Amplitude and Direction of Saccadic Eye Movements Depend on the Synchronicity of Collicular Population Activity

2004 ◽  
Vol 92 (1) ◽  
pp. 424-432 ◽  
Author(s):  
Michael Brecht ◽  
Wolf Singer ◽  
Andreas K. Engel
Keyword(s):  
Eye Movements ◽  
Saccadic Eye Movements ◽  
Brain Structures ◽  
High Temporal Resolution ◽  
Temporal Relations ◽  
Neuronal Responses ◽  
Population Activity ◽  
Neuronal Processing ◽  
The Individual ◽  
Cat Superior Colliculus

Synchronization of neuronal discharges has been observed in numerous brain structures, but opinions diverge regarding its significance in neuronal processing. Here we investigate whether the motion vectors of saccadic eye movements evoked by electrical multisite stimulation of the cat superior colliculus (SC) are influenced by varying the degree of synchrony between the stimulus trains. With synchronous activation of SC sites, the vectors of the resulting saccades correspond approximately to the averages of the vectors of saccades evoked from each site alone. In contrast, when the pulses of trains applied to the different sites are temporally offset by as little as 5–10 ms, the vectors of the resulting saccades come close to the sum of the individual vectors. Thus saccade vectors depend not only on the site and amplitude of collicular activation but also on the precise temporal relations among the respective spike trains. These data indicate that networks within or downstream from the SC discriminate with high temporal resolution between synchronous and asynchronous population responses. This supports the hypothesis that information is encoded not only in the rate of neuronal responses but also in the precise temporal relations between discharges.

scholarly journals A test of spatial temporal decoding mechanisms in the superior colliculus

2012 ◽  
Vol 107 (9) ◽  
pp. 2442-2452 ◽  
Author(s):  
Husam A. Katnani ◽  
A. J. Van Opstal ◽  
Neeraj J. Gandhi
Keyword(s):  
Nervous System ◽  
Motor Control ◽  
Eye Movements ◽  
Superior Colliculus ◽  
Motor Behavior ◽  
Saccadic Eye Movements ◽  
Population Coding ◽  
Population Activity ◽  
Low Levels

Population coding is a ubiquitous principle in the nervous system for the proper control of motor behavior. A significant amount of research is dedicated to studying population activity in the superior colliculus (SC) to investigate the motor control of saccadic eye movements. Vector summation with saturation (VSS) has been proposed as a mechanism for how population activity in the SC can be decoded to generate saccades. Interestingly, the model produces different predictions when decoding two simultaneous populations at high vs. low levels of activity. We tested these predictions by generating two simultaneous populations in the SC with high or low levels of dual microstimulation. We also combined varying levels of stimulation with visually induced activity. We found that our results did not perfectly conform to the predictions of the VSS scheme and conclude that the simplest implementation of the model is incomplete. We propose that additional parameters to the model might account for the results of this investigation.

Effects of eye position on electrically evoked saccades: a theoretical note

1988 ◽  
Vol 1 (2) ◽  
pp. 239-244 ◽  
Author(s):  
James T. McIlwain
Keyword(s):  
Eye Movements ◽  
Internal Representation ◽  
Target Position ◽  
Saccadic Eye Movements ◽  
Brain Structures ◽  
Initial Position ◽  
Eye Position ◽  
Saccadic System ◽  
Early Processing ◽  
The Difference

AbstractThe trajectories of saccadic eye movements evoked electrically from many brain structures are dependent to some degree on the initial position of the eye. Under certain conditions, likely to occur in stimulation experiments, local feedback models of the saccadic system can yield eye movements which behave in this way. The models in question assume that an early processing stage adds an internal representation of eye position to retinal error to yield a signal representing target position with respect to the head. The saccadic system is driven by the difference between this signal and one representing the current position of the eye. Albano & Wurtz (1982) pointed out that lesions perturbing the computation of eye position with respect to the head can result in initial position dependence of visually evoked saccades. It is shown here that position-dependent saccades will also result if electrical stimulation evokes a signal equivalent to retinal error but fails to effect a complete addition of eye position to this signal. Also, when multiple or staircase saccades are produced, as during long stimulus trains, they will have identical directions but decrease progressively in amplitude by a factor related to the fraction of added eye position.

scholarly journals Computational specialization within the cortical eye movement system

2021 ◽  
Author(s):  
Tom R Marshall ◽  
Maria Ruesseler ◽  
Laurence T Hunt ◽  
Jill X O'Reilly
Keyword(s):  
Eye Movements ◽  
Parietal Cortex ◽  
Neural Circuits ◽  
Saccadic Eye Movements ◽  
Model System ◽  
High Temporal Resolution ◽  
Cortical Circuits ◽  
Primate Brain ◽  
Integrative Process ◽  
Movement System

Animals actively sample their environment through actions such as whisking, sniffing, and saccadic eye movements. Computationally, sensorimotor control may be viewed as an interplay between two processes that place different demands on their neural circuits: a rapid/competitive process for promptly selecting each upcoming action, and a slow/integrative process weighing the outcomes of multiple prior actions to build a model of the environment. Using saccadic eye movements as a model system, we addressed the hypothesis that frontal and parietal cortex are computationally specialized for these two functions. Through biophysical modelling, we predicted neural signatures of the competitive and integrative processes. We localized these signals to the frontal eye fields and intra-parietal cortex, respectively, using whole-brain, high-temporal-resolution neuroimaging (MEG). This frontal/parietal specialization can be linked to the differential characteristics of cortical circuits, and thus may represent a more general organizing principle of sensorimotor function in the primate brain.

