scholarly journals The superior colliculus and the steering of saccades toward a moving visual target

2017 ◽  
Author(s):  
Laurent Goffart ◽  
Aaron Cecala ◽  
Neeraj Gandhi
Keyword(s):  
Superior Colliculus ◽  
Firing Rate ◽  
Target Location ◽  
Residual Activity ◽  
Target Motion ◽  
Moving Target ◽  
Average Firing Rate ◽  
Active Population ◽  
The Future ◽  
Movement Field

ABSTRACTFollowing the suggestion that a command encoding the expected here-and-now target location feeds the oculomotor system during interceptive saccades, we tested whether this command originates in the deep superior colliculus (SC). Monkeys generated saccades to targets that were static or moving along the preferred axis, away from (outward) or toward a fixated target (inward) with a constant speed (20°/s). Vertical and horizontal motions were also tested. Extracellular activity of 57 saccade-related neurons was recorded in 3 monkeys. The movement field (MF) parameters (boundaries, center and firing rate) were estimated after spline fitting the relation between the saccade amplitude and the average firing rate of the motor burst. During radial motion, the inner MF boundary shifted in the same direction as the target motion for some neurons, not all. During vertical motion, both lower and upper boundaries were shifted upward during upward motion whereas the upper boundary only shifted during downward motions. For horizontal motions, the medial boundaries were not changed. The MF center was shifted only for outward motion. Regardless of the motion direction, the average firing rate was consistently reduced during interceptive saccades. Our study shows an involvement of the saccade-related burst of SC neurons in steering the gaze toward a moving target. When observed, the shifts of MF boundary in the direction of target motion correspond to commands related to antecedent target locations. The absence of shift in the opposite direction shows that SC activity does not issue predictive commands related to the future target location.SIGNIFICANCE STATEMENTBy comparing the movement field (MF) of saccade-related neurons between saccades toward static and moving targets, we show that the motor burst issued by neurons in the superior colliculus does not convey commands related to the future location of a moving target. During interceptive saccades, the active population consists of a continuum of neurons, ranging from cells exhibiting a shift in the center or boundary of their MF to cells which exhibit no change. The shifts correspond to residual activity related to the fact that the active population does not change as fast as the target in the visual field. By contrast, the absence of shift indicates commands related to the current target location, as if it were static.

scholarly journals The superior colliculus and the steering of saccades toward a moving visual target

2017 ◽  
Vol 118 (5) ◽  
pp. 2890-2901 ◽  
Author(s):  
Laurent Goffart ◽  
Aaron L. Cecala ◽  
Neeraj J. Gandhi
Keyword(s):  
Superior Colliculus ◽  
Firing Rate ◽  
Target Location ◽  
Oculomotor System ◽  
Moving Target ◽  
Motion Direction ◽  
Active Population ◽  
Spline Fitting ◽  
Current Location ◽  
Consistent Change

Following the suggestion that a command encoding current target location feeds the oculomotor system during interceptive saccades, we tested the involvement of the deep superior colliculus (dSC). Extracellular activity of 52 saccade-related neurons was recorded in three monkeys while they generated saccades to targets that were static or moving along the preferred axis, away from (outward) or toward (inward) a fixated target with a constant speed (20°/s). Vertical and horizontal motions were tested when possible. Movement field (MF) parameters (boundaries, preferred vector, and firing rate) were estimated after spline fitting of the relation between the average firing rate during the motor burst and saccade amplitude. During radial target motions, the inner MF boundary shifted in the motion direction for some, but not all, neurons. Likewise, for some neurons, the lower boundaries were shifted upward during upward motions and the upper boundaries downward during downward motions. No consistent change was observed during horizontal motions. For some neurons, the preferred vectors were also shifted in the motion direction for outward, upward, and “toward the midline” target motions. The shifts of boundary and preferred vector were not correlated. The burst firing rate was consistently reduced during interceptive saccades. Our study demonstrates an involvement of dSC neurons in steering the interceptive saccade. When observed, the shifts of boundary in the direction of target motion correspond to commands related to past target locations. The absence of shift in the opposite direction implies that dSC activity does not issue predictive commands related to future target location. NEW & NOTEWORTHY The deep superior colliculus is involved in steering the saccade toward the current location of a moving target. During interceptive saccades, the active population consists of a continuum of cells ranging from neurons issuing commands related to past locations of the target to neurons issuing commands related to its current location. The motor burst of collicular neurons does not contain commands related to the future location of a moving target.

