Spontaneous Alpha Power Lateralization Predicts Detection Performance in an Un-Cued Signal Detection Task

Abstract

Focusing one’s attention by external guiding stimuli towards a specific area of the visual field produces systematical neural signatures. One of the most robust is the change in topological distribution of oscillatory alpha band activity across parieto-occipital cortices. In particular, decreases in alpha activity over contralateral and/or increases over ipsilateral scalp sites, respect to the side of the visual field where attention was focused. This evidence comes mainly from experiments where an explicit cue informs subjects where to focus their attention, thus facilitating detection of an upcoming target stimulus. However, recent theoretical models of attention have highlighted a stochastic or non-deterministic component related to visuospatial attentional allocation. In an attempt to evidence this component, here we analyzed alpha activity in a signal detection paradigm in the lack of informative cues; in the absence of preceding information about the location (and time) of appearance of target stimuli. We believe that the unpredictability of this situation could be beneficial for unveiling this component. Interestingly, although total alpha power did not differ between Seen and Unseen conditions, we found a significant lateralization of alpha activity over parieto-occipital electrodes, which predicted behavioral performance. This effect had a smaller magnitude compared to paradigms in which attention is externally guided (cued). However we believe that further characterization of this spontaneous component of attention is of great importance in the study of visuospatial attentional dynamics. These results support the presence of a spontaneous component of visuospatial attentional allocation and they advance pre-stimulus alpha-band lateralization as one of its neural signatures.

States and traits of neural irregularity in the age-varying human brain

“…While perceptual processes have been linked to influences of spontaneous variations in oscillatory power (e.g. Boncompte et al, 2016;Kayser et al, 2016) and phase Busch et al, 2009), we here state first evidence for the involvement of fluctuating neural noise. Changing neural states prior to stimulation might reflect subtle variations in excitability which impact the processing of sensory evidence and this way influence later decisions.…”

States and traits of neural irregularity in the age-varying human brain

“…A sensitive (and potentially more versatile) measure of neural irregularity or desynchronization should thus transfer these findings to the human brain and exhibit a negative relationship with low-frequency power. Notably, spontaneous variations in oscillatory power have also been linked to perceptual processes in humans 38 , 39 . Here, with higher irregularity prior to stimulus onset, power in low frequencies decreased.…”

The many characters of visual alpha oscillations

“…D; Worden et al ., ; Kelly et al ., ; Gould et al ., ; Samaha et al ., ). Such differences in alpha power between the two visual hemispheres have been associated with improved detection of attended, lateral stimuli in recordings of both spontaneous (Boncompte et al ., ) and task‐related brain activity (Gould et al ., ). Spontaneous reductions in alpha power have also been associated with increases in the excitability of visual cortex.…”