Recent studies from the field of interoception have highlighted the link between bodily and neural rhythms during action, perception, and cognition. The mechanisms underlying functional body-brain coupling, however, are poorly understood, as are the ways in which they modulate behaviour. We acquired respiration and human magnetoencephalography (MEG) data from a near-threshold spatial detection task to investigate the trivariate relationship between respiration, neural excitability, and performance. Respiration was found to significantly modulate perceptual sensitivity as well as posterior alpha power (8 - 13 Hz), a well-established proxy of cortical excitability. In turn, alpha suppression prior to detected vs undetected targets underscored the behavioural benefits of heightened excitability. Notably, respiration-locked excitability changes were maximised at a respiration phase lag of around -30° and thus temporally preceded performance changes. In line with interoceptive inference accounts, these results suggest that respiration actively aligns sampling of sensory information with transient cycles of heightened excitability to facilitate performance.

Perceptual decisions depend both on the features of the incoming stimulus and on the ongoing brain activity at the moment the stimulus is received. Specifically, trial-to-trial fluctuations in cortical excitability have been linked to fluctuations in the amplitude of pre-stimulus alpha oscillations (≈8-13 Hz), which are in turn are associated with fluctuations in subjects' tendency to report the detection of a stimulus. It is currently unknown whether alpha oscillations bias post-perceptual decision making, or even bias subjective perception itself. To answer this question, we used a contrast discrimination task in which subjects reported which of two gratings -one in each hemifield -was perceived as having a stronger contrast. Our EEG analysis showed that subjective contrast was reduced for the stimulus in the hemifield represented in the hemisphere with relatively stronger pre-stimulus alpha amplitude, reflecting reduced cortical excitability. Furthermore, the strength of this spontaneous hemispheric lateralization was strongly correlated with the magnitude of individual subjects' biases, suggesting that the spontaneous patterns of alpha lateralization play a role in explaining the intersubject variability in contrast perception. These results indicate that spontaneous fluctuations in cortical excitability, indicted by patterns of pre-stimulus alpha amplitude, affect perceptual decisions by altering the phenomenological perception of the visual world.

Attention and visual working memory (VWM) are among the most theoretically detailed and empirically tested constructs in human cognition. Nevertheless, the nature of the interrelation between selective attention and VWM still presents a fundamental controversy: Do they rely on the same cognitive resources or not? The present study aims at disentangling this issue by capitalizing on recent evidence showing that attention is a rhythmic phenomenon, oscillating over short time windows. Using a dual‐task approach, we combined a classic VWM task with a visual detection task in which we densely sampled detection performance during the time between the memory and the test array. Our results show that an increment in VWM load was related to reduced detection of near‐threshold visual stimuli. Importantly, we observed an oscillatory pattern in detection at ~7.5 Hz in the low VWM load conditions, which decreased towards ~5 Hz in the high VWM load condition. These findings suggest that the frequency of this sampling rhythm changes according to the allocation of attentional resources to either the VWM or the detection task. This pattern of results is consistent with a central sampling attentional rhythm which allocates shared attentional resources both to the flow of external visual stimulation and to the internal maintenance of visual information.

Attention and Visual Working Memory (VWM) are among the most theoretically detailed and empirically tested constructs in human cognition. Nevertheless, the nature of the interrelation between selective attention and VWM still presents a fundamental controversy: do they rely on the same cognitive resources or not? The present study aims at disentangling this issue by capitalizing on recent evidence showing that attention is a rhythmic phenomenon, oscillating over short time windows. Using a dual-task approach, we combined a classic VWM task with a detection task in which we densely sampled detection performance during the time between the memory and the test array. Our results show that an increment in VWM load was related to a worse detection of near threshold visual stimuli and, importantly, to the presence of an oscillatory pattern in detection performance at ~5 Hz. Furthermore, our findings suggest that the frequency of this sampling rhythm changes according to the strategic allocation of attentional resources to either the VWM or the detection task. This pattern of results is consistent with a central sampling attentional rhythm which allocates shared attentional resources both to the flow of external visual stimulation and also to the internal maintenance of visual information.

Recent studies from the field of interoception have highlighted the link between bodily and neural rhythms during action, perception, and cognition. The mechanisms underlying functional body-brain coupling, however, are poorly understood, as are the ways in which they modulate behaviour. We acquired respiration and human magnetoencephalography (MEG) data from a near-threshold spatial detection task to investigate the trivariate relationship between respiration, neural excitability, and performance. Respiration was found to significantly modulate perceptual sensitivity as well as posterior alpha power (8-13 Hz), a well-established proxy of cortical excitability. In turn, alpha suppression prior to detected vs undetected targets underscored the behavioural benefits of heightened excitability. Notably, respiration-locked excitability changes were maximised at a respiration phase lag of around -30 degrees and thus temporally preceded performance changes. In line with interoceptive inference accounts, these results suggest that respiration actively aligns sampling of sensory information with transient cycles of heightened excitability to facilitate performance.