Progression in Neuronal Processing for Saccadic Eye Movements From Parietal Cortex Area LIP to Superior Colliculus

2001 ◽  
Vol 85 (6) ◽  
pp. 2545-2562 ◽  
Author(s):  
Martin Paré ◽  
Robert H. Wurtz
Keyword(s):  
Eye Movements ◽  
Superior Colliculus ◽  
Parietal Cortex ◽  
Visual Stimulus ◽  
Saccadic Eye Movements ◽  
Processing Stage ◽  
Intermediate Layers ◽  
Cortex Area ◽  
Saccade Task ◽  
Neuronal Processing

Neurons in both the lateral intraparietal area (LIP) of the monkey parietal cortex and the intermediate layers of the superior colliculus (SC) are activated well in advance of the initiation of saccadic eye movements. To determine whether there is a progression in the covert processing for saccades from area LIP to SC, we systematically compared the discharge properties of LIP output neurons identified by antidromic activation with those of SC neurons collected from the same monkeys. First, we compared activity patterns during a delayed saccade task and found that LIP and SC neurons showed an extensive overlap in their responses to visual stimuli and in their sustained activity during the delay period. The saccade activity of LIP neurons was, however, remarkably weaker than that of SC neurons and never occurred without any preceding delay activity. Second, we assessed the dependence of LIP and SC activity on the presence of a visual stimulus by contrasting their activity in delayed saccade trials in which the presentation of the visual stimulus was either sustained (visual trials) or brief (memory trials). Both the delay and the presaccadic activity levels of the LIP neuronal sample significantly depended on the sustained presence of the visual stimulus, whereas those of the SC neuronal sample did not. Third, we examined how the LIP and SC delay activity relates to the future production of a saccade using a delayed GO/NOGO saccade task, in which a change in color of the fixation stimulus instructed the monkey either to make a saccade to a peripheral visual stimulus or to withhold its response and maintain fixation. The average delay activity of both LIP and SC neuronal samples significantly increased by the advance instruction to make a saccade, but LIP neurons were significantly less dependent on the response instruction than SC neurons, and only a minority of LIP neurons was significantly modulated. Thus despite some overlap in their discharge properties, the neurons in the SC intermediate layers showed a greater independence from sustained visual stimulation and a tighter relationship to the production of an impending saccade than the LIP neurons supplying inputs to the SC. Rather than representing the transmission of one processing stage in parietal cortex area LIP to a subsequent processing stage in SC, the differences in neuronal activity that we observed suggest instead a progressive evolution in the neuronal processing for saccades.

Activity Linked to Externally Cued Saccades in Single Units Recorded From Hippocampal, Parahippocampal, and Inferotemporal Areas of Macaques

1997 ◽  
Vol 78 (4) ◽  
pp. 2156-2163 ◽  
Author(s):  
Stanislaw Sobotka ◽  
Anna Nowicka ◽  
James L. Ringo
Keyword(s):  
Eye Movements ◽  
Visual Information ◽  
Visual Memory ◽  
Hippocampal Formation ◽  
Saccadic Eye Movements ◽  
Brain Structures ◽  
Single Units ◽  
Parahippocampal Gyrus ◽  
Visual Response ◽  
Extraretinal Signal

Sobotka, Stanislaw, Anna Nowicka, and James L. Ringo. Activity linked to externally cued saccades in single units recorded from hippocampal, parahippocampal, and inferotemporal areas of macaques. J. Neurophysiol. 78: 2156–2163, 1997. We studied whether target-directed, externally commanded saccadic eye movements (saccades) induced activity in single units in inferotemporal cortex, the hippocampal formation, and parahippocampal gyrus. The monkeys first were required to fix their gaze on a small cross presented to the left or right of center on the monitor screen. The cross was extinguished, and a random 600–1,000 ms thereafter, a small dot was presented for 200 ms. The dot was located either 10° above, below, right, or left of the position on which the fixation cross had been. The monkey made a saccadic eye movement to this dot (in darkness). The neuronal activity around this goal-directed saccade was analyzed. In addition, control conditions were imposed systematically in which similar dots were presented, but the monkey's task was to withhold the saccade. We recorded 290 units from two monkeys. From this group, 134 met two criteria, they did not show visual response in control trials and they had spike rates >2 Hz. These were analyzed further; 53% (71/134) showed modulation related to the target directed saccade, and 29% (39/134) showed saccadic modulation during spontaneous eye movements. These two groups were correlated only weakly. Of the units with significant saccadic modulation, 17% (12/71) showed significant directional selectivity, and 13% (9/71) showed significant position selectivity ( P < 0.01). At a lower criterion ( P < 0.05), almost one-half (33/71) showed one or the other spatial selectivity. Primates use saccades to acquire visual information. The appearance of strong saccadic modulation in brain structures previously characterized as mnemonic suggests the possibility that the mnemonic circuitry uses an extraretinal signal linked to saccades to control visual memory processes, e.g., synchronizing mnemonic processes to the pulsatile visual data inflow.

