Comparison of Memory- and Visually Guided Saccades Using Event-Related fMRI

2004 ◽  
Vol 91 (2) ◽  
pp. 873-889 ◽  
Author(s):  
M.R.G. Brown ◽  
J.F.X. DeSouza ◽  
H. C. Goltz ◽  
K. Ford ◽  
R. S. Menon ◽  
...  
Keyword(s):  
Inferior Frontal Gyrus ◽  
Stimulus Presentation ◽  
Delay Period ◽  
Frontal Eye Field ◽  
Peripheral Stimulus ◽  
Precentral Gyrus ◽  
Visually Guided ◽  
Related Activity ◽  
Eye Field ◽  
Sensory Processes

Previous functional imaging studies have shown an increased hemodynamic signal in several cortical areas when subjects perform memory-guided saccades than that when they perform visually guided saccades using blocked trial designs. It is unknown, however, whether this difference results from sensory processes associated with stimulus presentation, from processes occurring during the delay period before saccade generation, or from an increased motor signal for memory-guided saccades. We conducted fMRI using an event-related paradigm that separated stimulus-related, delay-related, and saccade-related activity. Subjects initially fixated a central cross, whose color indicated whether the trial was a memory- or a visually guided trial. A peripheral stimulus was then flashed at one of 4 possible locations. On memory-guided trials, subjects had to remember this location for the subsequent saccade, whereas the stimulus was a distractor on visually guided trials. Fixation cross disappearance after a delay period was the signal either to generate a memory-guided saccade or to look at a visual stimulus that was flashed on visually guided trials. We found slightly greater stimulus-related activation for visually guided trials in 3 right prefrontal regions and right rostral intraparietal sulcus (IPS). Memory-guided trials evoked greater delay-related activity in right posterior inferior frontal gyrus, right medial frontal eye field, bilateral supplementary eye field, right rostral IPS, and right ventral IPS but not in middle frontal gyrus. Right precentral gyrus and right rostral IPS exhibited greater saccade-related activation on memory-guided trials. We conclude that activation differences revealed by previous blocked experiments have different sources in different areas and that cortical saccade regions exhibit delay-related activation differences.

Delay-Period Activity in Visual, Visuomovement, and Movement Neurons in the Frontal Eye Field

2005 ◽  
Vol 94 (2) ◽  
pp. 1498-1508 ◽  
Author(s):  
Bonnie M. Lawrence ◽  
Robert L. White ◽  
Lawrence H. Snyder
Keyword(s):  
Spatial Information ◽  
Delay Period ◽  
Frontal Eye Field ◽  
Significant Delay ◽  
Related Activity ◽  
Null Direction ◽  
Preferred Direction ◽  
Canonical Neurons ◽  
Eye Field ◽  
Saccade Direction

In the present study, we examined the role of frontal eye field neurons in the maintenance of spatial information in a delayed-saccade paradigm. We found that visual, visuomovement, and movement neurons conveyed roughly equal amounts of spatial information during the delay period. Although there was significant delay-period activity in individual movement neurons, there was no significant delay-period activity in the averaged population of movement neurons. These contradictory results were reconciled by the finding that the population of movement neurons with memory activity consisted of two subclasses of neurons, the combination of which resulted in the cancellation of delay-period activity in the population of movement neurons. One subclass consisted of neurons with significantly greater delay activity in the preferred than in the null direction (“canonical”), whereas the other subclass consisted of neurons with significantly greater delay activity in the null direction than in the preferred direction (“paradoxical”). Preferred direction was defined by the saccade direction that evoked the greatest movement-related activity. Interestingly, the peak saccade-related activity of canonical neurons occurred before the onset of the saccade, whereas the peak saccade-related activity of paradoxical neurons occurred after the onset of the saccade. This suggests that the former, but not the latter, are directly involved in triggering saccades. We speculate that paradoxical neurons provide a mechanism by which spatial information can be maintained in a saccade-generating circuit without prematurely triggering a saccade.

