Distinct Sensory and Goal Related Signals Underlie the Gap Effect in the Superior Colliculus

2021 ◽  
Author(s):  
Robert A. Marino ◽  
Ron Levy ◽  
Douglas P. Munoz
Keyword(s):  
Superior Colliculus ◽  
Gap Effect

Saccadic Performance as a Function of the Presence and Disappearance of Auditory and Visual Fixation Stimuli

1999 ◽  
Vol 11 (2) ◽  
pp. 206-213 ◽  
Author(s):  
Tracy L. Taylor ◽  
Raymond M. Klein ◽  
Douglas P. Munoz
Keyword(s):  
Superior Colliculus ◽  
Human Subjects ◽  
Visual Stimuli ◽  
Visual Fixation ◽  
Gap Effect ◽  
Auditory Target ◽  
Auditory Stimuli ◽  
Noise Stimulus ◽  
Auditory Noise

Relative to when a fixated stimulus remains visible, saccadic latencies are facilitated when a fixated stimulus is extinguished simultaneously with or prior to the appearance of an eccentric auditory, visual, or combined visual-auditory target. In a study of nine human subjects, we determined whether such facilitation (the “gap effect”) occurs equivalently for the disappearance of fixated auditory stimuli and fixated visual stimuli. In the present study, a fixated auditory (noise) stimulus remained present (overlap) or else was extinguished simultaneously with (step) or 200 msec prior to (gap) the appearance of a visual, auditory (tone), or combined visual-auditory target 10° to the left or right of fixation. The results demonstrated equivalent facilitatory effects due to the disappearance of fixated auditory and visual stimuli and are consistent with the presumed role of the superior colliculus in the gap effect.

scholarly journals The role of the superior colliculus in saccade initiation: a study of express saccades and the gap effect

2000 ◽  
Vol 40 (20) ◽  
pp. 2763-2777 ◽  
Author(s):  
David Sparks ◽  
W.H. Rohrer ◽  
Yihong Zhang
Keyword(s):  
Superior Colliculus ◽  
Gap Effect ◽  
Express Saccades

The underrated role of the “move system” in determining saccade latency

1999 ◽  
Vol 22 (4) ◽  
pp. 681-682 ◽  
Author(s):  
Michael C. Dorris ◽  
Douglas P. Munoz
Keyword(s):  
Superior Colliculus ◽  
Target Location ◽  
Saccade Latency ◽  
Gap Effect ◽  
Target Specificity ◽  
Express Saccades ◽  
Latency Reduction ◽  
Extensive Training ◽  
Target Article

The Findlay & Walker target article emphasizes the role of the target-nonspecific “fixate” system while downplaying the role of the target-specific “move” system in determining saccade latency. We agree that disengagement of the fixate system is responsible for the target-nonspecific latency reduction associated with the gap effect. However, high target predictability and extensive training at a target location can also result in latency reductions, the culmination of this being express saccades. The target-specificity associated with the latter forms of latency reduction implicate a mechanism involving the move system. Recently discovered neurophysiological correlates underlying these behavioural phenomena reside in the superior colliculus.

Activity in the Primate Rostral Superior Colliculus during the “Gap Effect” for Pursuit and Saccades

2002 ◽  
Vol 956 (1) ◽  
pp. 409-413 ◽  
Author(s):  
RICHARD J. KRAUZLIS ◽  
NATALIE DILL ◽  
KRISTA KORNYLO
Keyword(s):  
Superior Colliculus ◽  
Gap Effect

A neural correlate for the gap effect on saccadic reaction times in monkey

1995 ◽  
Vol 73 (6) ◽  
pp. 2558-2562 ◽  
Author(s):  
M. C. Dorris ◽  
D. P. Munoz
Keyword(s):  
Superior Colliculus ◽  
Time Course ◽  
Discharge Rate ◽  
Reaction Times ◽  
Gap Effect ◽  
Saccade Target ◽  
Neural Correlate ◽  
Similar Time ◽  
Initial Fixation ◽  
Saccadic Reaction Times

1. The reduction in saccadic reaction time associated with the introduction of a period of darkness between the disappearance of an initial fixation point and the appearance of a new peripheral saccade target is known as the gap effect. Fixation cells in the rostral pole of the monkey superior colliculus have been implicated in the control of active visual fixation and suppressing saccadic eye movements. To determine whether specific variations of fixation cell discharge was correlated to the gap effect, we recorded the activity of fixation cells while a monkey generated visually guided saccades with various temporal gaps between the disappearance of the initial fixation point and the appearance of a peripheral saccade target. 2. The saccadic reaction times of the monkey were shortest with gap durations of 200-300 ms and increased with shorter or longer gap durations. The activity of fixation cells followed a similar time course, having a minimum discharge rate 200-300 ms into the gap, and increased activity at the time of target appearance with smaller or larger gap durations. 3. We propose that the activity of fixation cells in the monkey superior colliculus provide a neural correlate of the gap effect. The decrease in activity of fixation cells 200-300 ms into the gap weakens the powerful state of inhibition which they normally exert upon the saccade generating system, allowing targets to be acquired at shorter reaction times.

scholarly journals Control of Reflexive Saccades following Hemispherectomy

2011 ◽  
Vol 23 (6) ◽  
pp. 1368-1378 ◽  
Author(s):  
Patricia A. Reuter-Lorenz ◽  
Troy M. Herter ◽  
Daniel Guitton
Keyword(s):  
Superior Colliculus ◽  
Inhibitory Control ◽  
Intractable Epilepsy ◽  
Short Latency ◽  
Gap Effect ◽  
Express Saccades ◽  
Antisaccade Task ◽  
Intact Side ◽  
Reflexive Saccades ◽  
Saccade Generation

Individuals who have undergone hemispherectomy for treatment of intractable epilepsy offer a rare and valuable opportunity to examine the ability of a single cortical hemisphere to control oculomotor performance. We used peripheral auditory events to trigger saccades, thereby circumventing dense postsurgical hemianopia. In an antisaccade task, patients generated numerous unintended short-latency saccades toward contralesional auditory events, indicating pronounced limitations in the ability of a single hemicortex to exert normal inhibitory control over ipsilateral (i.e., contralesional) reflexive saccade generation. Despite reflexive errors, patients retained an ability to generate correct antisaccades in both directions. The prosaccade task revealed numerous contralesional express saccades, a robust contralesional gap effect, but the absence of both effects for ipsilesional saccades. These results indicate limits to the saccadic control capabilities following hemispherectomy: A single hemicortex can mediate antisaccades in both directions, but plasticity does not extend fully to the bilateral inhibition of reflexive saccades. We posit that these effects are due to altered control dynamics that reduce the responsivity of the superior colliculus on the intact side and facilitate the release of an auditory-evoked ocular grasp reflex into the blind hemifield that the intact hemicortex has difficulty suppressing.

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.

Reflexive or Not? Examining Attentional Orienting and the Gap Effect

2008 ◽  
Author(s):  
Kaitlin Laidlaw ◽  
Sara Stevens ◽  
Jim McAuliffe ◽  
Jay Pratt
Keyword(s):  
Gap Effect ◽  
Attentional Orienting

The Gap Effect for Eye and Hand Movements

1994 ◽  
Author(s):  
Jay Pratt ◽  
Heather Oonk ◽  
Harold Bekkering ◽  
Richard A. Abrams ◽  
Mark B. Law
Keyword(s):  
Gap Effect ◽  
Hand Movements
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