scholarly journals Visual attention is available at a task-relevant location rapidly after a saccade

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Tao Yao ◽  
Madhura Ketkar ◽  
Stefan Treue ◽  
B Suresh Krishna
Keyword(s):  
Eye Movements ◽  
Spatial Attention ◽  
Spatial Location ◽  
Temporal Analysis ◽  
Neuronal Population ◽  
Attentional Modulation ◽  
Attention Task ◽  
Fine Grained ◽  
The One ◽  
Precise Time

Maintaining attention at a task-relevant spatial location while making eye-movements necessitates a rapid, saccade-synchronized shift of attentional modulation from the neuronal population representing the task-relevant location before the saccade to the one representing it after the saccade. Currently, the precise time at which spatial attention becomes fully allocated to the task-relevant location after the saccade remains unclear. Using a fine-grained temporal analysis of human peri-saccadic detection performance in an attention task, we show that spatial attention is fully available at the task-relevant location within 30 milliseconds after the saccade. Subjects tracked the attentional target veridically throughout our task: i.e. they almost never responded to non-target stimuli. Spatial attention and saccadic processing therefore co-ordinate well to ensure that relevant locations are attentionally enhanced soon after the beginning of each eye fixation.

scholarly journals Rhythmic neural spiking and attentional sampling arising from cortical receptive field interactions

2018 ◽  
Author(s):  
Ricardo Kienitz ◽  
Joscha T. Schmiedt ◽  
Katharine A. Shapcott ◽  
Kleopatra Kouroupaki ◽  
Richard C. Saunders ◽  
...  
Keyword(s):  
Eye Movements ◽  
Receptive Field ◽  
Spatial Attention ◽  
Receptive Fields ◽  
Reaction Times ◽  
List Type ◽  
Attention Task ◽  
Area V4 ◽  
Fixational Eye Movements ◽  
Visual Cortical Area

SummaryGrowing evidence suggests that distributed spatial attention may invoke theta (3-9 Hz) rhythmic sampling processes. The neuronal basis of such attentional sampling is however not fully understood. Here we show using array recordings in visual cortical area V4 of two awake macaques that presenting separate visual stimuli to the excitatory center and suppressive surround of neuronal receptive fields elicits rhythmic multi-unit activity (MUA) at 3-6 Hz. This neuronal rhythm did not depend on small fixational eye movements. In the context of a distributed spatial attention task, during which the monkeys detected a spatially and temporally uncertain target, reaction times (RT) exhibited similar rhythmic fluctuations. RTs were fast or slow depending on the target occurrence during high or low MUA, resulting in rhythmic MUA-RT cross-correlations at at theta frequencies. These findings suggest that theta-rhythmic neuronal activity arises from competitive receptive field interactions and that this rhythm may subserve attentional sampling.HighlightsCenter-surround interactions induce theta-rhythmic MUA of visual cortex neuronsThe MUA rhythm does not depend on small fixational eye movementsReaction time fluctuations lock to the neuronal rhythm under distributed attention

Multisensory Integration and Exogenous Spatial Attention: A Time-window-of-integration Analysis

2019 ◽  
Vol 31 (5) ◽  
pp. 699-710
Author(s):  
Adele Diederich ◽  
Hans Colonius
Keyword(s):  
Spatial Attention ◽  
Multisensory Integration ◽  
Time Window ◽  
Formal Analysis ◽  
Integration Model ◽  
Attention Task ◽  
Visual Spatial ◽  
Spatial Cuing ◽  
Formal Framework ◽  
The One

Although it is well documented that occurrence of an irrelevant and nonpredictive sound facilitates motor responses to a subsequent target light appearing nearby, the cause of this “exogenous spatial cuing effect” has been under discussion. On the one hand, it has been postulated to be the result of a shift of visual spatial attention possibly triggered by parietal and/or cortical supramodal “attention” structures. On the other hand, the effect has been considered to be due to multisensory integration based on the activation of multisensory convergence structures in the brain. Recent RT experiments have suggested that multisensory integration and exogenous spatial cuing differ in their temporal profiles of facilitation: When the nontarget occurs 100–200 msec before the target, facilitation is likely driven by crossmodal exogenous spatial attention, whereas multisensory integration effects are still seen when target and nontarget are presented nearly simultaneously. Here, we develop an extension of the time-window-of-integration model that combines both mechanisms within the same formal framework. The model is illustrated by fitting it to data from a focused attention task with a visual target and an auditory nontarget presented at horizontally or vertically varying positions. Results show that both spatial cuing and multisensory integration may coexist in a single trial in bringing about the crossmodal facilitation of RT effects. Moreover, the formal analysis via time window of integration allows to predict and quantify the contribution of either mechanism as they occur across different spatiotemporal conditions.

scholarly journals Cholinergic manipulations affect sensory responses but not attentional enhancement in macaque MT