Frontoparietal Activation With Preparation for Antisaccades

2007 ◽  
Vol 98 (3) ◽  
pp. 1751-1762 ◽  
Author(s):  
Matthew R. G. Brown ◽  
Tutis Vilis ◽  
Stefan Everling
Keyword(s):  
Prefrontal Cortex ◽  
Anterior Cingulate Cortex ◽  
Human Subjects ◽  
Stimulus Presentation ◽  
Cingulate Cortex ◽  
Anterior Cingulate ◽  
Frontal Eye Field ◽  
Peripheral Stimulus ◽  
Supplementary Eye Field ◽  
Eye Field

Several current models hold that frontoparietal areas exert cognitive control by biasing task-relevant processing in other brain areas. Previous event-related functional magnetic resonance imaging (fMRI) studies have compared prosaccades and antisaccades, which require subjects to look toward or away from a flashed peripheral stimulus, respectively. These studies found greater activation for antisaccades in frontal and parietal regions at the ends of long (≥6 s) preparatory periods preceding peripheral stimulus presentation. Event-related fMRI studies using short preparatory periods (≤4 s) have not found such activation differences except in the frontal eye field. Here, we identified activation differences associated with short (1-s) preparatory periods by interleaving half trials among regular whole trials in a rapid fMRI design. On whole trials, a colored fixation dot instructed human subjects to make either a prosaccade toward or an antisaccade away from a peripheral visual stimulus. Half trials included only the instruction and not peripheral stimulus presentation or saccade generation. Nonetheless, half trials evoked stronger activation on antisaccades than on prosaccades in the frontal eye field (FEF), supplementary eye field (SEF), left dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex (ACC), intraparietal sulcus (IPS), and precuneus. Greater antisaccade response-related activation was found in FEF, SEF, IPS, and precuneus but not in DLPFC or ACC. These results demonstrate greater preparatory activation for antisaccades versus prosaccades in frontoparietal areas and suggest that prefrontal cortex and anterior cingulate cortex are more involved in presetting the saccade network for the antisaccade task than generating the actual antisaccade response.

Response Properties of Fixation Neurons and Their Location in the Frontal Eye Field in the Monkey

2009 ◽  
Vol 102 (4) ◽  
pp. 2410-2422 ◽  
Author(s):  
Yoshiko Izawa ◽  
Hisao Suzuki ◽  
Yoshikazu Shinoda
Keyword(s):  
Electrical Stimulation ◽  
Frontal Eye Field ◽  
Visually Guided ◽  
Related Activity ◽  
Strong Suppression ◽  
Steady Fixation ◽  
Eye Field ◽  
Suppression Mechanism ◽  
Attentive Fixation ◽  
Stimulation Of

Electrical stimulation of the frontal eye field (FEF) has recently been reported to suppress the generation of saccades, which supports the idea that the FEF plays a role in maintaining attentive fixation. This study analyzed the activity of fixation neurons that discharged during fixation in the FEF in relation to visual fixation and saccades in trained monkeys. The neural activity of fixation neurons increased at the start of fixation and was maintained during fixation. When a fixation spot of light disappeared during steady fixation, different fixation neurons exhibited different categories of response, ranging from a decrease in activity to an increase in activity, indicating that there is a continuum of fixation neurons, from neurons with foveal visual-related activity to neurons with activity that is related to the motor act of fixating. Fixation neurons usually showed a decrease in their firing rate before the onset of visually guided saccades (Vsacs) and memory-guided saccades in any direction. The reduction in activity of fixation neurons nearly coincided with, or occurred slightly before, the increase in the activity of saccade-related movement neurons in the FEF in the same monkey. Although fixation neurons were scattered in the FEF, about two thirds of fixation neurons were concentrated in a localized area in the FEF at which electrical stimulation induced strong suppression of the initiation of Vsacs bilaterally. These results suggest that fixation neurons in the FEF are part of a suppression mechanism that could control the maintenance of fixation and the initiation of saccades.

