scholarly journals Spatially Distributed Encoding of Covert Attentional Shifts in Human Thalamus

2010 ◽  
Vol 104 (6) ◽  
pp. 3644-3656 ◽  
Author(s):  
Oliver J. Hulme ◽  
Louise Whiteley ◽  
Stewart Shipp
Keyword(s):  
Visual Memory ◽  
Target Position ◽  
Covert Attention ◽  
Top Down ◽  
Human Thalamus ◽  
Spatially Distributed ◽  
Eye Field ◽  
Lateral Posterior ◽  
Attentional Shifts ◽  
Stimulus Offset

Spatial attention modulates signal processing within visual nuclei of the thalamus—but do other nuclei govern the locus of attention in top-down mode? We examined functional MRI (fMRI) data from three subjects performing a task requiring covert attention to 1 of 16 positions in a circular array. Target position was cued after stimulus offset, requiring subjects to perform target detection from iconic visual memory. We found positionally specific responses at multiple thalamic sites, with individual voxels activating at more than one direction of attentional shift. Voxel clusters at anatomically equivalent sites across subjects revealed a broad range of directional tuning at each site, with little sign of contralateral bias. By reference to a thalamic atlas, we identified the nuclear correspondence of the four most reliably activated sites across subjects: mediodorsal/central-intralaminar (oculomotor thalamus), caudal intralaminar/parafascicular, suprageniculate/limitans, and medial pulvinar/lateral posterior. Hence, the cortical network generating a top-down control signal for relocating attention acts in concert with a spatially selective thalamic apparatus—the set of active nuclei mirroring the thalamic territory of cortical “eye-field” areas, thus supporting theories which propose the visuomotor origins of covert attentional selection.

Caudal Prefrontal Cortex

2021 ◽  
pp. 153-190
Author(s):  
Richard E. Passingham
Keyword(s):  
Visual Search ◽  
Eye Movements ◽  
Covert Attention ◽  
Frontal Eye Field ◽  
Top Down ◽  
Cluttered Environment ◽  
Eye Field ◽  
Sensory Responses ◽  
Search For Objects ◽  
Oculomotor Nuclei

The caudal prefrontal (PF) cortex supports the visual search for objects such as foods both through eye movements and covert attention, and its connections explain how it can do this. The caudal PF cortex, which includes the frontal eye field, has connections with both the dorsal and ventral visual streams. The direction of eye movements depends on its connections with the superior colliculus and oculomotor nuclei. Covert attention depends on enhanced sensory responses that are mediated through top-down interactions with posterior sensory areas. Along with the granular parts of the orbital PF cortex, the caudal PF cortex evolved in early primates. Together, these two new areas led to improvements in searching for and evaluating objects that are hidden in a cluttered environment.

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 Integration of Eye-Centered and Landmark-Centered Codes in Frontal Eye Field Gaze Responses

2020 ◽  
Vol 30 (9) ◽  
pp. 4995-5013 ◽  
Author(s):  
Vishal Bharmauria ◽  
Amirsaman Sajad ◽  
Jirui Li ◽  
Xiaogang Yan ◽  
Hongying Wang ◽  
...  
Keyword(s):  
Frontal Cortex ◽  
Visual Information ◽  
Target Position ◽  
Frontal Eye Field ◽  
Visual Responses ◽  
Cellular Mechanisms ◽  
Behavioral Experiments ◽  
The Gaze ◽  
Field Activity ◽  
Eye Field

Abstract The visual system is thought to separate egocentric and allocentric representations, but behavioral experiments show that these codes are optimally integrated to influence goal-directed movements. To test if frontal cortex participates in this integration, we recorded primate frontal eye field activity during a cue-conflict memory delay saccade task. To dissociate egocentric and allocentric coordinates, we surreptitiously shifted a visual landmark during the delay period, causing saccades to deviate by 37% in the same direction. To assess the cellular mechanisms, we fit neural response fields against an egocentric (eye-centered target-to-gaze) continuum, and an allocentric shift (eye-to-landmark-centered) continuum. Initial visual responses best-fit target position. Motor responses (after the landmark shift) predicted future gaze position but embedded within the motor code was a 29% shift toward allocentric coordinates. This shift appeared transiently in memory-related visuomotor activity, and then reappeared in motor activity before saccades. Notably, fits along the egocentric and allocentric shift continua were initially independent, but became correlated across neurons just before the motor burst. Overall, these results implicate frontal cortex in the integration of egocentric and allocentric visual information for goal-directed action, and demonstrate the cell-specific, temporal progression of signal multiplexing for this process in the gaze system.