scholarly journals The influence of temporal predictability on express visuomotor responses

2020 ◽  
Author(s):  
Samuele Contemori ◽  
Gerald E. Loeb ◽  
Brian D. Corneil ◽  
Guy Wallis ◽  
Timothy J. Carroll
Keyword(s):  
Superior Colliculus ◽  
Onset Time ◽  
Surface Emg ◽  
Stimulus Onset ◽  
Target Motion ◽  
Target Velocity ◽  
Moving Target ◽  
Visuomotor Transformations ◽  
Shoulder Muscles ◽  
Temporal Predictability

ABSTRACTVolitional visuomotor responses in humans are generally thought to manifest 100ms or more after stimulus onset. Under appropriate conditions, however, much faster target-directed responses can be produced at upper limb and neck muscles. These “express” responses have been termed stimulus-locked responses (SLRs) and are proposed to be modulated by visuomotor transformations performed subcortically via the superior colliculus. Unfortunately, for those interested in studying SLRs, these responses have proven difficult to detect consistently across individuals. The recent report of an effective paradigm for generating SLRs in 100% of participants appears to change this. The task required the interception of a moving target that emerged from behind a barrier at a time consistent with the target velocity. Here we aimed to reproduce the efficacy of this paradigm for eliciting SLRs and to test the hypothesis that its effectiveness derives from the predictability of target onset time as opposed to target motion per se. In one experiment, we recorded surface EMG from shoulder muscles as participants made reaches to intercept temporally predictable or unpredictable targets. Consistent with our hypothesis, predictably timed targets produced more frequent and stronger SLRs than unpredictably timed targets. In a second experiment, we compared different temporally predictable stimuli and observed that transiently presented targets produced larger and earlier SLRs than sustained moving targets. Our results suggest that target motion is not critical for facilitating the expression of an SLR and that timing predictability does not rely on extrapolation of a physically plausible motion trajectory. These findings provide support for a mechanism whereby an internal timer, probably located in cerebral cortex, primes the processing of both visual input and motor output within the superior colliculus to produce SLRs.

scholarly journals Role of the Primate Superior Colliculus in the Control of Head Movements

2007 ◽  
Vol 98 (4) ◽  
pp. 2022-2037 ◽  
Author(s):  
Mark M. G. Walton ◽  
Bernard Bechara ◽  
Neeraj J. Gandhi
Keyword(s):  
Superior Colliculus ◽  
Firing Rate ◽  
Head Movements ◽  
Neural Basis ◽  
Average Firing Rate ◽  
Gaze Shifts ◽  
Burst Neurons ◽  
The Gaze ◽  
Head Displacement ◽  
Elevated Frequency

One important behavioral role for head movements is to assist in the redirection of gaze. However, primates also frequently make head movements that do not involve changes in the line of sight. Virtually nothing is known about the neural basis of these head-only movements. In the present study, single-unit extracellular activity was recorded from the superior colliculus while monkeys performed behavioral tasks that permit the temporal dissociation of gaze shifts and head movements. We sought to determine whether superior colliculus contains neurons that modulate their activity in association with head movements in the absence of gaze shifts and whether classic gaze-related burst neurons also discharge for head-only movements. For 26% of the neurons in our sample, significant changes in average firing rate could be attributed to head-only movements. Most of these increased their firing rate immediately prior to the onset of a head movement and continued to discharge at elevated frequency until the offset of the movement. Others discharged at a tonic rate when the head was stable and decreased their activity, or paused, during head movements. For many putative head cells, average firing rate was found to be predictive of head displacement. Some neurons exhibited significant changes in activity associated with gaze, eye-only, and head-only movements, although none of the gaze-related burst neurons significantly modulated its activity in association with head-only movements. These results suggest the possibility that the superior colliculus plays a role in the control of head movements independent of gaze shifts.

scholarly journals Discharge of Saccade-Related Superior Colliculus Neurons During Saccades Accompanied by Vergence

2003 ◽  
Vol 90 (2) ◽  
pp. 1124-1139 ◽  
Author(s):  
Mark M. G. Walton ◽  
Lawrence E. Mays
Keyword(s):  
Superior Colliculus ◽  
Firing Rate ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Spike Density ◽  
Level Of Activity ◽  
Saccade Velocity ◽  
Movement Field ◽  
A Cell ◽  
Superior Colliculus Neurons

