scholarly journals Decoding and Reconstructing the Focus of Spatial Attention from the Topography of Alpha-band Oscillations

2016 ◽  
Vol 28 (8) ◽  
pp. 1090-1097 ◽  
Author(s):  
Jason Samaha ◽  
Thomas C. Sprague ◽  
Bradley R. Postle
Keyword(s):  
Spatial Attention ◽  
Sustained Attention ◽  
Spatial Location ◽  
Covert Attention ◽  
Alpha Power ◽  
Alpha Band ◽  
Temporal Precision ◽  
Neural Populations ◽  
Stimulus Features ◽  
Spatial Locations

Many aspects of perception and cognition are supported by activity in neural populations that are tuned to different stimulus features (e.g., orientation, spatial location, color). Goal-directed behavior, such as sustained attention, requires a mechanism for the selective prioritization of contextually appropriate representations. A candidate mechanism of sustained spatial attention is neural activity in the alpha band (8–13 Hz), whose power in the human EEG covaries with the focus of covert attention. Here, we applied an inverted encoding model to assess whether spatially selective neural responses could be recovered from the topography of alpha-band oscillations during spatial attention. Participants were cued to covertly attend to one of six spatial locations arranged concentrically around fixation while EEG was recorded. A linear classifier applied to EEG data during sustained attention demonstrated successful classification of the attended location from the topography of alpha power, although not from other frequency bands. We next sought to reconstruct the focus of spatial attention over time by applying inverted encoding models to the topography of alpha power and phase. Alpha power, but not phase, allowed for robust reconstructions of the specific attended location beginning around 450 msec postcue, an onset earlier than previous reports. These results demonstrate that posterior alpha-band oscillations can be used to track activity in feature-selective neural populations with high temporal precision during the deployment of covert spatial attention.

scholarly journals Spatiotemporal dynamics of auditory attention synchronize with speech

2016 ◽  
Vol 113 (14) ◽  
pp. 3873-3878 ◽  
Author(s):  
Malte Wöstmann ◽  
Björn Herrmann ◽  
Burkhard Maess ◽  
Jonas Obleser
Keyword(s):  
Spatial Attention ◽  
Time Course ◽  
Speech Rate ◽  
Temporal Structure ◽  
Low Frequency ◽  
Spatial Location ◽  
Brain Regions ◽  
Hemispheric Lateralization ◽  
Speech Comprehension ◽  
Alpha Power

Attention plays a fundamental role in selectively processing stimuli in our environment despite distraction. Spatial attention induces increasing and decreasing power of neural alpha oscillations (8–12 Hz) in brain regions ipsilateral and contralateral to the locus of attention, respectively. This study tested whether the hemispheric lateralization of alpha power codes not just the spatial location but also the temporal structure of the stimulus. Participants attended to spoken digits presented to one ear and ignored tightly synchronized distracting digits presented to the other ear. In the magnetoencephalogram, spatial attention induced lateralization of alpha power in parietal, but notably also in auditory cortical regions. This alpha power lateralization was not maintained steadily but fluctuated in synchrony with the speech rate and lagged the time course of low-frequency (1–5 Hz) sensory synchronization. Higher amplitude of alpha power modulation at the speech rate was predictive of a listener’s enhanced performance of stream-specific speech comprehension. Our findings demonstrate that alpha power lateralization is modulated in tune with the sensory input and acts as a spatiotemporal filter controlling the read-out of sensory content.

scholarly journals Hemispheric asymmetry of globus pallidus relates to alpha modulation in reward-related attentional tasks

2018 ◽  
Author(s):  
C. Mazzetti ◽  
T. Staudigl ◽  
T. R. Marshall ◽  
J. M. Zumer ◽  
S. J. Fallon ◽  
...  
Keyword(s):  
Spatial Attention ◽  
Globus Pallidus ◽  
Alpha Activity ◽  
Hemispheric Lateralization ◽  
Monetary Reward ◽  
Alpha Power ◽  
Alpha Band ◽  
Subcortical Structures ◽  
Attention Task ◽  
Subcortical Regions

AbstractWhile subcortical structures like the basal ganglia have been widely explored in relation to motor control, recent evidence suggests that their mechanisms extend to the domain of attentional switching. We here investigated the subcortical involvement in reward related top-down control of visual alpha-band oscillations (8 – 13 Hz), which have been consistently linked to mechanisms supporting the allocation of visuo-spatial attention. Given that items associated with contextual saliency (e.g. monetary reward or loss) attract attention, it is not surprising that the acquired salience of visual items further modulates. The executive networks controlling such reward-dependent modulations of oscillatory brain activity have yet to be fully elucidated. Although such networks have been explored in terms of cortico-cortical interactions, subcortical regions are likely to be involved. To uncover this, we combined MRI and MEG data from 17 male and 11 female participants, investigating whether derived measures of subcortical structural asymmetries predict interhemispheric modulation of alpha power during a spatial attention task. We show that volumetric hemispheric lateralization of globus pallidus (GP) and thalamus (Th) explains individual hemispheric biases in the ability to modulate posterior alpha power. Importantly, for the GP, this effect became stronger when the value-saliency parings in the task increased. Our findings suggest that the GP and Th in humans are part of a subcortical executive control network, differentially involved in modulating posterior alpha activity in the presence of saliency. Further investigation aimed at uncovering the interaction between subcortical and neocortical attentional networks would provide useful insight in future studies.Significance statementWhile the involvement of subcortical regions into higher level cognitive processing, such as attention and reward attribution, has been already indicated in previous studies, little is known about its relationship with the functional oscillatory underpinnings of said processes. In particular, interhemispheric modulation of alpha band (8-13Hz) oscillations, as recorded with magnetoencephalography (MEG), has been previously shown to vary as a function of salience (i.e. monetary reward/loss) in a spatial attention task. We here provide novel insights into the link between subcortical and cortical control of visual attention. Using the same reward-related spatial attention paradigm, we show that the volumetric lateralization of subcortical structures (specifically Globus Pallidus and Thalamus) explains individual biases in the modulation of visual alpha activity.