Frontal eye field activity preceding aurally guided saccades

1994 ◽  
Vol 71 (3) ◽  
pp. 1250-1253 ◽  
Author(s):  
G. S. Russo ◽  
C. J. Bruce
Keyword(s):  
Spatial Location ◽  
Auditory Target ◽  
Frontal Eye Field ◽  
Visually Guided ◽  
Movement Vector ◽  
Initial Fixation ◽  
Field Activity ◽  
Eye Field ◽  
Movement Field ◽  
Visual Targets

1. We studied neuronal activity in the monkey's frontal eye field (FEF) in conjunction with saccades directed to auditory targets. 2. All FEF neurons with movement activity preceding saccades to visual targets also were active preceding saccades to auditory targets, even when such saccades were made in the dark. Movement cells generally had comparable bursts for aurally and visually guided saccades; visuomovement cells often had weaker bursts in conjunction with aurally guided saccades. 3. When these cells were tested from different initial fixation directions, movement fields associated with aurally guided saccades, like fields mapped with visual targets, were a function of saccade dimensions, and not the speaker's spatial location. Thus, even though sound location cues are chiefly craniotopic, the crucial factor for a FEF discharge before aurally guided saccades was the location of auditory target relative to the current direction of gaze. 4. Intracortical microstimulation at the sites of these cells evoked constant-vector saccades, and not goal-directed saccades. The direction and size of electrically elicited saccades generally matched the cell's movement field for aurally guided saccades. 5. Thus FEF activity appears to have a role in aurally guided as well as visually guided saccades. Moreover, visual and auditory target representations, although initially obtained in different coordinate systems, appear to converge to a common movement vector representation at the FEF stage of saccadic processing that is appropriate for transmittal to saccade-related burst neurons in the superior colliculus and pons.

Visually guided saccade versus eye-hand reach: contrasting neuronal activity in the cortical supplementary and frontal eye fields

1996 ◽  
Vol 75 (5) ◽  
pp. 2187-2191 ◽  
Author(s):  
H. Mushiake ◽  
N. Fujii ◽  
J. Tanji
Keyword(s):  
Eye Movement ◽  
Neuronal Activity ◽  
Motor Task ◽  
Oculomotor Control ◽  
Frontal Eye Field ◽  
Frontal Eye Fields ◽  
Saccadic Eye Movement ◽  
Visually Guided ◽  
Supplementary Eye Field ◽  
Eye Field

1. We studied neuronal activity in the supplementary eye field (SEF) and frontal eye field (FEF) of a monkey during performance of a conditional motor task that required capturing of a target either with a saccadic eye movement (the saccade-only condition) or with an eye-hand reach (the saccade-and-reach condition), according to visual instructions. 2. Among 106 SEF neurons that showed presaccadic activity, more than one-half of them (54%) were active preferentially under the saccade-only condition (n = 12) or under the saccade-and-reach condition (n = 45), while the remaining 49 neurons were equally active in both conditions. 3. By contrast, most (97%) of the 109 neurons in the FEF exhibited approximately equal activity in relation to saccades under the two conditions. 4. The present results suggest the possibility that SEF neurons, at least in part, are involved in signaling whether the motor task is oculomotor or combined eye-arm movements, whereas FEF neurons are mostly related to oculomotor control.

Activity of monkey frontal eye field neurons projecting to oculomotor regions of the pons

1992 ◽  
Vol 68 (6) ◽  
pp. 1967-1985 ◽  
Author(s):  
M. A. Segraves
Keyword(s):  
Electrical Stimulation ◽  
Visual Stimulation ◽  
Saccadic Eye Movements ◽  
Frontal Eye Field ◽  
Related Activity ◽  
Burst Neurons ◽  
Eye Field ◽  
Movement Field ◽  
Omnipause Neurons ◽  
Stimulation Of