Visual-Tactile Bottom-Up and Top-Down Attention

2013 ◽  
pp. 183-191
Author(s):  
Qiong Wu ◽  
Chunlin Li ◽  
Satoshi Takahashi ◽  
Jinglong Wu
Keyword(s):  
Visual Attention ◽  
Brain Structure ◽  
Frontal Eye Field ◽  
Superior Parietal Lobule ◽  
Top Down ◽  
Bottom Up ◽  
Temporoparietal Junction ◽  
Tactile Attention ◽  
Eye Field ◽  
Processing Mechanism

In recent years, there have been many studies on attention. These studies have found that there are two distinct kinds of neural networks employed for visual attention and tactile attention, respectively. This review summarizes the processing mechanism of these attention-related brain networks. One type is the top-down attention related brain structure, which includes the IPs/SPL (intraparietal sulcus/superior parietal lobule)-FEF (frontal eye field). The other is the bottom-up attention related brain structure, which includes the TPJ (temporoparietal junction)-VFC (ventral frontal cortex). Regarding research into tactile attention, in conclusion, the authors found that tactile attention had a similar neural network to that of visual attention in that there was top-down attention to the relevant IPs-FEF and bottom-up attention to the relevant TPJ-VFC.

On the brink: The demise of the item in visual search moves closer

2017 ◽  
Vol 40 ◽  
Author(s):  
Johan Hulleman ◽  
Christian N. L. Olivers
Keyword(s):  
Visual Search ◽  
Visual Field ◽  
Covert Attention ◽  
Contextual Influences ◽  
Top Down ◽  
Future Directions ◽  
Current State

AbstractWe proposed to abandon the item as conceptual unit in visual search and adopt a fixation-based framework instead. We treat various themes raised by our commentators, including the nature of the Functional Visual Field and existing similar ideas, alongside the importance of items, covert attention, and top-down/contextual influences. We reflect on the current state of, and future directions for, visual search.

scholarly journals Lateralized Frontal Eye Field Activity Precedes Occipital Activity Shortly before Saccades: Evidence for Cortico-cortical Feedback as a Mechanism Underlying Covert Attention Shifts

2010 ◽  
Vol 22 (9) ◽  
pp. 1931-1943 ◽  
Author(s):  
Tjerk P. Gutteling ◽  
Helene M. van Ettinger-Veenstra ◽  
J. Leon Kenemans ◽  
Sebastiaan F. W. Neggers
Keyword(s):  
Visual Cortex ◽  
Discrimination Performance ◽  
Covert Attention ◽  
Saccade Target ◽  
Frontal Eye Field ◽  
Cortical Connections ◽  
Field Activity ◽  
Eye Field ◽  
Frontal Activity ◽  
Saccade Direction

When an eye movement is prepared, attention is shifted toward the saccade end-goal. This coupling of eye movements and spatial attention is thought to be mediated by cortical connections between the FEFs and the visual cortex. Here, we present evidence for the existence of these connections. A visual discrimination task was performed while recording the EEG. Discrimination performance was significantly improved when the discrimination target and the saccade target matched. EEG results show that frontal activity precedes occipital activity contralateral to saccade direction when the saccade is prepared but not yet executed; these effects were absent in fixation conditions. This is consistent with the idea that the FEF exerts a direct modulatory influence on the visual cortex and enhances perception at the saccade end-goal.

scholarly journals Feature-based and location-based volitional covert attention affect memory at different timescales

2019 ◽  
Author(s):  
Kirsten Ziman ◽  
Madeline R. Lee ◽  
Alejandro R. Martinez ◽  
Ethan D. Adner ◽  
Jeremy R. Manning
Keyword(s):  
Memory Task ◽  
Spatial Location ◽  
Attentional Focus ◽  
Covert Attention ◽  
Subjective Experiences ◽  
Attentional Resources ◽  
Attentional Shifts ◽  
Feature Based ◽  
Stimulus Features ◽  
Prior Experiences

Our ongoing subjective experiences, and our memories of those experiences, are shaped by our prior experiences, goals, and situational understanding. These factors shape how we allocate our attentional resources over different aspects of our ongoing experiences. These attentional shifts may happen overtly (e.g., when we change where we are looking) or covertly (e.g., without any explicit physical manifestation). Additionally, we may attend to what is happening at a specific spatial location (e.g., because we think something important is happening there) or we may attend to particular features irrespective of their locations (e.g., when we search for a friend's face in a crowd). We ran two covert attention experiments that differed in how long they asked participants to maintain the focus of the features or locations they were attending. Later, the participants performed a recognition memory task for attended, unattended, and novel stimuli. Participants were able to shift the location of their covert attentional focus more rapidly than they were able to shift their focus of covert attention to stimulus features, and the effects of location-based attention on memory were longer-lasting than the effects of feature-based attention.

