scholarly journals Bilateral saccadic deficits following large and reversible inactivation of unilateral frontal eye field

2014 ◽  
Vol 111 (2) ◽  
pp. 415-433 ◽  
Author(s):  
Tyler R. Peel ◽  
Kevin Johnston ◽  
Stephen G. Lomber ◽  
Brian D. Corneil
Keyword(s):  
Visual Cues ◽  
Brain Area ◽  
Reaction Times ◽  
The Other ◽  
Frontal Eye Field ◽  
Visually Guided ◽  
Reversible Inactivation ◽  
Eye Field ◽  
And Performance ◽  
The Impact

Inactivation permits direct assessment of the functional contribution of a given brain area to behavior. Previous inactivation studies of the frontal eye field (FEF) have either used large permanent ablations or reversible pharmacological techniques that only inactivate a small volume of tissue. Here we evaluated the impact of large, yet reversible, FEF inactivation on visually guided, delayed, and memory-guided saccades, using cryoloops implanted in the arcuate sulcus. While FEF inactivation produced the expected triad of contralateral saccadic deficits (increased reaction time, decreased accuracy and peak velocity) and performance errors (neglect or misdirected saccades), we also found consistent increases in reaction times of ipsiversive saccades in all three tasks. In addition, FEF inactivation did not increase the proportion of premature saccades to ipsilateral targets, as was predicted on the basis of pharmacological studies. Consistent with previous studies, greater deficits accompanied saccades toward extinguished visual cues. Our results attest to the functional contribution of the FEF to saccades in both directions. We speculate that the comparative effects of different inactivation techniques relate to the volume of inactivated tissue within the FEF. Larger inactivation volumes may reveal the functional contribution of more sparsely distributed neurons within the FEF, such as those related to ipsiversive saccades. Furthermore, while focal FEF inactivation may disinhibit the mirroring site in the other FEF, larger inactivation volumes may induce broad disinhibition in the other FEF that paradoxically prolongs oculomotor processing via increased competitive interactions.

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.

scholarly journals SOCIO-CULTURAL FACTORS AND INTERNATIONAL COMPETITIVENESS

2015 ◽  
Vol 13 (2) ◽  
pp. 276-291 ◽  
Author(s):  
Madara Apsalone ◽  
Ērika Šumilo
Keyword(s):  
Economic Development ◽  
External Environment ◽  
International Competitiveness ◽  
Cultural Factors ◽  
The Other ◽  
Small Open Economies ◽  
Performance Orientation ◽  
Innovation Capacity ◽  
And Performance ◽  
The Impact

Socio-cultural factors – shared values, norms and attitudes are significant, but less acknowledged sources of international competitiveness. Previous studies have found socio-cultural factors positively affecting various aspects of international competitiveness – entrepreneurship, innovation, productivity and international cooperation. These factors are more sustainable and less affected by external environment changes in comparison with the traditional factors. Socio-cultural factors provide an opportunity to develop competitiveness strategies based on unique advantages. This research aims to explore the impact of socio-cultural factors on international competiveness in small, open economies. Analysing relationship between 400 socio-cultural indicators and competitiveness indicators such as productivity, economic development, business and government efficiency, innovation capacity and infrastructure in 37 countries, six socio-cultural factors have emerged: Collectivism and Hierarchy; Future, Cooperation and Performance Orientation, Self-expression, Monochronism and Rationality, Economic Orientation and Social structure. The first factor – Collectivism and Hierarchy – tends to reduce the international competitiveness; the other five affect it positively.

scholarly journals Representation of visual salience within the frontal eye field following reversible inactivation of parietal cortex

2016 ◽  
Vol 16 (12) ◽  
pp. 13
Author(s):  
Marc Zirnsak ◽  
Xiaomo Chen ◽  
Stephen Lomber ◽  
Tirin Moore
Keyword(s):  
Parietal Cortex ◽  
Frontal Eye Field ◽  
Visual Salience ◽  
Reversible Inactivation ◽  
Eye Field

Patronage and Performance: Factors in the Political Mobility of Provincial Leaders in Post-Deng China

2012 ◽  
Vol 212 ◽  
pp. 965-981 ◽  
Author(s):  
Eun Kyong Choi
Keyword(s):  
Economic Performance ◽  
Career Mobility ◽  
The Other ◽  
The Political ◽  
Performance Factors ◽  
Other Hand ◽  
And Performance ◽  
The Impact

AbstractThis paper attempts to estimate the impact of both factional ties and economic performance on the promotion of provincial Party secretaries and governors by analysing a person–year dataset of their career mobility for inclusive years 1989 to 2009. We found that for provincial Party secretaries whose promotion meant rising to a top national position, both factional ties and good economic performance increased their chance for promotion. On the other hand, for provincial governors whose promotion meant rising to a ministry-level position, only economic performance mattered for their promotion. Among provincial Party secretaries, the extent to which performance affected the likelihood of promotion was not different between factional members and non-members. This suggests that even factional members needed to show good performance to enhance the likelihood of their promotion.

