Biology subjects

Redding, Z. V.

Publications and source records attributed to Redding, Z. V..

3 recordsLinked to original sources

bioRxiv2025

Attention-related sampling of targets rhythmically alternates with increased susceptibility to co-occurring distractors

The Rhythmic Theory of Attention proposes that visual spatial attention is characterized by alternating states that promote either sampling at the present focus of attention or a higher likelihood of shifting attentional resources to another location. While theta-rhythmically (4-8 Hz) occurring windows of opportunity for shifting attentional resources might provide cognitive flexibility, these windows might also make us more susceptible to distractors. Here, we used EEG in humans to test how frequency-specific neural activity phasically influences behavioral performance and visual processing when high-contrast distractors co-occur with low-contrast targets. For trials with and without distractors, perceptual sensitivity at the cued target location depended on pre-stimulus theta phase ([~]7 Hz) recorded at central electrodes. For trials with distractors, there was a greater increase in false alarm rates at the same theta phase associated with lower hit rates (i.e., during the proposed shifting state), confirming theta-rhythmically occurring windows of increased susceptibility to distractors. In addition to these phase-behavior effects at central electrodes, we observed phase-behavior effects at frontocentral and occipital electrodes that (i) only occurred on trials with distractors, (ii) peaked in the alpha-frequency range ([~]9- 10 Hz) and (iii) were strongest at occipital electrodes that were contralateral to distractors. Alpha phase at these electrodes was also associated with fluctuations in the amplitude of distractor-evoked visual responses, consistent with an alpha-mediated gating of distractors. The present findings thus provide evidence for distinct theta- and alpha-mediated mechanisms of spatial attention that phasically modulate the influence of distractors on task performance. SignificanceThe Rhythmic Theory of Attention proposes that spatial attention is characterized by alternating states that promote either sampling at the present focus of attention or a higher likelihood of shifting attentional resources to another location. These alternating attentional states are associated with dynamic changes in attention-related neural and behavioral effects, occurring on a timescale in the theta-frequency range (4-8 Hz). Although interdigitated windows for shifting attentional resources might provide critical cognitive flexibility, they might also lead to an increased susceptibility to distractors. Here, we demonstrate such rhythmic fluctuations in susceptibility to high-contrast distractors that co-occur with low-contrast visual targets. Rhythmic attention-related sampling--while perhaps preventing us from becoming overly focused on any single location--can lead to behavioral disadvantages.

neuroscience↗

bioRxiv2023

Distractor suppression does and does not depend on pre-distractor alpha-band activity

Selective attention enhances behaviorally important information and suppresses distracting information. Research on the neural basis of selective attention has largely focused on sensory enhancement, with less focus on sensory suppression. Enhancement and suppression can operate through a push-pull relationship that arises from competitive interactions among neural populations. There has been considerable debate, however, regarding (i) whether suppression can also operate independent of enhancement and (ii) whether neural processes associated with the voluntary deployment of suppression can occur prior to distractor onset. We provide further behavioral and electrophysiological evidence of independent suppression at cued distractor locations while humans performed a visual search task. We specifically utilize two established EEG markers of suppression: alpha power ([~]8-15 Hz) and the distractor positivity (PD). Increased alpha power has been linked with attenuated sensory processing, while the PD--a component of event-related potentials--has been linked with successful distractor suppression. The present results demonstrate that cueing the location of an upcoming distractor speeded responding and led to an earlier onset PD, consistent with earlier suppression due to strategic use of a spatial cue. We further demonstrate that higher pre-distractor alpha power contralateral to distractors was generally associated with successful suppression on both cued and non-cued trials. However, there was no consistent change in alpha power associated with the spatial cue, meaning cueing effects on behavioral and neural measures occurred independent of alpha-related gating of sensory processing. These findings reveal the importance of pre-distractor neural processes for subsequent distractor suppression. Significance StatementSelective suppression of distracting information is important for survival, contributing to preferential processing of behaviorally important information. Does foreknowledge of an upcoming distractors location help with suppression? Here, we recorded EEG while subjects performed a target detection task with cues that indicated the location of upcoming distractors. Behavioral and electrophysiological results revealed that foreknowledge of a distractors location speeded suppression, thereby facilitating target detection. The results further revealed a significant relationship between pre-stimulus alpha-band activity and successful suppression; however, pre-stimulus alpha-band activity was not consistently lateralized relative to the spatially informative cues. The present findings therefore demonstrate that target detection can benefit from foreknowledge of distractor location in a process that is independent of alpha-related gating of sensory processing.

neuroscience↗

bioRxiv2022

Rhythmic temporal coordination of neural activity avoids representational conflict during working memory

Selective attention1 is characterized by alternating states associated with either attentional sampling or attentional shifting, helping to avoid functional conflicts by isolating function-specific neural activity in time2-5. We hypothesized that such rhythmic temporal coordination might also help to avoid representational conflicts during working memory6. Multiple items can be simultaneously held in working memory, and these items can be represented by overlapping neural populations7-9. Traditional theories propose that short-term storage of to-be-remembered items occurs through persistent neural activity10-12, but when neurons are simultaneously representing multiple items, persistent activity creates a potential for representational conflicts. In comparison, more recent, activity-silent theories of working memory propose that synaptic changes also contribute to the short-term storage of to-be-remembered items13-16. Transient bursts in neural activity17, rather than persistent activity, could serve to occasionally refresh these synaptic changes. Here, we used EEG and response times (RTs) to test whether rhythmic temporal coordination helps to isolate neural activity associated with different to-be-remembered items, which would help to avoid representational conflicts. Consistent with this hypothesis, we report that the relative strength of different item representations alternates over time as a function of frequency-specific phase. Although RTs were linked to theta (~6Hz) and beta (~25 Hz) phase during a memory delay, the relative strength of item representations only alternated as a function of beta phase. The present findings (i) are consistent with rhythmic temporal coordination being a general mechanism for avoiding either functional or representational conflicts during cognitive processes, and (ii) inform models describing the role of oscillatory dynamics in organizing working memory13,18-21.

neuroscience↗