scholarly journals Timing of Target Discrimination in Human Frontal Eye Fields

2004 ◽  
Vol 16 (6) ◽  
pp. 1060-1067 ◽  
Author(s):  
Jacinta O'Shea ◽  
Neil G. Muggleton ◽  
Alan Cowey ◽  
Vincent Walsh
Keyword(s):  
Visual Processing ◽  
Time Window ◽  
Time Windows ◽  
Cell Activity ◽  
Correct Rejection ◽  
Frontal Eye Field ◽  
Search Performance ◽  
Target Discrimination ◽  
Eye Field ◽  
The Right

Frontal eye field (FEF) neurons discharge in response to behaviorally relevant stimuli that are potential targets for saccades. Distinct visual and motor processes have been dissociated in the FEF of macaque monkeys, but little is known about the visual processing capacity of FEF in humans. We used double-pulse transcranial magnetic stimulation [(d)TMS] to investigate the timing of target discrimination during visual conjunction search. We applied dual TMS pulses separated by 40 msec over the right FEF and vertex. These were applied in five timing conditions to sample separate time windows within the first 200 msec of visual processing. (d)TMS impaired search performance, reflected in reduced d′ scores. This effect was limited to a time window between 40 and 80 msec after search array onset. These parameters correspond with single-cell activity in FEF that predicts monkeys' behavioral reports on hit, miss, false alarm, and correct rejection trials. Our findings demonstrate a crucial early role for human FEF in visual target discrimination that is independent of saccade programming.

scholarly journals Gaze Palsy as a Manifestation of Todd’s Phenomenon: Case Report and Review of the Literature

2020 ◽  
Vol 10 (5) ◽  
pp. 298
Author(s):  
Karmele Olaciregui Dague ◽  
Manuel Dafotakis ◽  
Jörg B. Schulz ◽  
Rainer Surges
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Clonic Seizure ◽  
Frontal Eye Field ◽  
Correct Identification ◽  
Eye Field ◽  
Narrative Literature Review ◽  
Stroke Mimic ◽  
Therapeutic Decision Making ◽  
The Right ◽  
Gaze Palsy

Background: Though Todd’s phenomenon (TP) is a relatively rare occurrence, its correct identification is of key diagnostic and therapeutic importance as a stroke mimic. Here we describe a case of isolated gaze palsy as a manifestation of TP, discuss periictal gaze abnormalities as lateralizing sign involving the frontal eye field (FEF), and present a narrative literature review. Methods: We reviewed the main features of the case and conducted a structured literature search of TP and gaze palsy using PubMed. We restricted the search to publications in English, Spanish, French, and German. Case presentation: A 71-year-old male with a history of right frontotemporal subarachnoid hemorrhage was admitted to the Emergency Department of our institution after suffering a first unprovoked focal to bilateral tonic-clonic seizure with ictal gaze deviation to the left. Cranial imaging showed no signs of ischemia, intracerebral hemorrhage, or tumor. The patient presented the following postictal features: involuntary eye deviation to the right due to left-sided gaze palsy and disorientation in time with preserved responsiveness. Eye movements were normal three days later. We concluded that the patient suffered from new-onset epilepsy due to sequelae following the right frontotemporal subarachnoid hemorrhage, affecting the FEF with contralateral ictal gaze deviation, and postictal gaze palsy with ipsilateral eye deviation as an unusual Todd’s phenomenon. Conclusion: Unusual manifestations of TP are uncommon but clinically highly relevant, as they can mimic stroke or epileptic status and are decisive in the diagnostic and therapeutic decision-making process. Though postictal gaze palsy has been reported associated with other deficits, this constitutes, to our knowledge, the first report of isolated gaze palsy as a form of TP. Further research into the underlying causes is needed. Ictal contralateral gaze and head deviation, and probably postictal ipsilateral gaze deviation if present, are very helpful for the lateralization of the seizure-onset zone.

scholarly journals Neural Correlates of Correct and Errant Attentional Selection Revealed Through N2pc and Frontal Eye Field Activity

2010 ◽  
Vol 104 (5) ◽  
pp. 2433-2441 ◽  
Author(s):  
Richard P. Heitz ◽  
Jeremiah Y. Cohen ◽  
Geoffrey F. Woodman ◽  
Jeffrey D. Schall
Keyword(s):  
Visual Search ◽  
Visual Processing ◽  
Neural Correlates ◽  
Event Related Potential ◽  
Covert Attention ◽  
Extrastriate Cortex ◽  
False Alarms ◽  
Frontal Eye Field ◽  
Physiological Basis ◽  
Eye Field

