Oscillatory Alpha-Band Mechanisms and the Deployment of Spatial Attention to Anticipated Auditory and Visual Target Locations: Supramodal or Sensory-Specific Control Mechanisms?

The voluntary, top-down allocation of visual spatial attention has been linked to changes in the alpha-band of the electroencephalogram (EEG) signal measured over occipital and parietal lobes. In the present study, we investigated how occipitoparietal alpha-band activity changes when people allocate their attentional resources in a graded fashion across the visual field. We asked participants to either completely shift their attention into one hemifield, to balance their attention equally across the entire visual field, or to attribute more attention to one-half of the visual field than to the other. As expected, we found that alpha-band amplitudes decreased stronger contralaterally than ipsilaterally to the attended side when attention was shifted completely. Alpha-band amplitudes decreased bilaterally when attention was balanced equally across the visual field. However, when participants allocated more attentional resources to one-half of the visual field, this was not reflected in the alpha-band amplitudes, which just decreased bilaterally. We found that the performance of the participants was more strongly reflected in the coherence between frontal and occipitoparietal brain regions. We conclude that low alpha-band amplitudes seem to be necessary for stimulus detection. Furthermore, complete shifts of attention are directly reflected in the lateralization of alpha-band amplitudes. In the present study, a gradual allocation of visual attention across the visual field was only indirectly reflected in the alpha-band activity over occipital and parietal cortexes.

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“Motor Oblique Effect”: Perceptual Direction Discrimination and Pointing to Memorized Visual Targets Share the Same Preference for Cardinal Orientations

Journal of Neurophysiology ◽

10.1152/jn.00515.2006 ◽

2007 ◽

Vol 97 (2) ◽

pp. 1068-1077 ◽

Cited By ~ 16

Author(s):

Nikolaos Smyrnis ◽

Asimakis Mantas ◽

Ioannis Evdokimidis

Keyword(s):

Visual Target ◽

Motor Task ◽

Oblique Effect ◽

Quadratic Function ◽

Initial Direction ◽

Direction Discrimination ◽

Pointing Movements ◽

Equivalent Measure ◽

Visual Targets ◽

Target Locations

In previous studies we observed a pattern of systematic directional errors when humans pointed to memorized visual target locations in two-dimensional (2-D) space. This directional error was also observed in the initial direction of slow movements toward visual targets or movements to kinesthetically defined targets in 2-D space. In this study we used a perceptual experiment where subjects decide whether an arrow points in the direction of a visual target in 2-D space and observed a systematic distortion in direction discrimination known as the “oblique effect.” More specifically, direction discrimination was better for cardinal directions than for oblique. We then used an equivalent measure of direction discrimination in a task where subjects pointed to memorized visual target locations and showed the presence of a motor oblique effect. We finally modeled the oblique effect in the perceptual and motor task using a quadratic function. The model successfully predicted the observed direction discrimination differences in both tasks and, furthermore, the parameter of the model that was related to the shape of the function was not different between the motor and the perceptual tasks. We conclude that a similarly distorted representation of target direction is present for memorized pointing movements and perceptual direction discrimination.

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Modulation of cardiovascular control mechanisms and their interaction

Physiological Reviews ◽

10.1152/physrev.1996.76.1.193 ◽

1996 ◽

Vol 76 (1) ◽

pp. 193-244 ◽

Cited By ~ 126

Author(s):

P. B. Persson

Keyword(s):

Nitric Oxide ◽

Black Box ◽

Control Element ◽

Control Mechanisms ◽

Severity Of Disease ◽

The Brain ◽

Specific Control ◽

Central Level ◽

Shed Light

It is generally held that the role of a specific control element can only be understood within its physiological environment. The reviewed studies make it clear that there is a potent interplay between locally produced substances such as adenosine, nitric oxide, prostaglandins, and various others all interacting with the central level of control. This can occur at central sites (e.g., nitric oxide in the brain) or in the periphery (e.g., neural influence on autoregulation). The interactions are more or less pronounced during specific physiological challenges. Furthermore, several of these interactions are altered under pathological circumstances, and in some cases, the interactions seem to maintain or even augment the severity of disease. When more than three parameters participate in an interaction, the resulting regulation may become extremely complex. If these parameters are nonlinearly coupled with each other, the only way to shed light onto the nature of control network is by treating it as a black box. With the use of spectral analysis or nonlinear methods, it is possible to disentangle the fundamental nature of the system in terms of the complexity and stability. Therefore, modern developments in cardiovascular physiology utilizing these techniques, some of which are derived from the "chaos theory," are reviewed.

