Prestimulus alpha power is related to the strength of stimulus representation

Abstract

20Spatial attention can modulate behavioural performance and is associated with several electrophysiological 21 markers. In this study, we used multivariate pattern analysis in electrophysiology data to investigate the effects 22 of covert spatial attention on the quality of stimulus processing and underlying mechanisms. Our results show 23 that covert spatial attention led to (i) an anticipatory alpha power desynchronization; (ii) enhanced stimuli 24 identity information. Moreover, we found that alpha power fluctuations in anticipation of the relevant stimuli 25 boosted and prolonged the coding of stimulus identity. 26Keywords: spatial attention, alpha oscillations, multivariate pattern analysis, EEG 27 2/15 28 Attention is essential to select and process sensory stimuli in the environment. One of the main difficulties in 29 studying attentional selection in humans is assessing the quality of processing of attended and ignored stimuli. 30 In general, measures such as the amplitude of electrophysiological evoked responses (i.e. N1, P1) have been 31 used as a reflection of this processing. However, a recent study has questioned this view since the amplitude 32 of the evoked response was not correlated with a boost in the target representation. 1 . Moreover, how well the 33 unattended stimulus is processed is particularly hard to assess, given that participants are typically asked not 34 to respond to these events. 35One possibility is to use methods which evaluate neural processing without necessarily requiring a 36 behavioural response. Recent studies have relied on multivariate pattern analysis (MVPA) techniques to 37 analyze EEG/MEG responses. [2][3][4] . In general, these methods are based on the theoretical basis that the 38 MEG/EEG signal reflects coupled dipoles activity of neural circuitry. Although the specific dipole activity 39 may not be identified, their summation would result in different patterns of activity across MEG/EEG 40 sensors 2-4 . These MVPA methods have been increasingly used to understand the effects of attention and its 41 underlying mechanisms. Several studies have shown that spatial attention modulates stimulus representation 42 in working memory 5-7 and sensory information input 8 . Moreover, temporal attention seems to enhance 43 relevant sensory information input, creating a temporal protection window against distractors 1 , and boosting 44 its representational content. 45Another pre-activating mechanism commonly described in the literature of spatial attention is the mod-46 ulations in the spectral characteristics of the alpha (8-16 Hz) band 9 . This oscillatory activity is associated 47 with cognitive functions such as visual attention 10 , working memory 11 and cognitive load 12 . For example, 48 anticipatory lateralized desynchronisation of alpha power is correlated with spatial expectations of a rel-49 evant upcoming stimuli in a particular hemifield 10, 13 . Studies suggest that alpha oscillations can play a 50 role in information processing by suppressing the activi...

One Thing Leads to Another: Anticipating Visual Object Identity Based on Associative-Memory Templates

“…Accordingly, we propose that the alpha attenuation also reflects engagement with visual processing areas to prepare a specific target template. As such, the alpha modulations reported here complement recent work showing that lower alpha power is associated with higher fidelity of stimulus-specific information (Barne, Lange, & Cravo, 2020;Griffiths et al, 2019;van Ede, Chekroud, Stokes, & Nobre, 2018). In this light, it is interesting to note that alpha-band oscillations were not significantly modulated by the anticipated perceptual difficulty in identifying the target, as might be expected from a pure "excitability" account (e.g.…”

Shaping information processing: the role of oscillatory dynamics in a working-memory task

“…Importantly, we demonstrate that pre-stimulus alpha power decrease enhances neural decodability (i.e., sensory representations) of subsequent task-relevant items. These results are in line with previous work reporting a negative relationship between decoding performance and pre-stimulus alpha power (Barne et al, 2020; van Ede et al, 2018), and shows how alpha through regulating cortical excitability might influence sensory representations.…”

“…In line with this view, it has been demonstrated that working-memory performance correlates positively with alpha activity in task-irrelevant (Haegens et al, 2010; Yu et al, 2017) and negatively in task-relevant regions (Jiang et al, 2015; van Ede et al, 2017), respectively. However, it remains unclear how this proposed alpha gating mechanism modulates the internal sensory representations (as indexed by decoding performance), with different studies reporting positive (i.e., decoding performance increases as alpha power increases; Kayser et al, 2016), negative (Barne et al, 2020), and null relationships (Griffiths et al, 2019). Here we will examine how alpha power correlates with working-memory performance as well as the decodability of task features.…”

Prestimulus Low-Alpha Frontal Networks Are Associated with Pareidolias in Parkinson's Disease

“…Anticipation of relevant stimuli also increases alpha activity, its strength proportional to the saliency of the stimuli (Barne et al, 2020). As pre-stimulus low-alpha power increases, participants consciously perceive low-level information as relevant (Babiloni et al, 2006).…”