The goal of this study was to obtain a better understanding of the physiological basis of errors of visual search. Previous research has shown that search errors occur when visual neurons in the frontal eye field (FEF) treat distractors as if they were targets. We replicated this finding during an inefficient form search and extended it by measuring simultaneously a macaque homologue of an event-related potential indexing the allocation of covert attention known as the m-N2pc. Based on recent work, we expected errors of selection in FEF to propagate to areas of extrastriate cortex responsible for allocating attention and implicated in the generation of the m-N2pc. Consistent with this prediction, we discovered that when FEF neurons selected a distractor instead of the search target, the m-N2pc shifted in the same, incorrect direction prior to the erroneous saccade. This suggests that such errors are due to a systematic misorienting of attention from the initial stages of visual processing. Our analyses also revealed distinct neural correlates of false alarms and guesses. These results demonstrate that errant gaze shifts during visual search arise from errant attentional processing.

scholarly journals Effect of Brightness of Visual Stimuli on EEG Signals

2019 ◽  
Author(s):  
Kübra Eroğlu ◽  
Temel Kayıkçıoğlu ◽  
Onur Osman
Keyword(s):  
Visual Processing ◽  
Time Window ◽  
Time Windows ◽  
Visual Stimuli ◽  
Average Power ◽  
Power Spectra ◽  
Brain Regions ◽  
Behavioral Data ◽  
Brain Responses ◽  
The Brain

The aim of this study was to examine brightness effect, which is the perceptual property of visual stimuli, on brain responses obtained during visual processing of these stimuli. For this purpose, brain responses of the brain to changes in brightness were explored comparatively using different emotional images (pleasant, unpleasant and neutral) with different luminance levels. Moreover, electroencephalography recordings from 12 different electrode sites of 31 healthy participants were used. The power spectra obtained from the analysis of the recordings using short time Fourier transform were analyzed, and a statistical analysis was performed on features extracted from these power spectra. Statistical findings obtained from electrophysiological data were compared with those obtained from behavioral data. The results showed that the brightness of visual stimuli affected the power of brain responses depending on frequency, time and location. According to the statistically verified findings, the distinctive effect of brightness occurred in the parietal and occipital regions for all the three types of stimuli. Accordingly, the increase in the brightness of pleasant and neutral images increased the average power of responses in the parietal and occipital regions whereas the increase in the brightness of unpleasant images decreased the average power of responses in these regions. However, the increase in brightness for all the three types of stimuli reduced the average power of frontal and central region responses (except for 100-300 ms time window for unpleasant stimuli). The statistical results obtained for unpleasant images were found to be in accordance with the behavioral data. The results also revealed that the brightness of visual stimuli could be represented by changing the activity power of the brain cortex. The main contribution of this research was to comprehensively examine brightness effect on brain activity for images with different emotional content and different frequency bands at different time windows of visual processing for different brain regions. The findings emphasized that the brightness of visual stimuli should be viewed as an important parameter in studies using emotional image techniques such as image classification, emotion evaluation and neuro-marketing.

scholarly journals Occipital activations and deactivations induced by stimulation of the right human frontal eye field

2010 ◽  
Vol 5 (8) ◽  
pp. 365-365
Author(s):  
C. C. Ruff ◽  
F. Blankenburg ◽  
O. Bjoertomt ◽  
S. Bestmann ◽  
J.-D. Haynes ◽  
...  
Keyword(s):  
Frontal Eye Field ◽  
Eye Field ◽  
The Right ◽  
Stimulation Of

scholarly journals Right frontal eye field has perceptual and oculomotor functions during optokinetic stimulation and nystagmus

2020 ◽  
Vol 123 (2) ◽  
pp. 571-586 ◽  
Author(s):  
Angela Mastropasqua ◽  
James Dowsett ◽  
Marianne Dieterich ◽  
Paul C. J. Taylor
Keyword(s):  
Eye Movements ◽  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Visual Motion ◽  
Optokinetic Nystagmus ◽  
Frontal Eye Field ◽  
Optokinetic Stimulation ◽  
Motion Discrimination ◽  
Eye Field ◽  
The Right