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Vera Katharina Veith ◽  
Cliodhna Quigley ◽  
Stefan Treue
Keyword(s):  
Visual Cortex ◽  
Spatial Attention ◽  
Rhesus Monkeys ◽  
Cell Activity ◽  
Extrastriate Cortex ◽  
Attentional Modulation ◽  
Cellular Mechanisms ◽  
Attention Task ◽  
Sensory Responses ◽  
Cholinergic Effect

Abstract Background Attentional modulation in the visual cortex of primates is characterized by multiplicative changes of sensory responses with changes in the attentional state of the animal. The cholinergic system has been linked to such gain changes in V1. Here, we aim to determine if a similar link exists in macaque area MT. While rhesus monkeys performed a top-down spatial attention task, we locally injected a cholinergic agonist or antagonist and recorded single-cell activity. Results Although we confirmed cholinergic influences on sensory responses, there was no additional cholinergic effect on the attentional gain changes. Neither a muscarinic blockage nor a local increase in acetylcholine led to a significant change in the magnitude of spatial attention effects on firing rates. Conclusions This suggests that the cellular mechanisms of attentional modulation in the extrastriate cortex cannot be directly inferred from those in the primary visual cortex.

Visual Attention with Auditory Stimulus

2011 ◽  
pp. 28-36
Author(s):  
Shuo Zhao ◽  
Chunlin Li ◽  
Jinglong Wu ◽  
Hongbin Han ◽  
Dehua Chui
Keyword(s):  
Brain Imaging ◽  
Spatial Attention ◽  
Auditory Stimulus ◽  
Spatial Location ◽  
Imaging Data ◽  
Attention Task ◽  
Visual Spatial Attention ◽  
Visual Spatial ◽  
Visual Orienting ◽  
Brain Imaging Data

Visual orienting attention is best studied using visual cues. Spatial and temporal attention have been compared using brain-imaging data. This chapter’s authors developed a visual orienting attention tool to compare auditory when a visual target was presented. They also designed a control task in which subjects had to click on the response key consistent with a simultaneous spatial task. The effect of clicking the response key was removed by subtracting the brain activations elicited by clicking the response key from the results of the visual voluntary attention task. The authors then measured brain activity in sixteen healthy volunteers using functional magnetic resonance imaging (Coull, Frith, Büchel & Nobre, 2000). In the task, visual spatial attention was manipulated by a visual cue, and participants were told to ignore the auditory stimulus. A neutral task was also performed, in which a neutral cue was used. Symbolic central cues oriented subjects to spatial location only (Coull & Nobre, 1998) or gave no information about spatial location. Subjects were also scanned during a resting baseline condition in which they clicked the reaction key ten times. The reaction time for spatial location attention was faster than that without an auditory stimulus. Brain-imaging data showed that the inferior parietal lobe (IPL) and anterior cingulated cortex (ACC) were activated in the visual-spatial attention task and that the activation was enhanced during the task with the auditory stimulus.

Visual Spatial Attention in Migraine Sufferers in Postictal and Interictal Phases: An Event-Related Potential Study

2001 ◽  
Vol 15 (1) ◽  
pp. 22-34 ◽  
Author(s):  
D.H. de Koning ◽  
J.C. Woestenburg ◽  
M. Elton
Keyword(s):  
Cerebral Cortex ◽  
Visual Attention ◽  
Migraine Attack ◽  
Spatial Attention ◽  
Event Related Potential ◽  
Significant Enhancement ◽  
Pathophysiological Mechanism ◽  
Attention Task ◽  
Visual Spatial Attention ◽  
Visual Spatial

Migraineurs with and without aura (MWAs and MWOAs) as well as controls were measured twice with an interval of 7 days. The first session of recordings and tests for migraineurs was held about 7 hours after a migraine attack. We hypothesized that electrophysiological changes in the posterior cerebral cortex related to visual spatial attention are influenced by the level of arousal in migraineurs with aura, and that this varies over the course of time. ERPs related to the active visual attention task manifested significant differences between controls and both types of migraine sufferers for the N200, suggesting a common pathophysiological mechanism for migraineurs. Furthermore, migraineurs without aura (MWOAs) showed a significant enhancement for the N200 at the second session, indicating the relevance of time of measurement within migraine studies. Finally, migraineurs with aura (MWAs) showed significantly enhanced P240 and P300 components at central and parietal cortical sites compared to MWOAs and controls, which seemed to be maintained over both sessions and could be indicative of increased noradrenergic activity in MWAs.

scholarly journals Mineralogy, Geochemistry and Provenance of Coastal Sands from Greece: New Insights on the REE Content of Black Coastal Sands from Aggelochori Area, N.-Greece

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 693
Author(s):  
Argyrios Papadopoulos ◽  
Stylianos Lazaridis ◽  
Afroditi Kipourou-Panagiotou ◽  
Nikolaos Kantiranis ◽  
Antonios Koroneos ◽  
...  
Keyword(s):  
Major And Trace Elements ◽  
Heavy Minerals ◽  
Sea Waves ◽  
Complex Flow ◽  
Fine Grained ◽  
Microscopy Analysis ◽  
Beach Sands ◽  
Geochemical Analyses ◽  
The One ◽  
Black Color

