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.

Use of interrupted saccade paradigm to study spatial and temporal dynamics of saccadic burst cells in superior colliculus in monkey

1994 ◽  
Vol 72 (6) ◽  
pp. 2754-2770 ◽  
Author(s):  
E. L. Keller ◽  
J. A. Edelman
Keyword(s):  
Eye Movements ◽  
Superior Colliculus ◽  
Temporal Dynamics ◽  
Saccadic Eye Movements ◽  
Eye Position ◽  
Visual Response ◽  
Intermediate Layers ◽  
Saccade Onset ◽  
Spatial And Temporal Dynamics ◽  
Motor Error

1. We recorded the spatial and temporal dynamics of saccade-related burst neurons (SRBNs) found in the intermediate layers of the superior colliculus (SC) in the alert, behaving monkey. These burst cells are normally the first neurons recorded during radially directed microelectrode penetrations of the SC after the electrode has left the more dorsally situated visual layers. They have spatially delimited movement fields whose centers describe the well-studied motor map of the SC. They have a rather sharp, saccade-locked burst of activity that peaks just before saccade onset and then declines steeply during the saccade. Many of these cells, when recorded during saccade trials, also have an early, transient visual response and an irregular prelude of presaccadic activity. 2. Because saccadic eye movements normally have very stereotyped durations and velocity trajectories that vary systematically with saccade size, it has been difficult in the past to establish quantitatively whether the activity of SRBNs temporally codes dynamic saccadic control signals, e.g., dynamic motor error or eye velocity, where dynamic motor error is defined as a signal proportional to the instantaneous difference between desired final eye position and the actual eye position during a saccade. It has also not been unequivocally established whether SRBNs participate in an organized spatial shift of ensemble activity in the intermediate layers of the SC during saccadic eye movements. 3. To address these issues, we studied the activity of SRBNs using an interrupted saccade paradigm. Saccades were interrupted with pulsatile electrical stimulation through a microelectrode implanted in the omnipauser region of the brain stem while recordings were made simultaneously from single SRBNs in the SC. 4. Shortly after the beginning of the stimulation (which was electronically triggered at saccade onset), the eyes decelerated rapidly and stopped completely. When the high-frequency (typically 300-400 pulses per second) stimulation was terminated (average duration 12 ms), the eye movement was reinitiated and a resumed saccade was made accurately to the location of the target. 5. When we recorded from SRBNs in the more caudal colliculus, which were active for large saccades, cell discharge was powerfully and rapidly suppressed by the stimulation (average latency = 3.8 ms). Activity in the same cells started again just before the onset of the resumed saccade and continued during this saccade even though it has a much smaller amplitude than would normally be associated with significant discharge for caudal SC cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Visuospatial Attentional Shifts and Choice Responses of Adults and ADHD and Non-ADHD Children

1994 ◽  
Vol 79 (3_suppl) ◽  
pp. 1479-1490 ◽  
Author(s):  
Phillip D. Tomporowski ◽  
Veronica Tinsley ◽  
Lisa D. Hager
Keyword(s):  
Cost Benefit Analysis ◽  
Cost Benefit ◽  
Response Speed ◽  
Spatial Location ◽  
Choice Response ◽  
Response Latencies ◽  
Adhd Children ◽  
Stimulus Cues ◽  
Response Task ◽  
Msec Delay

18 adults, 17 ADHD children, and 18 non-ADHD children performed a choice-response task on which the spatial location of a target was sometimes compatible and sometimes incompatible with priming cues that varied between 50 and 1000 msec. Children's response latencies differed from adults' response latencies as a function of the delay between priming cue and target onset. A cost-benefit analysis indicated that valid stimulus cues facilitated performance and invalid stimulus cues impeded performance similarly for the three groups. Choice-response errors following invalid cues did not differ between ADHD and non-ADHD children; however, adults made more choice errors than children at 150-msec. and 300-msec. delay intervals. Developmental factors that may underlie differences between children's and adults' response speed and response accuracy are discussed.