Dopamine neurons of the monkey midbrain: contingencies of responses to stimuli eliciting immediate behavioral reactions

1990 ◽  
Vol 63 (3) ◽  
pp. 607-624 ◽  
Author(s):  
W. Schultz ◽  
R. Romo
Keyword(s):  
Eye Movements ◽  
Saccadic Eye Movements ◽  
Contralateral Side ◽  
Dopamine Neurons ◽  
Direct Reaction ◽  
Neuronal Responses ◽  
Behavioral Reactions ◽  
Door Opening ◽  
Trigger Stimulus ◽  
Random Alternation

1. This study investigates the behavioral conditions in which dopamine (DA) neurons of substantia nigra and adjoining areas A8 and A10 respond with impulses to visual and auditory trigger stimuli eliciting immediate arm- and eye-movement reactions. 2. In a formal task, the rapid opening of the door of a small, food-containing box located at eye level ahead of the animal served as visible and audible trigger stimulus. Most DA neurons on the contralateral side responded to this stimulus with a short burst of impulses with median onset latency of 50 ms and duration of 90 ms (75% of 164 neurons). Similar responses were seen in a comparable fraction of DA neurons during ipsilateral task performance, suggesting that responses were not specific for the limb being used. 3. When the sensory components of the door opening stimulus were separated, DA neurons typically responded in a similar manner to the moving visual stimulus of the opening door, the low-intensity sliding noise of the opening door, and the 1-kHz sound of 90-92 dB intensity emitted from a distant source at the onset of door opening. Responses to each component alone were lower in magnitude than to all three together. 4. In a variation of the task, a neighboring, identical food box opened in random alternation with the other box but without permitting animals to reach out (asymmetric, direct-reaction go/no-go task). With each sensory component, DA neurons typically responded both to opening of go and no-go boxes. Responses were enhanced when stimuli elicited limb movements in go trials. 5. Monkeys reacted to door opening with target-directed saccadic eye movements in the majority of both go and no-go trials. Neuronal responses were equally present during the occasional absence of eye movements. Thus responses were not specific for the initiation of individual arm or eye movements. 6. Neuronal responses were absent when the same stimuli occurred outside of the behavioral task with target-direct arm and eye movements lacking. This shows that responses were not of purely sensory nature but were related to the capacity of the stimulus for eliciting behavioral reactions. 7. In a variation of the go/no-go task, an instruction light illuminated 2-3 s before door opening prepared the animal to perform the reaching movement on door opening or to refrain from moving (asymmetric, instruction-dependent go/no-go task).(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals A sensory memory to preserve visual representations across eye movements

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Amir Akbarian ◽  
Kelsey Clark ◽  
Behrad Noudoost ◽  
Neda Nategh
Keyword(s):  
Eye Movements ◽  
Visual Information ◽  
Visual Space ◽  
Saccadic Eye Movements ◽  
Visual Scene ◽  
High Temporal Resolution ◽  
Late Response ◽  
Visual World ◽  
Saccade Onset ◽  
Retinal Information

AbstractSaccadic eye movements (saccades) disrupt the continuous flow of visual information, yet our perception of the visual world remains uninterrupted. Here we assess the representation of the visual scene across saccades from single-trial spike trains of extrastriate visual areas, using a combined electrophysiology and statistical modeling approach. Using a model-based decoder we generate a high temporal resolution readout of visual information, and identify the specific changes in neurons’ spatiotemporal sensitivity that underly an integrated perisaccadic representation of visual space. Our results show that by maintaining a memory of the visual scene, extrastriate neurons produce an uninterrupted representation of the visual world. Extrastriate neurons exhibit a late response enhancement close to the time of saccade onset, which preserves the latest pre-saccadic information until the post-saccadic flow of retinal information resumes. These results show how our brain exploits available information to maintain a representation of the scene while visual inputs are disrupted.

The effect of task set on fixational saccadic eye movements

2013 ◽  
Author(s):  
Sara Spotorno ◽  
Guillaume S. Masson ◽  
Anna Montagnini
Keyword(s):  
Eye Movements ◽  
Saccadic Eye Movements ◽  
Task Set
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