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.

scholarly journals Alpha oscillations do not implement gain control in early visual cortex but rather gating in parieto-occipital regions

2020 ◽  
Author(s):  
Alexander Zhigalov ◽  
Ole Jensen
Keyword(s):  
Visual Cortex ◽  
Spatial Attention ◽  
Neuronal Excitability ◽  
Brain Activity ◽  
Gain Control ◽  
Alpha Power ◽  
Alpha Band ◽  
Alpha Oscillations ◽  
Early Visual Cortex ◽  
Broadband Frequency

AbstractSpatial attention provides a mechanism for respectively enhancing relevant and suppressing irrelevant information. While it is well-established that attention modulates oscillations in the alpha band, it remains unclear if alpha oscillations are involved in directly modulating the neuronal excitability associated with the allocation of spatial attention. In this study in humans, we utilized a novel broadband frequency (60 – 70 Hz) tagging paradigm to quantify neuronal excitability in relation to alpha oscillations in a spatial attention paradigm. We used magnetoencephalography to characterize ongoing brain activity as it allows for localizing the sources of both the alpha and frequency tagging responses. We found that attentional modulation of alpha power and the frequency tagging response are uncorrelated over trials. Importantly, the neuronal sources of the tagging response were localized in early visual cortex (V1) whereas the sources of the alpha activity were identified around parieto-occipital sulcus. Moreover, we found that attention did not modulate the latency of the frequency tagged responses. Our findings point to alpha band oscillations serving a downstream gating role rather than implementing gain control of excitability in early visual regions.Significance StatementBy combining magnetoencephalography and a novel broadband frequency tagging approach, we show that spatial attention differently modulates alpha oscillations and neuronal excitability. Importantly, the sources of the alpha oscillations and tagging responses were spatially distinct and the alpha power and tagging response were not related over trials. These results are inconsistent with previous ideas suggesting that alpha oscillations are involved in gain control of early sensory regions; rather alpha oscillations are involved in the allocation of neuronal resources in downstream regions.

scholarly journals Conceptual content in images triggers rapid shifts of covert attention

2018 ◽  
Author(s):  
Brad Wyble ◽  
Michael Hess ◽  
Chloe Callahan-Flintoft ◽  
Charles Folk
Keyword(s):  
Spatial Attention ◽  
Spatial Location ◽  
Natural Images ◽  
Covert Attention ◽  
Behavioral Experiment ◽  
Natural Image ◽  
Conceptual Content ◽  
Conceptual Information ◽  
Target Set ◽  
Target Sets

AbstractThe visual system can use conceptual information to search for targets even in the absence of clear featural signifiers1, and visual saccades are often directed at target objects defined by conceptual content2. These abilities are a core component of our facility with the visual world. Here, we evaluate whether contingent mechanisms of visual attention, known to trigger in response to target features such as motion, color or luminance3, are also triggered by visual patterns that match conceptually specified categories. These pre-registered experiments provide convergent behavioral and electrophysiological support that covert spatial attention is rapidly triggered by natural image exemplars from superordinate conceptually described target sets such as dinner food or four-legged animal, even when each target was viewed only once. In the behavioral experiment when two targets were presented with onsets separated by only 167ms, subjects reported the second target more often when it was in the same spatial location as the first. In the EEG experiment, images elicited clear N2pc and P3 components only when they matched the conceptually specified target set. The latency of the N2pc peaked at roughly 250ms, which is comparable to that commonly found in other N2pc studies for simpler stimulus types. These results suggest that vision quickly decodes conceptual information from natural images and selectively deploys spatial attention to locations containing information that matches current search goals.