Neurons in the monkey superior colliculus predict the visual result of impending saccadic eye movements

1995 ◽  
Vol 73 (5) ◽  
pp. 1988-2003 ◽  
Author(s):  
M. F. Walker ◽  
E. J. Fitzgibbon ◽  
M. E. Goldberg
Keyword(s):  
Receptive Field ◽  
Superior Colliculus ◽  
Eye Movement ◽  
Receptive Fields ◽  
Saccadic Eye Movements ◽  
Superficial Layer ◽  
Saccade Target ◽  
Visual Response ◽  
Intermediate Layers ◽  
Movement Field

1. Previous experiments have shown that visual neurons in the lateral intraparietal area (LIP) respond predictively to stimuli outside their classical receptive fields when an impending saccade will bring those stimuli into their receptive fields. Because LIP projects strongly to the intermediate layers of the superior colliculus, we sought to demonstrate similar predictive responses in the monkey colliculus. 2. We studied the behavior of 90 visually responsive neurons in the superficial and intermediate layers of the superior colliculus of two rhesus monkeys (Macaca mulatta) when visual stimuli or the locations of remembered stimuli were brought into their receptive fields by a saccade. 3. Thirty percent (18/60) of intermediate layer visuomovement cells responded predictively before a saccade outside the movement field of the neuron when that saccade would bring the location of a stimulus into the receptive field. Each of these neurons did not respond to the stimulus unless an eye movement brought it into its receptive field, nor did it discharge in association with the eye movement unless it brought a stimulus into its receptive field. 4. These neurons were located in the deeper parts of the intermediate layers and had relatively larger receptive fields and movement fields than the cells at the top of the intermediate layers. 5. The predictive responses of most of these neurons (16/18, 89%) did not require that the stimulus be relevant to the monkey's rewarded behavior. However, for some neurons the predictive response was enhanced when the stimulus was the target of a subsequent saccade into the neuron's movement field. 6. Most neurons with predictive responses responded with a similar magnitude and latency to a continuous stimulus that remained on after the saccade, and to the same stimulus when it was only flashed for 50 ms coincident with the onset of the saccade target and thus never appeared within the cell's classical receptive field. 7. The visual response of neurons in the intermediate layers of the colliculus is suppressed during the saccade itself. Neurons that showed predictive responses began to discharge before the saccade, were suppressed during the saccade, and usually resumed discharging after the saccade. 8. Three neurons in the intermediate layers responded tonically from stimulus appearance to saccade without a presaccadic burst. These neurons responded predictively to a stimulus that was going to be the target for a second saccade, but not to an irrelevant flashed stimulus. 9. No superficial layer neuron (0/27) responded predictively when a stimulus would not be brought into their receptive fields by a saccade.(ABSTRACT TRUNCATED AT 400 WORDS)

Dependence on Target Configuration of Express Saccade-Related Activity in the Primate Superior Colliculus

1998 ◽  
Vol 80 (3) ◽  
pp. 1407-1426 ◽  
Author(s):  
Jay A. Edelman ◽  
Edward L. Keller
Keyword(s):  
Superior Colliculus ◽  
Target Selection ◽  
Visual Response ◽  
Express Saccades ◽  
Related Activity ◽  
Express Saccade ◽  
Spatial Properties ◽  
Target Configuration ◽  
Single Target ◽  
Single Burst