1. This study identified neurons in the rhesus monkey's frontal eye field that projected to oculomotor regions of the pons and characterized the signals sent by these neurons from frontal eye field to pons. 2. In two behaving rhesus monkeys, frontal eye field neurons projecting to the pons were identified via antidromic excitation by a stimulating microelectrode whose tip was centered in or near the omnipause region of the pontine raphe. This stimulation site corresponded to the nucleus raphe interpositus (RIP). In addition, electrical stimulation of the frontal eye field was used to demonstrate the effects of frontal eye field input on neurons in the omnipause region and surrounding paramedian pontine reticular formation (PPRF). 3. Twenty-five corticopontine neurons were identified and characterized. Most frontal eye field neurons projecting to the pons were either movement neurons, firing in association with saccadic eye movements (48%), or foveal neurons responsive to visual stimulation of the fovea combined with activity related to fixation (28%). Corticopontine movement neurons fired before, during, and after saccades made within a restricted movement field. 4. The activity of identified corticopontine neurons was very similar to the activity of neurons antidromically excited from the superior colliculus where 59% had movement related activity, and 22% had foveal and fixation related activity. 5. High-intensity, short-duration electrical stimulation of the frontal eye field caused omnipause neurons to stop firing. The cessation in firing appeared to be immediate, within < or = 5 ms. The time that the omnipause neuron remained quiet depended on the intensity of the cortical stimulus and lasted up to 30 ms after a train of three stimulus pulses lasting a total of 6 ms at an intensity of 1,000 microA. Low-intensity, longer duration electrical stimuli (24 pulses, 75 microA, 70 ms) traditionally used to evoke saccades from the frontal eye field were also followed by a cessation in omnipause neuron firing, but only after a delay of approximately 30 ms. For these stimuli, the omnipause neuron resumed firing when the stimulus was turned off. 6. The same stimuli that caused omnipause neurons to stop firing excited burst neurons in the PPRF. The latency to excitation ranged from 4.2 to 9.8 ms, suggesting that there is at least one additional neuron between frontal eye field neurons and burst neurons in the PPRF. 7. The present study confirms and extends the results of previous work, with the use of retrograde and anterograde tracers, demonstrating direct projections from the frontal eye field to the pons.(ABSTRACT TRUNCATED AT 400 WORDS)

Psychology of attention

2012 ◽  
pp. 245-249
Author(s):  
Elizabeth Coulthard ◽  
Masud Husain
Keyword(s):  
Human Brain ◽  
Parietal Lobe ◽  
Inferior Frontal Gyrus ◽  
Good Deal ◽  
Anterior Cingulate ◽  
Frontal Eye Field ◽  
Temporoparietal Junction ◽  
Flexible Control ◽  
Eye Field ◽  
Brain Processing

Attention is generally taken to be the process by which people are able to concentrate on certain information or processes, while ignoring other events. It appears to be a fundamental attribute of human brain processing, although difficult to pin down in terms of mechanism. Psychologists have attempted to fractionate attention in many different ways, using ingenious behavioural paradigms. In this section we, too, will consider different aspects of attention: selective, phasic and sustained, divided and executive control of attention. However, it would be fair to say that all these aspects of attention do not normally operate in isolation. Instead they interact, and deficiencies in one aspect of attention, for example, in a patient population, often to do not occur in isolation. Functional imaging and lesion studies of attention have proliferated in recent years, attempting to place a neurobiological framework to these varied processes. In general, these studies also tend to confirm the view that attention is likely an emergent property of widespread brain networks, with a special emphasis on frontal and parietal regions of the human brain (Fig. 2.5.2.1). In this discussion we illustrate several aspects of attention with examples particularly from literature on visual attention, which is the most widely studied area, but it should be appreciated that many of the concepts discussed here extend to other domains. In fact, there is a good deal of evidence to suggest that several aspects of attention operate at a supra- or cross-modal level allowing integration of information from different sources. Recent studies suggest there are two fronto-parietal networks: (Fig. 2.5.2.1) a dorsal parieto-frontal network involving the superior parietal lobe (SPL) and dorsal frontal regions such as the frontal eye field (FEF); and a ventral network involving the inferior parietal lobe (IPL), temporoparietal junction (TPJ) and inferior frontal gyrus (IFG). In addition, dorsomedial frontal areas, including the anterior cingulate cortex (ACC) and pre-supplementary area (pre-SMA) may play a key role in flexible control of attention for strategic behaviour.