Dynamic Visual Noise Affects Visual Short-Term Memory for Surface Color, but not Spatial Location

2010 ◽  
Vol 57 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Kevin Dent
Keyword(s):  
Short Term Memory ◽  
Spatial Location ◽  
Visual Noise ◽  
Dynamic Visual Noise ◽  
Short Term ◽  
Surface Color ◽  
Term Memory ◽  
Visual Short Term Memory ◽  
Experimental Tool ◽  
Spatial Locations

In two experiments participants retained a single color or a set of four spatial locations in memory. During a 5 s retention interval participants viewed either flickering dynamic visual noise or a static matrix pattern. In Experiment 1 memory was assessed using a recognition procedure, in which participants indicated if a particular test stimulus matched the memorized stimulus or not. In Experiment 2 participants attempted to either reproduce the locations or they picked the color from a whole range of possibilities. Both experiments revealed effects of dynamic visual noise (DVN) on memory for colors but not for locations. The implications of the results for theories of working memory and the methodological prospects for DVN as an experimental tool are discussed.

scholarly journals Frontal eye field microstimulation induces task-dependent gamma oscillations in the lateral intraparietal area

2012 ◽  
Vol 108 (5) ◽  
pp. 1392-1402 ◽  
Author(s):  
Elsie Premereur ◽  
Wim Vanduffel ◽  
Pieter R. Roelfsema ◽  
Peter Janssen
Keyword(s):  
Spatial Attention ◽  
Field Potential ◽  
Gamma Oscillations ◽  
Oculomotor Control ◽  
Saccade Target ◽  
Frontal Eye Field ◽  
Alpha Power ◽  
Lateral Intraparietal Area ◽  
Electrical Microstimulation ◽  
Gamma Power

Macaque frontal eye fields (FEF) and the lateral intraparietal area (LIP) are high-level oculomotor control centers that have been implicated in the allocation of spatial attention. Electrical microstimulation of macaque FEF elicits functional magnetic resonance imaging (fMRI) activations in area LIP, but no study has yet investigated the effect of FEF microstimulation on LIP at the single-cell or local field potential (LFP) level. We recorded spiking and LFP activity in area LIP during weak, subthreshold microstimulation of the FEF in a delayed-saccade task. FEF microstimulation caused a highly time- and frequency-specific, task-dependent increase in gamma power in retinotopically corresponding sites in LIP: FEF microstimulation produced a significant increase in LIP gamma power when a saccade target appeared and remained present in the LIP receptive field (RF), whereas less specific increases in alpha power were evoked by FEF microstimulation for saccades directed away from the RF. Stimulating FEF with weak currents had no effect on LIP spike rates or on the gamma power during memory saccades or passive fixation. These results provide the first evidence for task-dependent modulations of LFPs in LIP caused by top-down stimulation of FEF. Since the allocation and disengagement of spatial attention in visual cortex have been associated with increases in gamma and alpha power, respectively, the effects of FEF microstimulation on LIP are consistent with the known effects of spatial attention.

Occipitoparietal alpha-band responses to the graded allocation of top-down spatial attention

2014 ◽  
Vol 112 (6) ◽  
pp. 1307-1316 ◽  
Author(s):  
Isabel Dombrowe ◽  
Claus C. Hilgetag
Keyword(s):  
Visual Field ◽  
Spatial Attention ◽  
Brain Regions ◽  
Alpha Band ◽  
Top Down ◽  
Attentional Resources ◽  
Parietal Lobes ◽  
Visual Spatial ◽  
Entire Visual Field ◽  
Band Activity

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.

scholarly journals Passive sensorimotor stimulation triggers long lasting alpha-band fluctuations in visual perception

2018 ◽  
Vol 119 (2) ◽  
pp. 380-388 ◽  
Author(s):  
Alice Tomassini ◽  
Alessandro D’Ausilio
Keyword(s):  
Visual Perception ◽  
Median Nerve ◽  
Movement Planning ◽  
Sensorimotor System ◽  
Alpha Power ◽  
Alpha Band ◽  
Movement Initiation ◽  
Visual Contrast ◽  
Sensorimotor Processes ◽  
Stimulation Of

Movement planning and execution rely on the anticipation and online control of the incoming sensory input. Evidence suggests that sensorimotor processes may synchronize visual rhythmic activity in preparation of action performance. Indeed, we recently reported periodic fluctuations of visual contrast sensitivity that are time-locked to the onset of an intended movement of the arm. However, the origin of the observed visual modulations has so far remained unclear because of the endogenous (and thus temporally undetermined) activation of the sensorimotor system that is associated with voluntary movement initiation. In this study, we activated the sensorimotor circuitry involved in the hand control in an exogenous and controlled way by means of peripheral stimulation of the median nerve and characterized the spectrotemporal dynamics of the ensuing visual perception. The stimulation of the median nerve triggers robust and long-lasting (∼1 s) alpha-band oscillations in visual perception, whose strength is temporally modulated in a way that is consistent with the changes in alpha power described at the neurophysiological level after sensorimotor stimulation. These findings provide evidence in support of a causal role of the sensorimotor system in modulating oscillatory activity in visual areas with consequences for visual perception. NEW & NOTEWORTHY This study shows that the peripheral activation of the somatomotor hand system triggers long-lasting alpha periodicity in visual perception. This demonstrates that not only the endogenous sensorimotor processes involved in movement preparation but also the passive stimulation of the sensorimotor system can synchronize visual activity. The present work suggests that oscillation-based mechanisms may subserve core (task independent) sensorimotor integration functions.

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

2018 ◽  
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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