It has long been believed that the superior colliculus (SC) is involved in the production of saccades but plays no role in the generation of vergence eye movements. However, results from several recent studies suggest that it may be worthwhile to examine the role of the SC in saccade-vergence interactions. Specifically, the available literature suggests two questions: do saccade-related neurons in SC have three-dimensional movement fields and is the slowing of saccades by vergence attributable, in part, to changes in the level of activity in SC? Single-unit data were recorded from 51 saccade-related neurons in rhesus monkey SC during saccades without vergence, saccades accompanied by convergence, and saccades accompanied by divergence. Most cells (78% for convergence, 86% for divergence) showed a significant reduction in peak spike density when the saccade was accompanied by vergence. A minority of cells (16% for convergence, 2% for divergence) increased their firing rate for saccades accompanied by vergence. Three cells were found that discharged in association with saccades, vergence, and the combination of the two. There were no cells that exhibited the pattern of discharge that would be expected of a cell tuned for saccades with divergence. Thus the present results do not support the hypothesis that saccade-related SC neurons are, as a rule, tuned in three dimensions. Small, but significant, differences in firing rate were often found for saccades without vergence at near and far distances. Approximately half of the cells showed a significant relationship between spike activity and saccade velocity, but the correlations tended to be very weak. This suggests that the decreased neuronal activity of SC neurons has only a limited effect on saccade velocity. For some cells, the movement field shifted for saccades with vergence. These shifts were highly variable from one cell to another.

scholarly journals Models for the Extrapolation of Target Motion for Manual Interception

2009 ◽  
Vol 102 (3) ◽  
pp. 1491-1502 ◽  
Author(s):  
John F. Soechting ◽  
John Z. Juveli ◽  
Hrishikesh M. Rao
Keyword(s):  
Target Location ◽  
Target Motion ◽  
Target Velocity ◽  
Finger Movement ◽  
Moving Target ◽  
Initial Direction ◽  
Target Speed ◽  
On Line ◽  
Finger Motion ◽  
Target Move

Intercepting a moving target requires a prediction of the target's future motion. This extrapolation could be achieved using sensed parameters of the target motion, e.g., its position and velocity. However, the accuracy of the prediction would be improved if subjects were also able to incorporate the statistical properties of the target's motion, accumulated as they watched the target move. The present experiments were designed to test for this possibility. Subjects intercepted a target moving on the screen of a computer monitor by sliding their extended finger along the monitor's surface. Along any of the six possible target paths, target speed could be governed by one of three possible rules: constant speed, a power law relation between speed and curvature, or the trajectory resulting from a sum of sinusoids. A go signal was given to initiate interception and was always presented when the target had the same speed, irrespective of the law of motion. The dependence of the initial direction of finger motion on the target's law of motion was examined. This direction did not depend on the speed profile of the target, contrary to the hypothesis. However, finger direction could be well predicted by assuming that target location was extrapolated using target velocity and that the amount of extrapolation depended on the distance from the finger to the target. Subsequent analysis showed that the same model of target motion was also used for on-line, visually mediated corrections of finger movement when the motion was initially misdirected.

Effects of Local Nicotinic Activation of the Superior Colliculus on Saccades in Monkeys

2005 ◽  
Vol 93 (1) ◽  
pp. 519-534 ◽  
Author(s):  
Masayuki Watanabe ◽  
Yasushi Kobayashi ◽  
Yuka Inoue ◽  
Tadashi Isa
Keyword(s):  
Superior Colliculus ◽  
Reaction Times ◽  
Low Frequency ◽  
Visually Guided ◽  
Population Activity ◽  
Affected Area ◽  
Movement Field ◽  
Neural Interactions ◽  
Restricted Region

To examine the role of competitive and cooperative neural interactions within the intermediate layer of superior colliculus (SC), we elevated the basal SC neuronal activity by locally injecting a cholinergic agonist nicotine and analyzed its effects on saccade performance. After microinjection, spontaneous saccades were directed toward the movement field of neurons at the injection site (affected area). For visually guided saccades, reaction times were decreased when targets were presented close to the affected area. However, when visual targets were presented remote from the affected area, reaction times were not increased regardless of the rostrocaudal level of the injection sites. The endpoints of visually guided saccades were biased toward the affected area when targets were presented close to the affected area. After this endpoint effect diminished, the trajectories of visually guided saccades remained modestly curved toward the affected area. Compared with the effects on endpoints, the effects on reaction times were more localized to the targets close to the affected area. These results are consistent with a model that saccades are triggered by the activities of neurons within a restricted region, and the endpoints and trajectories of the saccades are determined by the widespread population activity in the SC. However, because increased reaction times were not observed for saccades toward targets remote from the affected area, inhibitory interactions in the SC may not be strong enough to shape the spatial distribution of the low-frequency preparatory activities in the SC.