Our visual memories of complex scenes often appear as robust, detailed records of the past. Several studies have demonstrated that active exploration with eye movements improves recognition memory for scenes, but it is unclear whether this improvement is due to stronger feelings of familiarity or more detailed recollection. We related the extent and specificity of fixation patterns at encoding and retrieval to different recognition decisions in an incidental memory paradigm. After incidental encoding of 240 real-world scene photographs, participants ( N = 44) answered a surprise memory test by reporting whether an image was new, remembered (indicating recollection), or just known to be old (indicating familiarity). To assess the specificity of their visual memories, we devised a novel report procedure in which participants selected the scene region that they specifically recollected, that appeared most familiar, or that was particularly new to them. At encoding, when considering the entire scene,subsequently recollected compared to familiar or forgotten scenes showed a larger number of fixations that were more broadly distributed, suggesting that more extensive visual exploration determines stronger and more detailed memories. However, when considering only the memory-relevant image areas, fixations were more dense and more clustered for subsequently recollected compared to subsequently familiar scenes. At retrieval, the extent of visual exploration was more restricted for recollected compared to new or forgotten scenes, with a smaller number of fixations. Importantly, fixation density and clustering was greater in memory-relevant areas for recollected versus familiar or falsely recognized images. Our findings suggest that more extensive visual exploration across the entire scene, with a subset of more focal and dense fixations in specific image areas, leads to increased potential for recollecting specific image aspects.

We explore the world by constantly shifting our focus of attention towards salient stimuli, and then disengaging from them in search of new ones. The alpha rhythm (8-13 Hz) has been suggested as a pivotal neural substrate of these attentional shifts, due to its local synchronization and desynchronization that suppresses irrelevant cortical areas and facilitates relevant areas, a phenomenon called alpha lateralization. Whether alpha lateralization tracks the focus of attention from orienting toward a salient stimulus to disengaging from it is still an open question. In this study, we addressed this question by leveraging the well-established phenomenon of Inhibition of Return (IOR), consisting of an initial facilitation in response times (RTs) for target stimuli appearing at an exogenously cued location, followed by a suppression of that location. Our behavioral data showed a typical IOR effect with both early facilitation and subsequent inhibition. By contrast, alpha was lateralized only in the cued direction, but never re-lateralized in a manner compatible with the behavioral inhibition effect. Importantly, also the initial lateralization towards the cue ocurred too late to account for the behavioral facilitation effect. Furthermore, we analyzed the interaction between alpha lateralization and microsaccades: at the same time when alpha was lateralized towards the cued location, microsaccades were mostly oriented away from the cued location. Crucially, the two phenomena showed a significant positive correlation. These results indicate that alpha lateralization reflects primarily the processing of salient stimuli, challenging the view that alpha lateralization is directly involved in exogenous attentional orienting per se. We discuss the relevance of the present findings for an oculomotor account of alpha lateralization as a modulator of cortical excitability in preparation of a saccade.

Although visual input arrives continuously, sensory information is segmented into (quasi-)discrete events. Here, we investigated the neural correlates of spatiotemporal binding in humans with magnetoencephalography using 2 tasks where separate flashes were presented on each trial but were perceived, in a bistable way, as either a single or two separate events. The first task (two-flash fusion) involved judging one versus 2 flashes, whereas the second task (apparent motion: AM) involved judging coherent motion versus two stationary flashes. Results indicate two different functional networks underlying 2 unique aspects of temporal binding. In two-flash fusion trials, involving an integration window of ∼50 msec, evoked responses differed as a function of perceptual interpretation by ∼25 msec after stimuli offset. Multivariate decoding of subjective perception based on prestimulus oscillatory phase was significant for alpha-band activity in the right medial temporal (V5/MT) area, with the strength of prestimulus connectivity between early visual areas and V5/MT being predictive of performance. In contrast, the longer integration window (∼130 msec) for AM showed evoked field differences only ∼250 msec after stimuli offset. Phase decoding of the perceptual outcome in AM trials was significant for theta-band activity in the right intraparietal sulcus. Prestimulus theta-band connectivity between V5/MT and intraparietal sulcus best predicted AM perceptual outcome. For both tasks, phase effects found could not be accounted by concomitant variations in power. These results show a strong relationship between specific spatiotemporal binding windows and specific oscillations, linked to the information flow between different areas of the “where” and “when” visual pathways.