Macaque Frontal Eye Field Input to Saccade-Related Neurons in the Superior Colliculus

2003 ◽  
Vol 90 (2) ◽  
pp. 1046-1062 ◽  
Author(s):  
Janet O. Helminski ◽  
Mark A. Segraves
Keyword(s):  
Superior Colliculus ◽  
Rhesus Monkeys ◽  
Frontal Eye Field ◽  
Specific Class ◽  
Related Activity ◽  
Deep Layers ◽  
Eye Field ◽  
Visuomotor Tasks ◽  
Superior Colliculus Neurons ◽  
Made In

Extracellular recordings were made simultaneously in the frontal eye field and superior colliculus in awake, behaving rhesus monkeys. Frontal eye field microstimulation was used to orthodromically activate the superior colliculus both to locate the depth of the strongest frontal eye field input to the superior colliculus and to identify superior colliculus neurons receiving direct frontal eye field input. The activity of orthodromically driven colliculus neurons was characterized during visuomotor tasks. The purpose of this study was to identify the types of superior colliculus neurons that receive excitatory frontal eye field input. We found that microstimulation of the frontal eye field did not activate the superficial layers of the superior colliculus but did activate the deeper layers. This pattern of activation coincided with the prevalence of visual versus saccade-related activity in the superficial and deep layers. A total of 83 orthodromically driven superior colliculus neurons were identified. Of these neurons, 93% ( n = 77) exhibited a burst of activity associated with the onset of the saccade, and 25% ( n = 21) exhibited prelude/build-up activity prior to the onset of a saccade. In addition, it was common to see some activity synchronized with the onset of a visual target (30%, n = 25). In single neurons, these activity profiles could be observed alone or in combination. Superior colliculus neurons that were exclusively visual, however, were not excited by frontal eye field stimulation. We compared the activity of superior colliculus neurons that received frontal eye field input to descriptions of saccade-related neurons made in earlier reports and found that the distribution of neuron types in the orthodromically driven population was similar to the distribution within the overall population. This suggests that the frontal eye field does not selectively influence a specific class of collicular neurons, but, instead has a direct influence on all preparatory, and saccade-related activity within the deep layers of the superior colliculus.

scholarly journals Role of Supplementary Eye Field in Saccade Initiation: Executive, Not Direct, Control

2010 ◽  
Vol 103 (2) ◽  
pp. 801-816 ◽  
Author(s):  
Veit Stuphorn ◽  
Joshua W. Brown ◽  
Jeffrey D. Schall
Keyword(s):  
Discharge Rate ◽  
Stop Signal ◽  
Stop Signal Task ◽  
Frontal Eye Field ◽  
Signal Trial ◽  
Visually Guided ◽  
Supplementary Eye Field ◽  
Task Requirements ◽  
Gaze Holding ◽  
Eye Field

The goal of this study was to determine whether the activity of neurons in the supplementary eye field (SEF) is sufficient to control saccade initiation in macaque monkeys performing a saccade countermanding (stop signal) task. As previously observed, many neurons in the SEF increase the discharge rate before saccade initiation. However, when saccades are canceled in response to a stop signal, effectively no neurons with presaccadic activity display discharge rate modulation early enough to contribute to saccade cancellation. Moreover, SEF neurons do not exhibit a specific threshold discharge rate that could trigger saccade initiation. Yet, we observed more subtle relations between SEF activation and saccade production. The activity of numerous SEF neurons was correlated with response time and varied with sequential adjustments in response latency. Trials in which monkeys canceled or produced a saccade in a stop signal trial were distinguished by a modest difference in discharge rate of these SEF neurons before stop signal or target presentation. These findings indicate that neurons in the SEF, in contrast to counterparts in the frontal eye field and superior colliculus, do not contribute directly and immediately to the initiation of visually guided saccades. However the SEF may proactively regulate saccade production by biasing the balance between gaze-holding and gaze-shifting based on prior performance and anticipated task requirements.

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