The Wandering Eye: An Eye Tracking Approach to Mind Wandering

2018 ◽  
Author(s):  
Jessica Schnabel
Keyword(s):  
Eye Tracking ◽  
Task Performance ◽  
Target Location ◽  
External Environment ◽  
Mind Wandering ◽  
Individual Characteristics ◽  
Moving Target ◽  
Tracking Data ◽  
The Mind

Mind wandering, or “daydreaming,” is a shift in the contents of a thought away from a task and/or event in the external environment, to self-generated thoughts and feelings. This research seeks to test the reliability of eye tracking as an objective of measure mind wandering using the Wandering Eye Paradigm, as well as examine the relationships between mind wandering and individual characteristics. Fifty participants will be recruited for two appointments a day apart, on each day on each day completing two eye tracking sessions following a moving target. In this task, participants will be instructed to press the space bar if they feel they are mind wandering, and then answer three questions about their episode content. Questionnaires measuring mind wandering, procrastination, mindfulness, creativity and personality (in particular conscientiousness) will be completed between eye tracking sessions. By comparing the eye tracking data in the period prior to the spacebar press we can determine quantifiable indicators of the onset and duration of mind wandering episodes by analyzing gaze location in relation to the target location. It has been hypothesized that severity of task performance failures (losing track of the target) should correlate with the “depth” of the mind wandering episode content. Additionally, we expect the frequency of mind wandering episodes to correlate with individual characteristics, and that these measures will be consistent across trials. This research would provide a novel objective way to identify and measure mind wandering, and would help further advance the understanding of its behavioral and subjective dimensions.

Evidence That the Superior Colliculus Participates in the Feedback Control of Saccadic Eye Movements

2002 ◽  
Vol 87 (2) ◽  
pp. 679-695 ◽  
Author(s):  
Robijanto Soetedjo ◽  
Chris R. S. Kaneko ◽  
Albert F. Fuchs
Keyword(s):  
Superior Colliculus ◽  
Firing Rate ◽  
Saccadic Eye Movements ◽  
Burst Duration ◽  
Saccadic Amplitude ◽  
Optimal Vector ◽  
Deceleration Phase ◽  
Acceleration And Deceleration ◽  
Motor Error ◽  
Saccade Duration

There is general agreement that saccades are guided to their targets by means of a motor error signal, which is produced by a local feedback circuit that calculates the difference between desired saccadic amplitude and an internal copy of actual saccadic amplitude. Although the superior colliculus (SC) is thought to provide the desired saccadic amplitude signal, it is unclear whether the SC resides in the feedback loop. To test this possibility, we injected muscimol into the brain stem region containing omnipause neurons (OPNs) to slow saccades and then determined whether the firing of neurons at different sites in the SC was altered. In 14 experiments, we produced saccadic slowing while simultaneously recording the activity of a single SC neuron. Eleven of the 14 neurons were saccade-related burst neurons (SRBNs), which discharged their most vigorous burst for saccades with an optimal amplitude and direction (optimal vector). The optimal directions for the 11 SRBNs ranged from nearly horizontal to nearly vertical, with optimal amplitudes between 4 and 17°. Although muscimol injections into the OPN region produced little change in the optimal vector, they did increase mean saccade duration by 25 to 192.8% and decrease mean saccade peak velocity by 20.5 to 69.8%. For optimal vector saccades, both the acceleration and deceleration phases increased in duration. However, during 10 of 14 experiments, the duration of deceleration increased as fast as or faster than that of acceleration as saccade duration increased, indicating that most of the increase in duration occurred during the deceleration phase. SRBNs in the SC changed their burst duration and firing rate concomitantly with changes in saccadic duration and velocity, respectively. All SRBNs showed a robust increase in burst duration as saccadic duration increased. Five of 11 SRBNs also exhibited a decrease in burst peak firing rate as saccadic velocity decreased. On average across the neurons, the number of spikes in the burst was constant. There was no consistent change in the discharge of the three SC neurons that did not exhibit bursts with saccades. Our data show that the SC receives feedback from downstream saccade-related neurons about the ongoing saccades. However, the changes in SC firing produced in our study do not suggest that the feedback is involved with producing motor error. Instead, the feedback seems to be involved with regulating the duration of the discharge of SRBNs so that the desired saccadic amplitude signal remains present throughout the saccade.

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