Neural correlates of changing intention in the human FEF and IPS

2012 ◽  
Vol 107 (3) ◽  
pp. 859-867 ◽  
Author(s):  
Duncan E. Astle ◽  
Elena Nixon ◽  
Stephen R. Jackson ◽  
Georgina M. Jackson
Keyword(s):  
Event Related Potentials ◽  
Neural Correlates ◽  
Smooth Transition ◽  
Frontal Eye Field ◽  
Top Down ◽  
Mental Flexibility ◽  
Related Potentials ◽  
Eye Field ◽  
The Right ◽  
Prior Intention

Previous research demonstrates that our apparent mental flexibility depends largely on the strength of our prior intention; changing our intention in advance enables a smooth transition from one task to another (e.g., Astle DE, Jackson GM, Swainson R. J Cogn Neurosci 20: 255–267, 2008; Duncan J, Emslie H, Williams P, Johnson R, Freer C. Cogn Psychol 30: 257–303, 1996; Husain M, Parton A, Hodgson TL, Mort D, Rees G. Nat Neurosci 6: 117–118, 2003). However, these necessarily rapid anticipatory mechanisms have been difficult to study in the human brain. We used EEG and magnetoencephalography, specifically event-related potentials and fields (ERPs and ERFs), respectively, to explore the neural correlates of this important aspect of mental flexibility. Subjects performed a manual version of a pro/antisaccade task using preparatory cues to switch between the pro- and antirules. When subjects switched their intention, we observed a positivity over central electrodes, which correlated significantly with our behavioral data; the greater the ERP effect, the stronger the subject's change of intention. ERFs, alongside subject-specific structural MRIs, were used to project into source space. When subjects switched their intention, they showed significantly elevated activity in the right frontal eye field and left intraparietal sulcus (IPS); the greater the left IPS activity on switch trials, the stronger the subject's change of intention. This network has previously been implicated in the top-down control of eye movements, but here we demonstrate its role in the top-down control of a task set, in particular, that it is recruited when we change the task that we intend to perform.

Saccadic and attentional abnormalities in patients with schizophrenia

1998 ◽  
Vol 28 (5) ◽  
pp. 1091-1100 ◽  
Author(s):  
P. MARUFF ◽  
J. DANCKERT ◽  
C. PANTELIS ◽  
J. CURRIE
Keyword(s):  
Chronic Schizophrenia ◽  
Stimulus Onset ◽  
Error Rates ◽  
Covert Attention ◽  
Visually Guided ◽  
Antisaccade Task ◽  
Attentional Shifts ◽  
Abnormal Performance ◽  
Onset Asynchrony ◽  
Normal Performance

Background. Abnormal performance on the antisaccade task suggests that patients with schizophrenia have difficulty with the inhibition of reflexive attentional shifts. The aim of the study was to investigate whether deficits in the inhibition of reflexive attentional shifts were specific to the oculomotor modality or whether they could also occur when attentional shifts were made without eye movements (e.g. covert attentional shifts).Methods. Fifteen medicated patients with chronic schizophrenia and 15 matched controls performed the antisaccade task and the covert orientating task (COVAT) where the probability of targets appearing at the same location of a peripheral cue was varied so that voluntary and reflexive orientating systems had the same goal (80% probability of target and cued condition) or opposite goals (20%probability of target at cued location). A condition where only reflexive orientating was initiated was also included (50% probability of target at cued location). For each of these conditions the stimulus onset asynchrony (SOA) varied between 150 and 350 ms.Results. Patients with schizophrenia showed normal latency and accuracy for visually guided saccades but increased error rates and latency on the antisaccade task. For the COVAT, patients with schizophrenia were unable to use voluntary orientating strategies to inhibit reflexive shifts of covert attention. On conditions where only reflexive orientating was required or when the goals of the reflexive and voluntary orientating systems were the same, patients with schizophrenia showed normal performance.Conclusions. These results suggest the reflexive orientating mode is normal in patients with chronic schizophrenia. However, these patients have a reduced ability to utilize the voluntary orientating mode to control or inhibit reflexive orientating. This impairment of voluntary control is evident for both overt and covert attentional shifts.

Neuronal Mechanisms of Attentional Control

2014 ◽  
Author(s):  
Kelsey L. Clark ◽  
Behrad Noudoost ◽  
Robert J. Schafer ◽  
Tirin Moore
Keyword(s):  
Spatial Attention ◽  
Covert Attention ◽  
Extrastriate Cortex ◽  
Frontal Eye Field ◽  
Neural Signals ◽  
Electrical Microstimulation ◽  
Visual Spatial ◽  
Neuronal Mechanisms ◽  
Eye Field ◽  
Visual Cortical

Covert spatial attention prioritizes the processing of stimuli at a given peripheral location, away from the direction of gaze, and selectively enhances visual discrimination, speed of processing, contrast sensitivity, and spatial resolution at the attended location. While correlates of this type of attention, which are believed to underlie perceptual benefits, have been found in a variety of visual cortical areas, more recent observations suggest that these effects may originate from frontal and parietal areas. Evidence for a causal role in attention is especially robust for the Frontal Eye Field, an oculomotor area within the prefrontal cortex. FEF firing rates have been shown to reflect the location of voluntarily deployed covert attention in a variety of tasks, and these changes in firing rate precede those observed in extrastriate cortex. In addition, manipulation of FEF activity—whether via electrical microstimulation, pharmacologically, or operant conditioning—can produce attention-like effects on behaviour and can modulate neural signals within posterior visual areas. We review this evidence and discuss the role of the FEF in visual spatial attention.

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