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Stimulus-driven brain rhythms within the alpha band: The attentional-modulation conundrum

10.1101/336941 ◽

2018 ◽

Cited By ~ 2

Author(s):

Christian Keitel ◽

Anne Keitel ◽

Christopher SY Benwell ◽

Christoph Daube ◽

Gregor Thut ◽

...

Keyword(s):

Spatial Attention ◽

Visual Processing ◽

Visual Stimulation ◽

Brain Activity ◽

Gain Control ◽

Sensory Stimulation ◽

Alpha Band ◽

Visual Evoked Response ◽

Brain Rhythms ◽

Inhibitory Function

Two largely independent research lines use rhythmic sensory stimulation to study visual processing. Despite the use of strikingly similar experimental paradigms, they differ crucially in their notion of the stimulus-driven periodic brain responses: One regards them mostly as synchronised (entrained) intrinsic brain rhythms; the other assumes they are predominantly evoked responses (classically termed steady-state responses, or SSRs) that add to the ongoing brain activity. This conceptual difference can produce contradictory predictions about, and interpretations of, experimental outcomes. The effect of spatial attention on brain rhythms in the alpha-band (8-13 Hz) is one such instance: alpha-range SSRs have typically been found to increase in power when participants focus their spatial attention on laterally presented stimuli, in line with a gain control of the visual evoked response. In nearly identical experiments, retinotopic decreases in entrained alpha-band power have been reported, in line with the inhibitory function of intrinsic alpha. Here we reconcile these contradictory findings by showing that they result from a small but far-reaching difference between two common approaches to EEG spectral decomposition. In a new analysis of previously published EEG data, recorded during bilateral rhythmic visual stimulation, we find the typical SSR gain effect when emphasising stimulus-locked neural activity and the typical retinotopic alpha suppression when focusing on ongoing rhythms. These opposite but parallel effects suggest that spatial attention may bias the neural processing of dynamic visual stimulation via two complementary neural mechanisms.

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Multiple replication origins with diverse control mechanisms in Haloarcula hispanica

Nucleic Acids Research ◽

10.1093/nar/gkt1214 ◽

2013 ◽

Vol 42 (4) ◽

pp. 2282-2294 ◽

Cited By ~ 21

Author(s):

Zhenfang Wu ◽

Jingfang Liu ◽

Haibo Yang ◽

Hailong Liu ◽

Hua Xiang

Keyword(s):

Replication Initiation ◽

Control Mechanisms ◽

Replication Origins ◽

Dna Mutation ◽

Genome Wide ◽

Marker Frequency ◽

Haloarcula Hispanica ◽

Specific Control ◽

Main Chromosome ◽

Multiple Replication

Abstract The use of multiple replication origins in archaea is not well understood. In particular, little is known about their specific control mechanisms. Here, we investigated the active replication origins in the three replicons of a halophilic archaeon, Haloarcula hispanica, by extensive gene deletion, DNA mutation and genome-wide marker frequency analyses. We revealed that individual origins are specifically dependent on their co-located cdc6 genes, and a single active origin/cdc6 pairing is essential and sufficient for each replicon. Notably, we demonstrated that the activities of oriC1 and oriC2, the two origins on the main chromosome, are differently controlled. A G-rich inverted repeat located in the internal region between the two inverted origin recognition boxes (ORBs) plays as an enhancer for oriC1, whereas the replication initiation at oriC2 is negatively regulated by an ORB-rich region located downstream of oriC2-cdc6E, likely via Cdc6E-titrating. The oriC2 placed on a plasmid is incompatible with the wild-type (but not the ΔoriC2) host strain, further indicating that strict control of the oriC2 activity is important for the cell. This is the first report revealing diverse control mechanisms of origins in haloarchaea, which has provided novel insights into the use and coordination of multiple replication origins in the domain of Archaea.

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Human intestinal epithelial cell survival: differentiation state-specific control mechanisms

AJP Cell Physiology ◽

10.1152/ajpcell.2001.280.6.c1540 ◽

2001 ◽

Vol 280 (6) ◽

pp. C1540-C1554 ◽

Cited By ~ 68

Author(s):

Rémy Gauthier ◽

Charlène Harnois ◽

Jean-François Drolet ◽

John C. Reed ◽

Anne Vézina ◽

...

