance of a target and saccade initiation. Across our sample of neurons ( n = 64), discharge was highest when a saccade was made to a still-present visual target, regardless of whether the target had recently appeared or had been present for several hundred milliseconds. Discharge was intermediate when the target had recently disappeared and lowest when the target had never appeared during that trial. These results are consistent with the hypothesis that saccade-related discharge decreases as the time between the target disappearance and saccade initiation increases. Saccade velocity was also higher for saccades to visual targets, and correlated on a trial-by-trial basis with perisaccadic discharge for many neurons. However, discharge of many neurons was dependent on task but independent of saccade velocity, and across our sample of neurons, saccade velocity was higher for saccades made immediately after target appearance than would be predicted by discharge level. A tighter relationship was found between saccade precision and perisaccadic discharge. These findings suggest that just as the purpose of the saccadic system in primates is to drive the fovea to a visual target, presaccadic motor activity in the superior colliculus is most intense when such a target is actually present. This enhanced activity may, itself, contribute to the enhanced performance of the saccade system when the saccade is made to a real visual target.

Cross-modal synthesis in the midbrain depends on input from cortex

1994 ◽  
Vol 71 (1) ◽  
pp. 429-432 ◽  
Author(s):  
M. T. Wallace ◽  
B. E. Stein
Keyword(s):  
Superior Colliculus ◽  
Specific Effect ◽  
Association Cortex ◽  
Anterior Ectosylvian Sulcus ◽  
Modal Synthesis ◽  
Sensory Modalities ◽  
Superior Colliculus Neurons ◽  
Multisensory Information ◽  
Associative Functions ◽  
Unimodal Cues

1. The synthesis of information from different sensory modalities in the superior colliculus is an important precursor of attentive and orientation behavior. 2. This integration of multisensory information is critically dependent on inputs from a small area of association cortex, the anterior ectosylvian sulcus. Removal of these corticotectal influences can have a remarkably specific effect: it can eliminate multisensory integration in superior colliculus neurons while leaving their responses to unimodal cues intact. 3. Apparently, some of the associative functions of cortex are accomplished via its target neurons in the midbrain.

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