The right frontal eye field (rFEF) is associated with visual perception and eye movements. rFEF is activated during optokinetic nystagmus (OKN), a reflex that moves the eye in response to visual motion (optokinetic stimulation, OKS). It remains unclear whether rFEF plays causal perceptual and/or oculomotor roles during OKS and OKN. To test this, participants viewed a leftward-moving visual scene of vertical bars and judged whether a flashed dot was moving. Single pulses of transcranial magnetic stimulation (TMS) were applied to rFEF on half of trials. In half of blocks, to explore oculomotor control, participants performed an OKN in response to the OKS. rFEF TMS, during OKN, made participants more accurate on trials when the dot was still, and it slowed eye movements. In separate blocks, participants fixated during OKS. This not only controlled for eye movements but also allowed the use of EEG to explore the FEF’s role in visual motion discrimination. In these blocks, by contrast, leftward dot motion discrimination was impaired, associated with a disruption of the frontal-posterior balance in alpha-band oscillations. None of these effects occurred in a control site (M1) experiment. These results demonstrate multiple related yet dissociable causal roles of the right FEF during optokinetic stimulation. NEW & NOTEWORTHY This study demonstrates causal roles of the right frontal eye field (FEF) in motion discrimination and eye movement control during visual scene motion: previous work had only examined other stimuli and eye movements such as saccades. Using combined transcranial magnetic stimulation and EEG and a novel optokinetic stimulation motion-discrimination task, we find evidence for multiple related yet dissociable causal roles within the FEF: perceptual processing during optokinetic stimulation, generation of the optokinetic nystagmus, and the maintenance of alpha oscillations.

Visual Processing in the Macaque Frontal Eye Field

2003 ◽  
Author(s):  
Takashi Sato ◽  
Kirk Thompson ◽  
Jeffrey Schall ◽  
Aditya Murthy ◽  
Narcisse Bichot
Keyword(s):  
Visual Processing ◽  
Frontal Eye Field ◽  
Eye Field

scholarly journals Perceptual and motor processing stages identified in the activity of macaque frontal eye field neurons during visual search

1996 ◽  
Vol 76 (6) ◽  
pp. 4040-4055 ◽  
Author(s):  
K. G. Thompson ◽  
D. P. Hanes ◽  
N. P. Bichot ◽  
J. D. Schall
Keyword(s):  
Visual Search ◽  
Search Display ◽  
Saccade Latency ◽  
Frontal Eye Field ◽  
Visual Response ◽  
Response Latencies ◽  
Target Discrimination ◽  
Motor Processing ◽  
Eye Field ◽  
Saccade Programming

1. The latency between the appearance of a popout search display and the eye movement to the oddball target of the display varies from trial to trial in both humans and monkeys. The source of the delay and variability of reaction time is unknown but has been attributed to as yet poorly defined decision processes. 2. We recorded neural activity in the frontal eye field (FEF), an area regarded as playing a central role in producing purposeful eye movements, of monkeys (Macaca mulatta) performing a popout visual search task. Eighty-four neurons with visually evoked activity were analyzed. Twelve of these neurons had a phasic response associated with the presentation of the visual stimulus. The remaining neurons had more tonic responses that persisted through the saccade. Many of the neurons with more tonic responses resembled visuomovement cells in that they had activity that increased before a saccade into their response field. 3. The visual response latencies of FEF neurons were determined with the use of a Poisson spike train analysis. The mean visual latency was 67 ms (minimum = 35 ms, maximum = 138 ms). The visual response latencies to the target presented alone, to the target presented with distractors, or to the distractors did not differ significantly. 4. The initial visual activation of FEF neurons does not discriminate the target from the distractors of a popout visual search stimulus array, but the activity evolves to a state that discriminates whether the target of the search display is within the receptive field. We tested the hypothesis that the source of variability of saccade latency is the time taken by neurons involved in saccade programming to select the target for the gaze shift. 5. With the use of an analysis adapted from signal detection theory, we determined when the activity of single FEF neurons can reliably indicate whether the target or distractors are present within their response fields. The time of target discrimination partitions the reaction time into a perceptual stage in which target discrimination takes place, and a motor stage in which saccade programming and generation take place. The time of target discrimination occurred most often between 120 and 150 ms after stimulus presentation. 6. We analyzed the time course of target discrimination in the activity of single cells after separating trials into short, medium, and long saccade latency groups. Saccade latency was not correlated with the duration of the perceptual stage but was correlated with the duration of the motor stage. This result is inconsistent with the hypothesis that the time taken for target discrimination, as indexed by FEF neurons, accounts for the wide variability in the time of movement initiation. 7. We conclude that the variability observed in saccade latencies during a simple visual search task is largely due to postperceptual motor processing following target discrimination. Signatures of both perceptual and postperceptual processing are evident in FEF. Procrastination in the output stage may prevent stereotypical behavior that would be maladaptive in a changing environment.