Keyword(s):

Epithelial Cell ◽

Cell Survival ◽

Intestinal Epithelial Cell ◽

The State ◽

Control Mechanisms ◽

Intestinal Epithelial ◽

Human Intestinal Epithelial Cell ◽

Expression Levels ◽

Specific Control

To investigate whether human intestinal epithelial cell survival involves distinct control mechanisms depending on the state of differentiation, we analyzed the in vitro effects of insulin, pharmacological inhibitors of Fak, MEK/Erk, and PI3-K/Akt, and integrin (β1, β4)-blocking antibodies on the survival of the well-established human Caco-2 enterocyte-like and HIEC-6 cryptlike cell models. In addition, relative expression levels of six Bcl-2 homologs (Bcl-2, Bcl-XL, Mcl-1, Bax, Bak, and Bad) and activation levels of Fak, Erk-2, and Akt were analyzed. Herein, we report that 1) the enterocytic differentiation process results in the establishment of distinct profiles of Bcl-2 homolog expression levels, as well as p125Fak, p42Erk-2, and p57Aktactivated levels; 2) the inhibition of Fak, of the MEK/Erk pathway, or of PI3-K, have distinct impacts on enterocytic cell survival in undifferentiated (subconfluent Caco-2, confluent HIEC-6) and differentiated (30 days postconfluent Caco-2) cells; 3) exposure to insulin and the inhibition of Fak, MEK, and PI3-K resulted in differentiation state-distinct modulations in the expression of each Bcl-2 homolog analyzed; and 4) Fak, β1 and β4 integrins, as well as the MEK/Erk and PI3-K/Akt pathways, are distinctively involved in cell survival depending on the state of cell differentiation. Taken together, these data indicate that human intestinal epithelial cell survival is regulated according to differentiation state-specific control mechanisms.

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Interactions between Voluntary and Stimulus-driven Spatial Attention Mechanisms across Sensory Modalities

Journal of Cognitive Neuroscience ◽

10.1162/jocn.2008.21178 ◽

2009 ◽

Vol 21 (12) ◽

pp. 2384-2397 ◽

Cited By ~ 31

Author(s):

Valerio Santangelo ◽

Marta Olivetti Belardinelli ◽

Charles Spence ◽

Emiliano Macaluso

Keyword(s):

Spatial Attention ◽

Auditory Stimulus ◽

Attentional Control ◽

Spatial Information ◽

Visual Target ◽

Exogenous Attention ◽

Physiological Basis ◽

Sensory Modalities ◽

Visual Targets ◽

Task Irrelevant

In everyday life, the allocation of spatial attention typically entails the interplay between voluntary (endogenous) and stimulus-driven (exogenous) attention. Furthermore, stimuli in different sensory modalities can jointly influence the direction of spatial attention, due to the existence of cross-sensory links in attentional control. Using fMRI, we examined the physiological basis of these interactions. We induced exogenous shifts of auditory spatial attention while participants engaged in an endogenous visuospatial cueing task. Participants discriminated visual targets in the left or right hemifield. A central visual cue preceded the visual targets, predicting the target location on 75% of the trials (endogenous visual attention). In the interval between the endogenous cue and the visual target, task-irrelevant nonpredictive auditory stimuli were briefly presented either in the left or right hemifield (exogenous auditory attention). Consistent with previous unisensory visual studies, activation of the ventral fronto-parietal attentional network was observed when the visual targets were presented at the uncued side (endogenous invalid trials, requiring visuospatial reorienting), as compared with validly cued targets. Critically, we found that the side of the task-irrelevant auditory stimulus modulated these activations, reducing spatial reorienting effects when the auditory stimulus was presented on the same side as the upcoming (invalid) visual target. These results demonstrate that multisensory mechanisms of attentional control can integrate endogenous and exogenous spatial information, jointly determining attentional orienting toward the most relevant spatial location.

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Involuntary Listening Aids Seeing: Evidence From Human Electrophysiology

Psychological Science ◽

10.1111/1467-9280.00233 ◽

2000 ◽

Vol 11 (2) ◽

pp. 167-171 ◽

Cited By ~ 87

Author(s):

John J. McDonald ◽

Lawrence M. Ward

Keyword(s):

Visual Cortex ◽

Spatial Attention ◽

Sensory Processing ◽

Visual Target ◽

Modal Interactions ◽

Neural Basis ◽

Brain Potentials ◽

Attention Orienting ◽

Irrelevant Sound ◽

Human Electrophysiology

It is well known that sensory events of one modality can influence judgments of sensory events in other modalities. For example, people respond more quickly to a target appearing at the location of a previous cue than to a target appearing at another location, even when the two stimuli are from different modalities. Such cross-modal interactions suggest that involuntary spatial attention mechanisms are not entirely modality-specific. In the present study, event-related brain potentials (ERPs) were recorded to elucidate the neural basis and timing of involuntary, cross-modal spatial attention effects. We found that orienting spatial attention to an irrelevant sound modulates the ERP to a subsequent visual target over modality-specific, extrastriate visual cortex, but only after the initial stages of sensory processing are completed. These findings are consistent with the proposal that involuntary spatial attention orienting to auditory and visual stimuli involves shared, or at least linked, brain mechanisms.

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