Beach sands from Aggelochori coast line are investigated for their geochemistry and REE content, mineralogy and their provenance. These fluvial sands bear heavy minerals enriched horizons (containing minerals such as magnetite, zircon, ilmenite, hematite, rutile and titanite) that can be distinguished due to their black color and are formed usually due to the action of sea waves that deposit the heavy minerals and remove the lighter ones. After a suitable processing (washing, sieving, drying and magnetic separation) of the samples, the mineral constituents and their presence (wt.%) were estimated by XRD. Among the samples, the one being simultaneously the more fine grained and the more zircon-enriched (as suggested by XRPD data and optical microscopy analysis) has been selected for further geochemical analyses. The major and trace elements contents were compared to previously studied REE enriched beach sands from Kavala and Sithonia. Beach sands from Aggelochori area appear to have relatively low REE contents. Considering the provenance of these sediments, we suggest that these sands, are a product of the erosion of multi-sources, including the near-by Monopigado granite, as well as metamorphic rocks, as indicated by the presence of rutile and both ilmenite and magnetite in some samples. Therefore, there are indications of a complex flow pattern that existed at the paleo-catchment area of the deposition.

Spatial Attention and Eye Movements

2017 ◽  
pp. 159-196
Author(s):  
Stefan Van der Stigchel ◽  
Tanja C.W. Nijboer
Keyword(s):  
Eye Movements ◽  
Spatial Attention

Improving the Mechanical Properties of AZ31 Mg Alloy by High Ratio Extrusion

2006 ◽  
Vol 503-504 ◽  
pp. 865-870 ◽  
Author(s):  
Yongjun Chen ◽  
Qu Dong Wang ◽  
Jianguo Peng ◽  
Chun Quan Zhai
Keyword(s):  
Mechanical Properties ◽  
High Strength ◽  
High Ratio ◽  
Extrusion Ratio ◽  
Mg Alloy ◽  
Fine Grained ◽  
Az31 Mg Alloy ◽  
Industry Applications ◽  
One Step ◽  
The One

Experiments were conducted both to evaluate the potential for grain refinement, the subsequent mechanical properties at room temperature in samples of AZ31 Mg alloy and also to investigate the relationship between one-step and two-step high ratio extrusion (HRE). The one-step HRE was undertaken using a high extrusion ratio of 70:1 at 250, 300 and 350°C. And the two-step HRE was conducted with an extrusion ratio of 7 for the first step at 250, 300 and 350°C, followed by a second-step extrusion with an extrusion ratio of 10 at 250, 300 and 350°C. The initial grain size in the AZ31 ingot was 100μm and that after one-step HRE became similar to 5μm, after two-step HRE at 250, 300 and 350°C were 2, 4, 7μm, respectively, resulting in superior mechanical properties at ambient temperature. The microstructure of two-step HRE was finer and uniformer than that of one-step HRE and the strength of one-step and two-step HRE were similar, moreover, the elongation of one-step HRE was improved markedly than that of two-step HRE. Dynamic recrystallization and adjacent grain broking during HRE is introduced to explain the effects of one-step and two-step HRE on the microstructure and mechanical properties of AZ31 Mg alloy. The current results imply that the simple HRE method might be a feasible processing method for industry applications, and the multiply steps extrusion are effective to fabricate high strength of fine grained hcp metals.

scholarly journals Additive-error fine-grained quantum supremacy

Quantum ◽  
2020 ◽  
Vol 4 ◽  
pp. 329
Author(s):  
Tomoyuki Morimae ◽  
Suguru Tamaki
Keyword(s):  
Quantum Computing ◽  
Complexity Theory ◽  
Polynomial Time ◽  
Boolean Circuits ◽  
Exponential Time ◽  
Fine Grained ◽  
Additive Error ◽  
Universal Quantum ◽  
The One ◽  
Computing Models

It is known that several sub-universal quantum computing models, such as the IQP model, the Boson sampling model, the one-clean qubit model, and the random circuit model, cannot be classically simulated in polynomial time under certain conjectures in classical complexity theory. Recently, these results have been improved to ``fine-grained" versions where even exponential-time classical simulations are excluded assuming certain classical fine-grained complexity conjectures. All these fine-grained results are, however, about the hardness of strong simulations or multiplicative-error sampling. It was open whether any fine-grained quantum supremacy result can be shown for a more realistic setup, namely, additive-error sampling. In this paper, we show the additive-error fine-grained quantum supremacy (under certain complexity assumptions). As examples, we consider the IQP model, a mixture of the IQP model and log-depth Boolean circuits, and Clifford+T circuits. Similar results should hold for other sub-universal models.

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