Edelman, Jay A. and Edward L. Keller. Dependence on target configuration of express saccade-related activity in the primate superior colliculus. J. Neurophysiol. 80: 1407–1426, 1998. To help understand how complex visual stimuli are processed into short-latency saccade motor programs, the activity of visuomotor neurons in the deeper layers of the superior colliculus was recorded while two monkeys made express saccades to one target and to two targets. It has been shown previously that the visual response and perimotor discharge characteristic of visuomotor neurons temporally coalesce into a single burst of discharge for express saccades. Here we seek to determine whether the distributed visual response to two targets spatially coalesces into a command appropriate for the resulting saccade. Two targets were presented at identical radial eccentricities separated in direction by 45°. A gap paradigm was used to elicit express saccades. Express saccades were more likely to land in between the two targets than were saccades of longer latency. The speeds of express saccades to two targets were similar to those of one target of similar vector, as were the trajectories of saccades to one and two targets. The movement fields for express saccades to two targets were more broad than those for saccades to one target for all neurons studied. For most neurons, the spatial pattern of discharge for saccades to two targets was better explained as a scaled version of the visual response to two spatially separate targets than as a scaled version of the perimotor response accompanying a saccade to a single target. Only the discharge of neurons with large movement fields could be equally well explained as a visual response to two targets or as a perimotor response for a one-target saccade. For most neurons, the spatial properties of discharge depended on the number of targets throughout the entire saccade-related burst. These results suggest that for express saccades to two targets the computation of saccade vector is not complete at the level of the superior colliculus for most neurons and an explicit process of target selection is not necessary at this level for the programming of an express saccade.

Spatial Distribution and Discharge Characteristics of Superior Colliculus Neurons Antidromically Activated From the Omnipause Region in Monkey

1997 ◽  
Vol 78 (4) ◽  
pp. 2221-2225 ◽  
Author(s):  
Neeraj J. Gandhi ◽  
Edward L. Keller
Keyword(s):  
Spatial Distribution ◽  
Superior Colliculus ◽  
Oculomotor Control ◽  
Discharge Characteristics ◽  
Spatially Distributed ◽  
Superior Colliculus Neurons ◽  
Rostral Region ◽  
And Control ◽  
Omnipause Neurons

Gandhi, Neeraj J. and Edward L. Keller. Spatial distribution and discharge characteristics of superior colliculus neurons antidromically activated from the omnipause region in monkey. J. Neurophysiol. 78: 2221–2225, 1997. One proposed role of the superior colliculus (SC) in oculomotor control is to suppress or excite the activity of brain stem omnipause neurons (OPNs) to initiate or terminate saccades, respectively. Although connections from the SC to the OPNs have been demonstrated, the spatial distribution and discharge characteristics of the projecting neurons from the SC remain unknown. We mapped the spatial distribution of the deeper-layer neurons of the SC by stimulating the region of the OPNs to identify antidromic projections and found that the density of direct projections from the SC to the OPNs was greatest in the most rostral region and decreased gradually for more caudal sites. On the basis of saccade-related discharge characteristics, the antidromically driven neurons were predominantly fixation and buildup neurons. The spatially distributed SC projections to the OPNs and the discharge characteristics of the SC neurons suggest that the direct projections from SC to OPNs are excitatory. Finally, we propose how excitation and disfacilitation from SC activity can contribute to modulation of OPN response and control saccades.

Target Selection for Saccadic Eye Movements: Prelude Activity in the Superior Colliculus During a Direction-Discrimination Task

2001 ◽  
Vol 86 (5) ◽  
pp. 2543-2558 ◽  
Author(s):  
Gregory D. Horwitz ◽  
William T. Newsome
Keyword(s):  
Eye Movements ◽  
Superior Colliculus ◽  
Discrimination Task ◽  
Target Selection ◽  
Saccadic Eye Movements ◽  
Saccade Target ◽  
Visual Responses ◽  
Direction Discrimination ◽  
Motion Signal ◽  
Movement Field

We investigated the role of the superior colliculus (SC) in saccade target selection while macaque monkeys performed a direction-discrimination task. The monkeys selected one of two possible saccade targets based on the direction of motion in a stochastic random-dot display; the difficulty of the task was varied by adjusting the strength of the motion signal in the display. One of the two saccade targets was positioned within the movement field of the SC neuron under study while the other target was positioned well outside the movement field. Approximately 30% of the neurons in the intermediate and deep layers of the SC discharged target-specific preludes of activity that “predicted” target choices well before execution of the saccadic eye movement. Across the population of neurons, the strength of the motion signal in the display influenced the intensity of this “predictive” prelude activity: SC activity signaled the impending saccade more reliably when the motion signal was strong than when it was weak. The dependence of neural activity on motion strength could not be explained by small variations in the metrics of the saccadic eye movements. Predictive activity was particularly strong in a subpopulation of neurons with directional visual responses that we have described previously. For a subset of SC neurons, therefore, prelude activity reflects the difficulty of the direction discrimination in addition to the target of the impending saccade. These results are consistent with the notion that a restricted network of SC neurons plays a role in the process of saccade target selection.