The effect of frontal eye field and superior colliculus lesions on saccadic latencies in the rhesus monkey

1987 ◽  
Vol 57 (4) ◽  
pp. 1033-1049 ◽  
Author(s):  
P. H. Schiller ◽  
J. H. Sandell ◽  
J. H. Maunsell
Keyword(s):  
Eye Movements ◽  
Superior Colliculus ◽  
Short Latency ◽  
The Other ◽  
Frontal Eye Field ◽  
Express Saccades ◽  
Unimodal Distribution ◽  
Other Hand ◽  
Eye Field ◽  
The Mean

Rhesus monkeys were trained to make saccadic eye movements to visual targets using detection and discrimination paradigms in which they were required to make a saccade either to a solitary stimulus (detection) or to that same stimulus when it appeared simultaneously with several other stimuli (discrimination). The detection paradigm yielded a bimodal distribution of saccadic latencies with the faster mode peaking around 100 ms (express saccades); the introduction of a pause between the termination of the fixation spot and the onset of the target (gap) increased the frequency of express saccades. The discrimination paradigm, on the other hand, yielded only a unimodal distribution of latencies even when a gap was introduced, and there was no evidence for short-latency "express" saccades. In three monkeys either the frontal eye field or the superior colliculus was ablated unilaterally. Frontal eye field ablation had no discernible long-term effects on the distribution of saccadic latencies in either the detection or discrimination tasks. After unilateral collicular ablation, on the other hand, express saccades obtained in the detection paradigm were eliminated for eye movements contralateral to the lesion, leaving only a unimodal distribution of latencies. This deficit persisted throughout testing, which in one monkey continued for 9 mo. Express saccades were not observed again for saccades contralateral to the lesion, and the mean latency of the contralateral saccades was longer than the mean latency of the second peak for the ipsiversive saccades. The latency distribution of saccades ipsiversive to the collicular lesion was unaffected except for a few days after surgery, during which time an increase in the proportion of express saccades was evident. Saccades obtained with the discrimination paradigm yielded a small but reliable increase in saccadic latencies following collicular lesions, without altering the shape of the distribution. Unilateral muscimol injections into the superior colliculus produced results similar to those obtained immediately after collicular lesions: saccades contralateral to the injection site were strongly inhibited and showed increased saccadic latencies. This was accompanied by a decrease of ipsilateral saccadic latencies and an increase in the number of saccades falling into the express range. The results suggest that the superior colliculus is essential for the generation of short-latency (express) saccades and that the frontal eye fields do not play a significant role in shaping the distribution of saccadic latencies in the paradigms used in this study.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Suppression of Task-Related Saccades by Electrical Stimulation in the Primate's Frontal Eye Field

1997 ◽  
Vol 77 (5) ◽  
pp. 2252-2267 ◽  
Author(s):  
Douglas D. Burman ◽  
Charles J. Bruce
Keyword(s):  
Electrical Stimulation ◽  
Eye Movements ◽  
Frontal Lobe ◽  
Premotor Cortex ◽  
Saccadic Eye Movements ◽  
Association Cortex ◽  
Frontal Eye Field ◽  
Visually Guided ◽  
Low Intensity ◽  
Eye Field

Burman, Douglas D. and Charles J. Bruce. Suppression of task-related saccades by electrical stimulation in the primate's frontal eye field. J. Neurophysiol. 77: 2252–2267, 1997. Patients with frontal lobe damage have difficulty suppressing reflexive saccades to salient visual stimuli, indicating that frontal lobe neocortex helps to suppress saccades as well as to produce them. In the present study, a role for the frontal eye field (FEF) in suppressing saccades was demonstrated in macaque monkeys by application of intracortical microstimulation during the performance of a visually guided saccade task, a memory prosaccade task, and a memory antisaccade task. A train of low-intensity (20–50 μA) electrical pulses was applied simultaneously with the disappearance of a central fixation target, which was always the cue to initiate a saccade. Trials with and without stimulation were compared, and significantly longer saccade latencies on stimulation trials were considered evidence of suppression. Low-intensity stimulation suppressed task-related saccades at 30 of 77 sites tested. In many cases saccades were suppressed throughout the microstimulation period (usually 450 ms) and then executed shortly after the train ended. Memory-guided saccades were most dramatically suppressed and were often rendered hypometric, whereas visually guided saccades were less severely suppressed by stimulation. At 18 FEF sites, the suppression of saccades was the only observable effect of electrical stimulation. Contraversive saccades were usually more strongly suppressed than ipsiversive ones, and cells recorded at such purely suppressive sites commonly had either foveal receptive fields or postsaccadic responses. At 12 other FEF sites at which saccadic eye movements were elicited at low thresholds, task-related saccades whose vectors differed from that of the electrically elicited saccade were suppressed by electrical stimulation. Such suppression at saccade sites was observed even with currents below the threshold for eliciting saccades. Pure suppression sites tended to be located near or in the fundus, deeper in the anterior bank of the arcuate than elicited saccade sites. Stimulation in the prefrontal association cortex anterior to FEF did not suppress saccades, nor did stimulation in premotor cortex posterior to FEF. These findings indicate that the primate FEF can help orchestrate saccadic eye movements by suppressing inappropriate saccade vectors as well as by selecting, specifying, and triggering appropriate saccades. We hypothesize that saccades could be suppressed both through local FEF interactions and through FEF projections to subcortical regions involved in maintaining fixation.

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