The role of the right frontal eye field in overt visual attention deployment as assessed by free visual exploration

2015 ◽  
Vol 74 ◽  
pp. 37-41 ◽  
Author(s):  
Dario Cazzoli ◽  
Simon Jung ◽  
Thomas Nyffeler ◽  
Tobias Nef ◽  
Pascal Wurtz ◽  
...  
Keyword(s):  
Visual Attention ◽  
Visual Exploration ◽  
Frontal Eye Field ◽  
Eye Field ◽  
Attention Deployment ◽  
The Right

Some cognitive effects of frontal-lobe lesions in man

1982 ◽  
Vol 298 (1089) ◽  
pp. 211-226 ◽  
Keyword(s):  
Frontal Lobe ◽  
Focal Epilepsy ◽  
Cognitive Disorders ◽  
Oculomotor Control ◽  
Frontal Eye Field ◽  
Left Frontal Lobe ◽  
Environmental Signals ◽  
Eye Field ◽  
The Subject ◽  
The Right

The study of patients undergoing unilateral frontal-lobe excisions for the relief of focal epilepsy has revealed specific cognitive disorders that appear against a background of normal functioning on many intellectual, perceptual and memory tasks. Lesions that invade the frontal eye field cause subtle impairments of voluntary oculomotor control, which reveal themselves as an inability to suppress an initial glance at a potentially distracting stimulus. After frontal lobectomy in either hemisphere, deficits are found quite consistently on motor-differentiation tasks (Konorski 1972) in which the subject must learn to produce different responses to different, randomly presented, environmental signals. More directly related to the concept of planning are those sequential tasks in which the subject is free to choose his own order of responding, but must not make the same response twice. Here the left frontal lobe plays the major role, a finding consistent with the notion of left-hemisphere dominance for the programming of voluntary actions. In contrast, the right frontal lobe appears to be more critically involved in monitoring the temporal sequence of externally ordered events, although the verbal or non-verbal nature of the stimuli remains a relevant factor.

Transcranial Magnetic Stimulation of the Human Frontal Eye Field: Effects on Visual Perception and Attention

2002 ◽  
Vol 14 (7) ◽  
pp. 1109-1120 ◽  
Author(s):  
Marie-Hélène Grosbras ◽  
Tomáš Paus
Keyword(s):  
Eye Movements ◽  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Right Hemisphere ◽  
Visual Detection ◽  
Frontal Eye Field ◽  
Target Onset ◽  
Eye Field ◽  
The Right

When looking at one object, human subjects can shift their attention to another object in their visual field without moving the eyes. Such shifts of attention activate the same brain regions as those involved in the execution of eye movements. Here we investigate the role of one of the main cortical oculomotor area, namely, the frontal eye field (FEF), in shifts of attention. We used transcranial magnetic stimulation (TMS), a technique known to disrupt transiently eye-movements preparation. We hypothesized that if the FEF is a necessary element in the network involved in shifting attention without moving the eyes, then TMS should also disrupt visuospatial attention. For each volunteer, we positioned the TMS coil over the probabilistic anatomical location of the FEF, and we verified that single pulses delayed eye movements. We then applied TMS during a visuospatial attention task. In this task, a central arrow directed shifts of attention and the subject responded by a keypress to a subsequent visual peripheral target without moving the eyes from the central fixation point. In a few trials, the cue was invalid or uninformative, yielding slower responses than when the cue was valid. We delivered single pulses either 53 msec before or 70 msec after target onset. Contrary to our prediction, the main effect of the stimulation was a decrease in reaction time when it was applied 53 msec before target onset. TMS over the left hemisphere facilitated responses to targets in the right hemifield only and for all cueing conditions, whereas TMS over the right hemisphere had a bilateral effect for valid and neutral but not invalid cueing. Thus, TMS interfered with shift of attention only in the case of right hemisphere stimulation: it increased the cost of invalid cueing. Our results suggest that TMS over the FEF facilitates visual detection, and thereby reduces reaction time. This finding provides new insights into the role of the human FEF in processing visual information. The functional asymmetry observed for both facilitation of visual detection and interference with shifts of attention provides further evidence for the dominance of the right hemisphere for those processes. Our results also underline that the disruptive or facilitative effect of TMS over a given region depends upon the behavioral context.

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