scholarly journals Analog VLSI-Based Modeling of the Primate Oculomotor System

1999 ◽  
Vol 11 (1) ◽  
pp. 243-265 ◽  
Author(s):  
Timothy K. Horiuchi ◽  
Christof Koch
Keyword(s):  
Visual Processing ◽  
Large Scale ◽  
Target Selection ◽  
Saccadic Eye Movements ◽  
Oculomotor System ◽  
Analog Vlsi ◽  
Enabling Technology ◽  
Retinal Position ◽  
Cortical Visual Processing

One way to understand a neurobiological system is by building a simulacrum that replicates its behavior in real time using similar constraints. Analog very large-scale integrated (VLSI) electronic circuit technology provides such an enabling technology. We here describe a neuromorphic system that is part of a long-term effort to understand the primate oculomotor system. It requires both fast sensory processing and fast motor control to interact with the world. A one-dimensional hardware model of the primate eye has been built that simulates the physical dynamics of the biological system. It is driven by two different analog VLSI chips, one mimicking cortical visual processing for target selection and tracking and another modeling brain stem circuits that drive the eye muscles. Our oculomotor plant demonstrates both smooth pursuit movements, driven by a retinal velocity error signal, and saccadic eye movements, controlled by retinal position error, and can reproduce several behavioral, stimulation, lesion, and adaptation experiments performed on primates.

S-cone Visual Stimuli Activate Superior Colliculus Neurons in Old World Monkeys: Implications for Understanding Blindsight

2014 ◽  
Vol 26 (6) ◽  
pp. 1234-1256 ◽  
Author(s):  
Nathan Hall ◽  
Carol Colby
Keyword(s):  
Superior Colliculus ◽  
Experimental Testing ◽  
Critical Role ◽  
Visual Stimuli ◽  
Spatial Location ◽  
Apparent Lack ◽  
Behavioral Studies ◽  
Superior Colliculus Neurons ◽  
Definition Of ◽  
Prevailing View

The superior colliculus (SC) is thought to be unresponsive to stimuli that activate only short wavelength-sensitive cones (S-cones) in the retina. The apparent lack of S-cone input to the SC was recognized by Sumner et al. [Sumner, P., Adamjee, T., & Mollon, J. D. Signals invisible to the collicular and magnocellular pathways can capture visual attention. Current Biology, 12, 1312–1316, 2002] as an opportunity to test SC function. The idea is that visual behavior dependent on the SC should be impaired when S-cone stimuli are used because they are invisible to the SC. The SC plays a critical role in blindsight. If the SC is insensitive to S-cone stimuli blindsight behavior should be impaired when S-cone stimuli are used. Many clinical and behavioral studies have been based on the assumption that S-cone-specific stimuli do not activate neurons in the SC. Our goal was to test whether single neurons in macaque SC respond to stimuli that activate only S-cones. Stimuli were calibrated psychophysically in each animal and at each individual spatial location used in experimental testing [Hall, N. J., & Colby, C. L. Psychophysical definition of S-cone stimuli in the macaque. Journal of Vision, 13, 2013]. We recorded from 178 visually responsive neurons in two awake, behaving rhesus monkeys. Contrary to the prevailing view, we found that nearly all visual SC neurons can be activated by S-cone-specific visual stimuli. Most of these neurons were sensitive to the degree of S-cone contrast. Of 178 visual SC neurons, 155 (87%) had stronger responses to a high than to a low S-cone contrast. Many of these neurons' responses (56/178 or 31%) significantly distinguished between the high and low S-cone contrast stimuli. The latency and amplitude of responses depended on S-cone contrast. These findings indicate that stimuli that activate only S-cones cannot be used to diagnose collicular mediation.

Sign in / Sign up

Export Citation Format

Share Document